H. Watada et al., THE HUMAN GLUCOKINASE GENE BETA-CELL-TYPE PROMOTER - AN ESSENTIAL ROLE OF INSULIN PROMOTER FACTOR 1 PDX-1 IN ITS ACTIVATION IN HIT-T15 CELLS/, Diabetes, 45(11), 1996, pp. 1478-1488
Citations number
47
Categorie Soggetti
Endocrynology & Metabolism","Medicine, General & Internal
The glycolytic enzyme glucokinase plays a primary role in the glucose-
responsive secretion of insulin, and defects of this enzyme can cause
NIDDM, As a step toward understanding the molecular basis of glucokina
se (GK) gene regulation, we assessed the structure and regulation of h
e human GR gene beta-cell-tgpe promoter The results of reporter gene a
nalyses using HIT-T15 cells revealed that the gene promoter was compri
sed of multiple cis-acting elements, including two primarily important
cis-motifs: a palindrome structure, hPal-1, and the insulin gene cis-
motif A element-like hUPE3, While both elements were bound specificall
y by nuclear proteins, it was the homeodomain-containing transcription
factor insulin promoter factor 1 (IPF1)/STF-1/PDX-1 that bound to the
hUPE3 site: IPF1, when expressed in CHO-K1 cells, became bound to the
hUPE3 site and activated transcription. An andi-IPF1 antiserum used i
n gel-mobility shift analysis supershifted the DNA protein complex for
med with the hUPE3 probe and nuclear extracts from HIT-T15 cells, thus
supporting the involvement of IPF1 in GK gene activation in HIT-T15 c
ells. In contrast to the insulin gene, however, neither the synergisti
c effect of the Pan1 expression on the IPF1-induced promoter activatio
n nor the glucose responsiveness of the activity was observed for the
GK gene promoter. These results revealed some conservative but unique
features for the transcriptional regulation of the beta-cell-specific
genes in humans, Being implicated in insulin and GK gene regulations a
s a common transcription factor, IPF1/STF-1/PDX-1 is likely to play an
essential role in maintaining normal beta-cell functions.