PKCdelta and Salivary Gland Apoptosis

描述（由申请人提供）：了解细胞凋亡在唾液腺细胞中是如何调节的，对于开发保护唾液腺免受辐射诱导的损伤的治疗剂和治疗舍格伦综合征、唾液肿瘤和细胞凋亡改变可能导致的其它疾病是至关重要的。丝氨酸/苏氨酸蛋白激酶的信号转导在各种刺激诱导的细胞凋亡中起着重要作用。我们以前已经表明，在腮腺在体内的PKC 4的损失提供了对3-辐射诱导的细胞凋亡的保护。我实验室的长期目标是了解蛋白激酶C（PKC）如何调节细胞凋亡，并利用这些信息开发治疗策略来调节唾液腺细胞凋亡。我们以前已经表明，PKC 4的核保留是必要的，足以诱导细胞凋亡，并确定了核输入所需的PKC 4的C-末端核定位序列（NLS）。我们最近还发现了一个聚脯氨酸结合位点（PxxP），与NLS重叠，并调节PKC 4的核靶向。凋亡细胞中PKC 4的核滞留也需要调节结构域中关键酪氨酸残基的磷酸化，这表明PKC 4的磷酸化/去磷酸化起着促进细胞存活或细胞死亡的开关的作用。我们推测，磷酸化的酪氨酸激活其促凋亡功能，通过靶向细胞核，并在核的进口和出口的水平上调节核保留的PKC 4。我们目前的研究将集中在确定调控凋亡细胞中PKC 4核滞留的分子机制上，目的是确定合理的分子治疗靶点。在本申请中，我们将探索使用TAT-PKC 4抑制肽在体内瞬时保护唾液腺免受辐射诱导的损伤。 公共卫生相关性：放射是头颈部癌症治疗的关键组成部分，由于这些腺体靠近放射部位，对这些患者的唾液腺的附带损伤通常是不可避免的。每年约有40，000名新患者因头颈癌放射治疗而患上唾液腺功能障碍，严重影响了这些人的口腔健康和生活质量。慢性唾液腺功能减退被认为是由于对辐射敏感细胞，特别是腮腺的浆液腺泡细胞的不可逆细胞损伤所致。我们实验室和其他实验室最近的研究表明，对唾液腺的辐射损伤通过激活凋亡途径导致细胞死亡。我们的目标是了解唾液腺细胞凋亡是如何调节辐射的反应。这些研究可能会导致新的治疗策略，以防止唾液腺损伤的发展。

DESCRIPTION (provided by applicant): Understanding how apoptosis is regulated in salivary gland cells is critical for the development of therapeutics to protect salivary glands from irradiation induced damage and for the treatment of Sjogren's syndrome, salivary tumors and other diseases to which altered apoptosis may contribute. Signal transduction by serine/threonine protein kinases plays an essential role in apoptosis induced by a variety of stimuli. We have previously shown that loss of PKC4 in the parotid gland in vivo provides protection against 3-irradiation induced apoptosis. The long-term goal of my lab is to understand how protein kinase C (PKC) regulates apoptosis and to use this information to develop therapeutic strategies to modulate apoptosis in the salivary gland. We have previously shown the nuclear retention of PKC4 is necessary and sufficient to induce apoptosis, and have identified a C-terminal nuclear localization sequence (NLS) in PKC4 required for nuclear import. We have also recently discovered a polyproline binding site (PxxP) that overlaps with the NLS and that regulates nuclear targeting of PKC4. Nuclear retention of PKC4 in apoptotic cells also requires phosphorylation on key tyrosine residues in the regulatory domain, suggesting that phosphorylation/dephosphorylation of PKC4 functions as a switch to promote cell survival or cell death. We hypothesize that phosphorylation of PKC4 on tyrosine activates its pro-apoptotic function by targeting it to the nucleus, and that nuclear retention of PKC4 is regulated both at the level of both nuclear import and export. Our current studies will focus on identifying the molecular mechanisms that regulate nuclear retention of PKC4 in apoptotic cells, with the goal of identifying rational targets for molecular therapy. In this application we will explore the use of TAT-PKC4 inhibitory peptides to transiently protect the salivary gland from irradiation induced damage in vivo. PUBLIC HEALTH RELEVANCE: Radiation is a key component in the treatment of head and neck cancer, and collateral damage to the salivary glands is often inevitable in these patients due to the proximity of these glands to the radiation site. Each year approximately 40,000 new patients suffer from salivary gland dysfunction as a result of radiation therapy for head and neck cancer, significantly impacting the oral health and quality of life of these individuals. Chronic diminished salivary gland function is thought to result from irreversible cell damage to radiation sensitive cells, particularly the serous acinar cells of the parotid. Recent studies from our lab and others indicate that radiation damage to the salivary glands results in cell death via activation of apoptotic pathways. Our goal is to understand how salivary gland apoptosis is regulated in response to irradiation. These studies may lead to the development of novel therapeutic strategies to protect against salivary gland damage.