Matsubara N, Yanagisawa M, Nishimune Y, Obinata M, Matsui Y
Department of Cell Biology, Tohoku University, Sendai, Japan.
Mol Reprod Dev. 1995 Aug;41(4):407-15. doi: 10.1002/mrd.1080410403.
To identify key molecules that regulate germ cell proliferation and differentiation, we have attempted to isolate protein kinase genes preferentially expressed in germ line cells. One such cDNA cloned from murine embryonic germ(EG) cells encodes a nonreceptor type serine/threonine kinase and is predominantly expressed in the testis, ovary, and spleen of adult mouse. The nucleotide sequence of the entire coding regions shows that this clone, designated Plk1(polo like kinase 1), is identical with STPK13 previously cloned from murine erythro-leukemia cells. The protein encoded by Plk1 is closely related to the product of Drosophila polo that plays a role in mitosis and meiosis. To define the role of Plk1 in germ cell development, we have examined its expression in murine gonads by in situ hybridization. Here we show that the Plk1 gene is specifically expressed in spermatocytes of diplotene and diakinesis stage, in secondary spermatocytes, and in round spermatids in testes. It is also expressed in growing oocytes and ovulated eggs. The pattern of expression of the Plk1 gene suggests that the gene product is involved in completion of meiotic division, and like the Drosophila polo protein, is a maternal factor active in embryos at the early cleavage stage.
为了鉴定调控生殖细胞增殖和分化的关键分子，我们试图分离在生殖系细胞中优先表达的蛋白激酶基因。从鼠胚胎生殖（EG）细胞克隆的一个这样的cDNA编码一种非受体型丝氨酸/苏氨酸激酶，并且在成年小鼠的睾丸、卵巢和脾脏中主要表达。整个编码区的核苷酸序列表明，这个名为Plk1（类polo激酶1）的克隆与先前从鼠红白血病细胞克隆的STPK13相同。Plk1编码的蛋白质与果蝇polo的产物密切相关，后者在有丝分裂和减数分裂中起作用。为了确定Plk1在生殖细胞发育中的作用，我们通过原位杂交检测了它在鼠性腺中的表达。在这里我们表明，Plk1基因在双线期和终变期的精母细胞、次级精母细胞以及睾丸中的圆形精子细胞中特异性表达。它也在生长中的卵母细胞和排卵的卵子中表达。Plk1基因的表达模式表明，该基因产物参与减数分裂的完成，并且与果蝇polo蛋白一样，是在早期卵裂阶段胚胎中起作用的母体因子。
