Heat shock of human synovial and dermal fibroblasts induces delayed up-regulation of collagenase-gene expression.
We investigated the effect of heat shock on the expression of the collagenase gene in normal human synovial and dermal fibroblasts. Heat shock (42-44 degrees C for 1 h) caused a marked increase in heat-shock protein 70 (HSP-70) mRNA levels, followed by a delayed increase in collagenase mRNA levels, in both cell types. Pretreatment with cycloheximide had no effect on the heat-shock-induced increase in HSP-70 mRNA expression, but abrogated the induction of collagenase mRNA during the recovery. To study the mechanisms of collagenase-gene induction by heat shock, the transcriptional activity of a collagenase-promoter-driven chloramphenicol acetyltransferase (CAT) reporter gene was examined in transient transfection experiments. Heat shock was followed by a > 2-fold increase in CAT activity driven by a 3.8 kb fragment of the collagenase promoter, or by a construct containing an AP-1 binding site. A mutation in the AP-1 binding site abolished the effect of heat shock. Electrophoretic-mobility-shift assays revealed a marked increase in DNA-binding activity specific for the AP-1 binding site in nuclear extracts prepared from synovial fibroblasts recovering from heat shock. These results indicate that heat shock causes a delayed increase in collagenase-gene expression in human fibroblasts, and suggests that this stimulation involves, at least in part, transcriptional activation through an AP-1 binding site. Heat shock appears to initiate a programme of cellular events resulting in collagenase-gene expression, and therefore may contribute to connective-tissue degradation in disease states.
Hitraya
E G
EG
Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107-5541, USA.
Varga
J
J
Jimenez
S A
SA
D001665:Binding Sites / Q000235:genetics; D015152:Blotting, Northern; D002478:Cells, Cultured; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D017364:Collagenases / Q000235:genetics* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012867:Skin / Q000201:enzymology; D013583:Synovial Membrane / Q000201:enzymology; D013696:Temperature; D015533:Transcriptional Activation; D014162:Transfection / Q000235:genetics; D015854:Up-Regulation / Q000502:physiology*
D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D015500:Chloramphenicol O-Acetyltransferase; D017364:Collagenases