Aberrant splicing of proteolipid protein mRNA in the dysmyelinating jimpy mutant mouse.

Abstract

ABSTRACTcDNA clones encoding proteolipid protein (PLP) were isolated from a mouse brain library and sequenced. We describe two transcripts arising from the PLP locus by alternative splicing: the major one encodes the 277-amino acid PLP protein and the minor one corresponds to the DM-20 protein, a PLP-like protein of 20,000 Mr that shares both amino and carboxyl regions with PLP. These two transcripts lack -70 bases in PLP mRNA from the dysmyelinating jimpy mutant. The deletion spans amino acids 208-232; however, this region is present in thejimpy PLP-encoding gene. We propose that the jimpy mutant suffers a point mutation or the deletion of a few bases in the PLP gene that alters the normal splicing pattern and generates partially deleted PLP transcripts. RESULTS AND DISCUSSIONConservation of PLP Sequence. PLP is remarkably well conserved among mouse (this report), rat (1, 16), cow (2), and human (C.P., L.D.H., and R.A.L., unpublished work) at the amino acid and nucleotide level. The protein encoded by the mouse PLP cDNA (Fig. 1) is identical to the rat (16) and human (C.P., L.D.H., and R.A.L., unpublished work) PLP and displays only two conservative amino acid differences from the bovine sequence (2). The striking degree of conserAbbreviations: PLP, proteolipid protein; MBP, myelin basic protein.

Mutation of the proteolipid protein gene PLP in a human X chromosome-linked myelin disorder.

“…1). PLP is extremely conserved within and between species both at the protein and DNA level (6,7), which is reflected in the absence of base changes between our sequence of the human PLP genomic DNA and the over 1300 bp published by Stoffel and coworkers (26) and by the scarcity of restriction fragment length polymorphisms. Moreover, no differences have been observed in the coding or noncoding regions of four unrelated individuals whose PLP gene was sequenced from a genomic library, from a cDNA library (6), or from PCR-amplified DNA (data not shown).…”

“…Analysis of dysmyelinating animal models has reinforced the hypothesis that PLP performs a unique function in glial cells in addition to its structural role in the myelin sheath. In the jimpy (jp) mouse, in which a mutation at a splice site in the PLP gene creates aberrantly spliced transcripts (7)(8)(9)(10)(11)(12), the resulting absence of PLP has pronounced effects on glial cell differentiation. Few mature oligodendrocytes are found injp CNS, despite the presence of excessive numbers of precursor cells (13,14).…”

Splice site selection in the proteolipid protein (PLP) gene transcript and primary structure of the DM-20 protein of central nervous system myelin.

“…Its primary structure has been established by protein sequencing (2)(3)(4) and more recently from the cloning of PLP cDNAs from several species (5)(6)(7)(8)(9)(10). A mutation in the mouse PLP gene is the primary genetic defect of the dysmyelinating mutant mouse jimpy (8)(9)(10)(11)(12), which demonstrates the critical role of PLP in CNS myelin assembly.…”

Growth, Adipose, Brain, and Skin Alterations Resulting from Targeted Disruption of the Mouse Peroxisome Proliferator-Activated Receptor β(δ)

“…Membranes were hybridized in ULTRAhyb hybridization buffer (Ambion, Austin, Tex.) with one of the following previously described cDNA probes: mPPAR␣ (22), mPPAR␤(␦) (2), mPPAR␥ (27), mouse myelin basic protein (MBP) (23), mouse proteolipid protein (PLP) (21), rat transglutaminase I (TG-I) (42), rat involucrin (12), small proline-rich (SPR) proteins SPR1A (25) and SPR2H (46), mouse cyclin B1 (10), mouse cyclin-dependent kinase-1 (CDK-1) (49), mouse CDK-4 (36), mouse proliferating cellular nuclear antigen (PCNA) (40), or mouse ␤-actin (31). Mouse cDNA fragments for ornithine decarboxylase (ODC), CD36, and acyl coenzyme A synthases (ACS) ACS-2 and ACS-3 were obtained by cloning as described below.…”