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The Basic Helix‐Loop‐Helix/Leucine Zipper Transcription Factor USF2 Integrates Serum‐Induced PAI‐1 Expression and Keratinocyte Growth
Author(s) -
Qi Li,
Higgins Craig E.,
Higgins Stephen P.,
Law Brian K.,
Simone Tessa M.,
Higgins Paul J.
Publication year - 2014
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.24861
Subject(s) - e box , microbiology and biotechnology , biology , hacat , transcription factor , transcription (linguistics) , chemistry , cell culture , gene , enhancer , biochemistry , genetics , linguistics , philosophy
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 D 1 ; cyclin A) in synchronized human (HaCaT) keratinocytes, and previous cytometric assessments, indicated that PAI‐1 transcription occurred early after serum‐stimulation of quiescent (G 0 ) 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 G 0 → G 1 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. J. Cell. Biochem. 115: 1840–1847, 2014. © 2014 Wiley Periodicals, Inc.