STEROL INDEPENDENT REGULATION OF HMG-COA REDUCTASE

我们已经证明，已建立的果蝇细胞系(KC细胞)是 一种可行的定义非甾体激素的实验模型 HMG-CoA还原酶(HMGR)活性的调节。KC细胞对HMGR的调控 甲伐他汀可获得性的活动。此外，目前 有证据表明，一种调节信号分子，用于抑制HMGR， 位于焦磷酸异戊烯酯(IPP)的远端。我们观察到不是简单的 HMGR抑制与总IPP通量、总中性的相关性 类异戊二烯类脂合成，或水溶性类异戊二烯磷酸酯 侧写。KC细胞似乎最小限度地转移了50%的甲氧戊酸 碳转化为n-脂肪酸和三氯乙酸不溶的最终产物。因为我们没有 KC细胞如何代谢C10/C15戊烯醇或其潜在作用 这一途径的中间产物可能在甲氧戊酸的调节中发挥作用 综上所述，为这项建议制定了两个相关的目标：(1) 确定C10/C15戊烯醇分解代谢是否与甲氧戊酸介导有关 HMG-CoA还原酶活性的调节及(2)勾画KC细胞C10/C15 戊烯醇的分解代谢，并定义这一途径的部分酶。 为了直接证明HMG-CoA变化之间的因果联系 还原酶的功能特性及其可能的后IPP调控信号 分子，还制定了一个额外的特定目的：(3)利用一种 功能性、电穿孔KC细胞模型的识别、直接评估 推测的IPP后调控信号分子，并研究其模式 行动(S)。通过KC模式实现我们的具体目标，应该 更清楚地了解类固醇非依赖的调节 甲戊酸在真核细胞中的代谢。这类信息还将 提供了一个分析甲氧戊酸介导的调节的框架 更复杂的脊椎动物细胞中类异戊二烯的合成。

We have demonstrated that an established Drosophila cell line (Kc cells) is a viable experimental model in which to define sterol independent regulation of HMG-CoA reductase (HMGR) activity. Kc cells modulated HMGR activity in response to mevalonate availability. Furthermore, current evidence suggests that a regulatory signal molecule, for HMGR suppression, was distal to isopentenyll-pyrophosphate (IPP). We observed no simple correlation between HMGR suppression and total IPP flux, total neutral isoprenoid lipid synthesis, or water soluble isoprenoid phosphate ester profile. Kc cells appeared to divert minimally 50% of their mevalonate carbon to n-fatty acids and TCA insoluble end products. Since we do not knot how Kc cells metabolize C10/C15 prenols nor the potential role intermediates from this pathway might play in the regulation of mevalonate synthesis, two related aims were developed for this proposal: (1) to determine if C10/C15 prenol catabolism was linked to mevalonate mediated modulation of HMG-CoA reductase activity and (2) to outline Kc cell C10/C15 prenol catabolism and define selected enzymes of this pathway. In order to demonstrate directly causal linkages between changes in HMG-CoA reductase's functional capacity and the putative post IPP regulatory signal molecule, an additional specific aim was formulated: (3) to utilize a functional, electroporated Kc cell model to identify, directly evaluate putative post IPP regulatory signal molecules, and investigate their mode of action(s). Realization of our Specific Aims, with the Kc model, should provide a clearer understanding of sterol-independent regulation of mevalonate metabolism by eukaryotic cells. Such information will also provide a framework in which to analyze mevalonate mediated regulation of isoprenoid synthesis in the more complex vertebrate cell.