Emc, a negative HLH regulator with multiple functions in Drosophila development

Abstract

Expression and functional analyses of Emc have demonstrated that it is a prototype for a protein required for multiple processes in development. Initially characterized as a negative regulator of sensory organ development, it was later found to regulate many other developmental processes and cell proliferation. Its ability to block the function of bHLH proteins by forming heterodimers, which are ine ective in DNA binding, accounts for the role of Emc in preventing the acquisition of several cell fates which are under the control of bHLH proteins. However, while maintaining this repressive molecular mechanism, emc also appears to act as a positive regulator of di erentiation. Oncogene (2001) 20, 8299 ± 8307

The Complex Tale of the achaete–scute Complex: A Paradigmatic Case in the Analysis of Gene Organization and Function During Development

“…Following random mutagenesis in these potential genes, phenotypes of extrachaetae (similar to the Hw) were found in two loci, extramacrochaetae (emc) and hairy (h) (Botas et al 1982). Both genes also encode HLH proteins that regulate the expression of ac and sc (Hairy) and that interact with the Ac and Sc proteins, antagonizing their function (Emc) (Ellis et al 1990;Garrell and Modolell 1990;Van Doren et al 1991Ohsako et al 1994;Campuzano 2001). Similar mutagenesis experiments using a mutant background heterozygous for AS-C deficiencies did not yield any candidate for an activator gene.…”

The Drosophila Boundary Element-Associated Factors BEAF-32A and BEAF-32B Affect Chromatin Structure

“…Data indicate that BEAF forms trimers ( Figure 1C), although cooperative binding to two sites separated by 200 bp suggests that larger BEAF complexes also form, at least transiently (Hart et al 1997). The design of BID is based on the Drosophila Emc protein (Campuzano 2001) and the vertebrate family of Id proteins (Norton et al 1998). Emc and Id lack DNAbinding domains and form heterodimers with certain DNA-binding transcription factors.…”

“…This design is based on the Drosophila Emc and vertebrate Id proteins (Norton et al 1998;Campuzano 2001). These proteins lack DNA-binding domains and so inhibit DNA binding by their partner transcription factors by forming dimers that lack one DNA-binding domain.…”

Notch-dependent downregulation of the homeodomain gene cut is required for the mitotic cycle/endocycle switch and cell differentiation inDrosophilafollicle cells

“…Loss of emc function results in upregulated CycB and FasIII in follicle cells after stage 6, a phenotype similar to that of loss of Notch (Adam and Montell, 2004). Emc could function as a transcriptional repressor (Campuzano, 2001), and it is known to be involved in promoting differentiation (Cubas et al, 1994), so it is a good candidate for mediating Notch-dependent downregulation of Cut during the mitotic cycle/endocycle switch. We did not, however, find any change of Cut expression in emc loss-of-function clones generated by a null allele, emc AP6 (data not shown), thus excluding the possibility that cut is repressed by emc during the mitotic/endocycle switch.…”