Oct-6: a regulator of keratinocyte gene expression in stratified squamous epithelia.
POU domain proteins have been implicated as regulators of differentiation and development, particularly in early embryogenesis and in neural morphogenesis. Given that neural and epidermal lineages originate from a common precursor (ectodermal) cell, we explored the possibility that POU proteins are involved in epidermal differentiation. Using reverse transcription-PCR and degenerate oligonucleotides, we generated several POU domain cDNAs from cultured human epidermal mRNAs. One of these encoded a sequence identical to the rodent Tst-1/SCIP/Oct-6 POU domain. Subsequently, we isolated a cDNA encoding a 45.3-kDa protein with 98% sequence identity to rat Tst-1/SCIP and 94% identity to mouse Oct-6. This protein bound specifically to the canonical octamer motif, warranting its designation as human Oct-6. By RNase protection assays, by PCR, and by immunoblot analysis, Oct-6 was expressed in cultured epidermal keratinocytes. By in situ hybridization, Oct-6 mRNA was detected not only in epidermis but also a variety of other stratified squamous epithelia and with greater signals than testis, the tissue in which this POU protein was originally discovered. Moreover, Oct-6 exerted a marked and specific negative influence on expression of the K5 and K14 genes, abundantly expressed in most dividing stratified squamous epithelial cells and downregulated as cells commit to terminally differentiate. The repressive effect was complex, but it was not observed with Oct-1, nor was it seen with a truncated Oct-6 missing the POU domain. Taken together, our studies suggest that Oct-6 may play an important role in controlling gene expression in stratified squamous epithelia, including epidermis.
Faus
I
I
Department of Molecular Genetics and Cell Biology, Howard Hughes Medical Institute, University of Chicago, Illinois 60637.
Hsu
H J
HJ
Fuchs
E
E
D000595:Amino Acid Sequence; D001483:Base Sequence; D002294:Carcinoma, Squamous Cell; D002460:Cell Line; D002478:Cells, Cultured; D003001:Cloning, Molecular; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D005786:Gene Expression Regulation; D015972:Gene Expression Regulation, Neoplastic; D005801:Genes, Homeobox; D006801:Humans; D007231:Infant, Newborn; D015603:Keratinocytes / Q000378:metabolism*; D008969:Molecular Sequence Data; D050816:Octamer Transcription Factor-6; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D015183:Restriction Mapping; D012867:Skin / Q000378:metabolism*; D012878:Skin Neoplasms; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D004268:DNA-Binding Proteins; C494178:POU3F1 protein, human; D012333:RNA, Messenger; D014157:Transcription Factors; D050816:Octamer Transcription Factor-6