Forward chemical genetic approach identifies new role for GAPDH in insulin signaling

Abstract

Insulin and insulin-like growth factor have an essential role in growth, development and the maintenance of metabolic homeostasis, including glucose uptake from the bloodstream. Researchers have identified mutations in insulin receptors that cause severe insulin resistance, and a temperature-sensitive daf-2 (a gene encoding an insulin receptor-like protein) mutant in Caenorhabditis elegans has served as an insulin resistance model. Here we report a forward chemical genetic approach with a tagged library that we used to identify a small molecule, GAPDH segregator (GAPDS), that suppresses the dauer formation induced by the daf-2 mutant. Like insulin, GAPDS increased both glucose uptake and the concentration of phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P(3)) in mammalian preadipocytes. Using affinity matrices and RNA interference, we identified glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a GAPDS target. We discovered that GAPDH stimulates phosphatase activity against not only PtdIns(3,4,5)P(3) but also PtdIns(4,5)P(2). These results suggest that GAPDH is both an active regulator in the phosphoinositide-mediated signaling pathway and a potential new target for insulin resistance treatment.

GAPDH binds to active Akt, leading to Bcl-xL increase and escape from caspase-independent cell death

“…Altogether, our data suggest that once produced, binding of phospho-Akt to GAPDH limits the action of endogenous phosphatases (which remains to be found), thereby maintaining its activity over time ( Figure 3). In this direction, recent reports indicate that GAPDH can modulate the PI3K pathway 38 and that GAPDH has the ability to interact with Akt in other settings. 39,40 Therefore, once stabilized by GAPDH, activated Akt leads to FoxO phosphorylation (Figure 1a), preventing its nuclear relocalization and resulting in Bcl-6 downregulation (Figures 7a and b).…”

Potential pharmacological chaperones targeting cancer-associated MCL-1 and Parkinson disease-associated α-synuclein

“…Piperazines are found in many biologically active molecules and can be a good replacement of a phenyl ring in terphenyl structures (30)(31)(32). Triazine is a widely used privileged scaffold because of its broad range of biological activities and ease of synthetic manipulation (33,34). We used this scaffold as the backbone and functionalized its R 1 , R 2 , and R 3 groups to form α-helix mimetics.…”

Simple vertebrate models for chemical genetics and drug discovery screens: Lessons from zebrafish and Xenopus

“…This approach circumvents the wellknown problems of target identification and lack of mechanistic understanding associated with active compounds recovered from screens using conventional chemical libraries (Root et al, 2003). Forward chemical genetics has, therefore, become increasingly used in cell cultures to identify signaling pathways involved in cellular functions in vitro (Root et al, 2003;Rickardson et al, 2006;Diamandis et al, 2007), and more recently, whole organisms such as Drosophila, C. elegans, and zebrafish have been used for compound discovery (Min et al, 2007;Tran et al, 2007;Chang et al, 2008). Furthermore, biologically active small molecules recovered from chemical genetics screens also provide important structural information for the development of novel therapeutic agents.…”

“…Chemical genetics provides a complementary approach to loss-of-function mutations in the study of complex biological processes (Stockwell, 2000;Min et al, 2007). It makes use of small organic molecules with a molecular weight of typically less than 2,000 Dalton (Da) to alter the function of a gene product within a complex cellular context.…”