Londos C, Brasaemle D L, Gruia-Gray J, Servetnick D A, Schultz C J, Levin D M, Kimmel A R
Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-2715, USA.
Biochem Soc Trans. 1995 Aug;23(3):611-5. doi: 10.1042/bst0230611.
For several reasons it seems reasonable to suspect that perilipins participate in lipid hydrolysis. First, they are located at the lipid droplet surface, the presumed site of HSL and cholesteryl esterase action. Secondly, they are polyphosphorylated by PKA in concert with lipid hydrolysis. Finally, these proteins appear to be expressed primarily, if not solely, in adipocytes and steroidogenic cells, cells in which lipid hydrolysis is stimulated by cyclic AMP and mediated by HSL or cholesteryl esterase(s), whereas other cells that contain abundant neutral lipid depositions contain no perilipin [13]. Interestingly, these closely related hydrolases share no homology with other mammalian lipases [3]. Although such attributes provide a link between perilipin and lipid hydrolysis, we have no evidence that perilipins participate directly in, or are necessary for, lipid catabolism. The basis for the strong affinity between the perilipins and neutral lipids is unknown. Clearly, lipids and perilipins are tightly linked, as evidenced by selective targeting of epitope-tagged perilipin to lipid droplets and by the paradoxical appearance of lipid droplets in pre-adipocytes transfected with a sense perilipin A construct. Indeed, in differentiating adipocytes the earliest lipid depositions are associated with perilipins, and restriction of perilipin synthesis with anti-sense constructs may impede lipid formation and deposition. It remains to be determined if, in the normal course of events, perilipins are directed toward lipid depositions or if lipids are transported to perilipin foci. Whatever the temporal sequence, the result is that neutral lipids are encased in perilipin-bounded droplets.(ABSTRACT TRUNCATED AT 250 WORDS)
基于几个原因，怀疑周脂素参与脂质水解似乎是合理的。首先，它们位于脂滴表面，这是激素敏感脂肪酶（HSL）和胆固醇酯酶作用的假定位点。其次，它们与脂质水解协同被蛋白激酶A（PKA）多磷酸化。最后，这些蛋白质似乎主要（如果不是唯一）在脂肪细胞和类固醇生成细胞中表达，在这些细胞中，脂质水解受环磷酸腺苷（cAMP）刺激并由HSL或胆固醇酯酶介导，而其他含有大量中性脂质沉积的细胞则不含周脂素[13]。有趣的是，这些密切相关的水解酶与其他哺乳动物脂肪酶没有同源性[3]。尽管这些特性在周脂素和脂质水解之间建立了联系，但我们没有证据表明周脂素直接参与脂质分解代谢或对其是必需的。周脂素与中性脂质之间强亲和力的基础尚不清楚。显然，脂质和周脂素紧密相连，这通过表位标记的周脂素选择性靶向脂滴以及用周脂素A正义构建体转染的前脂肪细胞中脂滴的矛盾出现得到证明。事实上，在分化的脂肪细胞中，最早的脂质沉积与周脂素相关，用反义构建体限制周脂素合成可能会阻碍脂质形成和沉积。在正常情况下，周脂素是被导向脂质沉积还是脂质被转运到周脂素聚集点，仍有待确定。无论时间顺序如何，结果都是中性脂质被包裹在周脂素包被的液滴中。（摘要截断于250字）
