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（L3 PSP）是卤酸脱卤酶（HAD）超家族的广泛表达的成员，其酶活性是L-丝氨酸生物合成中的不可逆和限速步骤。L-丝氨酸生物合成失调的特征在于神经系统疾病、Williams-Beuren综合征、皮肤鱼鳞病和各种上皮肿瘤。然而，L3 PSP活性改变对这些疾病的发生和病程的意义尚不清楚。我们最近确定L3 PSP的微阵列分析中改变的整合素转基因小鼠模型，易患表皮增生和皮肤炎症，表明L3 PSP可能是一个重要的调节表皮稳态。该提案的目标是定义L3 PSP在皮肤发育和表皮疾病中的作用。我们的初步研究结果表明，异位表达L3 PSP的表皮增殖层导致缺陷的毛囊形态发生，毛囊数量减少和失调的毛囊周期。我们还发现了新的L3 PSP相互作用的候选蛋白，在sumoylation途径和蛋白质介导Fas配体凋亡的功能。我们将确定L3 PSP表达在破坏毛囊生长和周期中的作用是否依赖于其磷酸酶活性，以及L3 PSP表达是否刺激表皮角质形成细胞进行凋亡。为了证明L3 PSP在L-丝氨酸生物合成之外的新作用，我们将进行生化研究以验证L3 PSP与通过酵母双杂交分析鉴定的候选蛋白之间的假定相互作用。最后，为了确定表皮稳态中对L3 PSP的需求，我们将产生缺乏L3 PSP表达的鼠和人皮肤，并测量对表皮增殖、细胞凋亡和毛囊形态发生的影响。敷设总结：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中的程序性细胞死亡途径来调节毛囊的生长和维持。在这样做的过程中，本提案中概述的研究将对毛囊生物学和上皮细胞存活产生重要影响。

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.