Activation of AMP-activated protein kinase stimulates the nuclear localization of glyceraldehyde 3-phosphate dehydrogenase in human diploid fibroblasts

Abstract

In addition to its well-known glycolytic activity, GAPDH displays multiple functions, such as nuclear RNA export, DNA replication and repair, and apoptotic cell death. This functional diversity depends on its intracellular localization. In this study, we explored the signal transduction pathways involved in the nuclear translocation of GAPDH using confocal laser scanning microscopy of immunostained human diploid fibroblasts (HDFs). GAPDH was present mainly in the cytoplasm when cultured with 10% FBS. Serum depletion by culturing cells in a serum-free medium (SFM) led to a gradual accumulation of GAPDH in the nucleus, and this nuclear accumulation was reversed by the re-addition of serum or growth factors, such as PDGF and lysophosphatidic acid. The nuclear export induced by the re-addition of serum or growth factors was prevented by LY 294002 and SH-5, inhibitors of phosphoinositide 3-kinase (PI3K) and Akt/protein kinase B, respectively, suggesting an involvement of the PI3K signaling pathway in the nuclear export of GAPDH. In addition, 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR), an activator of AMP-activated protein kinase (AMPK), stimulated the nuclear translocation of GAPDH and prevented serum-and growth factor-induced GAPDH export. AMPK inhibition by compound C or AMPK depletion by siRNA treatment partially prevented SFM-and AICAR-induced nuclear translocation of GAPDH. Our data suggest that the nuclear translocation of GAPDH might be regulated by the PI3K signaling pathway acting mainly as a nuclear export signal and the AMPK signaling pathway acting as a nuclear import signal.

Cannabinoids inhibit energetic metabolism and induce AMPK-dependent autophagy in pancreatic cancer cells

“…34 Furthermore, also AMPK has been shown to stimulate GAPDH translocation into the nuclei. 36 Our data showed that both NAC and CC inhibited GAPDH nuclear translocation, demonstrating that this event was mediated by both ROS and AMPK.…”

CIB1 prevents nuclear GAPDH accumulation and non-apoptotic tumor cell death via AKT and ERK signaling

“…Inhibition of PI3K/AKT signaling can block the nuclear export of GAPDH (28), suggesting that PI3K/AKT negatively regulates nuclear GAPDH localization. We therefore asked if inhibition of AKT would mimic CIB1 depletion and induce GAPDH nuclear accumulation.…”

Compartmentation of GAPDH

“…The proposed signaling pathways that are involved in the translocation of GAPDH to and from the nucleus are illustrated. AMPK (for, AMP-activated protein kinase) activity results in a net influx of GAPDH to the nucleus [99], whereas the PI3K/Akt and Akt2 pathways allow for a net efflux from the nucleus [99,100]. Dotted lines represent the intermediate signals from the initial cell stimuli.…”

“…As one navigates through this book, one will notice that GAPDH is involved in some way to many of the proteins and events that just were mentioned as being associated with the overall process of insulin signaling and GLUT4-membrane trafficking, including PI3K, Akt [98][99][100], Rab proteins [101][102][103], cytoskeletal components (namely, microtubules and actin microfilaments; see Sect. 4.2.1), membrane fusion and clathrin-coated vesicles [104].…”

“…Kwon and coworkers [99] looked at the signal transduction pathways involved in GAPDH's translocation to and from the nucleus. The authors observed that in 10 % FBS (for, fetal bovine serum), GAPDH was predominately in the cytoplasm.…”