Chen EB et al. (1998) Trends Genet "Understanding cell migration guidance: lessons from sex myoblast migration in C. elegans."

Chen EB, Stern MJ

[Trends Genet, 1998]

Studies of sex myoblast (SM) migration in the nematode Caenorhabditis elegans have shown that multiple guidance mechanisms cooperate to ensure the accurate and reproducible targeting of the SMs. Many issues arise in the analysis of SM migration, including the action of multiple guidance mechanisms, redundant sources of guidance information, the multiple uses of molecular components, and whether factors affect cell fate determination events or the guidance mechanisms themselves. These issues are common to many cell migration events and make the analysis of SM migration instructive to our general understanding of how cell migrations are controlled.

Hedgecock EM et al. (1987) Development "Genetics of cell and axon migrations in Caenorhabditis elegans."

Stern BD, Culotti JG, Hall DH, Hedgecock EM

[Development, 1987]

The Caenorhabditis elegans epidermis comprises 78 cells which cover the external surface of the embryo as a single cell layer. These cells secrete the cuticle from their exterior faces and support the body wall muscles and most of the nervous system on their interior faces. The epidermal cells arise by autonomous embryonic cell lineages but show regulative interactions after their assembly into an epithelium. It is believed that the various epidermal cells express different kinds or amounts of surface molecules that govern their mutual assembly and also guide the attachments and migrations of the underlying body muscles and neurones. The first muscles and neurones may in turn express new surface molecules that refine later cell movements. Mutations in some 30 known genes disrupt the movements of cells or axons along the body wall.

Opperman CH et al. (1992) Parasitol Today "Nematode acetylcholinesterases--molecular forms and their potential role in nematode behavior."

Chang S-H, Opperman CH

[Parasitol Today, 1992]

Nematode movement is reliant upon the somatic musculature that runs longitudinally along the body wall. Neuromuscular synapses occur in the ventral and dorsal cords and employ the excitatory neurotransmitter, acetylcholine (ACh), for modulation of muscle activity. Acetylcholine activity is terminated by hydrolysis by acetylcholinesterase (AChE). Here, Charles Opperman and Stella Chang discuss the molecular forms and potential role of this enzyme.

Wang ZW (2010) J Neurosci Res "Origin of quantal size variation and high-frequency miniature postsynaptic currents at the Caenorhabditis elegans neuromuscular junction."

Wang ZW

[J Neurosci Res, 2010]

The neuromuscular junction (NMJ) of Caenorhabditis elegans has proved to be a very useful model synapse for investigating molecular mechanisms of synaptic transmission. Intriguingly, miniature postsynaptic currents (minis) at this synapse occur at an unusually high frequency (50-90 Hz in wild-type worms) and show large variation in quantal size (from <10 pA to >200 pA). It is important to understand the cellular and molecular bases for these properties of minis in order to interpret electrophysiological data from this synapse properly. Existing data suggest that several factors may contribute to the high frequency and quantal size variation, including 1) the establishment of multiple NMJs with each body-wall muscle cell, 2) diversity of postsynaptic receptors (two acetylcholine receptors and one GABA receptor), 3) association of one presynaptic site with several body-wall muscle cells, 4) effects of Ca(2+) at the presynaptic site, and 5) a possibly elevated (less negative) resting membrane potential in motoneurons. Neither the frequency nor the quantal size of minis is affected by electrical coupling of body-wall muscle cells. Furthermore, quantal size variation is not due to synchronized multivesicular release. Analyses of the C. elegans NMJ may lead to a better understanding of the mechanisms controlling the frequency and quantal size of minis of other synapses as well.

Otsuka AJ (1986) "sup-3 suppression affects muscle structure and myosin heavy chain accumulation in C. elegans."

Otsuka AJ

[1986]

Suppression of paramyosin mutations by sup-3 has been shown to result in the formation of thick filaments of normal appearance distributed in regions of partially organized muscle lattice structure. In the presence or absence of muscle mutations, sup-3 results in the elevation of MHCA, one of the two known body-wall myosin heavy chains. The correlation of sup-3 mutations with MHCA increase suggests that sup-3 may regulate the expression or accumulation of MHCA.

Culotti JG (1994) Curr Opin Genet Dev "Axon guidance mechanisms in Caenorhabditis elegans."

Culotti JG

[Curr Opin Genet Dev, 1994]

Genetic studies have identified an extracellular path cue molecule, UNC-6, and a neuronal receptor, UNC-5, that act to guide migrating pioneer growth cones along the dorsoventral coordinate of the Caenorhabditis elegans body wall. Ectopic expression studies and characterization of mutants have demonstrated directly the instructive action of these molecules, suggesting a molecular model for how they perform their guidance functions. Recent evidence suggests that these and other genetically identified axon guidance molecules are likely to have vertebrate counterparts.

Miller DM et al. (1986) "The sup-3 locus is closely linked to a myosin heavy chain gene in C. elegans."

Miller DM, Maruyama IN

[1986]

C. elegans body wall muscle thick filaments are assembled from two different types of myosin heavy chain, MHC A and MHC B. The structural gene for the MHC A protein has been identified from the reaction of bacterial fusion peptides with specific monoclonal antibodies. We have also shown that a mutation in the sup-3 locus that enhances the accumulation of the MHC A protein is closely linked to the MHC A gene. A model of sup-3 action is proposed.

Hutagalung AH et al. (2002) J Cell Sci "The UCS family of myosin chaperones."

Landsverk ML, Hutagalung AH, Price MG, Epstein HF

[J Cell Sci, 2002]

The canonical UCS (UNC-45/Crol/She4p) protein, Caenorhabditis elegans UNC-45, was one of the earliest molecules to be shown genetically to be necessary for sarcomere assembly. Genetic analyses of homologues in several fungal species indicate that the conserved UCS domain functionally interacts with conventional type II and unconventional type V myosins. In C. elegans and other invertebrate species, UNC-45 and its orthologues interact with both sarcomeric and non-sarcomeric myosins whereas, in vertebrates, there are two UNC-45 isoforms: a general cell (GC) and a striated muscle (SM) isoform. Although the mechanism of action of UCS proteins is unknown, recent biochemical studies suggest that they may act as molecular chaperones that facilitate the folding and/or maturation of myosin.

Rogalski TM et al. (2001) Biochem Soc Trans "UNC-52/perlecan isoform diversity and function in Caenorhabditis elegans."

Rogalski TM, Gilchrist EJ, Mullen GP, Bush JA, Moerman DG

[Biochem Soc Trans, 2001]

The unc-52 gene encodes the nematode homologue of mammalian perlecan, the major heparan sulphate proteoglycan of the extracellular matrix. This is a large complex protein with regions similar to low-density lipoprotein receptors, laminin and neural cell-adhesion molecules. Three major classes of UNC-52/perlecan isoforms are produced through alternative splicing, and these distinct proteins exhibit complex spatial and temporal expression patterns throughout development. The unc-52 gene plays an essential role in myofilament assembly in body-wall muscle during embryonic development.

Waterston RH et al. (1986) "Muscle genes and proteins in C. elegans."

Barstead RJ, Mori I, Waterston RH, Francis GR, Moerman DG, Benian GM

[1986]

Our efforts to understand the role of each of the muscle genes in C. elegans myogenesis and muscle contraction have followed three different but interrelated approaches. Antibodies have been developed and used to define additional components of C. elegans body wall musculature. Studies of gene interactions have revealed epistatic relationships that help to define the function of some gene products. Transposition of the repetitive element Tc1 into the muscle gene unc-22 has allowed us to clone this gene and begin the dissection of its function in the nematode.