Cyclic Stretch Induces VEGFA Alternative Splicing In Vascular Remodeling Under Hypertension

Abnormal proliferation and dedifferentiation of vascular smooth muscle cells(VSMCs)induced by high cyclic stretch is crucial in the vascular remodeling during hypertension.VEGFA alternative splicing plays important roles in the pathological process of vascular diseases and remodeling.However,the roles of VEGFA isoforms in modulating VSMC functions in response to cyclic stretch remain unclear.The hypertensive rat model was established by using the abdominal aortic constriction method.One week after the surgery,the blood pressure was measured through a catheter that was introduced into the carotid arteries.In vivo,HE staining was used for the visualization of vascular remodeling and RT-PCR was used to detect the expression level of different VEGFA variants.The results showed a significantly increased expression of VEGFA120 and VEGFA164,but not VEGFA188.In virto,Flexercell strain unit was used for the application of cyclic stretch,and the proliferation and differentiation level of stretched VSMCs was detected along with the mRNA expression level of VEGFA variants.The results showed an enhanced secretion and proliferation in the 15%-cyclic-stretch group and the de-differentiation of VSMCs.Based on the bioinformatic analysis,Serine/arginine-rich splicing factor 1 might have played an important role in the regulation of VEGFA alternative splicing.Thus,immunofluorescence was used to detect the expression and distribution of SRSF1 in the thoracic aorta from different rat groups and the results showed a higher nuclear colocalization in the hypertensive group.In virto,western blot and immunofluorescence showed the translocation of SRSF1 from cytoplasm to nuclei after 15% cyclic stretch application.To more convincingly show the importance of SRSF1 in the regulation of VEGFA alternative splicing,siRNA interference target SRSF1 was carried out.The results showed that after interference,15% cyclic stretch failed to induce the alternative splicing of VEGFA in the VSMCs.In conclusion,our results demonstrated that high cyclic stretch induced the translocation of SRSF1 and regulated the alternative splicing of VEGFA,which induced the secretion of VEGFA and stimulated the proliferation and de-differentiation of VSMCs.Those results may be valuable for understanding of the mechanobiology mechanisms during hypertension.