The indy gene - named for "I'm not dead yet" - was one of the earliest longevity mutations to be uncovered in flies, and consequently is somewhat better studied than the many that have followed since then. Here is an open access paper on the subject:

Decreased expression of the fly and worm Indy genes extends longevity. The fly Indy gene and its mammalian homolog are transporters of Krebs cycle intermediates, with the highest rate of uptake for citrate. Cytosolic citrate has a role in energy regulation by affecting fatty acid synthesis and glycolysis. Fly, worm, and mice Indy gene homologs are predominantly expressed in places important for intermediary metabolism. Consequently, decreased expression of Indy in fly and worm, and the removal of mIndy in mice exhibit changes associated with calorie restriction, such as decreased levels of lipids, changes in carbohydrate metabolism and increased mitochondrial biogenesis. Here we report that several Indy alleles in a diverse array of genetic backgrounds confer increased longevity.

The paper is a good example of the way in which calorie restriction muddies the water of longevity studies; the effects of calorie restriction on life span are very strong in lower animals like flies and worms, and many past studies failed to fully account for differing dietary calorie intakes between populations of these animals. The authors of this paper point out a number of past papers with results that may tainted due to differing calorie intake, and note that their own work tries to control for this.

Link: http://www.frontiersin.org/Genetics_of_Aging/10.3389/fgene.2013.00047/full

Source:
http://www.fightaging.org/archives/2013/04/indy-mutations-and-fly-longevity.php