β-1, 3-galactosyltransferase 2 promotes cerebral angiogenesis and neurological recovery during the ischemic repair phase through glycosylation modification of TGF-βR(II)/ALK1.

β-1,3-galactosyltransferase 2 (B3galt2) has been increasingly recognized as an essential mediator in the pathogenesis of ischemic stroke (IS); nonetheless, its exact functional role has not been fully elucidated. This research aimed to clarify the regulatory mechanisms by which B3galt2 influences cerebral angiogenesis during the repair phase following ischemic injury. A mouse model of cerebral ischemia/reperfusion (I/R) injury was generated by subjecting animals to 1-h middle cerebral artery occlusion (MCAO), succeeded by reperfusion for varying time intervals. Recombinant human B3galt2 (rh-B3galt2) was administered intranasally beginning on day one post-injury and continued until tissue collection. Experimental outcomes revealed that rh-B3galt2 substantially diminished brain atrophy and enhanced neurological recovery during the repair phase of ischemia. Furthermore, rh-B3galt2 facilitated angiogenesis through increased expression of vascular endothelial growth factor A (VEGFA) and the tight junction proteins, occludin and claudin 5. Moreover, rh-B3galt2 activated the TGF-βR(II)/ALK1/Smad1/5 pathway. The galactosylation levels of TGF-βR(II) and ALK1 were increased after rh-B3galt2 treatment, suggesting that B3galt2 may regulate TGF-βR(II) and ALK1 through glycosylation modification. Moreover, the advantageous impacts of rh-B3galt2 on reducing brain atrophy and alleviating neurological deficits were reversed upon treatment with the ALK1 inhibitor, ML347. ML347 also counteracted the angiogenic promotion induced by rh-B3galt2, demonstrating that inhibition of ALK1 abolishes the protective benefits mediated by rh-B3galt2. Collectively, the results indicated that rh-B3galt2 significantly promotes angiogenesis and neurological function recovery during the cerebral ischemic repair stage, likely by regulating TGF-βR(II)/ALK1/Smad1/5 signaling pathway through glycosylation modification.