title: Extramacrochaetae functions in dorsal-ventral patterning of Drosophila imaginal discs.
abstract: One of the seminal events in the history of a tissue is the establishment of the anterior-posterior, dorsal-ventral (D/V) and proximal-distal axes. Axis formation is important for the regional specification of a tissue and allows cells along the different axes to obtain directional and positional information. Within the Drosophila retina, D/V axis formation is essential to ensure that each unit eye first adopts the proper chiral form and then rotates precisely 90° in the correct direction. These two steps are important because the photoreceptor array must be correctly aligned with the neurons of the optic lobe. Defects in chirality and/or ommatidial rotation will lead to disorganization of the photoreceptor array, misalignment of retinal and optic lobe neurons, and loss of visual acuity. Loss of the helix-loop-helix protein Extramacrochaetae (Emc) leads to defects in both ommatidial chirality and rotation. Here, we describe a new role for emc in eye development in patterning the D/V axis. We show that the juxtaposition of dorsal and ventral fated tissue in the eye leads to an enrichment of emc expression at the D/V midline. emc expression at the midline can be eliminated when D/V patterning is disrupted and can be induced in situations in which ectopic boundaries are artificially generated. We also show that emc functions downstream of Notch signaling to maintain the expression of four-jointed along the midline.
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405, USA Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Carrie M
authors.initials: CM
authors.lastname: Spratford
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405, USA jkumar@indiana.edu.
authors.forename: Justin P
authors.initials: JP
authors.lastname: Kumar
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D019521:Body Patterning / Q000235:genetics / Q000502:physiology*; D004330:Drosophila / Q000196:embryology* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005123:Eye / Q000196:embryology* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D060227:Imaginal Discs / Q000196:embryology* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000196:embryology / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D029721:Drosophila Proteins; D012097:Repressor Proteins; C063577:emc protein, Drosophila
keywords: Dorsoventral patterning; Extra macrochaetae; Eye; Four-jointed; Notch; Retina