PUBLICATION
Identification of a conserved 125 base-pair Hb9 enhancer that specifies gene expression to spinal motor neurons
- Authors
- Nakano, T., Windrem, M., Zappavigna, V., and Goldman, S.A.
- ID
- ZDB-PUB-050602-3
- Date
- 2005
- Source
- Developmental Biology 283(2): 474-485 (Journal)
- Registered Authors
- Keywords
- Motor neurons; Promoters; Spinal muscular atrophy; Amyotrophic lateral sclerosis
- MeSH Terms
-
- Amino Acid Sequence
- Animals
- Cloning, Molecular
- Conserved Sequence
- Enhancer Elements, Genetic*
- Gene Expression Regulation, Developmental
- Genes, Homeobox
- Homeodomain Proteins/genetics*
- Homeodomain Proteins/metabolism
- Humans
- Mice
- Mice, Transgenic
- Molecular Sequence Data
- Motor Neurons/cytology
- Motor Neurons/metabolism*
- Promoter Regions, Genetic
- Rats
- Sequence Homology, Amino Acid
- Spinal Cord/cytology
- Spinal Cord/embryology
- Spinal Cord/metabolism*
- Takifugu
- Transcription Factors/genetics*
- Transcription Factors/metabolism
- Zebrafish
- PubMed
- 15913596 Full text @ Dev. Biol.
Citation
Nakano, T., Windrem, M., Zappavigna, V., and Goldman, S.A. (2005) Identification of a conserved 125 base-pair Hb9 enhancer that specifies gene expression to spinal motor neurons. Developmental Biology. 283(2):474-485.
Abstract
The homeobox gene Hb9 is expressed selectively by motor neurons (MNs) in the developing CNS. Previous studies have identified a 9-kb 5' fragment of the mouse Hb9 gene that is sufficient to direct gene expression to spinal MNs in vivo. Here, we sought to identify more discrete MN-specifying elements, using homology searches between genomic sequences of evolutionarily distant species. Based on homology screening of the mouse and human Hb9 promoters, we identified a 3.6-kb Hb9 enhancer that proved sufficient to drive MN-specific lacZ expression. We then compared mouse, human, and pufferfish (Fugu rubripes) genomic sequences, and identified a conserved 438-bp sequence, consisting of noncontiguous 313-bp and 125-bp fragments, residing within the 3.6-kb Hb9 enhancer. The zebrafish (Danio rerio) Hb9 genomic region was then found to have two identical copies of the 125-bp sequence, but no counterpart for the 313-bp sequence. Transgenic analysis showed that the 125-bp alone was both necessary and sufficient to direct spinal MN-specific lacZ expression, whereas the 313-bp sequence had no such enhancer activity. Moreover, the 125-bp Hb9 enhancer was found to harbor two Hox/Pbx consensus-binding sequences, mutations of which completely disrupted thoracolumbar Hb9 expression. These data suggest that Hox/Pbx plays a critical role in the segmental specification of spinal MNs. Together, these results indicate that the molecular pathways regulating Hb9 expression are evolutionarily conserved, and that MN-specific gene expression may be directed and achieved using a small 125-bp 5' enhancer.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping