A modifier screen in the Drosophila eye reveals that aPKC interacts with Glued during central synapse formation

Abstract

BackgroundThe Glued gene of Drosophila melanogaster encodes the homologue of the vertebrate p150Glued subunit of dynactin. The Glued1 mutation compromises the dynein-dynactin retrograde motor complex and causes disruptions to the adult eye and the CNS, including sensory neurons and the formation of the giant fiber system neural circuit.ResultsWe performed a 2-stage genetic screen to identify mutations that modified phenotypes caused by over-expression of a dominant-negative Glued protein. We screened over 34,000 flies and isolated 41 mutations that enhanced or suppressed an eye phenotype. Of these, 12 were assayed for interactions in the giant fiber system by which they altered a giant fiber morphological phenotype and/or altered synaptic function between the giant fiber and the tergotrochanteral muscle motorneuron. Six showed interactions including a new allele of atypical protein kinase C (aPKC). We show that this cell polarity regulator interacts with Glued during central synapse formation. We have mapped the five other interacting mutations to discrete chromosomal regions.ConclusionOur results show that an efficient way to screen for genes involved in central synapse formation is to use a two-step strategy in which a screen for altered eye morphology precedes the analysis of central synaptogenesis. This has highlighted a role for aPKC in the formation of an identified central synapse.

A deficiency screen of the 3rd chromosome for dominant modifiers of the Drosophila ER integral membrane protein, Jagunal

“…In addition, this approach has been very successful in identifying components of conserved cell signaling pathways and patterning during development that traditional biochemical approaches were unable to accomplish ( Banerjee et al 1987 ; Simon et al 1991 ; Halder et al 1995 ; Lee et al 2001 ). However, there are some caveats with performing a screen of this nature, including the presence of additional or second site modifiers being present in the genetic background which could confound the results ( Brand and Campos-Ortega 1990 ; Ma et al 2009 ; Chari and Dworkin 2013 ). Here, we performed a crossing strategy that expressed the Jagn-RNAi transgenic line in combination with deficiency lines covering the 3rd chromosome ( Fig.…”

A genome engineering resource to uncover principles of cellular organization and tissue architecture by lipid signaling

“…Previously, influential studies have used Drosophila eyes to screen for genes regulating cell growth and proliferation [reviewed in Tseng and Hariharan, 2002 ]. The Drosophila eye is composed of ~800 regularly arranged ommatidia, each containing eight photoreceptor neurons making the Drosophila eye an attractive tissue to study neurodegenerative diseases like Huntington’s disease ( Krench and Littleton, 2013 ) and screen for genes and genetic modifiers involved in neural development ( Ma et al, 2009 ). Moreover, photoreceptor neurons are an excellent model for phototransduction which in flies is largely dependent on PI signaling ( Raghu et al, 2012 ) and dysregulation of PI signaling leads to defects in the development, cellular structure and functions of the eye.…”

A novel co-segregatingDCTN1splice site variant in a family with Bipolar Disorder may hold the key to understanding the etiology

“…aPKCs differ from other PKC isozymes in that they are not dependent on calcium or diacylglycerol for their activity, but can nonetheless be activated by IP3 [94]. The neurodegenerative phenotype resulting from the Drosophila GLUED Gl 1 mutation (which results in ct-p150 Glued ) has been shown to be rescued by mutant alleles of aPKC, thus implying that factors that negatively regulate aPKC activation (which includes reduced IP3 levels) alleviate the mutant phenotype [95]. Given the analogy with the observations of ct-p150 Glued in AD brain samples discussed previously, and its predicted formation in the BD research cohort, this finding may provide some indication of the biochemical mechanisms involved in the beneficial effects of therapeutic interventions which negatively regulate IP3 signaling and PKC.…”