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The apelin receptor (APJ), a receptor for apelin and elabela/apela, induces vasodilation and vasoconstriction in blood vessels. However, the prolonged effects of increased APJ-mediated signalling, involving vasoconstriction, in smooth muscle cells have not been fully characterized. Here, we investigated the vasoactive effects of APJ gain of function under the control of the smooth muscle actin (SMA) gene promoter in mice. Transgenic overexpression of APJ (SMA-APJ) conferred sensitivity to blood pressure and vascular contraction induced by apelin administration in vivo. Interestingly, ex vivo experiments showed that apelin markedly increased the vasoconstriction of isolated aorta induced by noradrenaline (NA), an agonist for α- and β-adrenergic receptors, or phenylephrine, a specific agonist for α1-adrenergic receptor (α1-AR). In addition, intracellular calcium influx was augmented by apelin with NA in HEK293T cells expressing APJ and α1A-AR. To examine the cooperative action of APJ and α1A-AR in the regulation of vasoconstriction, we developed α1A-AR deficient mice using a genome-editing technique, and then established SMA-APJ/α1A-AR-KO mice. In the latter mouse line, aortic vasoconstriction induced by a specific agonist for α1A-AR, A-61603, were significantly less than in SMA-APJ mice. These results suggest that the APJ-enhanced response requires α1A-AR to contract vessels coordinately.

Males and females share the same genetic code, but gene expression profile often displays differences between two sexes. Mouse embryonic fibroblasts (MEFs) have been used to experiment as a useful tool to test gene function. They have also been characterized by gender-based differences in expressed genes such as Y-linked Sry or X-linked Hprt. However, there is no report on sex differences in global gene expression. Here, using the next-generation RNA sequencing, we compared the comprehensive transcriptome of MEFs derived from two sexes. In comparison with the female group, the male group up-regulated 27 differentially expressed genes (DEGs), in which a male-specific histone demethylase KDM5D gene is included, and 7 DEGs were down-regulated. Based on the results by searching the ENCODE analysis, it was shown that the expression of 15 genes identified is potentially regulated by the methylation of H3K4me1 or H3K4me3. Interestingly, we demonstrated that both of H3K4 methylation are induced by knocking down KDM5D, which causes changes in patterns of eight DEGs found in male MEFs. Collectively, these data not only suggest an importance of KDM5D-mediated demethylation of H3K4 involved in the sexually dimorphic gene expression in male MEFs, but also may provide information regarding sex-dependent changes in gene expression when MEFs are used for experiments.

The central dogma of molecular biology explains the fundamental flow of genetic information for life. Although genome sequence (DNA) itself is a static chemical signature, it includes multiple layers of information composed of mRNA, tRNA, rRNA and small RNAs, all of which are involved in protein synthesis and is passing from parents to offspring via DNA. Methylation is a biologically important modification, because DNA, RNAs and proteins, components of the central dogma, are methylated by a set of methyltransferases. Recent works focused on understanding a variety of biological methylation have shed light on new regulation of cellular functions. In this review, we briefly discuss some of those recent findings of methylation, including DNA, RNAs and proteins.

Protein arginine methyltransferase 1 (PRMT1) is involved in multiple cellular functions including proliferation and differentiation. Although PRMT1 is expressed in vascular endothelial cells (ECs), which are responsible for angiogenesis during embryonic development, its role has remained elusive. In this study, we generated endothelial-specific prmt1-knockout (Prmt1-ECKO) mice, and found that they died before embryonic day 15. The superficial temporal arteries in these embryos were poorly perfused with blood, and whole-mount 3D imaging revealed dilated and segmentalized luminal structures in Prmt1-ECKO fetuses in comparison with those of controls. Our findings provide evidence that PRMT1 is important for embryonic vascular formation.