Functional and molecular charecterization of targets of ultrabithorax in drosophila

Abstract

The Homeotic Hox genes are highly conserved throughout metazoan evolutionand code for homeodomain containing transcription factors that controlspecific developmental pathways The Hox gene Ultrabithorax Ubx isexpressed in third thoracic segment of Drosophila and regulates many wingpatterning genes to form haltere Loss of Ubx from developing haltere andectopic expression of Ubx in wing causes haltere to wing wing to halteretransformations respectively Genome wide and transcriptome studiesidentified many genes pathways involved in wing development as targets ofUbx in haltere Ubx regulates cellular processes such cell division cellproliferation cell differentiation cell size and cell affinity in developmentalstage specific manner to provide haltere a distinct morphology As comparedto wing haltere is highly reduced in size they lack wing type marginalbristles vein inter vein have reduced cell size different cell shape anddensely arranged trichomes However the functionality of genes and pathwaysrequired by Ubx to provide identity to haltere are not completely known Functional relevance of only few Pathways like Wingless Wg Decapentaplegic Dpp and epidermal growth factor receptor EGFR hasbeen studied previously Here we have addressed how differences in cell sizeand shape influence organ size and shape We have explained the role of two major organ size determiningpathways in haltere i e Insulin Insulin like signaling IIS pathway and Hippopathway Akt a central component of IIS pathway is down regulated inhaltere Hippo pathway component Yorkie Yki a transcriptional co activatorprotein is differentially regulated in wing and haltere Also regulation ofupstream component like Expanded Ex and down stream component likebantam microRNA is critical in haltere Interestingly while both overexpressionof Yki and knock down of ex caused significantly incr newline