A1F‐B, a novel CCAAT‐binding transcription activator that interacts with the aldolase B promoter

Abstract

We describe here a 70 kDa transcription factor AIF-B, which preferentially binds to an element encompassmg a CCAAT motif on the rat aldolase B promoter. Comparison of binding specificities, relative molecular masses, and subunit compositions with those of other known CCAAT-binding factors indicated that AIF-B 1s a novel member of CCAAT-binding factors.

A novel growth-inducible gene that encodes a protein with a conserved cold-shock domain

“…Considering the expression profile of aldolase B gene, it might be that RYB-a could function as a negative regulatory factor in the expression of aldolase B gene. In the fetal livers at days 14 and 16 of gestation, factor AlF-B which acts positively on site B (22,23) has, although to a lesser extent, already accumulated.…”

“…During the screening of cDNAs encoding regulatory factors that interact with an element (site B) locating in the rat aldolase B promoter (22,23), we isolated a cDNA that encodes a novel member of the Y-box binding protein family, and designated it as RYB-a (Rat Y-box Binding protein-a). We describe here the tissue-specific distribution and developmental stage-specific expression of RYB-a mRNA.…”

Eukaryotic Promoter Recognition

“…For example, on the order of half of all vertebrate promoters contain a somewhat conserved sequence element with a core sequence similar to CCAAT (Benoist et al 1980;Efstratiadis et al 1980). There seem to be a large number of factors that interact with CCAAT-like sequences, not all of which are known to actually influence transcription initiation (see Tsutsumi et al 1993 for a list). CCAAT box-binding factor (CBF, also called NFY and CP1) is a trimeric transcription factor that is known to be involved in the activity of a number of promoters (see Sinha et al 1996 for an overview).…”

Hereditary fructose intolerance.

“…'7 18 The 5' flanking sequences (up to 200 base pairs) of the aldolase B gene from different species are highly conserved, as expected for common promoter regions that are important for gene expression. The developmental stage specific and tissue specific expression of aldolase B has been shown to be linked with the chromatin structure of its promoter region (which encompasses an origin of DNA replication initiation),'9 20 the demethylation of a cytosine residue (position -129),21 and the simultaneous appearance of transcription factors, AIF-A (identical to liver specific factor HNF-122) and AIF-B (CCAAT binding protein, binds to residues at positions -129 and -128), which activate aldolase B gene transcription by binding to the promoter region.23 24 The transcription factors HNF-3 and RYB-a, which have overlapping binding sites with AIF-A and AIF-B respectively, have been identified to repress transcription from this promoter 5 26 suggesting that competition between these activators/repressors regulates aldolase B gene expression. 27 Recently, Sabourin et af8 used transgenic mouse models with expression construct transgenes to identify an intronic activator region (nucleotides 650-2448 in the aldolase B gene) which, in combination with the tissue specific promoter, is sufficient to mediate developmental expression of aldolase B mRNA expression but lacks the necessary site(s) for activation by dietary carbohydrate.…”