Role of L-3 phosphoserine phosphatase in epidermal apoptosis and carcinogenesis

描述（由申请人提供）：l -3-磷酸丝氨酸磷酸酶（L3PSP）是广泛表达的卤酸脱卤酶（HAD）超家族成员，其酶活性是l -丝氨酸生物合成的不可逆和限速步骤。l -丝氨酸生物合成失调是神经系统疾病、Williams-Beuren综合征、皮肤鱼鳞病和多种上皮肿瘤的特征。然而，L3PSP活性的改变在这些疾病的发生和发展过程中的意义尚不清楚。我们最近通过微阵列分析发现，在一个易发生表皮增生和皮肤炎症的整合素转基因小鼠模型中，L3PSP发生了改变，这表明L3PSP可能是表皮稳态的关键调节因子。本提案的目的是确定L3PSP在皮肤发育和表皮疾病中的作用。我们的初步结果表明，L3PSP在表皮增生层的异位表达导致毛囊形态发生缺陷，毛囊数量减少，毛囊循环失调。我们还发现了新的L3PSP相互作用候选蛋白，这些蛋白在sumo化途径中起作用，并介导Fas配体凋亡。我们将确定L3PSP表达对毛囊生长和循环中断的影响是否依赖于其磷酸酶活性，以及L3PSP表达是否刺激表皮角质形成细胞进行凋亡。为了证明L3PSP在l -丝氨酸生物合成之外的新作用，我们将进行生化研究来验证L3PSP与酵母双杂交分析确定的候选蛋白之间的相互作用。最后，为了确定表皮稳态对L3PSP的需求，我们将生成缺乏L3PSP表达的小鼠和人皮肤，并测量其对表皮增殖、凋亡和毛囊形态发生的影响。总结：总的来说，我们计划确定一种通常被认为在基本细胞氨基酸代谢中起作用的蛋白质是否也可以通过刺激皮肤细胞的程序性细胞死亡途径来调节毛囊的生长和维持。在此过程中，本提案中概述的研究将对毛囊生物学和上皮细胞存活具有重要意义。

DESCRIPTION (provided by applicant): L-3-phosphoserine phosphatase (L3PSP) is a widely expressed member of the haloacid dehalogenase (HAD) superfamily and its enzyme activity is the irreversible and rate limiting step in L-serine biosynthesis. Dysregulation of L-serine biosynthesis is featured in neurological disorders, Williams-Beuren syndrome, skin ichthyosis and a variety of epithelial neoplasms. However, the significance of altered L3PSP activity on the initiation and course of these diseases is still not clear. We recently identified L3PSP by microarray analysis to be altered in an integrin transgenic mouse model that is predisposed to epidermal hyperplasia and skin inflammation indicating that L3PSP may be a critical regulator of epidermal homeostasis. The goal of this proposal is to define the role for L3PSP in skin development and epidermal disease. Our preliminary results show that ectopic expression of L3PSP in the proliferative layer of the epidermis leads to defects in hair follicle morphogenesis, decreased hair follicle number and dysregulated hair follicle cycling. We have also uncovered novel L3PSP interaction candidate proteins that function in sumoylation pathways and proteins that mediate Fas ligand apoptosis. We will determine if the effects of L3PSP expression in disrupted hair follicle growth and cycling are dependent on its phosphatase activity and if L3PSP expression stimulates epidermal keratinocytes to undergo apoptosis. To demonstrate a new role(s) for L3PSP outside of L-serine biosynthesis we will conduct biochemical studies to validate putative interactions between L3PSP and candidate proteins identified by yeast two-hybrid analysis. Finally, to determine the requirement for L3PSP in epidermal homeostasis we will generate murine and human skin that is deficient in L3PSP expression and measure the effect on epidermal proliferation, apoptosis and hair follicle morphogenesis. Lay summary: Overall we plan to ascertain whether a protein normally thought to function in basic cellular amino acid metabolism may also regulate the growth and maintenance of hair follicles by stimulating programmed cell death pathways in skin cells. In doing so, the studies outlined in this proposal will have important implications for hair follicle biology and epithelial cell survival in general.