UV-Induced Ubiquitylation of XPC Protein Mediated by UV-DDB-Ubiquitin Ligase Complex

SummaryThe xeroderma pigmentosum group C (XPC) protein complex plays a key role in recognizing DNA damage throughout the genome for mammalian nucleotide excision repair (NER). Ultraviolet light (UV)-damaged DNA binding protein (UV-DDB) is another complex that appears to be involved in the recognition of NER-inducing damage, although the precise role it plays and its relationship to XPC remain to be elucidated. Here we show that XPC undergoes reversible ubiquitylation upon UV irradiation of cells and that this depends on the presence of functional UV-DDB activity. XPC and UV-DDB were demonstrated to interact physically, and both are polyubiquitylated by the recombinant UV-DDB-ubiquitin ligase complex. The polyubiquitylation altered the DNA binding properties of XPC and UV-DDB and appeared to be required for cell-free NER of UV-induced (6-4) photoproducts specifically when UV-DDB was bound to the lesion. Our results strongly suggest that ubiquitylation plays a critical role in the transfer of the UV-induced lesion from UV-DDB to XPC

先天性血友病患者の移行期の実態

【Introduction】Congenital hemophilia is a category of hemorrhagic disease caused by a genetic defect in the production of coagulation factors. It is treated by administering regular coagulation factor injections on an ongoing basis. Hemophilia is a hereditary illness, often causing social and psychological problems as a result of the disease. To analyze the objective effects of hemophilia, we conducted a retrospective analysis in Tokushima University Hospital. 【Result】All ２３ cases were men between the ages of２０and７２. Hemophilia A was present in１７cases, and hemophilia B was present in six. Nineteen out of ２３ cases were severe, and the others were intermediate. Medical assessments were conducted at pediatrics in seven cases and hematology in １６ cases. Adoption of the self-injection technique was not realized in five cases. Seventeen cases were complicated by hemophilic arthropathy, seven with human immunodeficiency virus（HIV）, and １２ with hepatitis C virus. Eight participants were unemployed, and１７were unmarried. 【Discussion】 Many adult hemophilia patients still visit pediatrics in our hospital. Hemophilia in the period of growth between adolescence and young adulthood is often accompanied by life-altering events such as entering higher education, marriage, and work experience. Therefore, collaboration among professionals of multiple occupations, such as doctors, nurses, pharmacists, medical social workers, and clinical psychologists, is essential. Furthermore, there are many cases of HIV and hepatitis C virus infections complicating hemophilia study due to the stigma surrounding HIV-tainted blood. 【Conclusion】It is imperative that we establish a long-term, sustainable, and multi-disciplinary transitional care and medical support system for patients and their families

Functional characterization of the regulators of calcineurin in Candida glabrata

The serine-threonine-specific protein phosphatase calcineurin is a key mediator of various stress responses in fungi. Herein, we characterized functions of the endogenous regulators of calcineurin (RCNs), Rcn1 and Rcn2, in the pathogenic fungus Candida glabrata. Rcn1 exerted both inhibitory and stimulatory effects on calcineurin signaling, but Rcn2 displayed only inhibitory activity. Phenotypic analyses of C. glabrata strains lacking either RCNs, calcineurin, or both revealed that calcineurin requires Rcn1, but not Rcn2, for antifungal tolerance in C. glabrata

The glycosylphosphatidylinositol-linked aspartyl protease Yps1 is transcriptionally regulated by the calcineurin-Crz1 and Slt2 MAPK pathways in Candida glabrata.

In the pathogenic fungus Candida glabrata, the YPS1 gene, which encodes a glycosylphosphatidylinositol-linked aspartyl protease, is required for cell wall integrity and virulence. Although the expression of YPS1 has been studied in Saccharomyces cerevisiae, the transcriptional regulation of this gene in C. glabrata is not well understood. Here, we report that C. glabrata Yps1 is required for cell growth at elevated temperatures, and that the heat-induced expression of YPS1 is regulated predominantly by the calcineurin-Crz1 pathway and partially by the Slt2 MAPK pathway. Although a total of 11 YPS genes are present in the C. glabrata genome, the loss of transcriptional induction in a calcineurin mutant was observed only for YPS1. The results of a YPS1 promoter-lacZ reporter assay using a series of constructs with mutated promoter elements indicated that the transcription factor Crz1 binds to multiple sites in the promoter region of YPS1. To date, as none of the putative Crz1 targets in C. glabrata have been characterized using a Δcrz1 mutant, monitoring the expression of YPS1 represents an effective method for measuring the activity of the calcineurin-Crz1 signaling pathway in this fungus

XAB2, a novel tetratricopeptide repeat protein, involved in transcription-coupled repair and transcription.

Nucleotide excision repair is a highly versatile DNA repair system responsible for elimination of a wide variety of lesions from the genome. It is comprised of two subpathways: transcription-coupled repair that accomplishes efficient removal of damage blocking transcription and global genome repair. Recently, the basic mechanism of global genome repair has emerged from biochemical studies. However, little is known about transcription-coupled repair in eukaryotes. Here we report the identification of a novel protein designated XAB2 (XPA-binding protein 2) that was identified by virtue of its ability to interact with XPA, a factor central to both nucleotide excision repair subpathways. The XAB2 protein of 855 amino acids consists mainly of 15 tetratricopeptide repeats. In addition to interacting with XPA, immunoprecipitation experiments demonstrated that a fraction of XAB2 is able to interact with the transcription-coupled repair-specific proteins CSA and CSB as well as RNA polymerase II. Furthermore, antibodies against XAB2 inhibited both transcription-coupled repair and transcription in vivo but not global genome repair when microinjected into living fibroblasts. These results indicate that XAB2 is a novel component involved in transcription-coupled repair and transcription