Nuclear sphingolipid metabolism in regulation of myogenesis

鞘磷脂(SLS)是膜的基本结构成分，为关键的 生物活性脂质，包括神经酰胺和鞘氨醇1-磷酸(S1P)。鉴于神经酰胺与 在细胞凋亡和生长停滞的情况下，S1P通常促进生存和增殖。最好的- S1P的特征靶点是定位于质膜上的S1P受体。S1P也可以在 通过结合和抑制I类组蛋白脱乙酰酶(HDAC)而使细胞核受损，组蛋白脱乙酰酶是主要的调节因子 关于基因表达的。SL信令的特征是高度划分的生成和定向 生物活性分子。对本地化S1P生产和针对血浆的深入了解 膜已被获得，但对细胞核中SL代谢的调节知之甚少。这 该项目涉及对在细胞核中产生生物活性SLS的潜在作用的蛋白质的研究。 这项工作包括分析定位于核膜(NE)的中性鞘磷脂酶，即 成肌细胞分化所必需的，这可能是核SL代谢所必需的。此组件和 其他与核SL代谢有潜在联系的酶将在培养的成肌细胞中进行分析 差异化模型。亚细胞分离和脂质组学将被用来表征这些 在成肌细胞分化过程中调节细胞核动态SL景观的蛋白质，以及在 产生包括S1P在内的生物活性SLS。此外，S1P在激活表达方面的潜在功能 将评估肌源性基因作为I类HDAC抑制配体的作用。总体而言，该项目将 研究一种假设，即核内有一种独特的SL代谢，这种代谢在 肌源性分化。这项工作与人类肌肉病理有明显的相关性，因为HDAC 在动物模型中，包括S1P在内的抑制剂已被证明可以改善肌肉营养不良。

Sphingolipids (SLs) are essential structural components of membranes and provide reservoirs for critical bioactive lipids, including ceramide and sphingosine 1-phosphate (S1P). Whereas ceramide is associated with apoptosis and growth arrest, S1P commonly promotes survival and proliferation. The best- characterized targets of S1P are S1P receptors localized to the plasma membrane. S1P also can act in the nucleus by binding to and inhibiting class I histone deacetylases (HDACs), which are major regulators of gene expression. SL signaling is characterized by highly compartmentalized generation and targeting of the bioactive molecules. Substantial insight on localized S1P production and targeting at the plasma membrane has been obtained, but little is known about regulation of SL metabolism in the nucleus. This project involves investigation of proteins with potential roles in generating bioactive SLs in the nucleus. The work includes analysis of a neutral sphingomyelinase localized to the nuclear envelope (NE) that is required for myoblast differentiation, which may be integral to nuclear SL metabolism. This component and other enzymes with potential links to nuclear SL metabolism will be analyzed in a cultured myoblast differentiation model. Subcellular fractionation and lipidomics will be used to characterize the role of these proteins in regulating the dynamic SL landscape of the nucleus during myoblast differentiation, and in producing bioactive SLs including S1P. In addition, the potential functions of S1P in activating expression of myogenic genes as an inhibitory ligand for class I HDACs will be evaluated. Overall this project will investigate the hypothesis that the nucleus houses a distinctive SL metabolism that has a major role in myogenic differentiation. The work has clear relevance to muscle pathology in humans, since HDAC inhibitors including S1P have been shown to ameliorate muscular dystrophies in animal models.