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Vagus nerve stimulation (VNS) paired with rehabilitative training enhances recovery of function in models of stroke and is currently under investigation for use in chronic stroke patients. Dosing is critical in translation of pharmacological therapies, but electrical stimulation therapies often fail to comprehensively explore dosing parameters in preclinical studies. Varying VNS parameters has non-monotonic effects on plasticity in the central nervous system, which may directly impact efficacy for stroke. We sought to optimize stimulation intensity to maximize recovery of motor function in a model of ischemic stroke. The study design was preregistered prior to beginning data collection (DOI: https://doi.org/10.17605/OSF.IO/BMJEK ). After training on an automated assessment of forelimb function and receiving an ischemic lesion in motor cortex, rats were separated into groups that received rehabilitative training paired with VNS at distinct stimulation intensities (sham, 0.4 mA, 0.8 mA, or 1.6 mA). Moderate-intensity VNS at 0.8 mA enhanced recovery of function compared with all other groups. Neither 0.4 mA nor 1.6 mA VNS was sufficient to improve functional recovery compared with equivalent rehabilitation without VNS. These results demonstrate that moderate-intensity VNS delivered during rehabilitation improves recovery and defines an optimized intensity paradigm for clinical implementation of VNS therapy.

The rat kidney matures during the first 2 wk of life, suggesting that temporal variations in the urinary proteome may occur during this period. We describe the urine proteome during postnatal development in the rat and demonstrate specific proteomic changes corresponding to developmental milestones. Urine was collected from 30 rats at five postnatal (P) days of life (P1, P3, P7, P14, and >P30) by bladder aspiration. The proteome was assessed by nano-ESI-LC-MS/MS. For identification, we used stringent criteria to provide a 1% false positive rate at the peptide level. The proteins in common at each time interval decreased during postnatal maturation. When comparing all five developmental times, six proteins were ubiquitously present. We detected 14 proteins involved with cellular adhesion, structure, or proliferation and differentiation only during neonatal development. Additionally, 30 proteins were specific to adults, of which 13 originated from the prostate or seminal vesicle. This is the first MS characterization of the normal urinary proteome in early postnatal rodent development that demonstrates distinct differences correlating with different stages of tissue maturation. Further characterization of the normal urinary proteome may provide the basis for identification of urinary biomarkers of diseases of the urinary tract.

Akt kinases mediate cell growth and survival. Here, we report that a pro-apoptotic kinase, Mst1/STK4, is a physiological Akt1 interaction partner. Mst1 was identified as a component of an Akt1 multiprotein complex isolated from lipid raft-enriched fractions of LNCaP human prostate cancer cells. Endogenous Mst1, along with its paralog, Mst2, acted as inhibitors of endogenous Akt1. Surprisingly, mature Mst1 as well as both of its caspase cleavage products, which localize to distinct subcellular compartments and are not structurally homologous, complexed with and inhibited Akt1. cRNAs encoding full-length Mst1, and N- and C-terminal caspase Mst1 cleavage products, reverted an early lethal phenotype in zebrafish development induced by expression of membrane-targeted Akt1. Mst1 and Akt1 localized to identical subcellular sites in human prostate tumors. Mst1 levels declined with progression from clinically localized to hormone refractory disease, coinciding with an increase in Akt activation with transition from hormone naïve to hormone-resistant metastases. These results position Mst1/2 within a novel branch of the phosphoinositide 3-kinase/Akt pathway and suggest an important role in cancer progression.

Androgen receptor (AR) plays an important role in normal prostate function as well as in the etiology of prostate cancer. Activation of AR is dictated by hormone binding and by interactions with coregulators. Several of these coregulators are known targets of Ras-related signals. Recent evidence suggests that Ras activation may play a causal role in the progression of prostate cancer toward a more malignant and hormone-insensitive phenotype. In the present study, we used a transcription factor-transcription factor interaction array method to identify the zinc finger protein Ras-responsive element binding protein (RREB-1) as a partner and coregulator of AR. In LNCaP prostate cancer cells, RREB-1 was found to be present in a complex with endogenous AR as determined by coimmunoprecipitation, glutathione S-transferase pull down, and immunofluorescence analyses. RREB-1 bound to the prostate-specific antigen (PSA) promoter as assessed by chromatin immunoprecipitation. Transient expression of RREB-1 down-regulated AR-mediated promoter activity and suppressed expression of PSA protein. The repressor activity of RREB-1 was significantly attenuated by cotransfection of activated Ras. Moreover, expression of the dominant-negative N-17-Ras or, alternatively, use of the MAPK kinase inhibitor PD98059 [2-(2-amino-3-methyoxyphenyl)-4H-1-benzopyran-4-one] abolished the effect of Ras in attenuating RREB-1-mediated repression. Furthermore, inhibition of RREB-1 expression by RNA interference enhanced the effect of Ras on PSA promoter activity and PSA expression. In addition, activation of the Ras pathway depleted AR from the RREB-1/AR complex. Collectively, our data for the first time identify RREB-1 as a repressor of AR and further implicate the Ras/MAPK kinase pathway as a likely antagonist of the inhibitory effects of RREB-1 on androgenic signaling.

The androgen receptor (AR) plays a key role in the development and function of male reproductive organs. Using a high-throughput transcription factor-transcription factor (TF-TF) interaction array method, we captured the AR interactomes in androgen-responsive LNCaP cells. Several known and unknown partners of AR, including AP-2, Pax 3/5 (BSAP), c-Rel, RREB-1, LIII BP, and NPAS2 were identified. We investigated one unreported AR-associated transcription factor, the proto-oncoprotein c-Rel, in detail. C-Rel belongs to the NF-kB/Rel families and is persistently active in a number of diseases, including cancer. The presence of c-Rel transcript, protein, and its in vitro and in vivo association with AR was determined. Co-localization of c-Rel with AR both in cytoplasm and nucleus was confirmed by indirect immunofluorescence analysis. Chromatin immunoprecipitation data indicated that c-Rel, like AR, is a part of the nucleoprotein complex regulating the androgen-responsive prostate-specific antigen (PSA) promoter. Overexpression of c-Rel downregulated the promoter activity of both PSA and GRE4-TATA-Luc plasmids in LNCaP and COS cells. Analysis of AR and c-Rel protein levels indicated that the promoter downregulation was not due to reciprocal decrease in the amounts of AR or c-Rel. In summary, we have identified several new partners of AR by using the TF-TF array method and have provided the first evidence of a functional role for c-Rel in androgen-responsive human prostate cancer cells.

Background: Neurofibromatosis type 2 (NF2) is an autosomal dominant disease predisposing individuals to the risk of developing tumors of cranial and spinal nerves. The NF2 tumor suppressor protein, known as Merlin/Schwanomin, is a member of the protein 4.1 superfamily that function as links between the cytoskeleton and the plasma membrane., Methods: Upon selective extraction of membrane-associated proteins from erythrocyte plasma membrane (ghosts) using low ionic strength solution, the bulk of NF2 protein remains associated with the spectrin-actin depleted inside-out-vesicles. Western blot analysis showed a approximately 70 kDa polypeptide in the erythrocyte plasma membrane. Furthermore, quantitative removal of NF2 protein from the inside-out-vesicles was achieved using 1.0 M potassium iodide, a treatment known to remove tightly-bound peripheral membrane proteins., Results: These results suggest a novel mode of NF2 protein association with the erythrocyte membrane that is distinct from the known membrane interactions of protein 4.1. Based on these biochemical properties, several purification strategies were devised to isolate native NF2 protein from human erythrocyte ghosts. Using purified and recombinant NF2 protein as internal standards, we quantified approximately 41-65,000 molecules of NF2 protein per erythrocyte., Conclusion: We provide evidence for the presence of NF2 protein in the human erythrocyte membrane. The identification of NF2 protein in the human erythrocyte membrane will make it feasible to discover novel interactions of NF2 protein utilizing powerful techniques of erythrocyte biochemistry and genetics in mammalian cells.

Papillomaviruses are small DNA viruses that infect epithelial tissues and cause warts. Human papillomavirus (HPV) infection is the primary risk factor for the development of cervical cancer. The E6 and E7 oncogenes are the only genes consistently expressed in HPV-positive cervical cancer cells. Cottontail rabbit papillomavirus (CRPV) induces papillomas and carcinomas on cottontail and domestic rabbits and provides an excellent animal model of HPV infection and vaccine development. CRPV encodes three transforming proteins; LE6, SE6, and E7. Each of these proteins is required for papilloma formation. Like HPV E7, the CRPV E7 protein binds to the tumor suppressor pRB. In contrast, unlike HPV E6, the CRPV E6 proteins do not bind the tumor suppressor p53. Although more than a dozen cellular proteins have been identified as HPV E6 interacting proteins, nothing is known about the cellular interacting proteins of CRPV E6s. Here we describe the association of CRPV E6s with hDlg/SAP97, the mammalian homolog of the Drosophila discs large tumor suppressor protein. HPV E6 has previously shown to bind and target hDlg/SAP97 for degradation. Our results demonstrate that both LE6 and SE6 interact with hDlg/SAP97, although their association does not lead to the degradation of hDlg/SAP97. The PDZ domains of hDlg were shown to be sufficient for interaction with CRPV E6 proteins while the C-terminus of CRPV E6 is essential for the interaction with hDlg. The association of hDlg with SE6 may be important but not sufficient for the transformation of NIH 3T3 cells by SE6. Importantly, a CRPV SE6 mutant defective for papilloma formation did not interact with hDlg. These results suggest that interaction with hDlg/SAP97 plays a role in the biological function of CRPV E6s., ((c) 2005 Wiley-Liss, Inc.)

Objective: Recent results have shown that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors referred to as statins rapidly activate the protein kinase Akt/PKB in endothelial cells (ECs) and endothelial precursor cells (EPCs). This pathway is critical for cellular responses that contribute to angiogenesis and EC function including nitric oxide production, cellular survival and migration., Methods: Here we tested whether statins control the translocation of recombinant and endogenous Akt to the plasma membrane of endothelial cells in a cholesterol-dependent manner., Results: Low doses of statins rapidly induce the translocation of Akt to discrete sites in endothelial cell plasma membrane that colocalize with F-actin-positive, focal adhesion kinase (FAK)-negative lamellipodia and filopodia. This translocation event requires the lipid-binding, pleckstrin homology domain of Akt. Treatment with phosphoinositide 3-kinase (PI 3-kinase) inhibitors or the HMG-CoA reductase reaction product L-mevalonate blocks the translocation of Akt in response to statin stimulation. Furthermore, the ability of statins to promote Akt activation and translocation to the membrane is inhibited by cholesterol delivery to cells, but cholesterol loading had no effect on VEGF-induced Akt activation., Conclusions: These results suggest that statin activation of Akt signaling is mediated by the translocation of Akt to cholesterol-sensitive membrane structures within activated ECs.

Erythroid dematin is a major component of red blood cell junctional complexes that link the spectrin-actin cytoskeleton to the overlying plasma membrane. Transcripts of dematin are widely distributed including human brain, heart, lung, skeletal muscle, and kidney. In vitro, dematin binds and bundles actin filaments in a phosphorylation-dependent manner. The primary structure of dematin consists of a C-terminal domain homologous to the 'headpiece' domain of villin, an actin-binding protein of the brush border cytoskeleton. Except filamentous actin, no other binding partners of dematin have been identified. To investigate the physiological function of dematin, we employed the yeast two-hybrid assay to identify dematin-interacting proteins in the adult human brain. Here, we show that dematin interacts with the guanine nucleotide exchange factor Ras-GRF2 by yeast two-hybrid assay, and this interaction is further confirmed by blot overlay, surface plasmon resonance, co-transfection, and co-immunoprecipitation assays. Human Ras-GRF2 is expressed in a variety of tissues and, similar to other guanine nucleotide exchange factors (GEFs), displays anchorage independent growth in soft agar. Co-transfection and immunoblotting experiments revealed that dematin blocks transcriptional activation of Jun by Ras-GRF2 and activates ERK1 via a Ras-GRF2 independent pathway. Because much of the present evidence has centered on the identification of the Rho family of GTPases as key regulators of the actin cytoskeleton, the direct association between dematin and Ras-GRF2 may provide an alternate mechanism for regulating the activation of Rac and Ras GTPases via the actin cytoskeleton.

Dematin is a cytoskeletal protein that bundles actin filaments in a phosphorylation-dependent manner. The primary structure of dematin is organized into an N-terminal core domain of unknown function and a C-terminal domain that is homologous to the "headpiece" domain of villin. We have previously localized the dematin gene on human chromosome 8p21.1, a region distal to the ankyrin locus for hereditary spherocytosis. Radiation hybrid mapping now places dematin between D8S258 and D8S137, two microsatellite markers frequently deleted in prostate cancer. The 8p21.1 region is also deleted in prostate, breast, colon, and bladder cancers, suggesting the presence of a tumor suppressor gene(s). Using laser-capture microdissection technique and fluorescence in situ hybridization (FISH), we demonstrate loss of heterozygosity (LOH) of the dematin gene in a majority of chromosomal region 8p21-linked prostate tumors. One allele of dematin was also deleted in the established prostate adenocarcinoma cell line PC-3, which displays a classic oncogenic phenotype. Overexpression of wild-type dematin in PC-3 cells resulted in the restoration of a more polarized, epithelial-like phenotype. Conversely, the heterologous expression of dominant negative mutants of dematin perturbed normal cell morphology of NIH 3T3 fibroblasts. These results suggest a biological function of dematin in the regulation of cell shape, with implications in the pathobiology of prostate tumorigenesis.

Only 5% to 10% of band 3 null mice survive the neonatal period. To determine the cause of death, 3 adult and 11 newborn band 3 null mice were submitted for histopathologic examination. All but 1 pup showed evidence of thrombosis including: (1) large thrombotic lesions in the heart, which were partially organized, calcified in some fields, and endothelialized, indicating a process that developed premortem (3 of 3 adults and 6 of 11 pups). (2) Subcapsular necrotic areas in the liver suggestive of premortem ischemic events caused by arteriolar occlusions (8 of 11 pups). (3) Large vein thrombi (4 of 11 pups). To investigate the etiology of this hypercoagulable state, we have used the Russell's viper venom test (RVV) to show that red blood cells (RBCs) from band 3 null mice significantly shorten the RVV clotting time of normal plasma in a dose-dependent fashion, whereas RBCs from normal mice have no effect, suggesting that the membrane of band 3 null RBCs provides a suitable surface for activation of the prothrombinase complex. Using flow cytometry, we have examined the phosphatidylserine (PS)-specific binding of fluorescein isothiocyanate (FITC)-annexin V to normal and band 3 null RBCs. A subpopulation of cells (3% to 5% of RBCs) with increased FITC-annexin V binding was detected in band 3 null RBCs as compared with normal RBCs. Furthermore, the entire cell population of band 3 null RBCs shows a measurable increase in the mean fluorescence intensity, suggesting that band 3 null RBCs may have increased PS exposure on the outer membrane leaflet. These findings are further supported by direct fluorescence microscopy of normal and band 3 null RBCs labeled with FITC-annexin V. Based on these observations, we postulate that the high mortality of band 3 null mice may be related to a hypercoagulable state, which appears to originate from changes in the phospholipid composition of the membrane leading to PS exposure on the outer leaflet., (Copyright 1998 by The American Society of Hematology.)

Glycophorin A is the major transmembrane sialoglycoprotein of red blood cells. It has been shown to contribute to the expression of the MN and Wright blood group antigens, to act as a receptor for the malaria parasite Plasmodium falciparum and Sendai virus, and along with the anion transporter, band 3, may contribute to the mechanical properties of the red blood cell membrane. Several lines of evidence suggest a close interaction between glycophorin A and band 3 during their biosynthesis. Recently, we have generated mice where the band 3 expression was completely eliminated by selective inactivation of the AE1 anion exchanger gene, thus allowing us to study the effect of band 3 on the expression of red blood cell membrane proteins. In this report, we show that the band 3 -/- red blood cells contain protein 4.1, adducin, dematin, p55, and glycophorin C. In contrast, the band 3 -/- red blood cells are completely devoid of glycophorin A (GPA), as assessed by Western blot and immunocytochemistry techniques, whereas the polymerase chain reaction (PCR) confirmed the presence of GPA mRNA. Pulse-label and pulse-chase experiments show that GPA is not incorporated in the membrane and is rapidly degraded in the cytoplasm. Based on these findings and other published evidence, we propose that band 3 plays a chaperone-like role, which is necessary for the recruitment of GPA to the red blood cell plasma membrane.

Neurofibromatosis 2 (NF2) protein (merlin; schwannomin) is a tumor suppressor involved in tumorigenesis of NF2-associated and sporadic schwannomas and meningiomas. The protein shares the domain structure of three homologous proteins: ezrin, radixin and moesin (ERM). ERM proteins function as membrane organizers and may act as linkers between plasma membrane molecules, such as CD44 and ICAM-2, and the cytoskeleton. We analyzed the distribution and effects of transfected NF2 protein in COS-1, CHO and 293 cells, and endogenous NF2 protein in U251 glioma cells. The distribution was compared to ezrin, CD44 and F-actin. Both transfected and endogenous NF2 protein localized underneath the plasma membrane in a pattern typical of an ERM protein. In COS-1 transfectants, NF2 protein typically codistributed with ezrin but, in cells with poorly developed actin cytoskeleton, it replaced ezrin in filopodia and ruffling edges. NF2 protein colocalized with CD44, which in transfected cells accumulated into restructured cell membrane protrusions. The association of CD44 and NF2 protein was further suggested by binding of CD44 from cellular lysates to recombinant NF2 protein. Interaction between NF2 protein and the actin-containing cytoskeleton was indicated by partial colocalization, by cytochalasin B-induced coclustering, and by retention of NF2 protein in the detergent-insoluble fraction. Transfected NF2 protein induced morphogenic changes. The cells contained restructured membrane extensions and blebs, and CHO cells expressing NF2 protein were more elongated than control transfectants. In conclusion, NF2 protein possesses functional properties of an ERM family member.

Neurofibromatosis type 2 (NF2) is an autosomal dominant disease which predisposes primarily to CNS tumors such as schwannomas (vestibular and spinal), meningiomas, ependymomas and juvenile posterior lenticular opacities. Allelic losses on chromosome 22q first suggested the existence of a tumor suppressor on this autosome in accordance with Knudson's 'two hit' model. The gene was identified by positional cloning and found to encode a novel protein schwannomin (also known as merlin), with high sequence similarity to the band 4.1 family of proteins. This similarity suggested a new mechanism of tumor suppression since it was the first time a structural protein had been associated with a human tumor. Mutation analysis confirmed that inactivation of the NF2 gene occurred in NF2 tumors and a majority of sporadic schwannomas and meningiomas. Expression and functional studies have provided additional information on the possible involvement of this novel tumor suppressor in cell differentiation, embryogenesis and growth suppression.

Neurofibromatosis type 2 (NF2) is an autosomal dominant disease in which loss of function mutations of the NF2 gene lead to the development of schwannomas, meningiomas and juvenile cataracts. We studied the mouse NF2 homologue (Nf2) to determine its precise pattern of mRNA and protein expression. In situ hybridization showed that Nf2 is expressed in neuronal cells as well as in epithelial and fibre cells of the lens. The Nf2 protein, schwannomin, is expressed as a single protein isoform of approximately 80 kDa in neuronal and non-neuronal tissues. In Purkinje cells of the cerebellum and motor neurones of the spinal cord, the protein is in the cytoplasm. In non-neuronal tissues immunostaining showed expression in cells of the tunica intima of blood vessels. We conclude that there is a widespread but cell type-specific expression of schwannomin.

Neurofibromatosis type 2 (NF2) is an autosomal dominant disease characterized by the development of central nervous system tumours. The NF2 gene was recently cloned and found to encode a protein, schwannomin (or merlin), with homology to the band 4.1 superfamily. This superfamily of proteins includes ezrin, moesin, radixin, and talin, as well as several protein tyrosine phosphatases. How does a cytoskeleton-associated protein act as a tumour suppressor? While this fundamental question remains unanswered, recent studies have begun to address key questions regarding the function of schwannomin. In this review, we examine what is known about the band 4.1 superfamily and how this information pertains to schwannomin. In addition, we summarize recent studies of schwannomin itself.

Cancer is a multistep process that involves the activation of oncogenes and the inactivation of antioncogenes. Recently, a new putative tumor suppressor, the neurofibromatosis type 2 (NF2) gene, was mapped to chromosome 22, cloned, and found to encode for a new protein, merlin/schwannomin, a member of the band 4.1 family of proteins. Members of this family have not been implicated previously in tumorigenesis. They possess significant homology in their NH2-terminal domain, which is thought to be important in the binding of the plasma membrane to the underlying actin cytoskeleton. To determine whether schwannomin may affect cell growth, we transfected NIH 3T3 cells with the wild type and an NF2 cDNA lacking 111 amino acids at the NH2 terminus. We observed slowing of growth and changes in cellular morphology only in cells expressing the wild-type NF2 cDNA. This finding suggests that schwannomin can suppress growth directly and confirms its role in tumor suppression. This system will provide a useful assay to identify important functional domains of the protein.

Neurofibromatosis type 2 (NF2) is an autosomal dominant disease which predisposes to the development of schwannomas, meningiomas, ependymomas, and juvenile cataracts. The NF2 gene (NF2) has recently been isolated and maps to chromosome 22q12 between the loci D22S212 and D22S32. Deletion studies in sporadic and NF2 associated schwannomas and meningiomas, and the presence of inactivating mutations in NF2 in patients suggest that it acts as a tumor suppressor gene. A candidate meningioma gene (MEN) has also been isolated from the same interval. A new highly polymorphic (CA)n marker, D22S268, which maps very near to NF2, has allowed us to identify a kindred with three living affected individuals, where the disease is presumably caused by a large germline deletion. Fluorescence in situ hybridization and pulsed field gel electrophoresis confirm the presence of a 700kb deletion which includes the neurofilament heavy chain subunit gene locus (NEFH), D22S268, NF2 and the putative MEN gene. The absence of meningiomas in this pedigree raises doubts as to the existence of a separate MEN locus in this region. These results support the hypothesis that NF2 results from the inactivation of a tumor suppressor gene on chromosome 22q.

Neurofibromatosis type 2 (NF2) is a monogenic dominantly inherited disease predisposing carriers to develop nervous system tumours. To identify the genetic defect, the region between two flanking polymorphic markers on chromosome 22 was cloned and several genes identified. One is the site of germ-line mutations in NF2 patients and of somatic mutations in NF2-related tumours. Its deduced product has homology with proteins at the plasma membrane and cytoskeleton interface, a previously unknown site of action of tumour suppressor genes in humans.