Genes Ancestral To The Thyroid/steroid Receptor Family

我们正在研究无脊椎动物的核激素受体。CHR3是一种核激素受体，对线虫的发育很重要(1，2)，在我们继续研究CHR3的工作中，我们寻找了相互作用的辅助因子。 我们进行了RNA干扰实验，以抑制我们通过与已知辅因子同源性确定的基因，并寻找类似于CHR3功能丧失的表型变化。 我们发现，抑制线虫Skip(CeSKIP)会导致与CHR3部分重叠的表型变化。Skip是一种辅因子，存在于Notch、TGFbeta和维生素D受体等多种调控通路中，在植物、酵母和动物中都是保守的。CeSKIP对线虫的生存和发展至关重要。我们的结果还表明，尽管RNA Pol II C末端结构域(CTD)被磷酸化，但CeSKIP RNAi胚胎停滞，其表型类似于RNA Pol II活性丧失，并且不表达多个胚胎GFP报告基因和一个内源基因(dpy-7)。我们还发现线虫SKIP与BIR-1共转录，BIR-1是一种与哺乳动物生存同源的凋亡抑制物(3)。由于组织在操纵子中的基因通常在功能上是相连的，我们一直在研究BIR-1是否除了在细胞分裂中的已知功能外，还在RNA聚合酶II的转录调控中发挥作用。 我们发现BIR-1具有发育调节作用，其功能丧失与CeSKIP和CHR3有部分重叠的表型。我们还发现，由于BIR-1功能丧失，一些转基因以及内源dpy-7受到抑制。BIR-1在包括甲状腺激素受体β1在内的异源基因导入系统中作为共激活剂。 我们目前正在努力寻找BIR-1通过RNA聚合酶II影响转录的机制。

We are studying nuclear hormone receptors in invertebrates. In continuation of our work on CHR3, a nuclear hormone receptor that is important for C. elegans development (1,2), we searched for interacting cofactors. We performed RNA interference experiments directed to inhibit genes that we identified by homology to known cofactors and searched for phenotypic changes similar to CHR3 loss of function. We found that inhibition of C.elegans SKIP (CeSKIP)leads to phenotypic changes partially overlapping with CHR3. SKIP is a cofactor identified in multiple regulatory pathways such as Notch, TGFbeta and vitamin D receptor, and is conserved between plants, yeast and animals. CeSKIP is essential for C. Elegans viability and development. Our results also showed that despite phosphorylation of the RNA Pol II C-terminal domain (CTD), CeSKIP RNAi embryos arrest with a phenotype similar to the loss of RNA Pol II activity and fail to express multiple embryonic GFP reporter genes, as well as an endogenous gene (dpy-7). We also found that C. elegans SKIP is co-transcribed with bir-1, an inhibitor of apoptosis that is homologeous to mammalian Surviving (3). Because genes organized in operons are often linked functionally, we have been studying if bir-1 has beyond its known function in cell division, also a role in regulation of transcription by RNA polymerase II. We found that bir-1 has a developmental regulatory role and its loss of function has partially overlapping phenotype with CeSKIP and CHR3. We also found, that several transgenes as well as endogenous dpy-7 are inhibited as consequence of bir-1 loss of functiion. bir-1 acts as co-activator in a heterologus transfection system including thyroid hormone receptor beta 1. We are currently trying to find the mechanism by which Bir-1 influences transcription by RNA polymerase II.