Conserved and divergent expression patterns of the proteolipid protein gene family in the amphibian central nervous system.
The recent discovery of a proteolipid protein gene family has revealed that its members are in fact widely distributed and are not exclusively associated with myelination. To date, three different gene products, DMalpha/DM-20/PLP, DMbeta/M6a, and DMgamma/M6b, have been isolated from certain primitive fish species, mouse, and human central nervous system (CNS). We cloned Xenopus laevis orthologues of DMbeta/M6a and DMgamma/M6b and investigated the expression patterns of these gene transcripts as well as that of PLP in developing Xenopus CNS. As is the case in shark and mouse, the mRNA encoding the major myelin integral protein, PLP, is first detected at stage 42/43 in tadpoles and is exclusively found in morphologically recognizable oligodendrocytes throughout the brain, while DMbeta mRNA is solely expressed in young presumptive neurons in the gray matter. There exist two distinct DMgamma mRNAs and, in contrast to these evolutionarily conserved expression patterns, DMgamma mRNAs distribute uniquely within the ventricular zone in young tadpoles (stage 25) through maturity. Furthermore, both DMbeta and DMgamma are expressed in the developing retina, and their distributions are different from one other. In Xenopus CNS, therefore, the expression patterns of three proteolipid proteins, PLP, DMbeta, and DMgamma, are distinct from each other, implying very different roles for their protein products within the cell populations in which they are expressed.
Yoshida
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The Brookdale Center for Biochemistry and Molecular Biology, Mount Sinai School of Medicine, New York, New York 10029, USA. yoshida@msvax.mssm.edu
Shan
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Colman
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002490:Central Nervous System / Q000033:anatomy & histology / Q000196:embryology / Q000378:metabolism*; D017124:Conserved Sequence; D004625:Embryo, Nonmammalian; D005123:Eye / Q000196:embryology / Q000378:metabolism; D017403:In Situ Hybridization; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011510:Proteolipids / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D012754:Sharks; D014982:Xenopus laevis
D011510:Proteolipids; D012333:RNA, Messenger