Search

ReportPeroxisome proliferator-activated receptor gamma(PPARc) regulates lactase expression and activity inthe gutMathurin Fumery1,2,3,†, Silvia Speca1,2,†, Audrey Langlois1,2, Anne-Marie Davila4, Caroline Dubuquoy5,Marta Grauso4, Anthony Martin Mena1,2, Martin Figeac6, Daniel Metzger7, Christel Rousseaux5,Jean-Frederic Colombel8, Laurent Dubuquoy1,2, Pierre Desreumaux1,2,9& Benjamin Bertin1,2,*Abstract 9

Genome analysis of the fruit fly Drosophila melanogaster reveals three new ligand-gated ion channel subunits with the characteristic YXCC motif found only in alpha-type nicotinic acetylcholine receptor subunits. The subunits are designated Dalpha5, Dalpha6, and Dalpha7. Cloning of the Dalpha5 embryonic cDNAs reveals an atypically large N terminus, part of which is without identifiable sequence motifs and is specified by two polymorphic alleles. Embryonic clones from Dalpha6 contain multiple variant transcripts arising from alternative splicing as well as A-to-I pre-mRNA editing. Alternative splicing in Dalpha6 involves exons encoding nAChR functional domains. The Dalpha6 transcript is a target of the Drosophila adenosine deaminase acting on RNA (dADAR). This is the first case for any organism where a nAChR gene is the target of mRNA editing. Seven adenosines could be modified in the extracellular ligand-binding region of Dalpha6, four of which are also edited in the Dalpha6 ortholog in the tobacco budworm Heliothis virescens. The conservation of an editing site between the insect orders Diptera and Lepidoptera makes nAChR editing the most evolutionarily conserved invertebrate RNA editing site so far described. These findings add to our understanding of nAChR subunit diversity, which is increased and regulated by mechanisms acting at the genomic and mRNA levels.

Monomeric human pancreatic RNase, devoid of any biological activity other than its RNA degrading ability, was engineered into a dimeric protein with a cytotoxic action on mouse and human tumor cells, but lacking any appreciable toxicity on mouse and human normal cells. This dimeric variant of human pancreas RNase selectively sensitizes to apoptotic death cells derived from a human thyroid tumor. Because of its selectivity for tumor cells, and because of its human origin, this protein represents a potentially very attractive, novel tool for anticancer therapy.