デグチ　アツコ   Deguchi Atsuko   出口　敦子    所属   医学研究科 医学研究科 (医学部医学科をご参照ください)    職種   教授
論文種別	原著
言語種別	英語
査読の有無	査読あり
表題	Inhibition of G1 cyclin expression in normal rat kidney cells by inostamycin, a phosphatidylinositol synthesis inhibitor.
掲載誌名	正式名：Journal Biochemistry
掲載区分	国外
巻・号・頁	120(6),pp.1118-1122
著者・共著者	Deguchi A, Imoto M, and Umezawa K.
発行年月	1996
概要	We previously reported that inostamycin, an inhibitor of CDP-DG: inositol transferase, inhibited cell proliferation in normal rat kidney (NRK) cells by blocking cell cycle progression at the G1 phase. In the present paper, we report the effect of inostamycin on the serum-induced activation of Ser/Thr protein kinases that are involved in G1 progression. In quiescent NRK cells mitogen-activated protein kinase (MAP kinase) and casein kinase II were activated within 15 min after serum addition. Neither activation was affected by the treatment with inostamycin. However, in the inostamycin-treated cell, cyclin-dependent kinase 2 (CDK2) failed to be activated after serum stimulation. Since serum-induced expression of cyclin E was also suppressed by inostamycin, this inhibitor would appear to block CDK2 activation by inhibiting cyclin E expression. Furthermore, inostamycin also inhibited cyclin D1 expression induced by serum; and consequently, hyperphosphorylation of retinoblastoma protein (pRB) by RB-kinases such as CDK4 and CDK2 was abolished, which would result in elimination of functional inactivation of pRB. Thus, early G1 arrest in NRK cells by inostamycin is due to the inhibition of cyclin D1 and E expressions.