TY - GEN
T1 - Evolution of insect dorsoventral patterning mechanisms
AU - Perry, M. W.
AU - Cande, J. D.
AU - Boettiger, A. N.
AU - Levine, M.
PY - 2009
Y1 - 2009
N2 - The dorsoventral (DV) patterning of the early Drosophila embryo depends on Dorsal, a maternal sequence-specific transcription factor related to mammalian NF-κB. Dorsal controls DV patterning through the differential regulation of ∼50 target genes in a concentration-dependent manner. Whole-genome methods, including ChIP-chip and ChIP-seq assays, have identified ∼100 Dorsal target enhancers, and more than one-third of these have been experimentally confirmed via transgenic embryo assays. Despite differences in DV patterning among divergent insects, a number of the Dorsal target enhancers are located in conserved positions relative to the associated transcription units. Thus, the evolution of novel patterns of gene expression might depend on the modification of old enhancers, rather than the invention of new ones. As many as half of all Dorsal target genes appear to contain "shadow" enhancers: a second enhancer that directs the same or similar expression pattern as the primary enhancer. Preliminary studies suggest that shadow enhancers might help to ensure resilience of gene expression in response to environmental and genetic perturbations. Finally, most Dorsal target genes appear to contain RNA polymerase II (pol II) prior to their activation. Stalled pol II fosters synchronous patterns of gene activation in the early embryo. In contrast, DV patterning genes lacking stalled pol II are initially activated in an erratic or stochastic fashion. It is possible that stalled pol II confers fitness to a population by ensuring coordinate deployment of the gene networks controlling embryogenesis.
AB - The dorsoventral (DV) patterning of the early Drosophila embryo depends on Dorsal, a maternal sequence-specific transcription factor related to mammalian NF-κB. Dorsal controls DV patterning through the differential regulation of ∼50 target genes in a concentration-dependent manner. Whole-genome methods, including ChIP-chip and ChIP-seq assays, have identified ∼100 Dorsal target enhancers, and more than one-third of these have been experimentally confirmed via transgenic embryo assays. Despite differences in DV patterning among divergent insects, a number of the Dorsal target enhancers are located in conserved positions relative to the associated transcription units. Thus, the evolution of novel patterns of gene expression might depend on the modification of old enhancers, rather than the invention of new ones. As many as half of all Dorsal target genes appear to contain "shadow" enhancers: a second enhancer that directs the same or similar expression pattern as the primary enhancer. Preliminary studies suggest that shadow enhancers might help to ensure resilience of gene expression in response to environmental and genetic perturbations. Finally, most Dorsal target genes appear to contain RNA polymerase II (pol II) prior to their activation. Stalled pol II fosters synchronous patterns of gene activation in the early embryo. In contrast, DV patterning genes lacking stalled pol II are initially activated in an erratic or stochastic fashion. It is possible that stalled pol II confers fitness to a population by ensuring coordinate deployment of the gene networks controlling embryogenesis.
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U2 - 10.1101/sqb.2009.74.021
DO - 10.1101/sqb.2009.74.021
M3 - Conference contribution
C2 - 19843594
AN - SCOPUS:77957742483
SN - 9780879698713
T3 - Cold Spring Harbor Symposia on Quantitative Biology
SP - 275
EP - 279
BT - Cold Spring Harbor Symposia on Quantitative Biology
ER -