Isolation and characterization of mammalian glycerophosphodiester phosphodiesterases

细菌甘油磷酸二酯磷酸二酯酶是一种重要的胞浆蛋白，在甘油磷脂水解为甘油磷酸和乙醇的过程中起着重要的作用。相比之下，最近发现了两种新的哺乳动物GP-PDE，GDE 1和GDE 3，并显示其参与多种生理功能。GP-PDE同源物GDE 2在脑组织中广泛表达，包括，并且GDE 2在神经母细胞瘤Neuro 2A细胞中的表达在视黄酸（RA）处理的神经元分化期间显著上调。GDE 2的稳定表达导致在没有RA的情况下神经突的形成，并且GDE 2在Neuro 2A细胞的核周和生长锥区域积累。此外，通过RNAi在Neuro 2A细胞中GDE 2的功能丧失阻断了RA诱导的神经突形成。这些结果表明，GDE 2在神经元分化过程中的表达对神经突起的生长起着重要作用.本研究利用生物信息学的方法，虚拟克隆了7个哺乳动物GP-PDE。一种新的GDE，GDE 7，蛋白的疏水性分析表明，两个不同的疏水区域位于N-末端和C-末端。GDE 7在小鼠皮肤中表达，可能参与角质形成细胞的维持.预测的GDE 5蛋白质序列不包含任何跨膜序列，表明GDE 5作为胞质蛋白发挥功能。GDE 5 mRNA的表达在禁食小鼠和糖尿病KK-Ay小鼠的骨骼肌中显示出调节，但其在骨骼肌中的功能仍然知之甚少。在这项研究中，我创建了在骨骼肌中特异性过表达GDE 5的转基因小鼠。这些小鼠的骨骼肌质量减少。微阵列分析显示，转基因小鼠骨骼肌中与细胞应激相关的几个基因的表达增加。

Bacterial glycerophosphodiester phosphodiesterases are well-characterized to be periplasmic and cytosolic proteins, which play a critical role in the hydrolysis of deacylated glycerophospholipids to glycerol phosphate and alcohol. In contrast, two novel mammalian GP-PDEs, GDE1 and GDE3, were recently identified, and were shown to be involved in several physiological functions.1. A GP-PDE homolog, GDE2, was widely expressed in brain tissues including, and that the expression of GDE2 in neuroblastoma Neuro2A cells was significantly up-regulated during neuronal differentiation by retinoic acid (RA) treatment. Stable expression of GDE2 resulted in neurite formation in the absence of RA, and GDE2 accumulated at the regions of perinuclear and growth cones in Neuro2A cells. Furthermore, a loss-of-function of GDE2 in Neuro2A cells by RNAi blocked RA-induced neurite formation. These results demonstrate that GDE2 expression during neuronal differentiation plays an important role for growing neurites.2. In this study, seven mammalian GP-PDEs were virtually cloned by the approach using bioinformatics. Analysis of the hydrophobicity profile of a novel GDE, GDE7, protein indicated that two distinct hydrophobic regions are located at the N-terminus and at the C-terminus. GDE7 was expressed in mouse skin, and might be involved in the maintenance of keratinocytes.3. The predicted protein sequence of GDE5 does not contain any transmembrane sequence, suggesting that GDE5 functions as a cytosolic protein. Expression of GDE5 mRNA was shown to be regulated in skeletal muscles of fasted mice and diabetic KK-Ay mice, but its functions in skeletal muscle have remained poorly understood. In this study, I created transgenic mice specifically overexpressing GDE5 in skeletal muscle. These mice had a reduced skeletal muscle mass. Microarray analysis revealed that the expression of several genes related to cellular stress was increased in skeletal muscles of transgenic mice.