TY - JOUR
T1 - Hoxb3 negatively regulates Hoxb1 expression in mouse hindbrain patterning
AU - Wong, Elaine Y M
AU - Wang, Xing An
AU - Mak, Siu Shan
AU - Sae-Pang, Jearn Jang
AU - Ling, Kam Wing
AU - Fritzsch, Bernd
AU - Sham, Mai Har
PY - 2011/4/15
Y1 - 2011/4/15
N2 - The spatial regulation of combinatorial expression of Hox genes is critical for determining hindbrain rhombomere (r) identities. To address the cross-regulatory relationship between Hox genes in hindbrain neuronal specification, we have generated a gain-of-function transgenic mouse mutant Hoxb3(Tg) using the Hoxb2 r4-specific enhancer element. Interestingly, in r4 of the Hoxb3(Tg) mutant where Hoxb3 was ectopically expressed, the expression of Hoxb1 was specifically abolished. The hindbrain neuronal defects of the Hoxb3(Tg) mutant mice were similar to those of Hoxb1(-/-) mutants. Therefore, we hypothesized that Hoxb3 could directly suppress Hoxb1 expression. We first identified a novel Hoxb3 binding site S3 on the Hoxb1 locus and confirmed protein binding to this site by EMSA, and by in vivo ChIP analysis using P19 cells and hindbrain tissues from the Hoxb3(Tg) mutant. We further showed that Hoxb3 could suppress Hoxb1 transcriptional activity by chick in ovo luciferase reporter assay. Moreover, in E10.5 wildtype caudal hindbrain, where Hoxb1 is not expressed, we showed by in vivo ChIP that Hoxb3 was consistently bound to the S3 site on the Hoxb1 gene. This study reveals a novel negative regulatory mechanism by which Hoxb3 as a posterior gene serves to restrict Hoxb1 expression in r4 by direct transcriptional repression to maintain the rhombomere identity.
AB - The spatial regulation of combinatorial expression of Hox genes is critical for determining hindbrain rhombomere (r) identities. To address the cross-regulatory relationship between Hox genes in hindbrain neuronal specification, we have generated a gain-of-function transgenic mouse mutant Hoxb3(Tg) using the Hoxb2 r4-specific enhancer element. Interestingly, in r4 of the Hoxb3(Tg) mutant where Hoxb3 was ectopically expressed, the expression of Hoxb1 was specifically abolished. The hindbrain neuronal defects of the Hoxb3(Tg) mutant mice were similar to those of Hoxb1(-/-) mutants. Therefore, we hypothesized that Hoxb3 could directly suppress Hoxb1 expression. We first identified a novel Hoxb3 binding site S3 on the Hoxb1 locus and confirmed protein binding to this site by EMSA, and by in vivo ChIP analysis using P19 cells and hindbrain tissues from the Hoxb3(Tg) mutant. We further showed that Hoxb3 could suppress Hoxb1 transcriptional activity by chick in ovo luciferase reporter assay. Moreover, in E10.5 wildtype caudal hindbrain, where Hoxb1 is not expressed, we showed by in vivo ChIP that Hoxb3 was consistently bound to the S3 site on the Hoxb1 gene. This study reveals a novel negative regulatory mechanism by which Hoxb3 as a posterior gene serves to restrict Hoxb1 expression in r4 by direct transcriptional repression to maintain the rhombomere identity.
KW - Animals
KW - Animals, Genetically Modified
KW - Avian Proteins/genetics
KW - Base Sequence
KW - Binding Sites/genetics
KW - Body Patterning
KW - Chick Embryo
KW - Craniofacial Abnormalities/embryology
KW - DNA Primers/genetics
KW - Gene Expression Regulation, Developmental
KW - Homeodomain Proteins/genetics
KW - Mice
KW - Mice, Mutant Strains
KW - Mice, Transgenic
KW - Models, Neurological
KW - Neurogenesis/genetics
KW - Rhombencephalon/embryology
U2 - 10.1016/j.ydbio.2011.02.003
DO - 10.1016/j.ydbio.2011.02.003
M3 - Article
C2 - 21320481
VL - 352
SP - 382
EP - 392
JO - Developmental Biology
JF - Developmental Biology
SN - 0012-1606
IS - 2
ER -