Background: Orexin plays a central role in the integration of sleep/wake states and feeding behaviors. Results: Orexin neurons were induced from pluripotent stem cells by supplementation of ManNAc. Conclusion: ManNAc induced switching of epigenetic factors from Sirt1/Ogt to Mgea5 at Hcrt gene locus. Significance: This study will be useful to investigate molecular mechanism in the orexin system and development of regenerative medicine.

We report here newly discovered O-linked-N-acetylglucosamine (O-GlcNAc) modification of histone H2A at Ser40 (H2AS40Gc). The mouse genome contains 18 H2A isoforms, of which 13 have Ser40 and the other five have Ala40. The combination of production of monoclonal antibody and mass spectrometric analyses with reverse-phase (RP)-high performance liquid chromatography (HPLC) fractionation indicated that the O-GlcNAcylation is specific to the Ser40 isoforms. The H2AS40Gc site is in the L1 loop structure where two H2A molecules interact in the nucleosome. Targets of H2AS40Gc are distributed genome-wide and are dramatically changed during the process of differentiation in mouse trophoblast stem cells. In addition to the mouse, H2AS40Gc was also detected in humans, macaques and cows, whereas non-mammalian species possessing only the Ala40 isoforms, such as silkworms, zebrafish and Xenopus showed no signal. Genome database surveys revealed that Ser40 isoforms of H2A emerged in Marsupialia and persisted thereafter in mammals. We propose that the emergence of H2A Ser40 and its O-GlcNAcylation linked a genetic event to genome-wide epigenetic events that correlate with the evolution of placental animals.

BackgroundWe have previously reported a novel O-GlcNAc modification at serine 40 (S40) of H2A (H2AS40Gc). S40-type H2A isoforms susceptible to O-GlcNAcylation are evolutionarily new and restricted to the viviparous animals; however, the biological function of H2AS40Gc is largely unknown. H2A isoforms are consisted of S40 and alanine 40 (A40) type and this residue on H2A is located in the L1 of the globular domain, which is also known as a variable portion that distinguishes between the canonical and non-canonical H2A variants. In this study, by considering the similarity between the S40-type H2A and histone H2A variants, we explored the function of H2AS40Gc in mouse embryonic stem cells (mESCs).ResultsWe found several similarities between the S40-type H2A isoforms and histone H2A variants such H2AZ and H2AX. mRNA of S40-type H2A isoforms (H2A1 N and H2A3) had a poly(A) tail and was produced throughout the cell cycle in contrast to that of A40-type. Importantly, H2AS40Gc level increased owing to chemical-induced DNA damage, similar to phosphorylated H2AX (γH2AX) and acetylated H2AZ (AcH2AZ). H2AS40Gc was accumulated at the restricted area (± 1.5 kb) of DNA damage sites induced by CRISPR/CAS9 system in contrast to accumulation of γH2AX, which was widely scattered. Overexpression of the wild-type (WT) H2A3, but not the S40 to A40 mutation (S40A-mutant), protected the mESC genome against chemical-induced DNA damage. Furthermore, 3 h after the DNA damage treatment, the genome was almost recovered in WT mESCs, whereas the damage advanced further in the S40A-mutant mESCs, suggesting functions of H2AS40Gc in the DNA repair mechanism. Furthermore, the S40A mutant prevented the accumulation of the DNA repair apparatus such as DNA-PKcs and Rad51 at the damage site. Co-immunoprecipitation experiment in WT and S40A-mutant mESCs revealed that H2AS40Gc physiologically bound to AcH2AZ at the initial phase upon DNA damage, followed by binding with γH2AX during the DNA damage repair process.ConclusionsThese data suggest that H2AS40Gc functions to maintain genome integrity through the DNA repair mechanism in association with AcH2AZ and γH2AX.Electronic supplementary materialThe online version of this article (doi:10.1186/s13072-017-0157-x) contains supplementary material, which is available to authorized users.

Effect of quantity and nutritional quality of dietary proteins on the content of mRNA of insulin-like growth factor-binding protein-1 (IGFBP-1) was studied in rat liver and kidney. IGFBP-1 mRNA content per unit RNA increased in liver and kidney of rats fed on a protein-free diet and in those of fasted rats compared with that in the rats fed on a casein diet. When rats were given a gluten diet for 7 d, IGFBP-1 mRNA content in liver did not change significantly but that in kidney increased considerably compared with that in those organs of the rats fed on the casein diet. Because IGFBP-1 mRNA has been demonstrated both in Liver parenchymal and non-parenchymal cells (Takenaka et al. 1991), the effect of the protein-free diet on these two types of cells has been studied. An increase in IGFBP-1 mRNA content under protein deprivation was observed in both liver parenchymal and non-parenchymal cells, suggesting that these two types of cells are regulated in a similar mode as far as IGFBP-1 mRNA content is concerned. The physiological and nutritional significance of the previously stated results on protein anabolism are discussed when considered together with our previous observations on the plasma concentrations of IGF-1 (Takahashi et af. 1990) and IGFBP (Umezawa et af. 1991) and insulin-like growth factor-1 mRNA content in liver (Miura et af. 1991).