High impact information on Hivep1

• This new protein, the angiotensinogen gene-inducible enhancer-binding protein 1 (AGIE-BP1), is encoded by a large continuous open reading frame and contains a zinc finger motif virtually identical to the DNA-binding domain of a recently described human protein, MBP-1/PRDII-BF1, and a homologous mouse protein, alpha A-CRYBP1 [1].
• alpha A-crystallin binding protein I (alpha A-CRYBP1) is a ubiquitously expressed DNA binding protein that was previously identified by its ability to interact with a functionally important sequence in the mouse alpha A-crystallin gene promoter [2].
• When introduced into the alpha TN4-1 mouse lens cell line, the antisense construct significantly inhibited expression from a heterologous promoter that utilized the alpha A-CRYBP1 binding site as an enhancer [2].
• Finally, we used an antisense expression construct derived from an alpha A-CRYBP1 cDNA clone to provide the first functional evidence that alpha A-CRYBP1 regulates gene expression [2].
• The alpha A-CRYBP1 gene produces a 9.5-kb transcript in 11 different tissues as well as a testis-specific, 7.7-kb transcript. alpha A-CRYBP1 cDNA clones were isolated from adult mouse brain and testis as well as from cell lines derived from mouse lens (alpha TN4-1) and muscle (C2C12) [2].

Biological context of Hivep1

• Here, we have cloned a single copy gene with 10 exons spanning greater than 70 kb of genomic DNA that encodes alpha A-CRYBP1 [2].
• One motif is similar to the alpha A-CRYBP1 binding site implicated earlier in the transcriptional regulation of the mouse alpha A-crystallin gene, and other motifs correspond to sites previously mapped by methylation interference studies in the mouse alpha A-crystallin promoter [3].
• Here we have used the bacterial chloramphenicol acetyltransferase (CAT) reporter gene to test the functional importance of the putative DE-1 and alpha A-CRYBP1 regulatory elements by site-specific and deletion mutagenesis in stably transformed alpha TN4-1 lens cells and in transgenic mice [4].
• The mice carrying transgenes with either site-specific mutations in both the DE-1 and alpha A-CRYBP1 sites or a deletion of the entire DE-1 and part of the alpha A-CRYBP1 site (-60/+46) fused to the CAT gene did not exhibit CAT activity above background in any of the tissues examined, including the lens [4].
• These included positions -111 to -97 (DE-1 region), positions -75 to -55 (alpha A-CRYBP1 region), positions -35 to -12 (TATA box and PE-1 region), and positions +23 to +43 (an AP-1 consensus sequence) [5].

Anatomical context of Hivep1

• The DNase I footprints of the DE-1 and alpha A-CRYBP1 regions, previously implicated as functional control elements, were substantially more pronounced using nuclear extract from the alpha TN4-1 cells than from the L929 fibroblasts, suggesting more stable protein binding with the former than with the latter [5].

Other interactions of Hivep1

• Mutation of the alpha A-CRYBP1-like site (-67/-57), necessary for function of the mouse alpha A-crystallin promoter, did not affect the activity of the chicken promoter [6].
• Two sizes (50 kDa and 90 kDa) of proteins reacting with the alpha A-CRYBP1-specific Ab were detected in both cell lines and, in addition, a > 200-kDa protein reacting with the Ab was unique to the fibroblast line [7].

Analytical, diagnostic and therapeutic context of Hivep1

• In the present study, we have used an antibody (specific to the alpha A-CRYBP1 protein and made against a synthetic peptide) to directly identify UV-crosslinked protein-DNA complexes via a double-label immunoblotting technique [7].
• Southern blot analysis indicated that AGIE-BP1 and alpha A-CRYBP1 are encoded by separate genes, thus defining a new family of DNA-binding proteins [1].

References