Type IV collagen is a major component of basement membranes. We have characterized 11 mutations in emb-9, the α1(IV) collagen gene of Caenorhabditis elegans, that result in a spectrum of phenotypes. Five are substitutions of glycines in the Gly-X-Y domain and cause semidominant, temperature-sensitive lethality at the twofold stage of embryogenesis. One is a glycine substitution that causes recessive, non–temperature-sensitive larval lethality. Three putative null alleles, two nonsense mutations and a deletion, all cause recessive, non–temperature-sensitive lethality at the threefold stage of embryogenesis. The less severe null phenotype indicates that glycine substitution containing mutant chains dominantly interfere with the function of other molecules. The emb-9 null mutants do not stain with anti–EMB-9 antisera and show intracellular accumulation of the α2(IV) chain, LET-2, indicating that LET-2 assembly and/or secretion requires EMB-9. Glycine substitutions in either EMB-9 or LET-2 cause intracellular accumulation of both chains. The degree of intracellular accumulation differs depending on the allele and temperature and correlates with the severity of the phenotype. Temperature sensitivity appears to result from reduced assembly/secretion of type IV collagen, not defective function in the basement membrane. Because the dominant interference of glycine substitution mutations is maximal when type IV collagen secretion is totally blocked, this interference appears to occur intracellularly, rather than in the basement membrane. We suggest that the nature of dominant interference caused by mutations in type IV collagen is different than that caused by mutations in fibrillar collagens.
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2 June 1997
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June 02 1997
Characterization of α1(IV) Collagen Mutations in Caenorhabditis elegans and the Effects of α1 and α2(IV) Mutations on Type IV Collagen Distribution
Malini C. Gupta,
Malini C. Gupta
Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
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Patricia L. Graham,
Patricia L. Graham
Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
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James M. Kramer
James M. Kramer
Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
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Malini C. Gupta
Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
Patricia L. Graham
Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
James M. Kramer
Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
1. Abbreviation used in this paper: NDS, normal donkey serum.
Address all correspondence to James M. Kramer, Northwestern University Medical School, Department of Cell and Molecular Biology, 303 E. Chicago Ave., Chicago, IL 60611. Tel.: (312) 503-7644. Fax: (312) 5032522 or 7912. E-mail: [email protected]
Received:
February 17 1997
Revision Received:
March 22 1997
Online ISSN: 1540-8140
Print ISSN: 0021-9525
1997
J Cell Biol (1997) 137 (5): 1185–1196.
Article history
Received:
February 17 1997
Revision Received:
March 22 1997
Citation
Malini C. Gupta, Patricia L. Graham, James M. Kramer; Characterization of α1(IV) Collagen Mutations in Caenorhabditis elegans and the Effects of α1 and α2(IV) Mutations on Type IV Collagen Distribution. J Cell Biol 2 June 1997; 137 (5): 1185–1196. doi: https://doi.org/10.1083/jcb.137.5.1185
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