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Roles of Caenorhabditis elegans EGL-9 in HIF-1 regulation and pathogen resistance.

【摘要】 Oxygen is critically important to metazoan life, and the EGL-9/PHD enzymes are key regulators of hypoxia (low oxygen) response. When oxygen levels are high, the EGL-9/PHD proteins hydroxylate hypoxia-inducible factor (HIF) transcription factors. Once hydroxylated, HIF&dotbelow;alpha subunits bind to von Hippel-Lindau (VHL) E3 ligases and are degraded. Prior genetic analyses in C. elegans had shown that EGL-9 also acted through a vhl-1-independent pathway to inhibit HIF-1 transcriptional activity. Here, we characterize this novel EGL-9 function. We employ an array of complementary methods to inhibit EGL-9 hydroxylase activity in vivo. These include hypoxia, hydroxylase inhibitors, mutation of the proline in HIF-1 that is normally modified by EGL-9, and mutation of the EGL-9 catalytic core. Remarkably, we find that each of these treatments or mutations eliminates oxygen-dependent degradation of HIF-1 protein, but none of them abolish EGL-9-mediated repression of HIF-1 transcriptional activity. Further, analyses of new egl-9 alleles reveal that the evolutionarily conserved MYND zinc finger domain does not have a major role in regulating HIF-1 protein stability of transcriptional activity. We conclude that C. elegans EGL-9 is a bifunctional protein. In addition to its well-established role as the oxygen sensor that regulates HIF-1 protein levels, EGL-9 inhibits HIF-1 transcriptional activity via a pathway that has little or no requirement for hydroxylase activity or for the EGL-9 MYND domain.

【作者】 Shao, Zhiyong.;

【作者单位】 Iowa State University.;

【授予单位】Iowa State University.;

【学科】Biology, Molecular.;Biology, Animal Physiology.;Biology, Genetics.

【学位】Ph.D.

【年(卷),期】2010(),

【年度】2010

【页码】143 p.

【总页数】143

【原文格式】PDF

【正文语种】eng

【中图分类】;

【关键词】;

【原文服务方】国家工程技术数字图书馆

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