Ischemic stroke causes blood–brain barrier (BBB) breakdown due to significant damage to the integrity of BBB components. Recent studies have highlighted the importance of pericytes in the repair process of BBB functions triggered by PDGFRβ up-regulation. Here, we show that perlecan, a major heparan sulfate proteoglycan of basement membranes, aids in BBB maintenance and repair through pericyte interactions. Using a transient middle cerebral artery occlusion model, we found larger infarct volumes and more BBB leakage in conditional perlecan ( Hspg2 )-deficient ( Hspg2 − / − - TG) mice than in control mice. Control mice showed increased numbers of pericytes in the ischemic lesion, whereas Hspg2 − / − - TG mice did not. At the mechanistic level, pericytes attached to recombinant perlecan C-terminal domain V (perlecan DV, endorepellin). Perlecan DV enhanced the PDGF-BB–induced phosphorylation of PDGFRβ, SHP-2, and FAK partially through integrin α5β1 and promoted pericyte migration. Perlecan therefore appears to regulate pericyte recruitment through the cooperative functioning of PDGFRβ and integrin α5β1 to support BBB maintenance and repair following ischemic stroke.

Alternative premRNA splicing is a major mechanism to generate diversity of gene products. However, the biological roles of alternative splicing during development remain elusive. Here, we focus on a neuron-specific RNA-binding protein, Rbfox3, recently identified as the antigen of the widely used anti-NeuN antibody. siRNA-mediated loss-of-function studies using the developing chicken spinal cord revealed that Rbfox3 is required to promote neuronal differentiation of postmitotic neurons. Numb premRNA encoding a signaling adaptor protein was found to be a target of Rbfox3 action, and Rbfox3 repressed the inclusion of an alternative exon via binding to the conserved UGCAUG element in the upstream intron. Depleting a specific Numb splice isoform reproduced similar neuronal differentiation defects. Forced expression of the relevant Numb splice isoform was sufficient to rescue, in an isoform-specific manner, postmitotic neurons from defects in differentiation caused by Rbfox3 depletion. Thus, Rbfox3-dependent Numb alternative splicing plays an important role in the progression of neuronal differentiation during vertebrate development.