Role of Prostaglandins & Phospholipase A in melanocytes

描述(申请人提供)：我们实验室的长期目标是确定人类黑素细胞(HM)树突和黑素小体(MS)转移的分子介体和信号中间体。前列腺素(PG)是角质形成细胞在紫外线照射后释放的脂质信号分子。我们的全球假设是PG通过UVR增加的特定PG受体的作用来刺激HM的色素沉积。我们认为这些受体(EP1、EP3和FP)激活RAC/CDC42和或抑制Rho，我们在第一个资助期已经证明了这一点介导了HM的树突性和MS的转移。自从这项修订提案提交以来，我们已经确定了HM中PGE2和PGF2受体的分布，确定了哪些PG受体介导了HM的树突性&显示了PGF2受体(FP)在HM树突性和色素沉着中的特别重要作用。新的数据表明，分泌型磷脂酶(SPLA2)-X通过释放溶血磷脂(LPL)溶血磷脂酰胆碱来调节HM树突和色素沉着。前两个目标将定义介导PG依赖的树突性和MS转移的信号中间体，并将分析UVR和旁分泌/自分泌因子对PG受体的调节。将检测HM在体内皮肤中的受体表达和UVR对其的调节，并对HM产生的PG进行鉴定。根据新的初步数据，我们假设sPLA2(S)对HM的作用主要不是通过依赖花生四烯酸的PG产生介导的，而是通过LPL对HM的受体或非受体依赖性作用介导的。在第三个目标中，我们将定义sPLA2和LPL&由分泌型磷脂酶活性产生的脂肪酸对HM树突和MS转移的影响，并将确定介导这一效应的潜在受体。最后，我们将研究胞浆磷脂酶A2(CPLA2)对HM的作用以及UVR对其潜在的调节作用。我们假设PG和磷脂酶通过不同的机制刺激HM树突、MS转移和色素沉积，这些机制协同作用调节UVR后皮肤的色素沉积。

DESCRIPTION (provided by applicant): The long-term goal of our laboratory is to define the molecular mediators and signaling intermediates of human melanocyte (HM) dendricity & melanosome (MS) transfer. Prostaglandins (PG) are lipid signaling molecules released by keratinocytes in response to UVR. Our global hypothesis is that PG stimulate HM pigmentation through the action of specific PG receptors that are increased by UVR. We propose that these receptors (EP1, EP3 and FP) activate Rac/Cdc42 and or inhibit Rho, which we have shown in the first funding period mediate HM dendricity and MS transfer. Since submission of this revised proposal we have defined the profile of PGE2 & PGF2_ receptors in HM, have identified which PG receptors that mediate HM dendricity & have shown a particularly important role for the PGF2_ receptor (FP) in HM dendricity and pigmentation. New data indicate that secretory phospholipase (sPLA2) -X modulates HM dendricity and pigmentation through the release of the lysophospholipid (LPL) lysophosphatidylcholine. The first two aims will define signaling intermediates that mediate PG-dependent dendricity, and MS transfer and will analyze PG receptor regulation by UVR and paracrine/autocrine factors. Receptor expression in HM in skin in vivo and regulation by UVR will be examined & identification of PG produced by HM will be analyzed. Based on new preliminary data, we hypothesize that effects of sPLA2(s) on HM are not mediated primarily by arachidonic acid-dependent PG production but rather through receptor or non-receptor dependent action of LPL on HM. In the third aim we will define effects of sPLA2 & LPL & fatty acids resulting from secretory phospholipase activity on HM dendricity and MS transfer, and will identify potential receptors that mediate this effect. Finally, we will examine the function of cytosolic PLA2 (cPLA2) on HM and its potential regulation by UVR. We hypothesize that PG and phospholipases stimulate HM dendricity, MS transfer & pigmentation through different mechanisms that act synergistically to modulate cutaneous pigmentation following UVR.