Conserved co-regulation and promoter sharing of hoxb3a and hoxb4a in zebrafish.

摘要: The expression of zebrafish hoxb3a and hoxb4a has been found to be mediated through five transcripts, transcripts I–III I–II, driven by four promoters. A ‘master’ promoter, located about 2 kb downstream hoxb5a, controls transcription a pre-mRNA comprising exon sequences both genes. This unique gene structure is proposed provide novel mechanism ensure overlapping, tissuespecific genes in the posterior hindbrain spinal cord. Transgenic approaches were used analyze functions hoxb3a/hoxb4a promoters enhancer containing regions homology that previously identified comparative genomics. Two neural enhancers shown establish specific anterior borders within mediate defined neuronal populations derived from rhombomeres (r) 5 8, suggesting late role cell lineage specification. Species comparison showed r5 r6 corresponded sequence mouse HoxA cluster controlling activity Hoxa3 r6, whereas homologous region HoxB activated Hoxb3 but limited r5. We conclude similarity hoxb3a/Hoxa3 regulatory mechanisms reflect shared descent single ancestral paralog group 3 gene.