UAS regulatory sequences drive the expression of a Hsap\RAB7A mutation (K157N) that has been associated with Charcot-Marie-Tooth 2B. The construct is tagged at the N-terminal with Venus.
The Charcot-Marie-Tooth 2B disease is a genetically dominant disorder as all patients contain one wild-type copy and one mutant copy of the human Hsap\RAB7A gene. It has been proposed that the mutant forms of Hsap\RAB7A that are seen in Charcot-Marie-Tooth 2B disease patients are gain of function mutations which cause the adult onset neurodegeneration characteristic of the disease. However, studies in a Drosophila model suggest that the neurodegeneration seen in Charcot-Marie-Tooth 2B disease may be caused by loss of normal Hsap\RAB7A function in the patients rather than by the presence of the mutant protein: mutant flies that completely lack function of the Drosophila Rab7 gene in the eye show adult onset neurodegeneration, while flies overexpressing mutant forms of Rab7 which have been identified in Charcot-Marie-Tooth 2B disease patients (the flies express either a mutant form of Hsap\RAB7A or express the equivalent mutations in the Drosophila Rab7 ortholog) do not show neurodegeneration.
Scer\GAL4Rab7-Gal4-KO/Hsap\RAB7AK157N.UAS.Venus is a suppressor of abnormal neurophysiology | dominant phenotype of Rab7Gal4-KO
Scer\GAL4Rab7-Gal4-KO/Hsap\RAB7AK157N.UAS.Venus is a suppressor of lethal - all die before end of pupal stage | recessive phenotype of Rab7Gal4-KO
Scer\GAL4Rab7-Gal4-KO/Hsap\RAB7AK157N.UAS.Venus is a suppressor of abnormal neurophysiology | somatic clone | adult stage | progressive phenotype of Rab7Gal4-KO
Scer\GAL4Rab7-Gal4-KO/Hsap\RAB7AK157N.UAS.Venus is a suppressor of abnormal neuroanatomy | somatic clone | adult stage | progressive phenotype of Rab7Gal4-KO
Hsap\RAB7AK157N.UAS.Venus, Rab7Gal4-KO, Scer\GAL4Rab7-Gal4-KO has viable phenotype
Flies expressing Hsap\RAB7AK157N.Scer\UAS.T:Avic\GFP-YFP.Venus under the control of one copy of Scer\GAL4Rab7.T:Disc\RFP (in a Rab7GAL4.T:Disc\RFP/+ mutant background) are viable and do not display any obvious behavioural defects or altered lifespan. Electroretinogram recordings from the larval neuromuscular junction are indistinguishable from wild type. The frequency and amplitudes of spontaneous single vesicle release events are normal, as are evoked neurotransmission events. As in wild type, no photoreceptor defects, either morphological or functional, are seen in adult flies that have been exposed to 10 days of constant light stimulation.
Expression of Hsap\RAB7AK157N.Scer\UAS.T:Avic\GFP-YFP.Venus under the control of Scer\GAL4Rab7.T:Disc\RFP rescues the lethality seen in homozygous Rab7GAL4.T:Disc\RFP mutant flies.
Expression of Hsap\RAB7AK157N.Scer\UAS.T:Avic\GFP-YFP.Venus under the control of Scer\GAL4Rab7.T:Disc\RFP partially rescues the progressive synaptic and neuronal degeneration seen in homozygous Rab7GAL4.T:Disc\RFP mutant eye clones after 10 days of constant light stimulation.
