Increased or decreased levels of Caenorhabditis elegans lon-3, a gene encoding a collagen, cause reciprocal changes in body length.
Body length in C. elegans is regulated by a member of the TGFbeta family, DBL-1. Loss-of-function mutations in dbl-1, or in genes encoding components of the signaling pathway it activates, cause worms to be shorter than wild type and slightly thinner (Sma). Overexpression of dbl-1 confers the Lon phenotype characterized by an increase in body length. We show here that loss-of-function mutations in dbl-1 and lon-1, respectively, cause a decrease or increase in the ploidy of nuclei in the hypodermal syncytial cell, hyp7. To learn more about the regulation of body length in C. elegans we carried out a genetic screen for new mutations causing a Lon phenotype. We report here the cloning and characterization of lon-3. lon-3 is shown to encode a putative cuticle collagen that is expressed in hypodermal cells. We show that, whereas putative null mutations in lon-3 (or reduction of lon-3 activity by RNAi) causes a Lon phenotype, increasing lon-3 gene copy number causes a marked reduction in body length. Morphometric analyses indicate that the lon-3 loss-of-function phenotype resembles that caused by overexpression of dbl-1. Furthermore, phenotypes caused by defects in dbl-1 or lon-3 expression are in both cases suppressed by a null mutation in sqt-1, a second cuticle collagen gene. However, whereas loss of dbl-1 activity causes a reduction in hypodermal endoreduplication, the reduction in body length associated with overexpression of lon-3 occurs in the absence of defects in hypodermal ploidy.
Nyström
Josefin
J
UCMP, Umeå University, SE-901 87 Umeå, Sweden.
Shen
Zai-Zhong
ZZ
Aili
Margareta
M
Flemming
Anthony J
AJ
Leroi
Armand
A
Tuck
Simon
S
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular; D003094:Collagen / Q000235:genetics* / Q000502:physiology; D018628:Gene Dosage; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000235:genetics; D016212:Transforming Growth Factor beta
D029742:Caenorhabditis elegans Proteins; C117509:Dbl-1 protein, C elegans; D009479:Neuropeptides; D016212:Transforming Growth Factor beta; C469571:lon-3 protein, C elegans; D003094:Collagen