Tropomyosin isoforms differentially affect muscle contractility in the head and body regions of the nematodeCaenorhabditis elegans

Abstract

The nematode Caenorhabditis elegans has a single gene, lev-11, encoding multiple tropomyosin isoforms. Two seventh exons are alternatively selected in the head and body regions of muscle cells and differentially affect muscle contractility in the respective regions.

Alternative splicing of the Caenorhabditis elegans lev‐11 tropomyosin gene is regulated in a tissue‐specific manner

“…LEV-11O, which also contains E1 and E9c (Fig. 1), was not detected in this assay but was detected when it was specifically enriched and amplified (our unpublished observations), consistently with our recent observations that LEV-11O is a very minor isoform that is expressed in a subset of head muscle cells (Barnes et al 2018). With the E3b/E9c primer pair, we detected a major lower band and a minor upper band (Fig.…”

“…5D). A subset of head muscle cells predominantly express LEV-11O that includes E7a (Barnes et al 2018). The pharynx expresses LEV-11E that includes E4a (Fig.…”

“…The intestine and neurons express LEV-11C, which includes E5c (Fig. 4F) and E7b (Barnes et al 2018), and excludes E9a (Fig. 5D).…”

“…1). Five isoforms have been confirmed to date by cloning of full-length cDNAs, which include three high-molecular-weight isoforms (LEV-11A, LEV-11D, and LEV-11O) and two low-molecular-weight isoforms (LEV-11C and LEV-11E) (Anyanful et al 2001; Barnes et al 2018; Kagawa et al 1995) (Fig. 1).…”

“…Some of lev-11 mutants are resistant to levamisole, an agonist for acetylcholine receptor that induces muscle contraction (Lewis et al 1980a; Lewis et al 1980b), because slow muscle relaxation occurs while cholinergic neurons are active (Hwang et al 2016). Splicing of two mutually exclusive exon 7s is differentially regulated in the head and body regions of the body wall muscle cells to express LEV-11O in the head muscles and LEV-11A in the rest of the body wall muscles, where these isoforms differentially regulate muscle contractility (Barnes et al 2018). In addition, lev-11 is important for sarcomere organization (Ono and Ono 2002; Yu and Ono 2006), muscle arm development (Dixon and Roy 2005), ovulatory myoepithelial sheath contraction (Ono and Ono 2004), and contractility of male sex muscle (Gruninger et al 2006).…”