PROTEIN SER/THR KINASE PRK AND CELL CYCLE PROGRESSION

描述：（改编自研究者摘要）本提案侧重于 基于新克隆的称为“PRK”的丝氨酸-苏氨酸激酶的作用。 这 激酶与芽殖酵母cdc 5和果蝇波罗同源， 而且与先前描述的鼠激酶高度同源 fnk。 Prk很可能是鼠fnk的人类同源物。 的 已经在几个系统中研究了这种激酶的生理作用 这些工人。 具体来说，它已被发现，以提高孕酮 诱导非洲爪蟾卵母细胞减数分裂成熟， 转录本抑制它们的成熟。 它能够拯救一个 酿酒酵母的热敏cdc 5突变体。 它的细胞周期 调节已经被调查，并发现高峰期晚S和G2 阶段。 最有趣的是，它的表达被血小板生成素激活， 在MO 7 e巨核细胞和其它巨核细胞系中， 与Dami细胞的巨核分化相关。 最后 已发现定位于染色体位点8 p21，这是一个被认为 含有肿瘤抑制基因。 已经发现， 与正常组织相比，在肺肿瘤中下调。 异位 在成纤维细胞中的表达降低了生长速率， 与pRB的互动。 建议研究的目的如下：1） 检查prk是否在调节巨核细胞内有丝分裂中起作用 通过异位表达和使用反义和显性抑制进行研究 阴性突变体; 2）研究prk是否突变、缺失和/或 在自发性肺癌和乳腺癌中失活; 3）鉴定蛋白质 通过亲和纯化与PRK相互作用， 系统和表达文库体外磷酸化筛选。

DESCRIPTION: (Adapted from investigator's abstract) This proposal focuses upon the role of a newly cloned serine-threonine kinase termed "prk". This kinase is homologous to the budding yeast cdc5 and Drosophila polo and moreover is strongly homologous with the previously described murine kinase fnk. Prk is most likely to be the human homolog of the murine fnk. The physiological role of this kinase has been investigated in several systems by these workers. Specifically, it has been found to enhance progesterone induced meiotic maturation of Xenopus oocytes whereas antisense prk transcripts inhibit their maturation. It is capable of rescuing a thermosensitive cdc5 mutant of Saccharomyces cerevisiae. Its cell cycle regulation has been investigated and found to peak in the late S and G2 phases. Most interestingly, its expression is activated by thrombopoietin in MO7e megakaryocyte cells and other megakaryocytic cell lines and correlated with megakaryocytic differentiation of Dami cells. Finally, it has been found to map to chromosomal locus 8p21, a region proposed to contain tumor suppressor genes. It has been found to be commonly down-regulated in lung tumors compared to normal tissues. Ectopic expression in fibroblasts reduces growth rate and there is some indication of interaction with pRB. The objectives of the proposed studies are: 1) To examine whether prk plays a role in regulating endomitosis in megakaryocytes studied by ectopic expression and by inhibition using antisense and dominant negative mutants; 2) To investigate whether prk is mutated, deleted, and/or inactivated in spontaneous lung and breast cancers; 3) To identify proteins interacting with prk through affinity purification, the yeast two-hybrid system and in vitro phosphorylation screening of an expression library.