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The purpose of this study was to evaluate the outcomes of the Boston type 1 keratoprosthesis (Kpro-1) in eyes with failed keratoplasty. A retrospective review was performed of every patient treated with a Kpro-1 at a tertiary eye care center between January 1, 2008 and July 1, 2013. Eyes with a failed keratoplasty originally performed for corneal edema, trauma, or keratoconus were included in the statistical analysis. The main outcome measures were visual outcome, prosthesis retention, and postoperative complications. Twenty-four eyes met the inclusion criteria, including 13 eyes with corneal edema, 8 eyes with trauma, and 3 eyes with keratoconus. After a mean follow-up period of 28.9 months (range 7-63 months), the median best corrected visual acuity (BCVA) was 20/125. The BCVA was ≥ 20/40 in 4 (16.7 %) eyes, ≥ 20/70 in 9 (37.5 %) eyes, and ≥ 20/200 in 14 (58.3 %) eyes. Overall, the postoperative BCVA improved in 17 (70.9 %) eyes, was unchanged in 3 (12.5 %) eyes, and was worse in 4 (16.7 %) eyes. The initial Kpro-1 was retained in 22 (91.7 %) eyes, and was successfully repeated in the other 2 eyes. One or more serious prosthesis- or sight-threatening complications occurred in 8 (33.3 %) eyes. These included 1 case of wound dehiscence leading to prosthesis extrusion, 1 case of fungal keratitis leading to prosthesis extrusion, 4 cases of endophthalmitis, and 5 retinal detachments. The Boston Kpro-1 is associated with an excellent prognosis for prosthesis retention and satisfactory visual improvement in eyes with previous failed keratoplasty.

HSV-1 continues to be the leading cause of infectious corneal blindness. Clinical trials for vaccines against genital HSV infection have been ongoing for more than three decades. Despite this, no approved vaccine exists, and no formal clinical trials have evaluated the impact of HSV vaccines on eye health. We review here the current state of development for an efficacious HSV-1 vaccine and call for involvement of ophthalmologists and vision researchers.

To evaluate the outcome of the Boston type 1 keratoprosthesis (Kpro-1) in eyes with failed interventions for chemical and thermal injury.A retrospective review was performed of every eye with chemical or thermal injury that was treated with a Kpro-1 at a tertiary eye care center between January 1, 2008 and July 1, 2013. The main outcome measures were visual outcome, prosthesis retention, and postoperative complications.Nine eyes met the inclusion criteria, including 7 eyes with alkali burns, 1 eye with an acid burn, and 1 eye with a thermal burn. After a mean follow-up of 40.7 months (range, 29-60 months), the median best-corrected visual acuity was 20/60 (range, 20/15 to no light perception). One eye was ≥20/20, 3 eyes were ≥20/40, and 6 eyes were ≥20/70. The initial Kpro-1 prosthesis was retained in 7 (77.7%) eyes and successfully replaced in the other 2 eyes. One or more serious complications occurred in 6 (66.7%) eyes. These included 2 cases of sterile corneal ulceration with prosthesis extrusion, 2 cases of microbial keratitis (1 bacterial and 1 fungal), 2 cases of bacterial endophthalmitis, and 2 cases of retinal detachments. These complications contributed to visual outcomes of hand motions in 2 eyes and no light perception in 1 eye.The Boston Kpro-1 is associated with highly satisfactory visual outcomes and prosthesis retention in most cases of severe chemical or thermal injury. Serious complications are common and may compromise the final outcome.

Purpose The aim of this study was to evaluate and compare the outcomes of Boston keratoprosthesis type 1 (Kpro-1) in eyes with herpes simplex virus (HSV) and herpes zoster virus (HZV) keratopathy. Methods A retrospective review was performed of the medical records of every patient treated with a Boston Kpro-1 at the University of Iowa Hospitals and Clinics between January 1, 2008 and July 1, 2012. Eyes with visual loss due to HSV or HZV keratopathy were included in the statistical analysis. The main outcome measures were graft retention, postoperative complications, and visual outcome. Results Nine eyes met the inclusion criteria, including 5 eyes in the HSV group and 4 eyes in the HZV group. The graft retention rate was 100% in the HSV group after a mean follow-up of 48.4 months, compared with 25% in the HZV group after 50.5 months (P = 0.048). There were 3 cases of microbial keratitis, including 2 eyes that also developed endophthalmitis, in the HZV group, compared with no cases in the HSV group (P = 0.048). There was significantly better best-corrected visual acuity at the most recent examination in the HSV group than in the HZV group (P = 0.019). All 5 HSV eyes had improved best-corrected visual acuity compared with preoperative acuity, whereas only 1 HZV eye experienced a similar result (P = 0.048). Conclusions Kpro-1 is associated with an excellent prognosis for graft retention, acceptably low prevalence of sight-threatening complications, and highly satisfactory visual improvement in eyes with HSV keratopathy, but not in eyes with HZV keratopathy.

Blood–retinal barrier (BRB) breakdown and related vascular changes are implicated in several ocular diseases. The molecules and mechanisms regulating BRB integrity and pathophysiology are not fully elucidated. Caveolin-1 (Cav-1) ablation results in loss of caveolae and microvascular pathologies, but the role of Cav-1 in the retina is largely unknown. We examined BRB integrity and vasculature in Cav-1 knockout mice and found a significant increase in BRB permeability, compared with wild-type controls, with branch veins being frequent sites of breakdown. Vascular hyperpermeability occurred without apparent alteration in junctional proteins. Such hyperpermeability was not rescued by inhibiting eNOS activity. Veins of Cav-1 knockout retinas exhibited additional pathological features, including i) eNOS-independent enlargement, ii) altered expression of mural cell markers (eg, down-regulation of NG2 and up-regulation of αSMA), and iii) dramatic alterations in mural cell phenotype near the optic nerve head. We observed a significant NO–dependent increase in retinal artery diameter in Cav-1 knockout mice, suggesting that Cav-1 plays a role in autoregulation of resistance vessels in the retina. These findings implicate Cav-1 in maintaining BRB integrity in retinal vasculature and suggest a previously undefined role in the retinal venous system and associated mural cells. Our results are relevant to clinically significant retinal disorders with vascular pathologies, including diabetic retinopathy, uveoretinitis, and primary open-angle glaucoma.

In recent years, host cell caveolae/caveolins have emerged as potentially important targets for pathogenic microorganisms; therefore, we investigated the role of caveolin-1 (Cav-1) in T. cruzi infection using Cav-1 null mice. Cav-1 null and wild type mice were infected with the virulent Tulahuen strain. The mortality was 100% in both groups, but death was slightly delayed in wild type mice. The parasitemia in the Cav-1 null mice was significantly reduced compared with wild type littermates. Histopathologic examination of the heart revealed numerous pseudocysts, myonecrosis, and marked inflammation, which was similar in both mouse groups. Real-time PCR confirmed these observations. Infection of cultured cardiac fibroblasts obtained from Cav-1 null and wild type mice revealed no differences in infectivity. Determination of serum levels of several inflammatory mediators revealed a striking reduction in IFN-γ, TNF-α and components of the nitric oxide pathway in infected Cav-1 null mice. Infection of wild type mice resulted in the expected enhancement of inflammatory mediators. The defective production of chemokines and cytokines observed in vivo is in part attributed to Cav-1 null macrophages. Despite these marked differences in the response to infection by inflammatory mediators between the two mouse strains, the final outcome was similar. These results suggest that Cav-1 may play an important role in the normal development of immune responses.

A number of studies have shown an association of pathogens with caveolae. To this date, however, there are no studies showing a role for caveolin-1 in modulating immune responses against pathogens. Interestingly, expression of caveolin-1 has been shown to occur in a regulated manner in immune cells in response to lipopolysaccharide (LPS). Here, we sought to determine the role of caveolin-1 (Cav-1) expression in Salmonella pathogenesis. Cav-1 −/− mice displayed a significant decrease in survival when challenged with Salmonella enterica serovar Typhimurium. Spleen and tissue burdens were significantly higher in Cav-1 −/− mice. However, infection of Cav-1 −/− macrophages with serovar Typhimurium did not result in differences in bacterial invasion. In addition, Cav-1 −/− mice displayed increased production of inflammatory cytokines, chemokines, and nitric oxide. Regardless of this, Cav-1 −/− mice were unable to control the systemic infection of Salmonella . The increased chemokine production in Cav-1 −/− mice resulted in greater infiltration of neutrophils into granulomas but did not alter the number of granulomas present. This was accompanied by increased necrosis in the liver. However, Cav-1 −/− macrophages displayed increased inflammatory responses and increased nitric oxide production in vitro in response to Salmonella LPS. These results show that caveolin-1 plays a key role in regulating anti-inflammatory responses in macrophages. Taken together, these data suggest that the increased production of toxic mediators from macrophages lacking caveolin-1 is likely to be responsible for the marked susceptibility of caveolin-1-deficient mice to S. enterica serovar Typhimurium.

The liver is an important target of Trypanosoma cruzi infection. Infection of CD-1 mice with T. cruzi (Brazil strain) resulted in parasitism of the liver, primarily in sinusoidal and Kupffer cells. Immunoblot analysis revealed activation of extra cellular signal-regulated kinase (ERK) during the acute and subacute period of infection, but p38 mitogen activated kinase (MAPK) and JNK were not activated. The activity of important cell cycle regulatory genes was also examined in the liver following infection. There was increased expression of cyclin D1, cyclin E and cyclin A as well as proliferating cell nuclear antigen (PCNA) at 45, 60 and 215 days post infection. In addition, the levels of the cyclin-dependent kinase inhibitors p27(KIP1), p21(WAF1) and the tumor suppressor p53 were increased in the livers obtained from infected mice. Quantitative PCR revealed increased abundance of mRNA for cyclins A, D1 and E. Interestingly, cyclin A and E are ordinarily not found in the adult liver. Thus infection caused a reversion to a fetal/neonatal phenotype. These data provide a molecular basis for cell proliferation in the liver following T. cruzi infection.

Lipid rafts, membrane sub-domains enriched in sterols and sphingolipids, are controversial because demonstrations of rafts have often utilized fixed cells. We showed in living sperm that the ganglioside G(M1) localized to a micron-scale membrane sub-domain in the plasma membrane overlying the acrosome. We investigated four models proposed for membrane sub-domain maintenance. G(M1) segregation was maintained in live sperm incubated under non-capacitating conditions, and after sterol efflux, a membrane alteration necessary for capacitation. The complete lack of G(M1) diffusion to the post-acrosomal plasma membrane (PAPM) in live cells argued against the transient confinement zone model. However, within seconds after cessation of sperm motility, G(M1) dramatically redistributed several microns from the acrosomal sub-domain to the post-acrosomal, non-raft sub-domain. This redistribution was not accompanied by movement of sterols, and was induced by the pentameric cholera toxin subunit B (CTB). These data argued against a lipid-lipid interaction model for sub-domain maintenance. Although impossible to rule out a lipid shell model definitively, mice lacking caveolin-1 maintained segregation of both sterols and G(M1), arguing against a role for lipid shells surrounding caveolin-1 in sub-domain maintenance. Scanning electron microscopy of sperm freeze-dried without fixation identified cytoskeletal structures at the sub-domain boundary. Although drugs used to disrupt actin and intermediate filaments had no effect on the segregation of G(M1), we found that disulfide-bonded proteins played a significant role in sub-domain segregation. Together, these data provide an example of membrane sub-domains extreme in terms of size and stability of lipid segregation, and implicate a protein-based membrane compartmentation mechanism.

Although the first successful full thickness corneal transplant was performed in 1905, it was not until 1998 that major advances in the field began to occur. During the 93 years between these events, there were attempts made to advance to field and these consisted of different suturing techniques and advances in eye banking technology; however, the surgical procedure remained largely unchanged. The full thickness transplant is immensely successful, but it is fraught with potential complications. The lamellar techniques described in 1998 and modified since that time has led to an easier, safer, and overall better surgical outcomes. This chapter describes the evolution of the lamellar endothelial corneal transplant in detail.

The eye needs a healthy, transparent cornea to perform normal visual function. Stem cells residing at the limbus of the adult eye, named limbal stem cells (LSCs), are responsible for maintenance and repair of the corneal surface, thus contributing to tissue health. In the case of deficiency of LSCs a blinding disorder named stem cell deficiency (LSCD) occurs, characterized by cornea opacity, vascularization, and inflammation. Understanding corneal stem cells is critical for the development of cell-based therapies directed to treat the diseased cornea. The focus of this chapter is to provide a summarized overview of the current knowledge on corneal stem cells, including their location, phenotypic and functional characteristics, causes and consequences of the depletion of the corneal stem cell niche, as well as therapeutic options and ongoing studies dedicated to improve the success of cell-based therapies in the treatment of cornea surface disease.

Caveolin-1 (Cav-1) is the primary structural component of caveolae and is implicated in the processes of vesicular transport, cholesterol balance, transformation, and tumorigenesis. Despite an abundance of data suggesting that Cav-1 has transformation suppressor properties both in vitro and in vivo, Cav-1 is expressed at increased levels in human prostate cancer. To investigate the role of Cav-1 in prostate cancer onset and progression, we interbred Cav-1(-/-) null mice with a TRAMP (transgenic adenocarcinoma of mouse prostate) model that spontaneously develops advanced prostate cancer and metastatic disease. We found that, although the loss of Cav-1 did not affect the appearance of minimally invasive prostate cancer, its absence significantly impeded progression to highly invasive and metastatic disease. Inactivation of one (+/-) or both (-/-) alleles of Cav-1 resulted in significant reductions in prostate tumor burden, as well as decreases in regional lymph node metastases. Moreover, further examination revealed decreased metastasis to distant organs, such as the lungs, in TRAMP/Cav-1(-/-) mice. Utilizing prostate carcinoma cell lines (C1, C2, and C3) derived from TRAMP tumors, we also showed a positive correlation between Cav-1 expression and the ability of these cells to form tumors in vivo. Furthermore, down-regulation of Cav-1 expression in these cells, using a small interfering RNA approach, significantly reduced their tumorigenic and metastatic potential. Mechanistically, we showed that loss or down-regulation of Cav-1 expression results in increased apoptosis, with increased prostate apoptosis response factor-4 and PTEN levels in Cav-1(-/-) null prostate tumors. Our current findings provide the first in vivo molecular genetic evidence that Cav-1 does indeed function as a tumor promoter during prostate carcinogenesis, rather than as a tumor suppressor.

Recently, we have shown that loss of caveolin-1 leads to marked alterations in insulin signaling and lipolysis in white adipose tissue. However, little is known about the role of caveolin-1 in brown adipose tissue (BAT), a tissue responsible for nonshivering thermogenesis. Here, we show that caveolin-1 null mice have a mildly, yet significantly, decreased resting core body temperature. To investigate this in detail, we next subjected the mice to fasting (for 24 h) or cold treatment (4°C for 24 h), individually or in combination. Interestingly, caveolin-1 null mice showed markedly decreased body temperatures in response to fasting or fasting/cold treatment; however, cold treatment alone had no effect. In addition, under these conditions caveolin-1 null mice failed to show the normal increase in serum nonesterified fatty acids induced by fasting or fasting/cold treatment, suggesting that these mice are unable to liberate triglyceride stores for heat production. In accordance with these results, the triglyceride content of BAT was reduced nearly 10-fold in wild-type mice after fasting/cold treatment, but it was reduced only 3-fold in caveolin-1 null mice. Finally, electron microscopy of adipose tissue revealed dramatic perturbations in the mitochondria of caveolin-1 null interscapular brown adipocytes. Taken together, our data provide the first molecular genetic evidence that caveolin-1 plays a critical functional and structural role in the modulation of thermogenesis via an effect on lipid mobilization.

It is generally well accepted that caveolin-3 expression is muscle specific, whereas caveolin-1 and -2 are coexpressed in a variety of cell types, including adipocytes, endothelial cells, epithelial cells, and fibroblasts. Caveolin-1 and -2 are known to form functional hetero-oligomeric complexes in cells where they are coexpressed, whereas caveolin-3 forms homo-oligomeric high molecular mass complexes. Although caveolin-2 might be expected to interact in a similar manner with caveolin-3, most studies indicate that this is not the case. However, this view has recently been challenged as it has been demonstrated that caveolin-2 and -3 are coexpressed in primary cultures of cardiac myocytes, where these two proteins can be coimmunoprecipitated. Thus it remains controversial whether caveolin-2 interacts with caveolin-3. Here, we directly address the issue of caveolin isoform protein-protein interactions by means of three distinct molecular genetic approaches. First, using caveolin-1-deficient mouse embryonic fibroblasts, in which we have stably expressed caveolin-1, -2, or -3, we find that caveolin-1 interacts with caveolin-2 in this setting, whereas caveolin-3 does not, in agreement with most published observations. Next, we used a transfected L6 myoblast cell system expressing all three caveolin proteins. Surprisingly, we found that caveolin-1, -2, and -3 all coimmunoprecipitate in this cell type, suggesting that this interaction is muscle cell specific. Similar results were obtained when the skeletal muscle of caveolin-1 transgenic animals was analyzed for caveolin-1 and caveolin-3 coimmunoprecipitation. Thus we conclude that all three caveolins can interact to form a discrete hetero-oligomeric complex, but that such complex formation is clearly muscle specific.

Caveolin-1 and caveolin-3 are expressed in the mammalian heart. Mice deficient in caveolin 1 or 3 exhibit cardiac abnormalities including left ventricular hypertrophy and reduced fractional shortening. Cardiac imaging technologies such as transthoracic echocardiography and cardiac-gated magnetic resonance imaging (MRI) are effective tools for the study of left ventricular morphology and function in mice; however, there has not been widespread use of these technologies in studies of right ventricular morphology. In particular, right ventricular wall thickness has been difficult to assess using cardiac imaging technologies. We report here the use of centerline analysis of cardiac-gated MR images to more accurately determine right ventricular wall thickness in the mouse heart. Right ventricular wall thickness was evaluated in Cav-1 null, Cav-3 null and Cav-1/3 null mice, as well as wild-type control mice. Using this technique, we find that caveolin null mice exhibit significant thickening of the right ventricular wall as compared with age-matched wild-type controls. Interestingly, right ventricular wall thickening is greatest in the Cav-1/3 null mice. Furthermore, significant right ventricular wall thickening is also seen in the Cav-1 null mice. Histological analyses revealed right ventricular hypertrophy consistent with the imaging results. These studies demonstrate the utility of MRI in determining right ventricular wall thickness and underscore the severity of the right ventricular hypertrophy in caveolin null mice.

Perilipins, the major structural proteins coating the surfaces of mature lipid droplets of adipocytes, play an important role in the regulation of triacylglycerol storage and hydrolysis. We have used proteomic analysis to identify CGI-58, a member of the alpha/beta-hydrolase fold family of enzymes, as a component of lipid droplets of 3T3-L1 adipocytes. CGI-58 mRNA is highly expressed in adipose tissue and testes, tissues that also express perilipins, and at lower levels in liver, skin, kidney, and heart. Both endogenous CGI-58 and an ectopic CGI-58-GFP chimera show diffuse cytoplasmic localization in 3T3-L1 preadipocytes, but localize almost exclusively to the surfaces of lipid droplets in differentiated 3T3-L1 adipocytes. The localization of endogenous CGI-58 was investigated in 3T3-L1 cells stably expressing mutated forms of perilipin using microscopy. CGI-58 binds to lipid droplets coated with perilipin A or mutated forms of perilipin with an intact C-terminal sequence from amino acid 382 to 429, but not to lipid droplets coated with perilipin B or mutated perilipin A lacking this sequence. Immunoprecipitation studies confirmed these findings, but also showed co-precipitation of perilipin B and CGI-58. Remarkably, activation of cAMP-dependent protein kinase by the incubation of 3T3-L1 adipocytes with isoproterenol and isobutylmethylxanthine disperses CGI-58 from the surfaces of lipid droplets to a cytoplasmic distribution. This shift in subcellular localization can be reversed by the addition of propanolol to the culture medium. Thus, CGI-58 binds to perilipin A-coated lipid droplets in a manner that is dependent upon the metabolic status of the adipocyte and the activity of cAMP-dependent protein kinase.

Tumorigenesis is a multistep process that involves a series of genetic changes or "multiple hits," leading to alterations in signaling, proliferation, immortalization, and transformation. Many of the molecular factors that govern tumor initiation and progression remain unknown. Here, we evaluate the transformation suppressor potential of caveolin-1 (Cav-1) and its ability to cooperate with a well established tumor suppressor, the INK4a locus. To study the effects of loss of caveolin-1 on cellular transformation, we established immortalized primary mouse embryonic fibroblasts (MEFs) expressing and lacking caveolin-1 by interbreeding Cav-1 (+/+) and Cav-1 (-/-) mice with INK4a (-/-) mice. Analysis of these cells reveals that loss of caveolin-1 confers a significant growth advantage, as measured via cellular proliferation and cell cycle analysis. Loss of caveolin-1 in the INK4a (-/-) genetic background results in constitutive hyperactivation of the p42/44 MAP kinase cascade, decreased expression of p21(Cip1), as well as cyclin D1 and PCNA overexpression, consistent with their hyperproliferative phenotype. Importantly, in cells lacking Cav-1 expression, transformation by activated oncogenes (H-Ras(G12V) or v-Src) results in increased tumor growth in vivo (up to >40-fold). Finally, INK4a (-/-)/Cav-1 (-/-) mice demonstrate disturbed mammary epithelial ductal morphology, with hyperplasia, increased side-branching, and fibrosis. Our results provide important new evidence for the transformation suppressor properties of Cav-1 and the first molecular genetic evidence that Cav-1 cooperates with a tumor suppressor, namely the INK4a genetic locus.

Recently, development of a caveolin-1-deficient (Cav-1 null) mouse model has allowed the detailed analysis of caveolin-1's function in the context of a whole animal. Interestingly, we now report that the hearts of Cav-1 null mice are markedly abnormal, despite the fact that caveolin-1 is not expressed in cardiac myocytes. However, caveolin-1 is abundantly expressed in the nonmyocytic cells of the heart, i.e., cardiac fibroblasts and endothelia. Quantitative imaging studies of Cav-1 null hearts demonstrate a significantly enlarged right ventricular cavity and a thickened left ventricular wall with decreased systolic function. Histological analysis reveals myocyte hypertrophy with interstitial/perivascular fibrosis. Because caveolin-1 is thought to act as a negative regulator of the p42/44 MAP kinase cascade, we performed Western blot analysis with phospho-specific antibodies that only recognize activated ERK1/2. As predicted, the p42/44 MAP kinase cascade is hyperactivated in Cav-1 null heart tissue (i.e., interstitial fibrotic lesions) and isolated cardiac fibroblasts. In addition, endothelial and inducible nitric oxide synthase levels are dramatically upregulated. Thus loss of caveolin-1 expression drives p42/44 MAP kinase activation and cardiac hypertrophy.

To describe the clinical course of a patient requiring ophthalmic care for entropion and fungal keratitis in the setting of undiagnosed enophthalmos after previous ventriculoperitoneal shunting consistent with silent brain syndrome.Case report.A 33-year-old man who had a history of ventriculoperitoneal shunting for an encephalocele during infancy presented because of ocular irritation and entropion, which was presumed to be entirely due to a chemical injury he had sustained 2 years before. He underwent 2 upper eyelid entropion repairs and developed fungal aspergilloma keratitis in the postoperative period. He underwent 2 penetrating keratoplasties and a limbal stem cell transplant but had complications with reinfection of the graft, eventually leading to a prephthisical painful eye. During enucleation, an aspergilloma was found within an enlarged superior fornix. Computed tomographic scan revealed severe enophthalmos with air between the lids and the globe, which was consistent with silent brain syndrome.In patients with silent brain syndrome, the lack of apposition between the eyelids and the globe results in entropion, trichiasis, lagophthalmos, and ocular irritation. This can complicate entropion repair and the severity of infectious keratitis. We also propose that the enlarged fornices seen in silent brain syndrome can also serve as a reservoir for infection, similar to the pathogenesis seen in the giant fornix syndrome.

The caveolin gene family consists of caveolins 1, 2, and 3. Caveolins 1 and 2 are co-expressed in many cell types, such as endothelial cells, fibroblasts, smooth muscle cells and adipocytes, where they form a heteroligomeric complex. In contrast, the expression of caveolin-3 is muscle-specific. Thus, the expression of caveolin-1 is required for caveolae formation in non-muscle cells, while the expression of caveolin-3 drives caveolae formation in striated muscle cell types (cardiac and skeletal). To create a truly caveolae-deficient mouse, we interbred Cav-1 null mice and Cav-3 null mice to generate Cav-1/Cav-3 double-knockout (Cav-1/3 dKO) mice. Here, we report that Cav-1/3 dKO mice are viable and fertile, despite the fact that they lack morphologically identifiable caveolae in endothelia, adipocytes, smooth muscle cells, skeletal muscle fibers, and cardiac myocytes. We also show that these mice are deficient in all three caveolin gene products, as caveolin-2 is unstable in the absence of caveolin-1. Interestingly, Cav-1/3 dKO mice develop a severe cardiomyopathy. At 2 months of age, analysis of Cav-1/3 dKO hearts via gated magnetic resonance imaging reveals a dramatic increase in left ventricular wall thickness, as compared with Cav-1-KO, Cav-3 KO, and wild-type mice. Further functional analysis of Cav-1/3 dKO hearts via transthoracic echocardiography demonstrates hypertrophy and dilation of the left ventricle, with a significant decrease in fractional shortening. As predicted, Northern analysis of RNA derived from the left ventricle of Cav-1/3 dKO mice shows a dramatic up-regulation of the atrial natriuretic factor message, a well-established biochemical marker of cardiac hypertrophy. Finally, histological analysis of Cav-1/3 dKO hearts reveals hypertrophy, disorganization, and degeneration of the cardiac myocytes, as well as chronic interstitial fibrosis and inflammation. Thus, dual ablation of both Cav-1 and Cav-3 genes in mice leads to a pleiotropic defect in caveolae formation and severe cardiomyopathy.

Caveolin-1 (Cav-1), the signature protein of caveolae is expressed in several cell types in the adult retina and is linked to ocular pathologies including uveitis, diabetic retinopathy, and primary open angle glaucoma. Genetic ablation of Cav-1 causes retinal functional deficits due to disruptions in environmental homeostasis. To better understand Cav-1 function in the retina, we examined its expression/localization during postnatal retinal development. From P0–P5, Cav-1 was detected only in the developing superficial retinal vessels, in hyaloid and choroidal vasculature, and in the retinal pigment epithelium (RPE). At P7, staining began to be observed centrally in radial cells in the neuroretina, and this staining increased dramatically by P9/10 in identifiable Müller glia. Prominent vascular staining continued throughout development. These results support the idea that Cav-1 is an indicator of Müller glial differentiation and suggests that it plays an important role in Müller cell function.

The purpose of this study was to test the hypothesis that tyrosine phosphorylation signaling events and protein kinase C (PKC) activation mediate vascular endothelial growth factor-A(165) (VEGF)-induced endothelial cell (EC) proliferation and barrier dysfunction in bovine pulmonary artery EC monolayers. A size-selective permeability assay showed that VEGF stimulated a delayed, prolonged (6-45 h), concentration-dependent (50-200 ng/ml, approximately 1-4 nM) increase in the number of predominantly small-"pore" transport pathways (60 A) across EC monolayers. The tyrosine kinase inhibitor herbimycin A (HA) and the selective PKC inhibitor bisindolylmaleimide (BIM) prevented this phenomenon. After 6-24 h, VEGF-treated monolayers displayed an HA- and BIM-sensitive reorganization of beta-catenin adherens junctions with fingerlike projections and the loss of beta-catenin at sites of small paracellular hole formation. HA and BIM prevented the VEGF-induced increase in EC growth. HA blocked the VEGF-induced rapid and prolonged (10 min-45 h) increases in the phosphotyrosine (PY) contents of VEGF receptor 2, phospholipase C-gamma1, paxillin, and beta-catenin as well as approximately 140- and 128- to 117-kDa proteins, whereas BIM inhibited only the tyrosine phosphorylation of beta-catenin. These data suggest that VEGF initiates increased EC growth and chronic, small-pore endothelial barrier dysfunction by PY signaling through beta-catenin that depends on PKC.

Herpes simplex virus type-1 (HSV-1) induces new lymphatic vessel growth (lymphangiogenesis) in the cornea via expression of vascular endothelial growth factor by virally infected epithelial cells. Here, we extend this observation to demonstrate the selective targeting of corneal lymphatics by HSV-1 in the absence of functional type I interferon (IFN) pathway. Specifically, we examined the impact of HSV-1 replication on angiogenesis using type I IFN receptor deficient (CD118(-/-)) mice. HSV-1-induced lymphatic and blood vessel growth into the cornea proper was time-dependent in immunocompetent animals. In contrast, there was an initial robust growth of lymphatic vessels into the cornea of HSV-1-infected CD118(-/-)mice, but such vessels disappeared by day 5 postinfection. The loss was selective as blood vessel integrity remained intact. Magnetic resonance imaging and confocal microscopy analysis of the draining lymph nodes of CD118(-/-) mice revealed extensive edema and loss of lymphatics compared with wild-type mice. In addition to a loss of lymphatic vessels in CD118(-/-) mice, HSV-1 infection resulted in epithelial thinning associated with geographic lesions and edema within the cornea, which is consistent with a loss of lymphatic vasculature. These results underscore the key role functional type I IFN pathway plays in the maintenance of structural integrity within the cornea in addition to the anti-viral characteristics often ascribed to the type I IFN cytokine family.

PURPOSE To report the outcomes of Boston keratoprosthesis (K-pro) type I implantation for congenital aniridia. METHODS A retrospective review of the medical records of every patient with congenital aniridia who underwent Boston K-pro type I implantation at the University of Iowa Hospitals and Clinics from January 1, 2009, through December 31, 2011 was performed. The main outcome measures were visual acuity, graft retention, and postoperative complications. RESULTS A total of 7 eyes (7 patients) met the inclusion criteria. The mean patient age was 52 years (range, 12-85 years). The preoperative visual acuity was 20/1600 in 6 eyes (85.7%) and hand motions in 1 eye (14.3%). After a median follow-up period of 18 months (range, 3-30 months), the median final best spectacle-corrected visual acuity was 20/200 (range, 20/100 to light perception). This included 2 eyes (28.6%) that were 20/100 and 5 eyes (71.4%) that were better than 20/300. Compared with the preoperative best spectacle-corrected visual acuity, the final vision was improved in 6 eyes (85.7%) and worse in 1 eye (14.3%). The K-pro graft was retained in all 7 eyes (100%). The most common complication was the formation of a retroprosthetic membrane in 3 eyes (42.9%), none of which required either a YAG capsulotomy or a vitrectomy. One eye (14.3%) developed a wound dehiscence that required surgical repair. CONCLUSIONS The Boston K-pro type I is a good option for the visual rehabilitation of eyes with congenital aniridia.

Purpose To compare the outcome of penetrating keratoplasty (PKP) and deep anterior lamellar keratoplasty (DALK) in the surgical management of keratoconus (KC). Patient and methods A retrospective review was conducted of the medical records of all patients treated with PKP or DALK for KC at University of Iowa Hospitals and Clinics from January 1, 2000, to December 31, 2006. The main outcome measures were visual outcome, graft survival, and complications. Cases with a minimum follow-up of 6 months were included in the statistical analysis. Results Of 41 eyes that met the inclusion criteria, 30 eyes were treated with PKP and 11 eyes were treated with DALK. The mean follow-up was almost identical for eyes treated with PKP or DALK (21.9 vs. 22.5 months, respectively). At the most recent examination, the mean best spectacle-corrected visual acuity (BSCVA) was 20/28 for the PKP group and 20/29 for the DALK group (P = 0.77). The percentage of eyes that achieved BSCVA of 20/25 or better was higher in the PKP group than in the DALK group (77.3 vs. 45.5%, respectively), but this difference was not statistically significant (P = 0.72). Endothelial rejection occurred in 4 (13.3%) eyes after PKP. Visually significant interface haze occurred in the early postoperative course in 2 (18.2%) eyes after DALK. No cases of late-onset endothelial failure were found in either group. Conclusion Treatment of KC with PKP or DALK is associated with similar visual outcomes, graft survival, and prevalence of sight-threatening complications.

Here, we examine the role of “non-muscle” caveolins (Cav-1 and Cav-2) in skeletal muscle biology. Our results indicate that skeletal muscle fibers from male Cav-1(−/−) and Cav-2(−/−) mice show striking abnormalities, such as tubular aggregates, mitochondrial proliferation/aggregation, and increased numbers of M-cadherin-positive satellite cells. Notably, these skeletal muscle defects were more pronounced with increasing age. Because Cav-2-deficient mice displayed normal expression levels of Cav-1, whereas Cav-1-null mice exhibited an almost complete deficiency in Cav-2, these skeletal muscle abnormalities seem to be due to loss of Cav-2. Thus, Cav-2(−/−) mice represent a novel animal model—and the first genetically well-defined mouse model—that can be used to study the pathogenesis of tubular aggregate formation, which remains a poorly understood age-related skeletal muscle abnormality. Finally, because Cav-1 and Cav-2 were not expressed within mature skeletal myofibers, our results indicate that development of these abnormalities probably originates in stem/precursor cells, such as satellite cells or myoblasts. Consistent with this hypothesis, skeletal muscle isolated from male Cav-3(−/−) mice did not show any of these abnormalities. As such, this is the first study linking stem cells with the genesis of these intriguing muscle defects.

Caveolin-1 (Cav-1) is the primary structural component of caveolae and is implicated in the processes of vesicular transport, cholesterol balance, transformation, and tumorigenesis. Despite an abundance of data suggesting that Cav-1 has transformation suppressor properties both in vitro and in vivo, Cav-1 is expressed at increased levels in human prostate cancer. To investigate the role of Cav-1 in prostate cancer onset and progression, we interbred Cav-1(-/-) null mice with a TRAMP (transgenic adenocarcinoma of mouse prostate) model that spontaneously develops advanced prostate cancer and metastatic disease. We found that, although the loss of Cav-1 did not affect the appearance of minimally invasive prostate cancer, its absence significantly impeded progression to highly invasive and metastatic disease. Inactivation of one (+/-) or both (-/-) alleles of Cav-1 resulted in significant reductions in prostate tumor burden, as well as decreases in regional lymph node metastases. Moreover, further examination revealed decreased metastasis to distant organs, such as the lungs, in TRAMP/Cav-1(-/-) mice. Utilizing prostate carcinoma cell lines (C1, C2, and C3) derived from TRAMP tumors, we also showed a positive correlation between Cav-1 expression and the ability of these cells to form tumors in vivo. Furthermore, down-regulation of Cav-1 expression in these cells, using a small interfering RNA approach, significantly reduced their tumorigenic and metastatic potential. Mechanistically, we showed that loss or down-regulation of Cav-1 expression results in increased apoptosis, with increased prostate apoptosis response factor-4 and PTEN levels in Cav-1(-/-) null prostate tumors. Our current findings provide the first in vivo molecular genetic evidence that Cav-1 does indeed function as a tumor promoter during prostate carcinogenesis, rather than as a tumor suppressor.

Caveolin-3 (Cav-3) is expressed predominantly in skeletal muscle fibers, where it drives caveolae formation at the muscle cell's plasma membrane. In vitro studies have suggested that Cav-3 may play a positive role in insulin signaling and energy metabolism. We directly address the in vivo metabolic consequences of genetic ablation of Cav-3 in mice as it relates to insulin action, glucose metabolism, and lipid homeostasis. At age 2 mo, Cav-3 null mice are significantly larger than wild-type mice, and display significant postprandial hyperinsulinemia, whole body insulin resistance, and whole body glucose intolerance. Studies using hyperinsulinemic-euglycemic clamps revealed that Cav-3 null mice exhibited 20% and 40% decreases in insulin-stimulated whole body glucose uptake and whole body glycogen synthesis, respectively. Whole body insulin resistance was mostly attributed to 20% and 40% decreases in insulin-stimulated glucose uptake and glucose metabolic flux in the skeletal muscle of Cav-3 null mice. In addition, insulin-mediated suppression of hepatic glucose production was significantly reduced in Cav-3 null mice, indicating hepatic insulin resistance. Insulin-stimulated glucose uptake in white adipose tissue, which does not express Cav-3, was decreased by ∼70% in Cav-3 null mice, suggestive of an insulin-resistant state for this tissue. During fasting, Cav-3 null mice possess normal insulin receptor protein levels in their skeletal muscle. However, after 15 min of acute insulin stimulation, Cav-3 null mice show dramatically reduced levels of the insulin receptor protein, compared with wild-type mice treated identically. These results suggest that Cav-3 normally functions to increase the stability of the insulin receptor at the plasma membrane, preventing its rapid degradation, i.e., by blocking or slowing ligand-induced receptor downregulation. Thus our results demonstrate the importance of Cav-3 in regulating whole body glucose homeostasis in vivo and its possible role in the development of insulin resistance. These findings may have clinical implications for the early diagnosis and treatment of caveolinopathies.

Here, we show that a caveolin-1 (Cav-1) deficiency leads to an amplification of the adult mammary stem cell population, both in vivo and in vitro. First, the expression of two stem cell markers, Sca-1 and Keratin 6, is dramatically increased in the hyperplastic mammary ducts of Cav-1 deficient mice, suggesting that loss of Cav-1 induces the accumulation of a progenitor cell population in the mammary gland. To independently validate these results, we reconstituted mammary acini formation in vitro via a 3D Matrigel assay system--using primary cultures of mammary epithelial cells derived from WT and Cav-1 deficient mice. We show that Cav-1 null 3D epithelial structures display an intense increase in the expression of three stem cell markers, i.e., Sca-1, keratin 6 and keratin 5. Overall, we observed a 2-to-3 fold increase in the number of Cav-1 KO acini that are positive for a given stem cell marker. Also, we show that such amplification of progenitor cells has functional consequences, as demonstrated by the abnormal presence of myoepithelial cells in the hyperplastic lesions of Cav-1 deficient mammary glands. Finally, we provide evidence that hyper-activation of Wnt/beta-catenin signaling may constitute one of the down-stream mechanisms leading to mammary stem cell accumulation. The longevity and slow-dividing properties of mammary stem cells facilitates the accumulation of genetic alterations, and renders these progenitor cells the likely precursors of malignant derivatives. As such, we propose that loss of Cav-1 induces the accumulation of mammary stem cells, and that this event may be an initiating factor during mammary tumorigenesis.

Although they were discovered more than 50 years ago, caveolae have remained enigmatic plasmalemmal organelles. With their characteristic “flasklike” shape and virtually ubiquitous tissue distribution, these interesting structures have been implicated in a wide range of cellular functions. Similar to clathrin-coated pits, caveolae function as macromolecular vesicular transporters, while their unique lipid composition classifies them as plasma membrane lipid rafts, structures enriched in a variety of signaling molecules. The caveolin proteins (caveolin-1, -2, and -3) serve as the structural components of caveolae, while also functioning as scaffolding proteins, capable of recruiting numerous signaling molecules to caveolae, as well as regulating their activity. That so many signaling molecules and signaling cascades are regulated by an interaction with the caveolins provides a paradigm by which numerous disease processes may be affected by ablation or mutation of these proteins. Indeed, studies in caveolin-deficient mice have implicated these structures in a host of human diseases, including diabetes, cancer, cardiovascular disease, atherosclerosis, pulmonary fibrosis, and a variety of degenerative muscular dystrophies. In this review, we provide an in depth summary regarding the mechanisms by which caveolae and caveolins participate in human disease processes.

Recently, it was shown that caveolin-1 can be redirected from the cell surface to intracellular lipid droplets in a variety of cell types. Here, we directly address the role of caveolin-1 in lipid droplet formation and breakdown, showing that caveolin-1 null mice exhibit markedly attenuated lipolytic activity. Mechanistically, although the activity of protein kinase A (PKA) was greatly increased in caveolin-1 null adipocytes, the phosphorylation of perilipin was dramatically reduced, indicating that caveolin-1 may facilitate the PKA-mediated phosphorylation of perilipin. In support of this hypothesis, coimmunoprecipitation experiments revealed that treatment with a beta(3)-adrenergic receptor agonist resulted in ligand-induced complex formation between perilipin, caveolin-1, and the catalytic subunit of PKA in wild-type but not in caveolin-1 null fat pads. We also show that caveolin-1 expression is important for efficient lipid droplet formation because caveolin-1 null embryonic fibroblasts stably transfected with perilipin accumulated approximately 4.5-fold less lipid than perilipin-transfected wild-type cells. Finally, high-pressure freeze-substitution electron microscopy of adipose tissue revealed dramatic perturbations in the architecture of the "lipid droplet cortex" (the interface between the lipid droplet surface and the cytoplasm) in caveolin-1 null perigonadal adipocytes. Taken together, our data provide the first molecular genetic evidence that caveolin-1 plays a critical functional and structural role in the modulation of both lipid droplet biogenesis and metabolism in vivo.

Tumorigenesis is a multistep process that involves a series of genetic changes or "multiple hits," leading to alterations in signaling, proliferation, immortalization, and transformation. Many of the molecular factors that govern tumor initiation and progression remain unknown. Here, we evaluate the transformation suppressor potential of caveolin-1 (Cav-1) and its ability to cooperate with a well established tumor suppressor, the INK4a locus. To study the effects of loss of caveolin-1 on cellular transformation, we established immortalized primary mouse embryonic fibroblasts (MEFs) expressing and lacking caveolin-1 by interbreeding Cav-1 (+/+) and Cav-1 (-/-) mice with INK4a (-/-) mice. Analysis of these cells reveals that loss of caveolin-1 confers a significant growth advantage, as measured via cellular proliferation and cell cycle analysis. Loss of caveolin-1 in the INK4a (-/-) genetic background results in constitutive hyperactivation of the p42/44 MAP kinase cascade, decreased expression of p21(Cip1), as well as cyclin D1 and PCNA overexpression, consistent with their hyperproliferative phenotype. Importantly, in cells lacking Cav-1 expression, transformation by activated oncogenes (H-Ras(G12V) or v-Src) results in increased tumor growth in vivo (up to40-fold). Finally, INK4a (-/-)/Cav-1 (-/-) mice demonstrate disturbed mammary epithelial ductal morphology, with hyperplasia, increased side-branching, and fibrosis. Our results provide important new evidence for the transformation suppressor properties of Cav-1 and the first molecular genetic evidence that Cav-1 cooperates with a tumor suppressor, namely the INK4a genetic locus.

Caveolae are 50-100 nm flask-shaped invaginations of the plasma membrane found in most cell types. Caveolin-1 is the principal protein component of caveolae membranes in nonmuscle cells. The recent development of Cav-1-deficient mice has allowed investigators to study the in vivo functional role of caveolae in the context of a whole animal model, as these mice lack morphologically detectable caveolae membrane domains. Surprisingly, Cav-1 null mice are both viable and fertile. However, it remains unknown whether loss of caveolin-1 significantly affects the overall life span of these animals. To quantitatively determine whether loss of Cav-1 gene expression confers any survival disadvantages with increasing age, we generated a large cohort of mice (n = 180), consisting of Cav-1 wild-type (+/+) (n = 53), Cav-1 heterozygous (+/-) (n = 70), and Cav-1 knockout (-/-) (n = 57) animals, and monitored their long-term survival over a 2 year period. Here, we show that Cav-1 null (-/-) mice exhibit an approximately 50% reduction in life span, with major declines in viability occurring between 27 and 65 weeks of age. However, Cav-1 heterozygous (+/-) mice did not show any changes in long-term survival, indicating that loss of both Cav-1 alleles is required to mediate a reduction in life span. Mechanistically, these dramatic reductions in life span appear to be secondary to a combination of pulmonary fibrosis, pulmonary hypertension, and cardiac hypertrophy in Cav-1 null mice. Taken together, our results provide the first demonstration that loss of Cav-1 gene expression and caveolae organelles dramatically affects the long-term survival of an organism. In addition, aged Cav-1 null mice may provide a new animal model to study the pathogenesis and treatment of progressive hypertrophic cardiomyopathy and sudden cardiac death syndrome.

Caveolae are specialized membrane microdomains present within the plasma membrane of the vast majority of cell types. They have a unique composition in that they are highly enriched in cholesterol, sphingolipids, and their coat proteins the caveolins (-1, -2, and -3). In recent years it has been recognized that caveolae act as signaling platforms, serving as a concentrating point for numerous signaling molecules, as well as regulating flux through many distinct signaling cascades. Although caveolae are found in a variety of cell types, they are most abundant in adipose tissue. This fact has led to the intense study of the function of these organelles in adipocytes. It has now become apparent that effective insulin signaling in the adipocyte may be strictly dependent on localization of at least two insulin-responsive elements to caveolae (insulin receptor and GLUT4), as well as on a direct functional interaction between caveolin-1 and the insulin receptor. We present a critical discussion of these recent findings.

The myocardium of CD1 mice was examined for the activation of signal transduction pathways leading to cardiac inflammation and subsequent remodeling duringTrypanosoma cruziinfection (Brazil strain). The activity of three pathways of the mitogen-activated protein kinases (MAPKs) was determined. Immunoblotting revealed a persistent elevation of phosphorylated (activated) extracellular-signal-regulated kinase (ERK), which regulates cell proliferation. During infection there was a transient activation of p38 MAPK but no activation of Jun N-terminal kinase. Early targets of activated ERK, c-Jun and c-Fos, were elevated during infection, as demonstrated by semiquantitative reverse transcription-PCR. Immunostaining revealed that the endothelium and the interstitial cells were most intensely stained with antibodies to c-Jun and c-Fos. Soon after infection, AP-1 and NF-κB DNA binding activity was increased. Protein levels of cyclin D1, the downstream target of ERK and NF-κB, were induced during acute infection. Immunostaining demonstrated increased expression of cyclin D1 in the vascular and endocardial endothelium, inflammatory cells, and the interstitial areas. Increased expression of the cyclin D1-specific phosphorylated retinoblastoma protein (Ser780) was also evident. Immunoblotting and immunostaining also demonstrated increased expression of proliferating cellular nuclear antigen that was predominantly present in the inflammatory cells, interstitial areas (i.e., fibroblasts), and endothelium. These data demonstrate thatT. cruziinfection results in activation of the ERK-AP-1 pathway and NF-κB. Cyclin D1 expression was also increased. These observations provide a molecular basis for the activation of pathways involved in cardiac remodeling in chagasic cardiomyopathy.

Several lines of evidence suggest that a functional relationship exists between caveolin-1 and insulin signaling. However, it remains unknown whether caveolin-1 is normally required for proper insulin receptor signaling in vivo. To address this issue, we examined the status of insulin receptor signaling in caveolin-1 (–/–)-deficient (Cav-1 null) mice. Here, we show that Cav-1 null mice placed on a high-fat diet for 9 mo develop postprandial hyperinsulinemia. An insulin tolerance test (ITT) revealed that young Cav-1 null mice on a normal chow diet are significantly unresponsive to insulin, compared with their wild-type counterparts. This insulin resistance is due to a primary defect in adipose tissue, as evidenced by drastically reduced insulin receptor protein levels (>90%), without any changes in insulin receptor mRNA levels. These data suggest that caveolin-1 acts as a molecular chaperone that is necessary for the proper stabilization of the insulin receptor in adipocytes in vivo. In support of this notion, we demonstrate that recombinant expression of caveolin-1 in Cav-1 null mouse embryo fibroblasts rescues insulin receptor protein expression. These data provide evidence that the lean body phenotype observed in the Cav-1 knockout mice is due, at least in part, to a defect in insulin-regulated lipogenesis.

Caveolin-1 is the principal structural component of caveolae microdomains, which represent a subcompartment of the plasma membrane. Several independent lines of evidence support the notion that caveolin-1 functions as a suppressor of cell transformation. For example, the human CAV-1 gene maps to a suspected tumor suppressor locus (D7S522/7q31.1) that is frequently deleted in a number of carcinomas, including breast cancers. In addition, up to 16% of human breast cancers harbor a dominant-negative mutation, P132L, in the CAV-1 gene. Despite these genetic associations, the tumor suppressor role of caveolin-1 still remains controversial. To directly assess the in vivo transformation suppressor activity of the caveolin-1 gene, we interbred Cav-1 (−/−) null mice with tumor-prone transgenic mice (MMTV-PyMT) that normally develop multifocal dysplastic lesions throughout the entire mammary tree. Herein, we show that loss of caveolin-1 gene expression dramatically accelerates the development of these multifocal dysplastic mammary lesions. At 3 wk of age, loss of caveolin-1 resulted in an approximately twofold increase in the number of lesions (foci per gland; 3.3 ± 1.0 vs. 7.0 ± 1.2) and an approximately five- to sixfold increase in the total area occupied by these lesions. Similar results were obtained at 4 wk of age. However, complete loss of caveolin-1 was required to accelerate the appearance of these dysplastic mammary lesions, because Cav-1 (+/−) heterozygous mice did not show any increases in foci development. We also show that loss of caveolin-1 increases the extent and the histological grade of these mammary lesions and facilitates the development of papillary projections in the mammary ducts. Finally, we demonstrate that cyclin D1 expression levels are dramatically elevated in Cav-1 (−/−) null mammary lesions, consistent with the accelerated appearance and growth of these dysplastic foci. This is the first in vivo demonstration that caveolin-1 can function as a transformation suppressor gene.

A growing body of evidence suggests that muscle cell caveolae may function as specialized membrane micro-domains in which the dystrophin-glycoprotein complex and cellular signaling molecules reside. Caveolin-3 (Cav-3) is the only caveolin family member expressed in striated muscle cell types (cardiac and skeletal). Interestingly, skeletal muscle fibers from Cav-3 (-/-) knock-out mice show a number of myopathic changes, consistent with a mild-to-moderate muscular dystrophy phenotype. However, it remains unknown whether a loss of Cav-3 affects the phenotypic behavior cardiac myocytes in vivo. Here, we present a detailed characterization of the hearts of Cav-3 knock-out mice. We show that these mice develop a progressive cardiomyopathic phenotype. At four months of age, Cav-3 knock-out hearts display significant hypertrophy, dilation, and reduced fractional shortening, as revealed by gated cardiac MRI and transthoracic echocardiography. Histological analysis reveals marked cardiac myocyte hypertrophy, with accompanying cellular infiltrates and progressive interstitial/peri-vascular fibrosis. Interestingly, loss of Cav-3 expression in the heart does not change the expression or the membrane association of the dystrophin-glycoprotein (DG) complex. However, a marker of the DG complex, alpha-sarcoglycan, was specifically excluded from lipid raft domains in the absence of Cav-3. Because activation of the Ras-p42/44 MAPK pathway in cardiac myocytes can drive cardiac hypertrophy, we next assessed the activation state of this pathway using a phospho-specific antibody probe. We show that p42/44 MAPK (ERK1/2) is hyperactivated in hearts derived from Cav-3 knock-out mice. These results are consistent with previous in vitro data demonstrating that caveolins may function as negative regulators of the p42/44 MAPK cascade. Taken together, our data argue that loss of Cav-3 expression is sufficient to induce a molecular program leading to cardiac myocyte hypertrophy and cardiomyopathy.

Caveolin-1 (Cav-1) is the primary structural component of caveolae and is implicated in the processes of vesicular transport, cholesterol balance, transformation, and tumorigenesis. Despite an abundance of data suggesting that Cav-1 has transformation suppressor properties both in vitro and in vivo, Cav-1 is expressed at increased levels in human prostate cancer. To investigate the role of Cav-1 in prostate cancer onset and progression, we interbred Cav-1(-/-) null mice with a TRAMP (transgenic adenocarcinoma of mouse prostate) model that spontaneously develops advanced prostate cancer and metastatic disease. We found that, although the loss of Cav-1 did not affect the appearance of minimally invasive prostate cancer, its absence significantly impeded progression to highly invasive and metastatic disease. Inactivation of one (+/-) or both (-/-) alleles of Cav-1 resulted in significant reductions in prostate tumor burden, as well as decreases in regional lymph node metastases. Moreover, further examination revealed decreased metastasis to distant organs, such as the lungs, in TRAMP/Cav-1(-/-) mice. Utilizing prostate carcinoma cell lines (C1, C2, and C3) derived from TRAMP tumors, we also showed a positive correlation between Cav-1 expression and the ability of these cells to form tumors in vivo. Furthermore, down-regulation of Cav-1 expression in these cells, using a small interfering RNA approach, significantly reduced their tumorigenic and metastatic potential. Mechanistically, we showed that loss or down-regulation of Cav-1 expression results in increased apoptosis, with increased prostate apoptosis response factor-4 and PTEN levels in Cav-1(-/-) null prostate tumors. Our current findings provide the first in vivo molecular genetic evidence that Cav-1 does indeed function as a tumor promoter during prostate carcinogenesis, rather than as a tumor suppressor.