Echinoid synergizes with the Notch signaling pathway in Drosophila mesothorax bristle patterning.
echinoid (ed) encodes an immunoglobulin domain-containing cell adhesion molecule that negatively regulates the Egfr signaling pathway during Drosophila photoreceptor development. We show a novel function of Ed, i.e. the restriction of the number of notum bristles that arise from a proneural cluster. Thus, loss-of-function conditions for ed give rise to the development of extra macrochaetae near the extant ones and increase the density of microchaetae. Analysis of ed mosaics indicates that extra sensory organ precursors (SOPs) arise from proneural clusters of achaete-scute expression in a cell-autonomous way. ed embryos also exhibit a neurogenic phenotype. These phenotypes suggest a functional relation between ed and the Notch (N) pathway. Indeed, loss-of-function of ed reduces the expression of the N pathway effector E(spl)m8 in proneural clusters. Moreover, combinations of moderate loss-of-function conditions for ed and for different components of the N pathway show clear synergistic interactions manifested as strong neurogenic bristle phenotypes. We conclude that Ed is not essential for, but it facilitates, N signaling. It is known that the N and Egfr pathways act antagonistically in bristle development. Consistently, we find that Ed also antagonizes the bristle-promoting activity of the Egfr pathway, either by the enhancement of N signalling or, similar to the eye, by a more direct action on the Egfr pathway.
Escudero
Luis M
LM
Centro de Biología Molecular Severo Ochoa, C.S.I.C. and U.A.M., Cantoblanco, 28049 Madrid, Spain.
Wei
Shu-Yi
SY
Chiu
Wei-Hsin
WH
Modolell
Juan
J
Hsu
Jui-Chou
JC
D000595:Amino Acid Sequence; D000818:Animals; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D004331:Drosophila melanogaster / Q000196:embryology*; D004357:Drug Synergism; D000939:Epitopes / Q000737:chemistry; D018507:Gene Expression Regulation, Developmental; D008565:Membrane Proteins / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009030:Mosaicism; D005810:Multigene Family; D016296:Mutagenesis; D009420:Nervous System / Q000196:embryology; D010446:Peptide Fragments / Q000737:chemistry; D010786:Photoreceptor Cells / Q000196:embryology*; D051880:Receptors, Notch; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D014738:Vibrissae / Q000196:embryology / Q000502:physiology*
D015815:Cell Adhesion Molecules; D029721:Drosophila Proteins; C422623:ED protein, Drosophila; D000939:Epitopes; D008565:Membrane Proteins; C497759:N protein, Drosophila; D010446:Peptide Fragments; D051880:Receptors, Notch; D012097:Repressor Proteins