An accelerated assay for the identification of lifespan-extending interventions in Drosophila melanogaster

Abstract

Recent advances in aging research have uncovered genes and genetic pathways that influence lifespan in such diverse organisms as yeast, nematodes, flies, and mice. The discovery of genes and drugs that affect lifespan has been delayed by the absence of a phenotype other than survivorship, which depends on the measurement of age at death of individuals in a population. The use of survivorship to identify genetic and pharmacological interventions that prolong life is time-consuming and requires a large number of homogeneous animals. Here, we report the development of an assay in Drosophila melanogaster using the expression of molecular biomarkers that accelerates the ability to evaluate potential lifespan-altering interventions. Coupling the expression of an age-dependent molecular biomarker to a lethal toxin reduces the time needed to perform lifespan studies by 80%. The assay recapitulates the effect of the three best known environmental lifespan-extending interventions in the fly: ambient temperature, reproductive status, and calorie reduction. Single gene mutations known to extend lifespan in the fly such as Indy and rpd3 also extend lifespan in this assay. We used this assay as a screen to identify drugs that extend lifespan in flies. Lipoic acid and resveratrol were identified as being beneficial in our assay and shown to extend lifespan under normal laboratory conditions. We propose that this assay can be used to screen pharmacological as well as genetic interventions more rapidly for positive effects on lifespan.aging ͉ biomarker ͉ lifespan extension ͉ drug screen ͉ resveratrol

Pharmacological intervention in invertebrate aging

“…Recently, a-lipoic acid was shown to have no effect on mouse lifespan (Lee et al 2004), however, in a separate study, a 12% increase in lifespan was observed when female Drosophila were treated from day 10 past eclosion (Bauer et al 2004). In this study, a-lipoic acid was identified in an Faccelerated screening assay_ in which age-dependent enhancer-trap lines were constructed that expressed tetanus toxin light chain as a lethal reporter.…”

“…Agedependant expression of the toxin resulted in a greatly shortened lifespan with one line having a mean survival of 8 days and a maximal survival of 15 days, which is 80% shorter than normal fly lifespan. This is potentially an interesting route to speeding up drug testing in the fly (Bauer et al 2004).…”

Endocrine targets for pharmacological intervention in aging in Caenorhabditis elegans

“…This raises the possibility that automated fluorescence detection could be used to screen for compounds that delay the age-related rise in auto-fluorescence signal. The utility of biomarkers as a means of accelerating survival analysis has recently been demonstrated in flies (Bauer et al, 2004). By coupling a lethal toxin to an age-dependent biomarker that is expressed in young adults, the lifespans of control strains were reduced to 20% of normal.…”

“…Principally, there is the opportunity to examine the effects of compounds in a whole animal setting thus quickly eliminating toxic drugs or drugs that affect multiple processes. A number of groups have demonstrated that lifespan can be increased in invertebrate model organisms by antioxidants (Harrington & Harley, 1988;Brack et al ., 1997;Bauer et al ., 2004;Ishii et al ., 2004), anticonvulsants (Evason et al ., 2005) and small molecules that target histone acetylation status (Kang et al ., 2002;Howitz et al ., 2003;Wood et al ., 2004). However, these studies have tended to be small-scale targeted screens rather than large-scale unbiased surveys for compounds that affect aging.…”

Effect of Resveratrol as Caloric Restriction Mimetic and Environmental Enrichment on Neurobehavioural Responses in Young Healthy Mice

“…Resveratrol (3,5 ,4-trihydroxystilbene), a natural polyphenolic compound found mainly in the skin of grapes and red wine, has previously been shown to extend lifespan in yeast (Saccharomyces cerevisiae), nematode worm (Caenorhabditis elegans), fruit fly (Drosophila melanogaster), and short-lived fish (Nothobranchius furzeri) through a sirtuins 1 dependent mechanism [9][10][11][12][13]. Studies have shown that mice fed with a high fat diet supplemented with high levels of resveratrol were shown to have extended lifespan compared to the control animals and several metabolic alterations similar to what is observed with CR; thus, resveratrol is said to have caloric restriction-like properties [2,14].…”