Multiple promoter elements are required for the stimulatory effect of insulin on human collagenase-1 gene transcription. Selective effects on activator protein-1 expression may explain the quantitative difference in insulin and phorbol ester action.
Several of the complications seen in patients with both type I and type II diabetes mellitus are associated with alterations in the expression of matrix metalloproteinases. To identify the cis-acting elements that mediate the stimulatory effect of insulin on collagenase-1 (matrix metalloproteinase-1) gene transcription a series of collagenase-chloramphenicol acetyltransferase (CAT) fusion genes were transiently transfected into HeLa cells. Multiple promoter elements, including an Ets and activator protein-1 (AP-1) motif, were required for the effect of insulin. The AP-1 motif appears to be a target for insulin signaling because it is sufficient to mediate an effect of insulin on the expression of a heterologous fusion gene, whereas the data suggest that the Ets motif acts to enhance the effect of insulin mediated through the AP-1 motif. Multiple promoter elements were also required for the stimulatory effect of phorbol esters on collagenase-CAT gene transcription, and the AP-1 motif was also a target for phorbol ester signaling. However, the cis-acting elements required for the effects of insulin and phorbol esters were not identical. Moreover, phorbol esters were a much more potent inducer of collagenase-CAT gene transcription than insulin, a difference that may be explained by selective effects of insulin and phorbol esters on AP-1 expression.
Chapman
S C
SC
Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee 37232, USA.
Ayala
J E
JE
Streeper
R S
RS
Culbert
A A
AA
Eaton
E M
EM
Svitek
C A
CA
Goldman
J K
JK
Tavar
J M
JM
O'Brien
R M
RM
D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D017364:Collagenases / Q000235:genetics*; D006224:Cricetinae; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D020781:Matrix Metalloproteinase 1; D010703:Phorbol Esters / Q000494:pharmacology*; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017510:Protein Folding; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects*
D007328:Insulin; D010703:Phorbol Esters; D018808:Transcription Factor AP-1; D015500:Chloramphenicol O-Acetyltransferase; D017364:Collagenases; D020781:Matrix Metalloproteinase 1; D010729:Phosphoenolpyruvate Carboxykinase (GTP)