ROLE OF PKC IN CELL TURNOVER IN THE MAMMARY GLAND

乳腺的发育和退化是一个复杂的过程，部分是通过细胞增殖和凋亡的动态变化来调节的。在乳腺中，细胞凋亡有助于导管发育，并且对于哺乳后退化期间乳腺上皮细胞的清除是必不可少的。蛋白激酶C δ（PKC δ）是丝氨酸/苏氨酸激酶的PKC家族的普遍表达的同种型，并且小鼠敲除的分析 PKC δ的表达表明该亚型调节细胞增殖和凋亡。我们的研究表明，PKC δ的功能在凋亡途径的早期，我们最近已经确定信号转导和转录激活因子1（STAT 1）作为PKC δ在凋亡细胞的下游目标。PKC δ对于用细胞因子和干扰素处理的细胞中的STAT 3活化也是必需的。在乳腺中，乳腺需要STATS 妊娠期间的发育，而STATS协调乳腺退化。PKC δ在上皮细胞凋亡中的中心作用，连同PKC 5和STAT激活之间的联系，表明PKC δ可能对乳腺稳态至关重要。在本研究中，我们将使用PKC δ基因被破坏的小鼠（deltaKO小鼠）和原发性乳腺癌小鼠（p53）来探索PKC δ在乳腺发育和退化中的作用。 来自野生型和deltaKO小鼠的乳腺上皮细胞。在目的1中，我们将检验体内PKC δ缺失导致退化抑制或延迟并可能导致乳腺发育异常的假设。我们将确定PKC δ基因敲除（deltaKO）小鼠的乳腺发育和/或退化是否改变，deltaKO小鼠的乳腺表型是否是组织自主的，以及PKC δ基因敲除小鼠的乳腺表型是否重建。 可以逆转表型。在目标2中，我们将探讨PKC δ调节乳腺上皮细胞凋亡的分子机制，我们将测试的假设，PKC δ是所需的催乳素和IL 6家族细胞因子的下游信号转导。我们将探讨PKC δ对与退化相关的凋亡刺激的反应，并确定PKC δ的功能结构域，这些结构域是细胞凋亡和退化所必需的。 细胞凋亡。我们将确定来自deltaKO小鼠的MEC是否对这些刺激诱导的细胞凋亡具有抗性，并探索这种抗性的分子机制。这些研究将加深我们对调控乳腺发育和退化的信号转导通路的理解。

Mammary gland development and involution are complex processes which are regulated in part through dynamic changes in cell proliferation and apoptosis. In the mammary gland apoptosis contributes to ductal development and is essential for the clearance of mammary epithelial cells during post-lactational involution. Protein kinase Cdelta (PKCdelta) is a ubiquitously expressed isoform of the PKC family of serine/threonine kinases, and analysis of the mouse knock-out of PKCdelta suggests that this isoform regulates both cell proliferation and apoptosis. Our studies indicate that PKCdelta functions early in the apoptotic pathway and we have recently identified Signal Transducer and Activator of Transcription 1 (STAT1) as a downstream target of PKCdelta in apoptotic cells. PKCdelta is also essential for STAT3 activation in cells treated with cytokines and interferon. In the mammary gland, STATS is required for mammary gland development during pregnancy, while STATS orchestrates mammary gland involution. The central role PKCdelta plays in epithelial cell apoptosis, together with the link between PKC5 and STAT activation, suggests that PKCdelta may be critical for mammary gland homeostasis. In this proposal we will explore the role of PKCdelta in mammary gland development and involution using mice in which the PKCdelta gene has been disrupted (deltaKO mice) and primary mammary epithelial cells derived from wild type and deltaKO mice. In Aim 1 we will test the hypothesis that loss of PKCdelta in vivo result in suppression or delay of involution and may result in abnormal mammary gland development. We will determine if mammary gland development and/or involution are altered in PKCdelta knock-out (deltaKO) mice, if the mammary gland phenotype in the deltaKO mice is tissue autonomous, and if reconstitution of PKCdelta can reverse the phenotype. In Aim 2 we will explore the molecular mechanisms by which PKCdelta regulates mammary epithelial cell apoptosis, and we will test the hypothesis that PKCdelta is required for signal transduction downstream of prolactin and the IL6 family cytokines. We will explore PKCdelta activation in response to apoptotic stimuli relevant to involution and determine the functional domains of PKCdelta that are required for apoptosis in MECs. We will determine if MECs from deltaKO mice are resistant to apoptosis induced by these stimuli and explore the molecular mechanism which underlies this resistance. The proposed studies will enhance our understanding of the signal transduction pathways which regulate mammary gland development and involution.