ISSN:
0886-1544
Keywords:
fiber type
;
immunohistochemistry
;
myofibril
;
Northern blot analysis
;
radioimmunoassay
;
sarcoplasmic reticulum
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
In this study radioimmunoassay, immunohistochemistry, Northern blot analysis, and a gel overlay technique have been used to examine the level, subcellular distribution, and potential target proteins of the S100 family of calcium-modulated proteins in adult and developing rat skeletal muscles. Adult rat muscles contained high levels of S100 proteins but the particular form present was dependent on the muscle type: cardiac muscle contained exclusively S100α, slow-twitch skeletal muscle fibers contained predominantly S100α, vascular smooth muscle contained both S100α and S100β, and fast-twitch skeletal muscle fibers contained low but detectable levels of S100α and S100β. While the distribution of S100 mRNAs paralled the protein distribution in all muscles there was no direct correlation between the mRNA and protein levels in different muscle types, suggesting that S100 protein expression is differentially regulated in different muscle types. Immunohistochemical analysis of the cellular distribution of S100 proteins in adult skeletal muscles revealed that S100α staining was associated with muscle cells, while S100β staining was associated with nonmuscle cells. Radioimmunoassays of developing rat skeletal muscles demonstrated that all developing muscles contained low levels of S100α at postnatal day 1 and that as development proceeded the S100α levels increased. In contrast to adult muscle, S100α expression as confined to fast-twitch fibers in developing skeletal muscle until postnatal day 21. At postnatal day 1, developing contractile elements were S100α positive, but no staining periodicity was detectable. At postnatal day 21, S100α exhibited the same subcellular localization as seen in the adult: colocalization with the A-band and/or longitudinal sarcoplasmic reticulum. Comparison of the S100α-binding protein profiles in fast- and slow-twitch fibers of various species revealed few, if any, species- or fiber type-specific S100 binding proteins. Isolated sarcoplasmic reticulum fractions and myo fibrils contained multiple S100α-hinding proteins. The colocalization of S100α and S100α-binding proteins with the contractile apparatus and sarcoplasmic reticulum suggest that S100α may regulate excitation and/or contraction in slow-twitch fibers.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cm.970200408
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