Identification and characterization of a novel collagenase in Xenopus laevis: possible roles during frog development.
Matrix metalloproteinases (MMPs) participate in extracellular matrix remodeling and degradation and have been implicated in playing important roles during organ development and pathological processes. Although it has been hypothesized for > 30 years that collagenase activities are responsible for collagen degradation during tadpole tail resorption, none of the previously cloned amphibian MMPs have been biochemically demonstrated to be collagenases. Here, we report a novel matrix metalloproteinase gene from metamorphosing Xenopus laevis tadpoles. In vitro biochemical studies demonstrate that this Xenopus enzyme is an interstitial collagenase and has an essentially identical enzymatic activity toward a collagen substrate as the human interstitial collagenase. Sequence comparison of this enzyme to other known MMPs suggests that the Xenopus collagenase is not a homologue of any known collagenases but instead represents a novel collagenase, Xenopus collagenase-4 (xCol4, MMP-18). Interestingly, during development, xCol4 is highly expressed only transiently in whole animals, at approximately the time when tadpole feeding begins, suggesting a role during the maturation of the digestive tract. More importantly, during metamorphosis, xCol4 is regulated in a tissue-dependent manner. High levels of its mRNA are present as the tadpole tail resorbs. Similarly, its expression is elevated during hindlimb morphogenesis and intestinal remodeling. In addition, when premetamorphic tadpoles are treated with thyroid hormone, the causative agent of metamorphosis, xCol4 expression is induced in the tail. These results suggest that xCol4 may facilitate larval tissue degeneration and adult organogenesis during amphibian metamorphosis.
Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
M A
MA
Stolow
D D
DD
Bauzon
J
J
Li
T
T
Sedgwick
V C
VC
Liang
Q A
QA
Sang
Y B
YB
Shi
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017364:Collagenases / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D004790:Enzyme Induction / Q000187:drug effects; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D005796:Genes; D006614:Hindlimb / Q000201:enzymology / Q000254:growth & development; D006801:Humans; D007422:Intestines / Q000201:enzymology / Q000254:growth & development; D007814:Larva / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D008675:Metamorphosis, Biological; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009928:Organ Specificity; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013623:Tail / Q000254:growth & development; D014284:Triiodothyronine / Q000494:pharmacology; D014982:Xenopus laevis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D011993:Recombinant Fusion Proteins; D014284:Triiodothyronine; D017364:Collagenases