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General Comment |
Mano H, et al reported that IF3, a novel cell-differentiation factor, is highly expressed in
murine liver and ovary.
The IF3 gene was isolated by expression cloning from a cDNA library of mouse
oocytes. This gene was revealed to have no homology to any known gene and its
cDNA encodes a 202-amino acid protein that contains a signal-peptide sequence.
Moreover, an IF3 isoform, IF3(2), was expressed in both liver and ovary. Its
cDNA encoded a 92-amino acid protein contains a signal-peptide sequence, which
may be an alternative splice and frameshift form of IF3. The mRNA of IF3s was
expressed in oocytes, ovary, and liver. Moreover, the gene expression of IF3s
was regulated in a development-dependent manner in preimplantation-embryo and
liver. Both IF3(1) and IF3(2) isoforms induced the differentiation of 2T3 and
ATDC5 cells to the osteogenic and chondrogenic phenotype, respectively,
suggesting that IF3s may modulate the differentiation status. The findings
suggest that IF3 may be one of the secreted factors that regulate oogenesis
and certain liver functions.
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