Studies n Functional Roles of Fatty Acid-Binding Proteins

我们从以下几个方面对细胞脂肪酸结合蛋白的功能进行了研究：(1)脂肪酸结合蛋白的膜转运机制：利用体外荧光能量转移实验，我们证明了H-脂肪酸结合蛋白和L-脂肪酸结合蛋白通过不同的机制转运到细胞膜。H-FABP中的脂肪酸是通过碰撞作用转移的，而L-FABP中的限速步骤是脂肪酸在水介质中的解离速率。(2)大鼠皮肤中的一种新的脂肪酸结合蛋白(C-FABP)：我们从大鼠皮肤中纯化了H-FABP的一个新亚型，并克隆了该蛋白。该克隆推导的氨基酸序列由15 kDa的多肽残基组成，一级结构与H-FABP家族蛋白同源。有趣的是，它有六个半胱氨酸和两个分子内二硫键存在。这是FABP超家族中首次发现的二硫键形成蛋白。这种新型FABP的三维结构可能为未来该蛋白家族的功能作用提供新的视角。(3)H-FABP在主动脉中表达的调控机制：我们分析了H-FABP在糖尿病大鼠主动脉中的表达，并提供了与H-FABP在心脏组织中的表达相比，主动脉中H-FABP基因受胰岛素特异性和唯一性调控的证据。胰岛素调节的主动脉H-FABP表达可能参与糖尿病血管并发症的发生。(4)I-FABP的临床应用：利用I-FABP仅局限于肠道组织表达的优势，我们将I-FABP作为诊断工具。我们已经证明，I-FABP在肠缺血急性期被释放到循环中。因此，血清I-FABP的测定可用于缺血性肠病的诊断。

We have studied on functional roles of cellular fatty acid-binding proteins (FABPs) in the following aspects.(1) Transfer mechanism of FABP bound-fatty acids to membranes :Using an in vitro fluorescence energy transfer assay, we presented the evidence that H-FABP and L-FABP bound-fatty acids are transferred to membranes through different mechanism. Fatty acids from H-FABP was transferred by collisional interaction, while the rate limiting step from L-FABP was the dissociation rate of fatty acids to aqueous medium.(2) A new FABP (C-FABP) from rat skin :We have purified a new subtype of H-FABP from rat skin and cloned this protein. The deduced amino acid sequence of the cDNA clone comprises residues yielding a molecular mass for the polypeptide of 15 kDa and the primary structure is homologus to H-FABP family proteins. Interestingly, it has six cysteines and two intramolecular disulfide bridges are present. This is the first presentation of disulfide formed protein among FABPs superfamily. Three dimensional structure of this new type of FABP may afford a new sight of functional roles of this protein family in the future.(3) Regulatory mechanism of H-FABP expression in aorta :We have analyzed the H-FABP expression in diabetic rat aorta and provided the evidence that the H-FABP gene in aorta is specifically and uniquely regulated by insulin when compared to the H-FABP expression in heart tissue. Insulin regulated H-FABP expression in aorta may be involved in diabetic complications of blood vessels.(4) Clinical application of I-FABP :Taking the advantage of specific expression of I-FABP limited in intestinal tissue, we have applied the I-FABP as a diagnostic tool. We have showed that the I-FABP is released into the circulation in the acute phase of intestinal ischaemia. Accordingly, the measurement of I-FABP in serum can be used in establishing the diagnosis of ischaemic intestinal diseases.