Salivary Acinar Cell Apoptosis: Regulation of p53 by Akt

描述(申请人提供)：细胞凋亡在哺乳动物发育中起着至关重要的作用，存在复杂的控制机制来调节这些信号通路。头颈部放疗、化疗药物或干燥综合征的继发性副作用可导致唾液腺的异常细胞凋亡。P53是DNA损伤诱导细胞凋亡的重要调节因子。两个p53同源物p73和p63的鉴定，以及这些不同的同源物选择性地激活凋亡靶基因，增加了理解如何执行细胞凋亡决定的复杂性。P53应答基因Bax和Fas在干燥综合征患者的泪腺和唾液腺中的表达增加，P53被认为与自身免疫性疾病的发病机制有关。 这项建议的总体目标是了解唾液腺泡细胞中P53反应基因的诱导以及促生存的丝氨酸/苏氨酸蛋白激酶Akt对这一活性的调节。具体地说，Akt在DNA损伤后抑制细胞凋亡中的作用以及与P53蛋白家族的相互作用将被研究。我们推测Akt通过调控P53转录因子家族抑制DNA损伤诱导的细胞凋亡。具体目标1将确定Akt抑制伽玛射线诱导的唾液腺细胞凋亡的体内机制。特定目标2将确定在伽玛射线诱导的唾液腺细胞凋亡中对P53转录激活的要求。具体目标3将检测唾液腺泡细胞中p73活性的诱导以及激活Akt对其抑制的影响。具体目标4将研究p63在唾液腺泡细胞中的功能以及Akt调节这些功能的能力。从小鼠分离的原代培养的颌下腺或腮腺腺泡细胞提供了一个独特的环境来检测细胞凋亡的调节。此外，一种表达激活Akt的转基因小鼠品系已被用作一种新的试剂，用于了解各种刺激对唾液腺泡细胞凋亡的抑制作用。对P53调控的基本生物学过程的新认识可能会对唾液腺的临床治疗产生重大影响。

DESCRIPTION (provided by applicant): Apoptosis plays a crucial role in mammalian development and complex control mechanisms exist to regulate these signaling pathways. Aberrant apoptosis of the salivary glands is induced by secondary side effects of head and neck irradiation, chemotherapeutics, or Sjogren's syndrome. p53 is an important regulator of apoptosis induced by DNA damage. The identification of two p53 homologues, p73 and p63, along with the selective activation of apoptotic target genes by these different homologues have added additional complexity in the understanding of how the decision to undergo apoptosis is executed. Increased expression of the p53 responsive genes bax and Fas has been shown in the lacrimal and salivary glands of Sjogren's syndrome patients and p53 is hypothesized to be associated in the pathogenesis of autoimmune disorders. The general goal of this proposal is to understand the induction of the p53 responsive genes in salivary acinar cells and regulation of this activity by the pro-survival serine/threonine protein kinase Akt. Specifically, the role Akt serves in suppressing apoptosis following DNA damage and the interaction with the p53 family of proteins will be examined. We hypothesize that Akt suppresses DNA damage induced apoptosis through a modulation of the p53 family of transcription factors. Specific Aim 1 will define the in vivo mechanisms by which Akt suppresses gamma-irradiation-induced apoptosis in the salivary gland. Specific Aim 2 will identify the requirement for p53 transcriptional activation in gamma-irradiation-induced salivary gland apoptosis. Specific Aim 3 will examine the induction of p73 activity in salivary acinar cells and the effect of its suppression by activated Akt. Specific Aim 4 will investigate the functions of p63 in salivary acinar cells and the ability of Akt to regulate these functions. Transiently cultured primary submandibular or parotid acinar cells isolated from mice provide a unique environment to examine the regulation of apoptosis. In addition, a transgenic mouse strain that expresses activated Akt has been used as a novel reagent in understanding the suppression of apoptosis induced by a variety of stimuli in salivary acinar cells. New understanding of the fundamental biological process of p53 regulation could have a powerful impact on clinical therapeutics for salivary glands.