Biochemical genetics of Coenorhabditis elegans

Babu, Punuri Jayasekhar

doi:10.1007/bf00433899

Cited by 53 publications

(27 citation statements)

References 4 publications

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“…We examined several other candidate genes with possible roles in lysosome biogenesis. Briefly, abnormal fluorescence (flu) mutants have abnormal gut granule autofluorescence (Babu, 1974) and are thought to function in tryptophan catabolism (Siddiqui and Babu, 1980). We found that none of the four flu mutants had Glo phenotypes as embryos or adults (Table 1).…”

Section: Biogenesis Of Gut Granules Requires the Activity Of Genes Immentioning

confidence: 96%

Genetic Analysis of Lysosomal Trafficking inCaenorhabditis elegans

Hermann

Schroeder

Hieb

et al. 2005

MBoC

245

464

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The intestinal cells of Caenorhabditis elegans embryos contain prominent, birefringent gut granules that we show are lysosome-related organelles. Gut granules are labeled by lysosomal markers, and their formation is disrupted in embryos depleted of AP-3 subunits, VPS-16, and VPS-41. We define a class of gut granule loss (glo) mutants that are defective in gut granule biogenesis. We show that the glo-1 gene encodes a predicted Rab GTPase that localizes to lysosome-related gut granules in the intestine and that glo-4 encodes a possible GLO-1 guanine nucleotide exchange factor. These and other glo genes are homologous to genes implicated in the biogenesis of specialized, lysosome-related organelles such as melanosomes in mammals and pigment granules in Drosophila. The glo mutants thus provide a simple model system for the analysis of lysosome-related organelle biogenesis in animal cells. INTRODUCTIONLysosomes are ubiquitous membrane-bound organelles that function as major degradative sites within eukaryotic cells (Tappel, 1969). Lysosomes contain an assortment of aciddependent hydrolases that function in the breakdown of proteins, lipids, nucleic acids, and oligosaccharides. Lysosomes receive exogenous material through the endocytic pathway and are characterized as being the terminal compartment of the endocytic pathway. Lysosomes also receive material via the secretory pathway and directly from the cytoplasm (Kornfeld and Mellman, 1989;Mullins and Bonifacino, 2001;Luzio et al., 2003). Lysosomes function in diverse and important cellular processes including cell surface receptor turnover, destruction of pathogens, antigen processing, digestion, starvation responses, tissue remodeling, ion storage, autophagy, and plasma membrane repair.The yeast vacuole shares several characteristics with the lysosomes of higher animals. Genetic screens have led to the identification of Ͼ150 genes necessary for the transport and sorting of newly synthesized proteins to the yeast vacuole (Jones, 1977;Bankaitis et al., 1986;Rothman and Stevens, 1986;Bonangelino et al., 2002). These genes control two pathways of Golgi-to-vacuole transport, the carboxypeptidase Y (CPY) and alkaline phosphatase (ALP) sorting pathways (Burd et al., 1998;Conibear and Stevens, 1998;Mullins and Bonifacino, 2001). Proteins trafficked via the CPY pathway transit an endosomal prevacuolar compartment en route to the vacuole. The ALP pathway mediates transport to the vacuole independent of the prevacuolar compartment.Many of the genes involved in transport to the yeast vacuole have homologues in higher animals (Lemmon and Traub, 2000;Mullins and Bonifacino, 2001;Bonangelino et al., 2002). For example, the HOPS complex proteins (Vps11p, Vps16p, Vps18p, and Vps33p) regulate membrane fusion events necessary for lysosomal delivery within yeast (Rieder and Emr, 1997;Peterson and Emr, 2001), Drosophila melanogaster (Sevrioukov et al., 1999;Sriram et al., 2003), and mammalian (Poupon et al., 2003;Richardson et al., 2004) endosomal systems. Similarly, the proteins compos...

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Section: Biogenesis Of Gut Granules Requires the Activity Of Genes Immentioning

confidence: 96%

Genetic Analysis of Lysosomal Trafficking inCaenorhabditis elegans

Hermann

Schroeder

Hieb

et al. 2005

MBoC

245

464

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“…In cases where a mouth pipette and needle were insufficient for blastomere separation, a micropipette was pulled by hand over a flame and the uncut tip was laid down between blastomeres to separate them. In most experiments, embryos were checked the next day for the presence of birefringent gut granules, an indicator of proper cell fate specification (Babu, 1974;Laufer, 1980). A small percentage of embryos did not make gut granules (~3% of all experiments), and these were not included in data analyses.…”

Section: Devitellinization and Blastomere Culture/isolationmentioning

confidence: 99%

Mechanisms of cell positioning during C. elegans gastrulation

2003

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Cell rearrangements are crucial during development. In this study, we use C. elegans gastrulation as a simple model to investigate the mechanisms of cell positioning. During C. elegans gastrulation, two endodermal precursor cells move from the ventral surface to the center of the embryo, leaving a gap between these ingressing cells and the eggshell. Six neighboring cells converge under the endodermal precursors, filling this gap. Using an in vitro system, we observed that these movements occurred consistently in the absence of the eggshell and the vitelline envelope. We found that movement of the neighbors towards each other is not dependent on chemotactic signaling between these cells. We further found that C. elegans gastrulation requires intact microfilaments, but not microtubules. The primary mechanism of microfilament-based motility does not appear to be through protrusive structures, such as lamellipodia or filopodia. Instead, our results suggest an alternative mechanism. We found that myosin activity is required for gastrulation, that the apical sides of the ingressing cells contract, and that the ingressing cells determine the direction of movement of their neighboring cells. Based on these results, we propose that ingression is driven by an actomyosin-based contraction of the apical side of the ingressing cells, which pulls neighboring cells underneath. We conclude that apical constriction can function to position blastomeres in early embryos, even before anchoring junctions form between cells.Movies available on-line

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“…Nomenclature for translocations conforms to that used by McKim et al (1988). The bli-4(e937) allele was isolated using 32p (Babu 1974;Brenner 1974). Most of the class II lethal mutants were identified previously from a set of lethal mutations induced in ethylmethane sulfonate (EMS) screens (Howell et al 1987;Peters et al 1991;C.…”

Section: Nematode Strains and Culture Conditionsmentioning

confidence: 99%

The bli-4 locus of Caenorhabditis elegans encodes structurally distinct kex2/subtilisin-like endoproteases essential for early development and adult morphology.

Thacker¹,

Peters²,

Srayko³

et al. 1995

Genes Dev.

101

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Many secreted proteins are excised from inactive proproteins by cleavage at pairs of basic residues. Recent studies have identified several serine endoproteases that catalyze this cleavage in the secretory pathways of yeast and metazoans. These enzymes belong to the kex2/subtilisin-like family of proprotein convertases. In this paper we describe the molecular characterization of the bli-4 gene from Caenorhabditis elegans, which was shown previously by genetic analysis of lethal mutants to be essential for the normal development of this organism. Sequencing of cDNA and genomic clones has revealed that bli-4 encodes gene products related to the kex2/subtilisin-like family of proprotein convertases. Analysis of bli-4 cDNAs has predicted four protein products, which we have designated blisterases A,B,C, and D. These protein products share a common amino terminus, but differ at the carboxyl termini, and are most likely produced from alternatively spliced transcripts. We have determined the molecular lesions for three bli-4 alleles (h199, hlOlO, and q508) that result in developmental arrest during late embryogenesis. In each case, the molecular lesions are within exons common to all of the BLI-4 isoforms. The original defining allele of bli-4, e937, is completely viable yet exhibits blistering of the adult cuticle. Molecular analysis of this allele revealed a deletion that removes exon 13, which is unique to blisterase A. No RNA transcript corresponding to exon 13 is detectable in the blistered mutants. These findings suggest that blisterase A is required for the normal function of the adult cuticle. The bli-4 gene is a complex locus as evidenced by the characterization of mutant strains and RNA transcripts.Furthermore, our data show that functional redundancy may exist among the various BLI-4 isoforms.

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Biochemical genetics of Coenorhabditis elegans

Cited by 53 publications

References 4 publications

Genetic Analysis of Lysosomal Trafficking inCaenorhabditis elegans

Genetic Analysis of Lysosomal Trafficking inCaenorhabditis elegans

Mechanisms of cell positioning during C. elegans gastrulation

The bli-4 locus of Caenorhabditis elegans encodes structurally distinct kex2/subtilisin-like endoproteases essential for early development and adult morphology.

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