Dimethylation of histone H3 lysine 9 （H3K9me2） is an important epigenetic mark associated with transcription repression. Here, we identified PHF8, a JmjC-domain-containing protein, as a histone demethylase specific for this repressing mark. Recombinant full-length wild type protein could remove methylation from H3K9me2, but mutation of a conserved histidine to alanine H247A abolished the demethylase activity. Overexpressed exogenous PHF8 was colocalized with B23 staining. Endogenous PHF8 was also colocalized with B23 and fibrillarin, two well-established nucleolus proteins, suggesting that PHF8 is localized in the nucleolus and may regulate rRNA transcription. Indeed, PHF8 bound to the promoter region of the rDNA gene. Knockdown of PHF8 reduced the expression of rRNA, and overexpression of the gene resulted in upregulation of rRNA transcript. Concomitantly, H3K9me2 level was elevated in the promoter region of the rDNA gene in PHF8 knockdown cells and reduced significantly when the wild type but not the catalytically inactive H247A mutant PHF8 was overexpressed. Thus, our study identified a histone demethylase for H3K9me2 that regulates rRNA transcription.
The aim of this study was to determine the effects of antioxidants,including α-ketoacids （α-ketoglutarate and pyruvate）,lactate and glutamate/malate combination,against oxidative stress on rat spermatozoa. Our results showed that H2O2 （250 μmol L^-1）-induced damages,such as impaired motility,adenosine triphosphate （ATP） depletion,inhibition of sperm protein phosphorylation,reduced acrosome reaction and decreased viability,could be significantly prevented by incubation of the spermatozoa with α-ketoglutarate （4 mmol L^-1） or pyruvate （4 mmol L^-1）. Without exogenous H2O2 in the medium,the addition of pyruvate （4 mmol L^-1） significantly increased the superoxide anion （O2^-·） level in sperm suspension （P≤0.01）,whereas the addition of α-ketoglutarate （4 mmol L^-1） and lactate （4 mmol L^-1） significantly enhanced tyrosine-phosphorylated proteins with the size of 95 kDa （P≤0.04）. At the same time,α-ketoglutarate,pyruvate,lactate,glutamate and malate supplemented in media can be used as important energy sources and supply ATP for sperm motility. In conclusion,the present results show that α-ketoacids could be effective antioxidants for protecting rat spermatozoa from H2O2 attack and could be effective components to improve the antioxidant capacity ofBiggers,Whitten and Whittingham media.
Shi-Feng Li Hai-Xiong Liu Yun-Bin Zhang Yuan-Chang Yan Yi-Ping Li
Amphioxus is an important animal model for phylogenetic analysis,including comparative immunology.Exploring the immune system in amphioxus contributes to our understanding of the origin and evolution of the vertebrate immune system.We investigated the amphioxus immune system using ultrastructural examination and in situ hybridization.The expression patterns of TLR1(toll-like receptor 1),C1Q(complement component 1,q subcomponent),ECSIT(evolutionarily conserved signaling intermediate in Toll pathways),SoxC,DDAHa(Dimethylarginine dimethylaminohydrolase a),and NOS(nitric oxide synthase) show that these genes play key roles in amphioxus immunity.Our results suggest that the epidermis and alimentary canal epithelium may play important roles in immune defense,while macrophages located in the coelom and so-called lymph spaces may also be crucial immune cells.
LIN YuShuangCHEN DongYanZHANG WeiCAI ZhaoPingCHEN ZhongKeZHANG NingMAO BingYuZHANG HongWei
