Regulation of involucrin expression in normal human corneal epithelial cells: a role for activator protein one.
OBJECTIVE
Understanding the mechanisms that regulate gene expression in the human cornea is an important goal. In the present study, the involucrin gene was used as a model to study this regulation. Human involucrin (hINV) is a structural protein that is selectively expressed in surface epithelia, including corneal epithelial cells.


METHODS
Regulation of involucrin gene expression was monitored in cultures of normal human primary corneal epithelial cells.


RESULTS
The studies revealed that an activator protein (AP)-1 DNA-binding site is essential for appropriate basal and stimulus-dependent hINV promoter activity. Mutation of this site, AP1-1, results in a loss of hINV promoter activity. A gel mobility supershift analysis revealed interaction of the AP1 factors, Fra-1, Fra-2, and JunB, with this element. Inhibition of AP1 function with a dominant-negative form of AP1 also inhibited expression. Treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C activator, increased hINV gene expression, a response that correlates with increased nuclear AP1 factor level and binding to the hINV gene AP1-1 response element. Expression of the endogenous hINV gene is also increased by TPA treatment.


CONCLUSIONS
These findings point to an important role for AP1 transcription factors in the regulation of human corneal epithelial cell involucrin gene expression.
Adhikary
Gautam
G
Departments of Physiology and Biophysics, Case School of Medicine, Cleveland, Ohio 44106-4970, USA.
Crish
James
J
Lass
Jonathan
J
Eckert
Richard L
RL
D000368:Aged; D002273:Carcinogens / Q000494:pharmacology; D018929:Cell Culture Techniques; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D019573:Epithelium, Corneal / Q000187:drug effects / Q000378:metabolism*; D051921:Fos-Related Antigen-2; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D011498:Protein Precursors / Q000235:genetics* / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D000099169:Fos-Related Antigen 1
D002273:Carcinogens; D004268:DNA-Binding Proteins; D051921:Fos-Related Antigen-2; D011498:Protein Precursors; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D013755:Tetradecanoylphorbol Acetate; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D000099169:Fos-Related Antigen 1; C497872:FOSL2 protein, human; C032253:involucrin