Myelin basic protein gene dosage effects in the PNS.
Myelin basic protein (MBP) plays an essential adhesive role in the formation of compact myelin in the central nervous system (CNS), but not in the peripheral nervous system (PNS). Morphologic data suggest that MBP controls the number of cytoplasmic channels or Schmidt-Lanterman incisures (SLI) present in PNS myelin. The levels of connexin-32 (Cx32) and myelin-associated glycoprotein (MAG), two components of the incisures, are inversely proportional to the levels of MBP in sciatic nerves of mice affected by the shiverer (shi) mutation, while protein zero (P0) and peripheral membrane protein 22 (PMP22), two structural components of compact myelin, remain constant. The levels of P0, PMP22, Cx32, and MAG mRNA do not vary in relationship to the levels of MBP. This indicates that MBP exerts its effect on Cx32 and MAG at a posttranscriptional level and suggests a new function for MBP in regulating gene expression in the PNS.
Smith-Slatas
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Department of Neurology, University of Connecticut Health Center, Farmington 06030, USA.
Barbarese
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D000818:Animals; D016375:Antisense Elements (Genetics); D017630:Connexins / Q000032:analysis / Q000235:genetics; D003593:Cytoplasm / Q000737:chemistry / Q000502:physiology; D018628:Gene Dosage; D005786:Gene Expression Regulation / Q000502:physiology; D051379:Mice; D008809:Mice, Inbred C3H; D008818:Mice, Neurologic Mutants; D004676:Myelin Basic Protein / Q000032:analysis / Q000235:genetics*; D018993:Myelin P0 Protein / Q000032:analysis / Q000235:genetics; D009185:Myelin Proteins / Q000032:analysis / Q000235:genetics; D009186:Myelin Sheath / Q000737:chemistry / Q000502:physiology*; D018992:Myelin-Associated Glycoprotein / Q000032:analysis / Q000235:genetics; D017933:Peripheral Nervous System / Q000737:chemistry / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D012583:Schwann Cells / Q000737:chemistry / Q000502:physiology; D012584:Sciatic Nerve / Q000737:chemistry / Q000502:physiology; D000097002:Gap Junction beta-1 Protein
D016375:Antisense Elements (Genetics); D017630:Connexins; D004676:Myelin Basic Protein; D018993:Myelin P0 Protein; D009185:Myelin Proteins; D018992:Myelin-Associated Glycoprotein; D012333:RNA, Messenger; D000097002:Gap Junction beta-1 Protein; C489545:Pmp22 protein, mouse