PROLACTIN INDUCES PHOSPHORYLATION OF TYR694 OF STAT5 (MGF), A PREREQUISITE FOR DNA-BINDING AND INDUCTION OF TRANSCRIPTION
PROLACTIN INDUCES PHOSPHORYLATION OF TYR694 OF STAT5 (MGF), A PREREQUISITE FOR DNA-BINDING AND INDUCTION OF TRANSCRIPTION
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DOI：
10.1002/j.1460-2075.1994.tb06756.x
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发表时间：
1994-09-15
期刊：
影响因子：
11.4
通讯作者：
GRONER, B
中科院分区：
文献类型：
--
作者：
GOUILLEUX, F;WAKAO, H;GRONER, B
乳腺因子（MGF）是一种最初在哺乳动物乳腺上皮细胞中发现的转录因子。它赋予催乳激素对乳蛋白基因的反应。我们最近报道了MGF基因cDNA的分离，MGF是一个新的精氨酸调节转录因子基因家族成员。该基因家族的成员介导干扰素α/β和干扰素γ诱导基因转录，以及对表皮生长因子和白细胞介素-6的应答，并已被命名为信号转导和转录激活因子（Stat）。Stat 5的名称已分配给MGF。我们研究了共转染编码Stat 5和催乳素受体的cDNA的COS细胞中Stat 5的催乳素激活机制。催乳素处理的转染细胞引起激活Stat 5在5-10分钟内。这种激活不需要进行蛋白质合成。酪氨酸激酶抑制剂防止转染COS细胞中的Stat 5活化。在体外用酪氨酸特异性蛋白磷酸酶处理重组Stat 5废除其DNA结合活性。催乳素刺激转染细胞诱导Stat 5酪氨酸磷酸化。体外转录和翻译的Stat 5与Jak 2酪氨酸激酶磷酸化，但不与fyn、林恩或lck磷酸化，赋予DNA结合活性。β-酪蛋白乳蛋白基因启动子的催乳素应答可以在用编码Stat 5和催乳素受体的长形式的cDNA载体转染的COS细胞中观察到。催乳素受体的短形式不能促进Stat 5磷酸化并在COS细胞中赋予转录诱导。Stat 5序列中694位酪氨酸残基的磷酸化对于催乳素调节是必需的。Tyr 694被苯丙氨酸残基取代可阻止酪氨酸磷酸化、DNA结合诱导和催乳素反式激活。通过催乳素受体的信号转导与细胞因子/造血细胞生成素受体基因家族的其他成员具有共同的特征，即通过酪氨酸磷酸化快速激活因子，酪氨酸磷酸化充当第二信使和转录激活剂。
Mammary gland factor (MGF) is a transcription factor discovered initially in the mammary epithelial cells of lactating animals. It confers the lactogenic hormone response to the milk protein genes. We reported recently the isolation of the cDNA encoding MGF, MGF is a novel member of the cytokine-regulated transcription factor gene family. Members of this gene family mediate interferon alpha/beta and interferon gamma induction of gene transcription, as well as the response to epidermal growth factor and interleukin-6, and have been named signal transducers and activators of transcription (Stat). The name Stat5 has been assigned to MGF. We studied the mechanisms involved in the prolactin activation of Stat5 in COS cells co-transfected with cDNA encoding Stat5 and the prolactin receptor. Prolactin treatment of the transfected cells caused activation of Stat5 within 5-10 min. This activation does not require ongoing protein synthesis. Tyrosine kinase inhibitors prevent Stat5 activation in transfected COS cells. Treatment of recombinant Stat5 with a tyrosine-specific protein phosphatase in vitro abolishes its DNA binding activity. Prolactin stimulation of transfected cells induces Stat5 phosphorylation on tyrosine. Phosphorylation of iii vitro transcribed and translated Stat5 with the Jak2 tyrosine kinase, but not with fyn, lyn or lck, confers DNA binding activity, The prolactin response of the beta-casein milk protein gene promoter can be observed in COS cells transfected with cDNA vectors encoding Stat5 and the long form of the prolactin receptor. The short form of the prolactin receptor is unable to promote Stat5 phosphorylation and confer transcriptional induction in COS cells, Phosphorylation of the tyrosine residue at position 694 in the Stat5 sequence is essential for prolactin regulation. Replacement of Tyr694 by a phenylalanine residue prevents tyrosine phosphorylation, induction of DNA binding and transactivation by prolactin. Signal transduction via the prolactin receptor shares common features with other members of the cytokine/hematopoietin receptor gene family, i.e. the rapid activation of a factor through tyrosine phosphorylation which serves as a second messenger and an activator of transcription.