Cloning, sequencing and expression of two isoforms of the murine oct-1 transcription factor.
Oct-1 is a ubiquitously expressed regulatory gene of the POU domain family. The Oct-1 protein binds to the octamer motif present in the control regions of a variety of genes such as the immunoglobulins, histone H2B and snRNAs. To learn about Oct-1 and its possible role in B-cell maturation, we have used oct-2 cDNA to screen a murine pre-B cell, cDNA library. Two cDNA clones were identical in their POU-homeo box DNA binding domain, but differed in their 3'-region. Whereas one clone (oct-1a) was very similar to its human oct-1 homologue, the other (oct-1b), contained an additional 72 bp sequence (designated E1) at the serine threonine rich coding region (position 1485 of the human oct-1), and a deletion of another 72 bp sequence (designated E2) downstream (position 1920). These changes preserve the protein reading frame. DNA blot analysis indicates that murine oct-1 is a single copy gene and that the two oct-1 isoforms oct-1 is expressed as a large approximately 10 kb transcript in all the cell are generated by alternative RNA splicing. RNA blots showed that oct-1 is expressed as a large approximately 10 kb transcript in all the cell lines tested. PCR analysis of the E1 and E2 72 bp regions, indicated the presence of a third isoform containing both E1 and E2 (Oct-1c). Oct-1a and Oct-1b were present in all cell types examined, but the level of expression was lower in liver and spleen as compared to testis, thymus and kidney. The ratio of Oct-1b to Oct-1a ranged between 0.2 to 0.5, for all tissues examined except for testis which expressed higher amounts of oct-1b and/or oct-1c. Our findings thus show that the pattern of expression of the oct-1 gene is more complex than hitherto thought.
Jaffe
J
J
Hubert Humphrey Center for Experimental Medicine and Cancer Research, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Hochberg
M
M
Riss
J
J
Hasin
T
T
Reich
L
L
Laskov
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051863:Host Cell Factor C1; D051379:Mice; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D016133:Polymerase Chain Reaction; D012326:RNA Splicing; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C497693:Hcfc1 protein, mouse; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; C494166:Pou2f1 protein, mouse; D014157:Transcription Factors