title: The basic helix-loop-helix/leucine zipper transcription factor USF2 integrates serum-induced PAI-1 expression and keratinocyte growth.
abstract: Plasminogen activator inhibitor type-1 (PAI-1), a major regulator of the plasmin-dependent pericellular proteolytic cascade, is prominently expressed during the tissue response to injury although the factors that impact PAI-1 induction and their role in the repair process are unclear. Kinetic modeling using established biomarkers of cell cycle transit (c-MYC; cyclin D1; cyclin A) in synchronized human (HaCaT) keratinocytes, and previous cytometric assessments, indicated that PAI-1 transcription occurred early after serum-stimulation of quiescent (G0) cells and prior to G1 entry. It was established previously that differential residence of USF family members (USF1→USF2 switch) at the PE2 region E box (CACGTG) characterized the G0  → G1 transition period and the transcriptional status of the PAI-1 gene. A consensus PE2 E box motif (5'-CACGTG-3') at nucleotides -566 to -561 was required for USF/E box interactions and serum-dependent PAI-1 transcription. Site-directed CG → AT substitution at the two central nucleotides inhibited formation of USF/probe complexes and PAI-1 promoter-driven reporter expression. A dominant-negative USF (A-USF) construct or double-stranded PE2 "decoy" attenuated serum- and TGF-β1-stimulated PAI-1 synthesis. Tet-Off induction of an A-USF insert reduced both PAI-1 and PAI-2 transcripts while increasing the fraction of Ki-67(+) cells. Conversely, overexpression of USF2 or adenoviral-delivery of a PAI-1 vector inhibited HaCaT colony expansion indicating that the USF1 → USF2 transition and subsequent PAI-1 transcription are critical events in the epithelial go-or-grow response. Collectively, these data suggest that USF2, and its target gene PAI-1, regulate serum-stimulated keratinocyte growth, and likely the cadence of cell cycle progression in replicatively competent cells as part of the injury repair program.
authors.affiliation: Center for Cell Biology & Cancer Research, Albany Medical College, Albany, New York, 12208.
authors.forename: Li
authors.initials: L
authors.lastname: Qi
authors.forename: Craig E
authors.initials: CE
authors.lastname: Higgins
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Higgins
authors.forename: Brian K
authors.initials: BK
authors.lastname: Law
authors.forename: Tessa M
authors.initials: TM
authors.lastname: Simone
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Higgins
mesh_terms: D002455:Cell Division; D002460:Cell Line; D049109:Cell Proliferation / Q000235:genetics*; D019925:Cyclin A; D019938:Cyclin D1; D004268:DNA-Binding Proteins / Q000378:metabolism; D016193:G1 Phase / Q000235:genetics; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D019394:Ki-67 Antigen / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis / Q000235:genetics*; D017396:Plasminogen Activator Inhibitor 2 / Q000235:genetics; D011401:Promoter Regions, Genetic; D016271:Proto-Oncogene Proteins c-myc; D014158:Transcription, Genetic; D053773:Transforming Growth Factor beta1; D051720:Upstream Stimulatory Factors / Q000096:biosynthesis / Q000235:genetics*; D014945:Wound Healing / Q000235:genetics*
chemical_list: C530104:CCND1 protein, human; D019925:Cyclin A; D004268:DNA-Binding Proteins; D019394:Ki-67 Antigen; C489427:MYC protein, human; D017395:Plasminogen Activator Inhibitor 1; D017396:Plasminogen Activator Inhibitor 2; D016271:Proto-Oncogene Proteins c-myc; C051321:SERPINE1 protein, human; D053773:Transforming Growth Factor beta1; C497181:USF1 protein, human; C497184:USF2 protein, human; D051720:Upstream Stimulatory Factors; D019938:Cyclin D1
keywords: EXPRESSION PROFILING; GENE REGULATION; KERATINOCYTES; PAI-1; SERPINE1; TRANSCRIPTION; USF