title: BHLHB4 is a bHLH transcriptional regulator in pancreas and brain that marks the dimesencephalic boundary.
abstract: We have cloned a basic helix-loop-helix (bHLH) factor gene, Bhlhb4, from a mouse beta-cell line. Fluorescence in situ hybridization (FISH) and genetic mapping place Bhlhb4 at the telomeric end of mouse chromosome 2 (H3-H4), syntenic to human chromosome 20q13. Based on phylogenetic analysis, BHLHB4 belongs to a new subgroup of bHLH factors including at least four previously identified mouse bHLH factors: BHLHB5, MIST1, OLIG1, OLIG2, and OLIG3. In the developing nervous system, Bhlhb4 was found to mark the dimesencephalic boundary, suggesting that Bhlhb4 may have a role in diencephalic regionalization. In the pancreas, Bhlhb4 is expressed in a transient fashion that suggests a role in the pancreatic endocrine cell lineage. Transfection experiments show that BHLHB4 can repress transcriptional activation mediated through the pancreatic beta-cell specific insulin promoter enhancer RIPE3. Together, these data suggest that BHLHB4 may modulate the expression of genes required for the differentiation and/or maintenance of pancreatic and neuronal cell types.
authors.affiliation: Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA. debrab@bcm.tmc.edu
authors.forename: Debra E
authors.initials: DE
authors.lastname: Bramblett
authors.forename: Neal G
authors.initials: NG
authors.lastname: Copeland
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Jenkins
authors.forename: Ming-Jer
authors.initials: MJ
authors.lastname: Tsai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D002874:Chromosome Mapping; D002890:Chromosomes, Human, Pair 20; D004027:Diencephalon / Q000196:embryology / Q000378:metabolism*; D005809:Genes, Regulator; D018257:Helix-Loop-Helix Motifs / Q000235:genetics; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D010179:Pancreas / Q000378:metabolism*; D010802:Phylogeny; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D014157:Transcription Factors; C455509:Bhlhb4 protein, mouse