The Inverted CCAAT Motif is an Indispensable Element of the Enhancer B of the Mouse Major Histocompatibility IH2-K^bGene

Abstract

We have identified a strong binding of nuclear proteins derived from Ltk(-) fibroblasts to the enhancer B of the mouse MHC class I H2-K(b) gene. The inverted CCAAT motif and its adjacent upstream sequences have been revealed as protein-binding sites by electrophoretic mobility-shift, methylation interference, and DNase I footprint assays. Specific mutations in the inverted CCAAT motif as well as in the 5'-flanking cytosine pentanucleotide abrogated the formation of the major DNA-protein complex. Transcription of the chloramphenicol acetyltransferase (CAT) reporter gene driven by the H2-K(b) promoter in the Ltk(-) cell line was reduced substantially when a two-nucleotide mutation was introduced into the CCAAT element (CCAATCgcAT). The indicated two-nucleotide mutation decreased transcription initiated from both the homologous and a heterologous promoter. Furthermore, cotransfected MHC class II transactivator (CIITA) elevated the transcription of the reporter gene under the control of the H2-K(b) upstream sequences in the NIH 3T3 cell line. The intact enhancer B involving both the inverted CCAAT motif and the site alpha was found to play an indispensable role in the CIITA-mediated gene transactivation. The band-shift assay with the enhancer B probe revealed forming of a protein complex in a cooperative manner, which was again prevented by mutations in either element. Our results suggest an essential role of the inverted CCAAT element in the constitutive as well as inducible transcription of the mouse MHC class I genes.

An Extended Pyrrolobenzodiazepine–Polyamide Conjugate with Selectivity for a DNA Sequence Containing the ICB2 Transcription Factor Binding Site

“…Some lowmolecular-weight ligands are known to recognize specific DNA sequences and inhibit transcription factor binding and so could be exploited to modulate transcription and block cellular proliferation. 1−8 Nuclear factor Y (NF-Y) is a ubiquitous CCAAT-binding 9 transcription factor comprising three subunits, NF-YA, NF-YB, and NF-YC, and is involved in cell differentiation and cell cycle progression. 10−12 It has been shown that binding of the heterotrimeric NF-Y to five inverted CCAAT boxes (ICBs) within the promoter region of DNA topoisomerase IIα (Topo IIα) results in control of transcriptional expression at confluence, p53-induced down-regulation, and response to heat-shock-induced up-regulation.…”

“…Transcription factor binding sites in disease-related genes are potential therapeutic targets for small molecules. Some low-molecular-weight ligands are known to recognize specific DNA sequences and inhibit transcription factor binding and so could be exploited to modulate transcription and block cellular proliferation. − Nuclear factor Y (NF-Y) is a ubiquitous CCAAT-binding transcription factor comprising three subunits, NF-YA, NF-YB, and NF-YC, and is involved in cell differentiation and cell cycle progression. − It has been shown that binding of the heterotrimeric NF-Y to five inverted CCAAT boxes (ICBs) within the promoter region of DNA topoisomerase IIα (Topo IIα) results in control of transcriptional expression at confluence, p53-induced down-regulation, and response to heat-shock-induced up-regulation. ,− In mammalian cells, Topo IIα represents one of the most important cellular targets for a range of anticancer drugs . High levels of topoisomerase II gene expression correlate with the relative sensitivity of cells to these agents, while low levels confer drug resistance.…”

Jun oncoproteins do not function as primary transcription factors for the mouse major histocompatibility complex class I H‐2 genes in fibroblasts

“…However, the direct negative regulation of the swine class I PD1 gene by c‐jun (Howcroft et al ., 1993) could be explained by evolutionary divergence. Differential regulation of the MHC class I genes of various species has been demonstrated, for example with regard to lymphoid specific expression between the H2‐K b and PD1 genes (Weissman & Singer, 1991; Hatina et al ., 1999), the position‐independent expression of the transgene between the H2‐K b and HLA‐B7 genes (Chamberlain et al ., 1991; Drezen et al ., 1992; Hatina et al ., 1999), and the regulatory sequences mediating transcriptional activation of the H2‐K b and PD1 genes by the coactivator CIITA (Jansa & Hatina, 2003).…”

Thymidine kinase 1 through the ages: a comprehensive review

“…Transcription signals within the 5′ region contain TATAA, CCAAT, and G-C elements [58,65]. One of these elements, a 12-base pair inverted CCAAT repeat, has been established as a transcriptional protein binding site [58,65,66]. The inverted CCAAT motif responsible for transcriptional activation of TK1 is most likely recognized by the transcription factor CCAAT-binding protein CP1 due to sequence homology with other genes regulated by CP1 [4,65].…”