These studies examine myelin assembly employing designs directed at intracellular processing of two integral proteins, proteolipid protein (PLP) and myelin associated glycoprotein (MAG). We will use an in vitro system of tissue slices prepared from actively myelinating murine brainstem. Different labeling protocols and specific inhibitors will be used to delineate the intracellular itinerary and the sites of co- and posttranslational modifications, specifically acylation of PLP and glycosylation of MAG. The kinetics of passage through different subcellular organelles (half-lifes and turn-over rates) will reveal whether PLP and MAG follow the same or different intracellular pathways, and whether the same or different mechanisms regulate their intracellular transport. We will employ specific inhibitors of protein glycosylation to block processing of MAG at different stages in order to determine the role of the oligosaccharide moiety in the sorting and trafficking of proteins. The dysmyelinating mouse mutant quaking which is characterized by genetic underexpression of 72p MAG and overexpression of 67p MAG polypeptides, and their abnormal glycosylation will be a useful biological probe to study the regulatory role of MAG in myelinogenesis. The aberrant MAG metabolism may be the primary disorder in quaking. We will study co- and posttranslational processing of MAG polypeptides in cellular organelles to gain insight into their metabolic relationship(s) during assembly. In addition, we will explore the possibility that the primary structure of MAG polypeptides are altered in quaking. We believe that these studies will lead to new concepts regarding the biochemical events controlling myelination. Once the mechanisms of myelin sheath formation are understood, therapies can be developed to potentiate remyelination in such diseases as multiple sclerosis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS012044-13
Application #
3394691
Study Section
Neurology C Study Section (NEUC)
Project Start
1976-05-01
Project End
1990-11-30
Budget Start
1988-12-01
Budget End
1990-11-30
Support Year
13
Fiscal Year
1989
Total Cost
Indirect Cost
Name
Medical University of South Carolina
Department
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
Chakrabarti, A K; Banik, N L; Lobo, D C et al. (1993) Calcium-activated neutral proteinase (calpain) in rat brain during development: compartmentation and role in myelination. Brain Res Dev Brain Res 71:107-13
Banik, N L; Chakrabarti, A K; Konat, G W et al. (1992) Calcium-activated neutral proteinase (calpain) activity in C6 cell line: compartmentation of mu and m calpain. J Neurosci Res 31:708-14
Bong, M; Chakrabarti, A; Banik, N et al. (1991) Differential regulation of myelin gene expression in SV40 T antigen-transfected rat glioma C6 cells. Metab Brain Dis 6:7-17
Chakrabarti, A K; Banik, N L; Powers, J M et al. (1989) The regional and subcellular distribution of calcium activated neutral proteinase (CANP) in the bovine central nervous system. Neurochem Res 14:259-66
Hsu, C Y; Halushka, P V; Spicer, K M et al. (1988) Temporal profile of thromboxane-prostacyclin imbalance in experimental spinal cord injury. J Neurol Sci 83:55-62
Chakrabarti, A K; Yoshida, Y; Powers, J M et al. (1988) Calcium-activated neutral proteinase in rat brain myelin and subcellular fractions. J Neurosci Res 20:351-8
Konat, G; Trojanowska, M; Gantt, G et al. (1988) Expression of myelin protein genes in quaking mouse brain. J Neurosci Res 20:19-22
Banik, N L; Happel, R D; Sostek, M B et al. (1987) Ca2+-mediated degradation of central nervous system (CNS) proteins: topographic and species variation. Metab Brain Dis 2:117-26
Banik, N L; Chakrabarti, A K; Gantt, G et al. (1987) Distribution of calcium-activated neutral proteinase activity in quaking mouse brain: a subcellular study. Brain Res 435:57-62
Banik, N L; Chakrabarti, A K; Hogan, E L (1987) Distribution of calcium activated neutral proteinase (mM CANP) in myelin and cytosolic fractions in bovine brain white matter. Life Sci 41:1089-95

Showing the most recent 10 out of 14 publications