Gould R M, Freund C M, Palmer F, Feinstein D L
Department of Pharmacology, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA.
J Neurochem. 2000 Nov;75(5):1834-44. doi: 10.1046/j.1471-4159.2000.0751834.x.
The targeting of mRNAs to specific subcellular locations is believed to facilitate the rapid and selective incorporation of their protein products into complexes that may include membrane organelles. In oligodendrocytes, mRNAs that encode myelin basic protein (MBP) and select myelin-associated oligodendrocytic basic proteins (MOBPs) locate in myelin sheath assembly sites (MSAS). To identify additional mRNAs located in MSAS, we used a combination of subcellular fractionation and suppression subtractive hybridization. More than 50% of the 1,080 cDNAs that were analyzed were derived from MBP or MOBP mRNAs, confirming that the method selected mRNAs enriched in MSAS. Of 90 other cDNAs identified, most represent one or more mRNAs enriched in rat brain myelin. Five cDNAs, which encode known proteins, were characterized for mRNA size(s), enrichment in myelin, and tissue and developmental expression patterns. Two of these, peptidylarginine deiminase and ferritin heavy chain, have recognized roles in myelination. The corresponding mRNAs were of different sizes than the previously identified mRNA, and they had tissue and development expression patterns that were indistinguishable from those of MBP mRNA. Three other cDNAs recognize mRNAs whose proteins (SH3p13, KIF1A, and dynein light intermediate chain) are involved in membrane biogenesis. Although enriched in myelin, the tissue and developmental distribution patterns of these mRNAs differed from those of MBP mRNA. Six other cDNAs, which did not share significant sequence homology to known mRNAs, were also examined. The corresponding mRNAs were highly enriched in myelin, and four had tissue and developmental distribution patterns indistinguishable from those of MBP mRNA. These studies demonstrate that MSAS contain a diverse population of mRNAs, whose locally synthesized proteins are placed to contribute to myelin sheath assembly and maintenance. Characterization of these mRNAs and proteins will help provide a comprehensive picture of myelin sheath assembly.
信使核糖核酸（mRNA）靶向特定亚细胞位置被认为有助于其蛋白质产物快速、选择性地整合到可能包括膜细胞器的复合物中。在少突胶质细胞中，编码髓鞘碱性蛋白（MBP）和特定髓鞘相关少突胶质细胞碱性蛋白（MOBP）的mRNA定位于髓鞘组装位点（MSAS）。为了鉴定位于MSAS的其他mRNA，我们结合了亚细胞分级分离和抑制性消减杂交技术。在分析的1080个互补DNA（cDNA）中，超过50%来源于MBP或MOBP mRNA，这证实了该方法选择的是在MSAS中富集的mRNA。在鉴定出的其他90个cDNA中，大多数代表一种或多种在大鼠脑髓鞘中富集的mRNA。对五个编码已知蛋白质的cDNA进行了mRNA大小、在髓鞘中的富集情况以及组织和发育表达模式的表征。其中两个，即肽基精氨酸脱亚氨酶和铁蛋白重链，在髓鞘形成中具有公认的作用。相应的mRNA大小与先前鉴定的mRNA不同，并且它们的组织和发育表达模式与MBP mRNA的表达模式无法区分。另外三个cDNA识别的mRNA，其蛋白质（SH3p13、KIF1A和动力蛋白轻中间链）参与膜生物合成。尽管这些mRNA在髓鞘中富集，但其组织和发育分布模式与MBP mRNA不同。还检查了另外六个与已知mRNA没有显著序列同源性的cDNA。相应的mRNA在髓鞘中高度富集，其中四个的组织和发育分布模式与MBP mRNA无法区分。这些研究表明，MSAS包含多种mRNA，其局部合成的蛋白质有助于髓鞘组装和维持。对这些mRNA和蛋白质的表征将有助于全面了解髓鞘组装过程。
