Immunochemical localization of myosin heavy chain isoforms and paramyosin in developmentally and structurally diverse muscle cell types of the nematode Caenorhabditis elegans.

Abstract

Abstract. The nematode Caenorhabditis elegans contains two major groups of muscle cells that exhibit organized sarcomeres: the body wall and pharyngeal muscles. Several additional groups of muscle cells of more limited mass and spatial distribution include the vulval muscles of hermaphrodites, the male sex muscles, the anal-intestinal muscles, and the gonadal sheath of the hermaphrodite. These muscle groups do not exhibit sarcomeres and therefore may be considered smooth. Each muscle cell has been shown to have a specific origin in embryonic cell lineages and differentiation, either embryonically or postembryonically (Sulston, J. E., and H. R. Horvitz. 1977. Dev. Biol. 56:110-156; Sulston, J. E., E. Schierenberg, J. White, and J. N. Thomson. 1983. Dev. Biol. 100:64-119). Each muscle type exhibits a unique combination of lineage and onset of differentiation at the cellular level.Biochemically characterized monoclonal antibodies to myosin heavy chains A, B, C, and D and to paramyosin have been used in immunochemical localization experiments. Paramyosin is detected by immunofluorescence in all muscle cells. Myosin heavy chains C and D are limited to the pharyngeal muscle cells, whereas myosin heavy chains A and B are localized not only within the sarcomeres of body wall muscle cells, as reported previously, but to the smooth muscle cells of the minor groups as well. Myosin heavy chains A and B and paramyosin proteins appear to be compatible with functionally and structurally distinct muscle cell types that arise by multiple developmental pathways.

Structural components of the nonstriated contractile apparatuses in the Caenorhabditis elegans gonadal myoepithelial sheath and their essential roles for ovulation

“…As reported previously (Ardizzi and Epstein, 1987), MYO-3 myosin heavy chain A (myoA; Fig. 2A-C) and UNC-15 paramyosin ( Fig.…”

“…Previous studies by others have shown that the myoepithelial sheath cells express MYO-3 (myoA; Fig. 4A-C) and UNC-54 (myoB) myosin heavy chains (Ardizzi and Epstein, 1987) that are also expressed in the striated body wall muscle and that UNC-54 localizes to the outer regions, whereas MYO-3 is limited to the central part of the thick filaments (Rose et al, 1997) as observed in the thick filaments in the striated body wall muscle (Miller et al, 1983). UNC-15 paramyosin was also expressed in the myoepithelial sheath (Ardizzi and Epstein, 1987;Fig.…”

“…UNC-15 paramyosin was also expressed in the myoepithelial sheath (Ardizzi and Epstein, 1987;Fig. 4D-F).…”

“…The proximal sheath cells (pairs 3-5; Fig. 1) are smooth musclelike cells with distinct thin and thick filaments and designated as the myoepithelial sheath (Hirsh et al, 1976;Strome, 1986;Ardizzi and Epstein, 1987;Hall et al, 1999). Contraction of the myoepithelial sheath is periodically enhanced upon maturation of the most proximal oocytes (McCarter et al, 1997(McCarter et al, , 1999.…”

“…The myoepithelial sheath cells express MYO-3 and UNC-54 myosin heavy chains (Ardizzi and Epstein, 1987), which are also expressed in striated body wall muscle (Miller et al, 1983). Ovulation is perturbed by disturbing functions of several structural proteins, including MUP-2 troponin T (Myers et al, 1996), PAT-10 troponin C (Ono and Ono, 2004), LEV-11 tropomyosin (Ono and Ono, 2004), PAT-3 ␤-integrin , talin (Cram et al, 2003), PAT-4 integrin-linked kinase (Xu et al, 2006), and UNC-112 Mig-2 (Xu et al, 2006).…”