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Introduction Cerebral cavernous malformations (CCMs) are vascular anomalies caused by mosaic inactivation of KRIT1 (also known as CCM1), CCM2, or PDCD10 (also known as CCM3) (1). We recently used CRISPR/Cas9 [...], Propranolol, a pleiotropic [beta]-adrenergic blocker, has been anecdotally reported to reduce cerebral cavernous malformations (CCMs) in humans. However, propranolol has not been rigorously evaluated in animal models, nor has its mechanism of action in CCM been defined. We report that propranolol or its S(-) enantiomer dramatically reduced embryonic venous cavernomas in ccm2 mosaic zebrafish, whereas R-(+)-propranolol, lacking p antagonism, had no effect. Silencing of the [beta]1, but not p2, adrenergic receptor mimicked the beneficial effects of propranolol in a zebrafish CCM model, as did the [beta]1- selective antagonist metoprolol. Thus, propranolol ameliorated cavernous malformations by [beta]1 adrenergic antagonism in zebrafish. Oral propranolol significantly reduced lesion burden in 2 chronic murine models of the exceptionally aggressive Pdcd10/Ccm3 form of CCM. Propranolol or other [beta]1-selective antagonists may be beneficial in CCM disease.

Introduction Stroke is the fourth leading cause of death in the US, with almost 800,000 new cases occurring each year (1). The majority (over 80%) of strokes are of ischemic [...], Risk for ischemic stroke has a strong genetic basis, but heritable factors also contribute to the extent of damage after a stroke has occurred. We previously identified a locus on distal mouse chromosome 7 that contributes over 50% of the variation in postischemic cerebral infarct volume observed between inbred strains. Here, we used ancestral haplotype analysis to fine-map this locus to 12 candidate genes. The gene encoding the IL-21 receptor (Il21r) showed a marked difference in strain- specific transcription levels and coding variants in neonatal and adult cortical tissue. Collateral vessel connections were moderately reduced in Il27r-deficient mice, and cerebral infarct volume increased 2.3-fold, suggesting that Il21r modulates both collateral vessel anatomy and innate neuroprotection. In brain slice explants, oxygen deprivation (OD) activated apoptotic pathways and increased neuronal cell death in IL-21 receptor-deficient (IL-21R-deficient) mice compared with control animals. We determined that the neuroprotective effects of IL-21R arose from signaling through JAK/STAT pathways and upregulation of caspase 3. Thus, natural genetic variation in murine Il21r influences neuronal cell viability after ischemia by modulating receptor function and downstream signal transduction. The identification of neuroprotective genes based on naturally occurring allelic variations has the potential to inform the development of drug targets for ischemic stroke treatment.

********** Cerebral cavernous malformations are common vascular malformations that affect the systemic and central nervous system (CNS) vasculature with a prevalence of I in 200 to 250 individuals (1,2) in [...], Cerebral cavernous malformation (CCM) is a common vascular dysplasia that affects both systemic and central nervous system blood vessels. Loss of function mutations in the CCM2 gene cause CCM. Here we show that targeted disruption of Ccm2 in mice results in failed lumen formation and early embryonic death through an endothelial cell autonomous mechanism. We show that CCM2 regulates endothelial cytoskeletal architecture, cell-to-cell interactions and lumen formation. Heterozygosity at Ccm2, a genotype equivalent to that in human CCM, results in impaired endothelial barrier function. On the basis of our biochemical studies indicating that loss of CCM2 results in activation of RHOA GTPase, we rescued the cellular phenotype and barrier function in heterozygous mice with simvastatin, a drug known to inhibit Rho GTPases. These data offer the prospect for pharmacological treatment of a human vascular dysplasia with a widely available and safe drug.

Loss-of-function activin receptor-like kinase 1 gene mutation ([ALK1.sup.+/-]) is associated with brain arteriovenous malformations (AVM) in hereditary hemorrhagic telangiectasia type 2. Other determinants of the lesional phenotype are unknown. In the present study, we investigated the influence of high vascular flow rates on [ALK1.sup.+/-] mice by manipulating cerebral blood flow (CBF) using vasodilators. Adult male [ALK1.sup.+/-] mice underwent adeno-associated viral-mediated vascular endothelial growth factor (AAVVEGF) or lacZ (AAV-lacZ as a control) gene transfer into the brain. Two weeks after vector injection, hydralazine or nicardipine was infused intraventricularly for another 14 days. CBF was measured to evaluate relative tissue perfusion. We analyzed the number and morphology of capillaries. Results demonstrated that hydralazine or nicardipine infusion increased focal brain perfusion in all mice. It was noted that focal CBF increased most in AAVVEGF-injected [ALK1.sup.+/-] mice following hydralazine or nicardipine infusion (145 [+ or -] 23% or 150 [+ or -] 11%; P < 0.05). There were more detectable dilated and dysplastic capillaries (2.4 [+ or -] 0.3 or 2.0 [+ or -] 0.4 dysplasia index; P < 0.01) in the brains of [ALK1.sup.+/-] mice treated with AAVVEGF and hydralazine or nicardipine compared with the mice treated with them individually. We concluded that increased focal tissue perfusion and angiogenic factor VEGF stimulation could have a synergistic effect to promote capillary dysplasia in a genetic deficit animal model, which may have relevance to further studies of AVMs. activin receptor-like kinase 1; angiogenesis; vascular endothelial growth factor

Multiplex ligation-dependent probe analysis is carried out in genes responsible for cerebral cavernous malformations (CCM) to analyze potential deletions or duplications in CCM-1, -2 and -3 mutation-negative probands within the genes as a common cause of CCM. The study documents that large deletions in the CCM2 gene represent a major cause of CCM.

Patients with unexplained hamartomatous or hyperplastic/mixed polyposis were systematically classified by extensive molecular analysis in the context of central rereview of histopathology results. Systematic molecular classification of 49 patients with unexplained hamartomatous or hyperplastic polyposis uncovered a potential novel susceptibility gene, ENG, for juvenile polyposis.

Endoglin (CD105) is expressed on the surface of endothelial and haematopoietic cells in mammals and binds TGF(Beta) isoforms 1 and 3 in combination with the signaling complex of TGF(Beta) receptors types I and II. Endoglin expression increases during angiogenesis, wound healing, and inflammation, all of which are associated with TGF(Beta) signaling and alterations in vascular structure. The importance of endoglin for normal vascular architecture is further indicated by the association of mutations in the endoglin gene with the inherited disorder Hereditary Haemorrhagic Telangiectasia Type 1 (HHT1), a disease characterised by bleeding from vascular malformations. In order to study the role of endoglin in vivo in more detail and to work toward developing an animal model of HHT1, we have derived mice that carry a targeted nonsense mutation in the endoglin gene. Studies on these mice have revealed that endoglin is essential for early development. Embryos homozygous for the endoglin mutation fail to progress beyond 10.5 days postcoitum and fail to form mature blood vessels in the yolk sac. This phenotype is remarkably similar to that of the TGF(Beta)1 and the TGF(Beta) receptor II knockout mice, indicating that endoglin is needed in vivo for TGF(Beta)1 signaling during extraembryonic vascular development. In addition, we have observed cardiac defects in homozygous endoglin-deficient embryos, suggesting endoglin also plays a role in cardiogenesis. We anticipate that heterozygous mice will ultimately serve as a useful disease model for HHT1, as some individuals have dilated and fragile blood vessels similar to vascular malformations seen in HHT patients.

The role of genetic mutations in vascular dysmorphogenesis was analyzed by the chromosome mapping of the TIE2 gene in insect cells. The phosphorylation activity of TIE2 was enhanced by mutations in the R849W polymorphism which is expressed in two disparate families with dominantly inherited mucocutaneous vascular malformations. The activation of the mutant TIE2 gene also increased the number of endothelial cells compared to smooth muscle cells during venous morphogenesis.

Hereditary hemorrhagic telangiectasia may occur in many locations throughout the body and may respond favorably to various treatments. Telangiectasia is an abnormal permanent dilation of normal blood vessels in the skin or other mucous membranes resulting in the mixing of arterial and venous blood in the affected area and creating small red lesions. Hereditary hemorrhagic telangiectasia occurs in the stomach, intestinal tracts, brain, lung, skin, and nose. Treatments currently used for this disorder include laser therapy, transcatheter embolotherapy, vascular surgery, and estrogen therapy. Periodic evaluation for telangiectasia in the lung and brain may be advisable for otherwise affected patients. More precise identification of the genetic links to hereditary hemorrhagic telangiectasia may hold promise for future gene replacement therapy.

Type 1 Neurofibromatosis Gene: Identification of a Large Transcript Disrupted in Three NFI Patients THE VARIABLE AND DIVERSE MANIFESTATIONS of neurofibromatosis (NF1) have puzzled clinicians and neurobiologists alike since the [...]

We would like to correct an error of interpretation in our report describing the cloning of a large transcript from the neurofibromatosis locus (denoted NF1LT) [1]. Although the Southern blot [...]