Complex regulation of plasminogen activator inhibitor type-1 (PAI-1) gene expression by serum and substrate adhesion.
Expression of plasminogen activator inhibitor type-1 (PAI-1), a member of the serine protease inhibitor (SERPIN) superfamily that functions to negatively regulate the plasmin-based pericellular proteolytic cascade, was induced early after exposure of growth-arrested normal rat kidney (NRK) cells to serum-containing medium. Increased PAI-1 transcription was rapid (evident within 10 min of serum addition) and involved immediate-early response kinetics. [3H]Thymidine autoradiography was used to map the time frame of PAI-1 expression during a synchronous growth cycle. PAI-1 transcript accumulation peaked in mid-G1 phase (approx. 4-6 h post-stimulation) and declined prior to, or concomitant with, the onset of DNA synthetic phase. Serum increased PAI-1 expression in NRK cells in agarose suspension, as well as monolayer, culture; induction in suspended cells (similar to monolayer culture conditions) also occurred in the presence of cyclohexamide or puromycin. The serum-inductive pathway leading to PAI-1 gene activation is thus functional regardless of adhesive conditions or capacity for de novo protein synthesis. The amplitude of induction and maintenance of expression in later stages of G1, however, were subject to adhesive influences. PAI-1 transcript accumulation at 4 and 8 h post-stimulation in newly adherent cells, moreover, was blocked by puromycin, indicating that both immediate-early and secondary mechanisms regulate PAI-1 mRNA levels during progression of NRK cells through an 'activated' G1 growth phase.
Ryan
M P
MP
Department of Microbiology, Immunology and Molecular Genetics, Albany Medical College, New York 12208, USA.
Kutz
S M
SM
Higgins
P J
PJ
D000818:Animals; D001769:Blood; D015152:Blotting, Northern; D002448:Cell Adhesion; D002453:Cell Cycle; D002455:Cell Division; D002460:Cell Line; D003470:Culture Media; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D016193:G1 Phase; D005786:Gene Expression Regulation / Q000187:drug effects; D007668:Kidney; D007700:Kinetics; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis*; D011691:Puromycin / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D013997:Time Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D003470:Culture Media; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D011691:Puromycin; D004247:DNA; D003513:Cycloheximide