Gene Structure, cDNA Sequence, and mRNA Distribution

The rat HNF-3 (hepatocyte nuclear factor 3) gene family encodes
three transcription factors known to be important in the regulation
of gene expression in liver and lung. We have cloned and
characterized the mouse genes and cDNAs for HNF-3α, β, and γ and
analyzed their expression patterns in various adult tissues and
mouse embryonic stages. The HNF-3 proteins are highly conserved
between mouse and rat, with the exception of the amino terminus of
HNF-3γ, which in mouse is more similar to those of HNF-3α and β
than to the amino termini of the rat HNF-3γ protein. The mouse
HNF-3 genes are small and contain only two or three (HNF-3β) exons
with conserved intron-exon boundaries. The proximal promoter of the
mouse HNF3β gene is remarkably similar to that of the previously
cloned rat HNF-3β gene, but is different from the promoters of the
HNF-3α and γ genes. The mRNA distribution of the mouse HNF-3 genes
was analyzed by quantitative RNase protection with gene-specific
probes. While HNF-3α and β are restricted mainly to
endoderm-derived tissues (lung, liver, stomach, and small
intestine), HNF-3γ is more extensively expressed, being present
additionally in ovary, testis, heart, and adipose tissue, but
missing from lung. Transcripts for HNF-3β and α are detected most
abundantly in midgestation embryos (Day 9.5), while HNF-3γ
expression peaks around Day 15.5 of gestation.