Harris I R, Farrell A M, Memon R A, Grunfeld C, Elias P M, Feingold K R
Department of Veterans Affairs Medical Center and Department of Dermatology, University of California, San Francisco 94121, USA.
J Invest Dermatol. 1998 Nov;111(5):722-6. doi: 10.1046/j.1523-1747.1998.00383.x.
The epidermis has a requirement for fatty acids in order to synthesize cellular membranes and the extracellular lipid lamellar membranes in the stratum corneum. Despite high endogenous production of fatty acids the transport of exogenous essential fatty acids into the epidermis is an absolute requirement. Fatty acid uptake by keratinocytes has been shown to be mediated by a transport system. In this study we determined in murine epidermis and human cultured keratinocytes the expression of three putative fatty acid transport related proteins and fatty acyl CoA synthase, an enzyme that facilitates the uptake of fatty acids by promoting their metabolism. In cultured human keratinocytes, mRNA for fatty acid transport protein (FATP), plasma membrane fatty acid binding protein (FABP-pm), and fatty acyl CoA synthase (FACS) were detectable. Differentiation, induced by high calcium, did not affect FATP mRNA levels, but resulted in an approximately 50% increase in FACS mRNA, while decreasing FABP-pm mRNA by 50%. Fatty acid translocase (FAT) mRNA was not detected in cultured human keratinocytes. In murine epidermis, FATP, FABP-pm, FACS, and FAT mRNA were all present. Barrier disruption by either tape stripping or acetone treatment increased FAT mRNA levels by approximately 2-fold without affecting FATP, FABP-pm, or FACS. Occlusion with an impermeable membrane immediately after barrier disruption completely blocked the increase in FAT mRNA levels, indicating that this increase is related to barrier disruption rather than a nonspecific injury effect. In summary, this study demonstrates that several putative fatty acid transport related proteins as well as fatty acyl CoA synthase are expressed in keratinocytes and epidermis, and that the expression of these proteins may be regulated by differentiation and/ or barrier disruption.
表皮需要脂肪酸来合成细胞膜以及角质层中的细胞外脂质层膜。尽管脂肪酸有较高的内源性生成，但外源性必需脂肪酸向表皮的转运是绝对必要的。角质形成细胞对脂肪酸的摄取已被证明是由一个转运系统介导的。在本研究中，我们在小鼠表皮和人培养角质形成细胞中测定了三种假定的脂肪酸转运相关蛋白以及脂肪酰辅酶A合酶（一种通过促进脂肪酸代谢来促进其摄取的酶）的表达。在培养的人角质形成细胞中，可检测到脂肪酸转运蛋白（FATP）、质膜脂肪酸结合蛋白（FABP-pm）和脂肪酰辅酶A合酶（FACS）的mRNA。高钙诱导的分化不影响FATP mRNA水平，但导致FACS mRNA增加约50%，同时FABP-pm mRNA减少50%。在培养的人角质形成细胞中未检测到脂肪酸转位酶（FAT）mRNA。在小鼠表皮中，FATP、FABP-pm、FACS和FAT mRNA均存在。通过胶带剥离或丙酮处理破坏屏障后，FAT mRNA水平增加约2倍，而不影响FATP、FABP-pm或FACS。屏障破坏后立即用不可渗透膜封闭完全阻断了FAT mRNA水平的增加，表明这种增加与屏障破坏有关，而不是非特异性损伤效应。总之，本研究表明，几种假定的脂肪酸转运相关蛋白以及脂肪酰辅酶A合酶在角质形成细胞和表皮中表达，并且这些蛋白的表达可能受分化和/或屏障破坏的调节。
