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Hajdu-Cronin YM, Chen WJ, Patikoglou G, Koelle MR, Sternberg PW. Antagonism between G(o)alpha and G(q)alpha in Caenorhabditis elegans: the RGS protein EAT-16 is necessary for G(o)alpha signaling and regulates G(q)alpha activity. Genes Dev 1999; 13:1780-93. [PMID: 10421631 PMCID: PMC316886 DOI: 10.1101/gad.13.14.1780] [Citation(s) in RCA: 154] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
To elucidate the cellular role of the heterotrimeric G protein G(o), we have taken a molecular genetic approach in Caenorhabditis elegans. We screened for suppressors of activated GOA-1 (G(o)alpha) that do not simply decrease its expression and found mutations in only two genes, sag-1 and eat-16. Animals defective in either gene display a hyperactive phenotype similar to that of goa-1 loss-of-function mutants. Double-mutant analysis indicates that both sag-1 and eat-16 act downstream of, or parallel to, G(o)alpha and negatively regulate EGL-30 (G(q)alpha) signaling. eat-16 encodes a regulator of G protein signaling (RGS) most similar to the mammalian RGS7 and RGS9 proteins and can inhibit endogenous mammalian G(q)/G(11) in COS-7 cells. Animals defective in both sag-1 and eat-16 are inviable, but reducing function in egl-30 restores viability, indicating that the lethality of the eat-16; sag-1 double mutant is due to excessive G(q)alpha activity. Analysis of these mutations indicates that the G(o) and G(q) pathways function antagonistically in C. elegans, and that G(o)alpha negatively regulates the G(q) pathway, possibly via EAT-16 or SAG-1. We propose that a major cellular role of G(o) is to antagonize signaling by G(q).
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Affiliation(s)
- Y M Hajdu-Cronin
- Howard Hughes Medical Institute (HHMI) and Division of Biology, California Institute of Technology, Pasadena, California 91125 USA
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2
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Sluder AE, Lindblom T, Ruvkun G. The Caenorhabditis elegans orphan nuclear hormone receptor gene nhr-2 functions in early embryonic development. Dev Biol 1997; 184:303-19. [PMID: 9133437 DOI: 10.1006/dbio.1997.8544] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have identified a Caenorhabditis elegans gene, nhr-2, that is a member of the nuclear hormone receptor superfamily of transcription factors and defines a new subclass of the superfamily. nhr-2 messenger RNA is expressed in the maternal germline and during the first half of embryogenesis. Zygotic expression of nhr-2 begins by the 16-cell stage, making it one of the earliest genes known to be transcribed in the embryo. Immunolocalization detects NHR-2 protein in embryonic nuclei as early as the 2-cell stage. The protein is present in every nucleus until the 16- to 20-cell stage. Subsequently, expression continues in many, but not all, cell lineages, becoming progressively restricted to the anterior and dorsal regions of the embryo and disappearing during the initial stages of morphogenesis. Disruption of nhr-2 function with antisense RNA results in embryonic and early larval arrest, indicating that the gene has an essential function in embryonic development. nhr-2 does not correspond to known mutations mapped to the same genetic interval, and will provide an entry point for further study of a heretofore uncharacterized zygotic gene regulatory pathway.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Caenorhabditis elegans/embryology
- Caenorhabditis elegans/genetics
- Caenorhabditis elegans/growth & development
- Caenorhabditis elegans Proteins
- Chromosome Mapping
- Cloning, Molecular
- Embryo, Nonmammalian/metabolism
- Embryonic Development
- Gene Expression Regulation, Developmental
- Genes, Helminth
- Microscopy, Fluorescence
- Molecular Sequence Data
- Morphogenesis
- Mutation
- Promoter Regions, Genetic
- RNA, Antisense/genetics
- RNA, Antisense/pharmacology
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/physiology
- Sequence Alignment
- Transcription Factors/chemistry
- Transcription Factors/genetics
- Zinc Fingers/genetics
- beta-Galactosidase/genetics
- beta-Galactosidase/metabolism
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Affiliation(s)
- A E Sluder
- Department of Cellular Biology, University of Georgia, Athens 30602, USA.
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3
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Basson M, Horvitz HR. The Caenorhabditis elegans gene sem-4 controls neuronal and mesodermal cell development and encodes a zinc finger protein. Genes Dev 1996; 10:1953-65. [PMID: 8756352 DOI: 10.1101/gad.10.15.1953] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Neuronal and mesodermal cell types are generated in separate cell lineages during the larval development of Caenorhabditis elegans. Here we demonstrate that the gene sem-4 is required in both types of lineages for the normal development of neuronal and mesodermal cell types. The sem-4 gene encodes a protein containing seven zinc finger motifs of the C2H2 class, four of which are arranged in two pairs widely separated in the primary sequence of the protein. These pairs of zinc fingers are similar to pairs of zinc fingers in the protein encoded by the Drosophila homeotic gene spalt and in the human transcription factor PRDII-BF1. Analysis of sem-4 alleles suggests that different zinc fingers in the SEM-4 protein may function differentially in neuronal and mesodermal cell types. We propose that sem-4 interacts with different transcription factors in different cell types to control the transcription of genes that function in the processes of neuronal and mesodermal cell development.
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Affiliation(s)
- M Basson
- Howard Hughes, Medical Institute, Massachusetts Institute of Technology, Cambridge 02139, USA
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4
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Lundquist EA, Herman RK, Rogalski TM, Mullen GP, Moerman DG, Shaw JE. The mec-8 gene of C. elegans encodes a protein with two RNA recognition motifs and regulates alternative splicing of unc-52 transcripts. Development 1996; 122:1601-10. [PMID: 8625846 DOI: 10.1242/dev.122.5.1601] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutations in the mec-8 gene of Caenorhabditis elegans were previously shown to affect the functions of body wall muscle and mechanosensory and chemosensory neurons. Mutations in mec-8 also strongly enhance the mutant phenotype of specific mutations in unc-52, a gene that encodes, via alternative splicing of pre-mRNA, a set of basement membrane proteins, homologs of perlecan, that are important for body wall muscle assembly and attachment to basement membrane, hypodermis and cuticle. We have cloned mec-8 and found that it encodes a protein with two RNA recognition motifs, characteristic of RNA binding proteins. We have used reverse transcription-PCR and RNase protection experiments to show that mec-8 regulates the accumulation of a specific subset of alternatively spliced unc-52 transcripts. We have also shown with antibodies to UNC-52 that mec-8 affects the abundance of a subset of UNC-52 isoforms. We propose that mec-8 encodes a trans-acting factor that regulates the alternative splicing of the pre-mRNA of unc-52 and one or more additional genes that affect mechanosensory and chemosensory neuron function.
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Affiliation(s)
- E A Lundquist
- Department of Genetics and Cell Biology, University of Minnesota, St. Paul 55108, USA
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5
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Thacker C, Peters K, Srayko M, Rose AM. The bli-4 locus of Caenorhabditis elegans encodes structurally distinct kex2/subtilisin-like endoproteases essential for early development and adult morphology. Genes Dev 1995; 9:956-71. [PMID: 7774813 DOI: 10.1101/gad.9.8.956] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
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, h1010, 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.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C Thacker
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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6
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Goetinck S, Waterston RH. The Caenorhabditis elegans muscle-affecting gene unc-87 encodes a novel thin filament-associated protein. J Cell Biol 1994; 127:79-93. [PMID: 7929573 PMCID: PMC2120179 DOI: 10.1083/jcb.127.1.79] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Mutations in the unc-87 gene of Caenorhabditis elegans affect the structure and function of bodywall muscle, resulting in variable paralysis. We cloned the unc-87 gene by taking advantage of a transposon-induced allele of unc-87 and the correspondence of the genetic and physical maps in C. elegans. A genomic clone was isolated that alleviates the mutant phenotype when introduced into unc-87 mutants. Sequence analysis of a corresponding cDNA clone predicts a 357-amino acid, 40-kD protein that is similar to portions of the vertebrate smooth muscle proteins calponin and SM22 alpha, the Drosophila muscle protein mp20, the deduced product of the C. elegans cDNA cm7g3, and the rat neuronal protein np25. Analysis of the genomic sequence and of various transcripts represented in a cDNA library suggest that unc-87 mRNAs are subject to alternative splicing. Immunohistochemistry of wildtype and mutant animals with antibodies to an unc-87 fusion protein indicates that the gene product is localized to the I-band of bodywall muscle. Studies of the UNC-87 protein in other muscle mutants suggest that the unc-87 gene product associates with thin filaments, in a manner that does not depend on the presence of the thin filament protein tropomyosin.
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Affiliation(s)
- S Goetinck
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
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7
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McKim KS, Matheson C, Marra MA, Wakarchuk MF, Baillie DL. The Caenorhabditis elegans unc-60 gene encodes proteins homologous to a family of actin-binding proteins. MOLECULAR & GENERAL GENETICS : MGG 1994; 242:346-57. [PMID: 8107682 DOI: 10.1007/bf00280425] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Mutations in the unc-60 gene of the nematode Caenorhabditis elegans result in paralysis. The thin filaments of the muscle cells are severely disorganized and not bundled with myosin into functional contractile units. Here we report the cloning and sequence of unc-60. Two unc-60 transcripts, 1.3 and 0.7 kb in size, were detected. The transcripts share a single exon encoding only the initial methionine, yet encode proteins with homologous sequences. The predicted protein products are 165 and 152 amino acids in length and their sequences are 38% identical. Both proteins are homologous to a family of actin depolymerizing proteins identified in vertebrate, plant and protozoan systems. We propose that the unc-60 locus encodes proteins that depolymerize growing actin filaments in muscle cells, and that these proteins are required for the assembly of actin filaments into the contractile myofilament lattice of C. elegans muscle. unc-60 has an essential function in development, since one unc-60 allele, s1586, has a recessive lethal phenotype. Our characterization of s1586 has shown that it is a small deletion which disrupts both coding regions.
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Affiliation(s)
- K S McKim
- Department of Biological Sciences, Simon Fraser University, Burnaby, B.C. Canada
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McKim KS, Starr T, Rose AM. Genetic and molecular analysis of the dpy-14 region in Caenorhabditis elegans. MOLECULAR & GENERAL GENETICS : MGG 1992; 233:241-51. [PMID: 1603066 DOI: 10.1007/bf00587585] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Essential genes have been identified in the 1.5 map unit (m.u.) dpy-14-unc-29 region of chromosome 1 in Caenorhabditis elegans. Previous work defined nine genes with visible mutant phenotypes and nine genes with lethal mutant phenotypes. In this study, we have identified an additional 28 essential genes with 97 lethal mutations. The mutations were mapped using eleven duplication breakpoints, eight deficiencies and three-factor recombination experiments. Genes required for the early stages of development were common, with 24 of the 37 essential genes having mutant phenotypes arresting at an early larval stage. Most mutants of a gene have the same time of arrest; only four of the 20 essential genes with multiple alleles have alleles with different phenotypes. From the analysis of complementing alleles of let-389, alleles with the same time-of-arrest phenotype were classified as either hypomorphic or amorphic. Mutants of let-605, let-534 and unc-37 have both uncoordinated and lethal phenotypes, suggesting that these genes are required for the coordination of movement and for viability. The physical and genetic maps in the dpy-14 region were linked by positioning two N2/BO polymorphisms with respect to duplications in the region, and by localizing the right breakpoint of the deficiency hDf8 on the physical map. Using cross-species hybridization to C. briggsae, ten regions of homology have been identified, eight of which are known to be coding regions, based on Northern analysis and/or the isolation of cDNA clones.
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Affiliation(s)
- K S McKim
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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Wiseman H, Cannon M, Arnstein HR, Halliwell B. Mechanism of inhibition of lipid peroxidation by tamoxifen and 4-hydroxytamoxifen introduced into liposomes. Similarity to cholesterol and ergosterol. FEBS Lett 1990; 274:107-10. [PMID: 2253763 DOI: 10.1016/0014-5793(90)81341-k] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The anticancer drug tamoxifen when introduced into phospholipid liposomes during their preparation inhibited Fe(III)-ascorbate induced lipid peroxidation to a greater extent than similarly introduced cholesterol. Ergosterol was equipotent with tamoxifen, but much less effective than 4-hydroxytamoxifen. Possible mechanisms underlying these effects are discussed in relation to structural mimicry of the sterols by these triphenylethylene drugs as membrane stabilizers against lipid peroxidation.
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Affiliation(s)
- H Wiseman
- Department of Biochemistry, University of London, King's College, UK
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10
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Harris LJ, Prasad S, Rose AM. Isolation and sequence analysis of Caenorhabditis briggsae repetitive elements related to the Caenorhabditis elegans transposon Tc1. J Mol Evol 1990; 30:359-69. [PMID: 2161057 DOI: 10.1007/bf02101890] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have identified two repetitive element families in the genome of the nematode Caenorhabditis briggsae with extensive sequence identity to the Caenorhabditis elegans transposable element Tc1. Five members each of the TCb1 (previously known as Barney) and TCb2 families were isolated by hybridization to a Tc1 probe. Tc1-hybridizing repetitive elements were grouped into either the TCb1 or TCb2 family based on cross-hybridization intensities among the C. briggsae elements. The genomic copy number of the TCb1 family is 15 and the TCb2 family copy number is 33 in the C. briggsae strain G16. The two transposable element families show numerous genomic hybridization pattern differences between two C. briggsae strains, suggestive of transpositional activity. Two members of the TCb1 family, TCb1#5 and TCb1#10, were sequenced. Each of these two elements had suffered an independent single large deletion. TCb1#5 had a 627-bp internal deletion and TCb1#10 had lost 316 bp of one end. The two sequenced TCb1 elements were highly conserved over the sequences they shared. A 1616-bp composite TCb1 element was constructed from TCb1#5 and TCb1#10. The composite TCb1 element has 80-bp terminal inverted repeats with three nucleotide mismatches and two open reading frames (ORFs) on opposite strands. TCb1 and the 1610-bp Tc1 share 58% overall nucleotide sequence identity, and the greatest similarity occurs in their ORF1 and inverted repeat termini.
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Affiliation(s)
- L J Harris
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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