Endocrine Abstracts

Angiotensin II (AngII) is an octapeptide hormone, which participates in physiological and pathological mechanisms. AngII exerts a number of biological effects through the type 1 angiotensin II receptor (AT1R). One of the main targets of AngII are vascular smooth muscle and its stimulation activates numerous signaling pathways that cause contraction and could also result in gene expression changes in vascular smooth muscle cells (VSMCs). Next-generation sequencing (NGS) experiments were performed to analyze the effects of AngII stimulation on gene expression in VSMCs. The experiments were conducted using a rat aortic primary isolated VSMC cell line. In our experimental set-up more than 200 genes were upregulated in response to AngII stimulation in VSMCs. The transcriptome analysis revealed the upregulation of several DUSP genes, such as DUSP 5, 6, 10, 4, and 14. We also investigated the kinetics of the gene-expression changes and the signaling pathways involved in AngII-mediated responses. The results of the quantitative PCR measurements also confirmed the increased expression of selected genes upon AngII stimulation. Transcription of most genes was largest two hours after AngII stimulation. Based on our results, the regulation of the studied gene expression induced by AngII is much more complex than we originally thought, due to the multiple signaling pathways that mediate them. We assume that the regulation of expression changes is probably determined by the interaction of the involved signaling cascades. Based on our data, the expression changes of the studied genes can occur through classical G_q/11 activation, which triggers Ca²⁺-mediated mechanisms leading to epidermal growth factor receptor transactivation dependent or independent responses. During the search of the signaling pathway(s) which is/are responsible for certain gene-expression changes, we found that dasatinib, an Src-family tyrosine kinase inhibitor, was able to selectively inhibit the AngII induced gene-expression changes. We have also demonstrated that the imatinib, a selective inhibitor of Bcr-Abl kinases, was not able to achieve the similar effect as the dasatinib. Our data suggest that Src-family tyrosine kinase(s) may play an important role in AngII-induced long-term cellular responses. Our data can provide new insight into the physiology of VSMCs in response to AngII stimulation, and better understanding of the mechanism of AT1-R-mediated gene expression changes in primary VSMCs, which may lead to the development of novel types of drugs for the treatment of cardiovascular and other diseases. This work was supported by the National Research, Development and Innovation Fund (NKFI K116954, K139231, VEKOP-2.3.2-16-2016-00002 and NVKP_16-1-2016-0039).