title: Biogenesis of transverse tubules and triads: immunolocalization of the 1,4-dihydropyridine receptor, TS28, and the ryanodine receptor in rabbit skeletal muscle developing in situ.
abstract: Our previous immunofluorescence studies support the conclusion that the temporal appearance and subcellular distribution of TS28 (a marker of transverse (T) tubules and caveolae in adult skeletal muscle [Jorgensen, A. O., W. Arnold, A. C.-Y. Shen. S. Yuan, M. Gover, and K. P. Campbell, 1990, J. Cell Biol. 110:1173-1185]), correspond very closely to those of T-tubules forming de novo in developing rabbit skeletal muscle (Yuan, S., W. Arnold, and A. O. Jorgensen, 1990, J. Cell Biol. 110:1187-1198). To extend our morphological studies of the biogenesis of T-tubules and triads, the temporal appearance and subcellular distribution of the alpha 1-subunit of the 1,4-dihydropyridine receptor (a marker of the T-tubules and caveolae) was compared to (a) that of TS28; and (b) that of the ryanodine receptor (a marker of the junctional sarcoplasmic reticulum) in rabbit skeletal muscle cells developing in situ (day 19 of gestation to 10 d newborn) by double immunofluorescence labeling. The results presented show that the temporal appearance and relative subcellular distribution of the alpha 1-subunit of the 1,4-dihydropyridine receptor (alpha 1-DHPR) are distinct from those of TS28 at the onset of the biogenesis of T-tubules. Thus, in a particular developing myotube the alpha 1-DHPR appeared before TS28 (secondary myotubes; day 19-24 of gestation). Furthermore, the alpha 1-DHPR was distributed in discrete foci at the outer zone of the cytosol, while TS28 was confined to foci and rod-like structures at the cell periphery. As development proceeded (primary myotubes; day 24 of gestation) approximately 50% of the foci were positively labeled for both TS28 and the alpha 1-DHPR, while approximately 20 and 30% of the foci were uniquely labeled for TS28 and the alpha 1-DHPR, respectively. The foci labeled for both TS28 and the alpha 1-DHPR and the foci uniquely labeled for TS28 were generally confined to the cell periphery, while the foci uniquely labeled for the alpha 1-DHPR were mostly confined to the outer zone of the cytosol. 1-2 d after birth, TS28 was distributed in a chickenwire-like network throughout the cytosol, while the alpha 1-DHPR was confined to cytosolic foci. In contrast, the temporal appearance and subcellular distribution of the alpha 1-DHPR and the ryanodine receptor were very similar, if not identical, throughout all the stages of the de novo biogenesis of T-tubules and triads examined.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Department of Anatomy, University of Toronto, Canada.
authors.forename: S H
authors.initials: SH
authors.lastname: Yuan
authors.forename: W
authors.initials: W
authors.lastname: Arnold
authors.forename: A O
authors.initials: AO
authors.lastname: Jorgensen
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies; D015220:Calcium Channels; D005455:Fluorescent Antibody Technique; D008954:Models, Biological; D024510:Muscle Development; D009124:Muscle Proteins / Q000032:analysis / Q000378:metabolism*; D009132:Muscles / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D011817:Rabbits; D011950:Receptors, Cholinergic / Q000032:analysis / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000032:analysis / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel
chemical_list: D000906:Antibodies; D015220:Calcium Channels; D009124:Muscle Proteins; D011950:Receptors, Cholinergic; D011978:Receptors, Nicotinic; D019837:Ryanodine Receptor Calcium Release Channel