Project description:Severe acute pancreatitis (SAP) is the most serious type of pancreatitis with high morbidity and mortality. The underlying pathophysiological mechanism of SAP is complicated and lacking in effective therapeutic options in clinic. In recent years, circular RNAs (circRNAs) are found to be N6-methyladenosine (m6A)-modified and m6A modification of circRNAs plays important roles in physiological and pathological processes. However, the role of m6A modification of circRNAs in SAP remains unknown. Here, we aim to identify differentially expressed m6A circRNAs in SAP and to determine their biological significance and potential mechanisms in SAP. Firstly, we identified 903 m6A peaks that distribute on 781 circRNAs in SAP and control groups. Among them, 57 circRNAs with differentially expressed m6A peaks were identified, of which 32 were upregulated and 25 were downregulated. The total m6A level of circRNAs was reduced compared with control group. Moreover, the function analysis of these m6A circRNAs in SAP found that some important pathways involved in the pathogenesis of SAP, such as protein digestion and regulation of autophagy. In m6A circRNA-microRNA networks, several important miRNAs involved in the occurrence and development of SAP were found to bind to these m6A circRNAs potentially, such as miR-24-3p, miR-26a, miR-92b, miR-216b, miR-324-5p and miR-762. Notably, ALKBH5 was found to be upregulated in SAP. In conclusion, these results demonstrated that m6A modification of circRNAs was widely existed and may play important roles in the pathogenesis of SAP. Our findings provide novel insights regarding understanding the pathophysiological mechanism of SAP and seeking new therapeutic targets for SAP.
Project description:SAF-A is conserved throughout vertebrates and has emerged as an important factor regulating a multitude of nuclear functions, including lncRNA localization, gene expression, and splicing. SAF-A has several functional domains, including an N-terminal SAP domain that binds directly to DNA. Phosphorylation of SAP domain serines S14 and S26 are important for SAF-A localization and function during mitosis, however whether these serines are involved in interphase functions of SAF-A is not known. In this study we tested for the role of the SAP domain, and SAP domain serines S14 and S26 in X chromosome inactivation, protein dynamics, gene expression, splicing, and cell proliferation. Here we show that the SAP domain serines S14 and S26 are required to maintain XIST RNA localization and polycomb-dependent histone modifications on the inactive X chromosome in female cells. In addition, we present evidence that an Xi localization signal resides in the SAP domain. We found that that the SAP domain is not required to maintain gene expression and plays only a minor role in mRNA splicing. In contrast, the SAF-A SAP domain, in particular serines S14 and S26, are required for normal protein dynamics, and to maintain normal cell proliferation. We propose a model whereby dynamic phosphorylation of SAF-A serines S14 and S26 mediates rapid turnover of SAF-A interactions with DNA during interphase.
Project description:SAF-A is conserved throughout vertebrates and has emerged as an important factor regulating a multitude of nuclear functions, including lncRNA localization, gene expression, and splicing. SAF-A has several functional domains, including an N-terminal SAP domain that binds directly to DNA. Phosphorylation of SAP domain serines S14 and S26 are important for SAF-A localization and function during mitosis, however whether these serines are involved in interphase functions of SAF-A is not known. In this study we tested for the role of the SAP domain, and SAP domain serines S14 and S26 in X chromosome inactivation, protein dynamics, gene expression, splicing, and cell proliferation. Here we show that the SAP domain serines S14 and S26 are required to maintain XIST RNA localization and polycomb-dependent histone modifications on the inactive X chromosome in female cells. In addition, we present evidence that an Xi localization signal resides in the SAP domain. We found that that the SAP domain is not required to maintain gene expression and plays only a minor role in mRNA splicing. In contrast, the SAF-A SAP domain, in particular serines S14 and S26, are required for normal protein dynamics, and to maintain normal cell proliferation. We propose a model whereby dynamic phosphorylation of SAF-A serines S14 and S26 mediates rapid turnover of SAF-A interactions with DNA during interphase.