Comparison of histone modifications in in vivo and in vitro fertilization mouse embryos

Histone modifications are thought to play important roles in various cellular functions. In this article, the distribution patterns of acetylation on histone H4, methylation on histone H3 lysine 9, and phosphorylation on histone H3 serine 10 were examined in in vivo and in vitro fertilization (IVF) preimplantation mouse embryos by using indirect immunofluorescence and scanning confocal microscopy. We desired to know whether the IVF, which has been widely used as a routine assisted reproductive technology in animal and human, was safe at the epigenetic level. As results, we found that there was no difference in these histone modification patterns in in vivo and IVF mouse embryos from zygote to blastocyst stage. Moreover, these histone modifications had different distributions at all examined stages, but they were consistent with the mouse embryo developmental stages.     

Preliminary study on a potential antibacterial peptide derived from histone H2A in hemocytes of scallop Chlamys farreri

Histone H2A is reported to participate in host defense response through producing novel antimicrobial peptides (AMPs) from its N-terminus in vertebrates and invertebrates, while the AMPs derived from H2A have not to our knowledge been reported in mollusca. In the present study, gene cloning, mRNA expression of H2A from scallop Chlamys farreri, and the recombinant expression of its N-terminus were conducted to investigate whether a similar mechanism exists in mollusca. The full-length DNA of H2A was identified by the techniques of homology cloning and genomic DNA walking. The full-length DNA of the scallop H2A was 696bp long, including a 5'-terminal untranslated region (UTR) of 90bp, a 3'-terminal UTR of 228bp with a stem-loop structure and a canonical polyadenylation signal sequence AATAAA, and an open reading frame of 375bp encoding a polypeptide of 125 amino acids. The mRNA expression of H2A in the hemocytes of scallop challenged by microbe was measured by semi-quantitative RT-PCR. The expression of H2A was not upregulated after stimulation, suggesting that H2A did not participate in immunity response directly. The DNA fragment of 117bp encoding 39 amino acids corresponding to the N-terminus of scallop H2A, which was homologous to buforin I in vertebrates, was cloned into Pichia pastoris GS115. The transformants (His(+) Mut(+)) containing multi-copy gene insertion were selected with increasing concentration of antibiotic G418. The peptide of 39 amino acids was expressed by induction of 0.5% methanol. The recombinant product exerted antibacterial activity against both Gram-positive (G(+)) and Gram-negative (G(-)) bacteria. The antibacterial activity toward G(+) bacteria was 2.5 times more than that against G(-) bacteria. The results elucidated that N-terminus of H2A was a potential AMP and provided a promising candidate for a new antibiotic screening. However, whether H2A is really involved in scallop immune response mechanisms needs to be further investigated.     

The nuclear proteasome and the degradation of oxidatively damaged proteins

Summary. The accumulation of oxidized proteins is known to be linked to some severe neurodegenerative diseases like Alzheimer’s, Parkinson’s and Huntington’s disease. Furthermore, the aging process is also accompanied by an ongoing aggregation of misfolded and damaged proteins. Therefore, mammalian cells have developed potent degradation systems, which selectively degrade damaged and misfolded proteins. The proteasomal system is largely responsible for the removal of oxidatively damaged proteins form the cellular environment. Not only cytosolic proteins are prone to oxidative stress, also nuclear proteins are readily oxidized. The nuclear proteasomal system is responsible for the degradation of these proteins. This review is focused on the specific degradation of oxidized nuclear proteins, the role of the proteasome in this process and the regulation of the nuclear proteasomal system under oxidative conditions.     

Mass spectrometric analysis of protein histidine phosphorylation

Summary. Protein histidine phosphorylation is now recognized as an important form of post-translational modification. The acid-lability of phosphohistidine has meant that this phosphorylation has not been as well studied as serine/threonine or tyrosine phosphorylation. We show that phosphohistidine and phosphohistidine-containing phosphopeptides derived from proteolytic digestion of phosphohistone H4 are detectable by ESI-MS. We also demonstrate reverse-phase HPLC separation of these phosphopeptides and their detection by MALDI-TOF-MS.     

组蛋白去甲基化酶KDM7家族在脑疾病中研究进展

组蛋白去甲基化酶KDM7家族包括KDM7A、KDM7B、KDM7C三种蛋白,主要通过去除与转录沉默相关的特定组蛋白赖氨酸甲基化修饰,进而对基因转录发挥调控作用。目前,对KDM7家族的研究主要集中于其在神经分化、肿瘤发生发展等过程中的作用,而对其在脑神经疾病中的作用却知之甚少。本文从该蛋白家族表观遗传调控机制、结构生物学及其在脑神经疾病中的作用等方面进行了综述,以期为研究其在脑神经疾病中的功能机制提供参考,为理解脑神经疾病分子病理机制以及探索基于该机制的有效治疗靶点带来新的启示。