MCF-10A were treated as with Fig. breast Flavopiridol (Alvocidib) cancers. The phosphoinositide 3-kinase (PI3K)-pathway regulates cytoskeletal functions such as cell movement and intracellular compartmentalization, examined in (Cantley, 2002), and also modulates multiple methods in glucose uptake and rate of metabolism (Rathmell et al., 2003). Binding of insulin and additional growth factors to their specific cell membrane receptors activates PI3K, resulting in production of phosphatidylinositol-3,4,5-trisphosphate (PIP3) and recruitment of PIP3-binding proteins to the cytosolic part of the plasma membrane, therefore initiating signaling events that control glucose rate of metabolism, cell growth and movement. While there is Flavopiridol (Alvocidib) considerable evidence that glucose uptake and phosphorylation Flavopiridol (Alvocidib) are mediated by PIP3-dependent activation of the protein Ser/Thr kinase AKT, actin redesigning is definitely mediated by PIP3-dependent activation of guanine nucleotide exchange factors (GEFs), namely the Rho/Rac/CDC42 family members (Hanna and El-Sibai, 2013). Here we display that full activation of glycolysis by PI3K requires both AKT activation and Rac-dependent actin redesigning. We display that in quiescent epithelial cells aldolase is definitely caught in the actin cytoskeleton in a low activity state and that activation of PI3K releases aldolase A, resulting in enhanced flux through glycolysis. We propose that coordination of actin redesigning with glycolysis may facilitate macromolecular biosynthesis needed for cell growth and cell division. Results PI3K inhibition blocks the aldolase step of glycolysis in an AKT-independent manner In order to dissect the contributions of PI3K pathway parts to the rules of glycolysis, we examined the effects of specific enzyme inhibitors within the reduction of NAD(+) (Nicotinamide adenine dinucleotide) to NADH, happening in the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) step (Fig. 1 A) as well as on extracellular acidification rate Flavopiridol (Alvocidib) (ECAR, Fig. 1 B), as read-outs for glycolysis in mammary epithelial cells (MCF10A). The pan-PI3K inhibitor BKM120, Buparlisib (Maira et al., 2012) and the PI3K specific inhibitor BYL719, Alpelisib (Furet et al., 2013) led to a decrease in the NADH/NAD(+) percentage in MCF10A cells starting within minutes and reaching a minimum plateau at 4 hours (Fig. 1 A, first two panels), while inhibition of AKT with MK2206 or mTOR with rapamycin caused only a transient decrease in the NADH/NAD(+) percentage (Fig. 1A, 3d and 4th panel). Both, BKM120 and BYL719 reduced the initial ECAR increase in response to insulin activation and a glucose challenge, and drastically reduced the cells ability to mobilize the glycolytic reserve, i.e. to respond with increased glycolysis after addition of Oligomycin to the medium (Fig. 1 B, 1st two panels). MK2206 and rapamycin also decreased the ECAR after addition of glucose, as expected (Rathmell et al., 2003), but different from the PI3K-inhibitors, the AKT- and the mTOR-inhibitor did not block mobilization of the glycolytic reserve (Fig. 1 B, ideal two panels). When we examined the ECAR in MCF10A cells expressing constitutively active, myristoylated AKT, mAKT, (Barthel et al., 1997), the PI3K-inhibitors BYL719 and BKM120 prevented mobilization of the glycolytic reserve (Fig. S1A), suggestive of a specific part for PI3K for the maximum achievable glycolytic rate that can not be compensated for by constitutive activation of AKT. The PI3K inhibitor TGX221 and GSK650394, an inhibitor of serum and glucocorticoid-induced protein kinase (SGK), experienced little effect on the NADH/NAD(+) percentage (Fig. S1 B) or the ECAR (Fig. S1C). The concentration of drugs used achieved target inhibition (Fig. Flavopiridol (Alvocidib) S1 D). All the inhibitors caused a variable degree of glucose uptake inhibition (Fig. S1 E, F) while the long term effects within the NADH/NAD+ percentage (Fig. 1A) and on mobilization of the glycolytic reserve (Fig. 1B) were specific to pan-PI3K and PI3K-inhibition. These data suggest that PI3K exerts a regulatory part within the maximal glycolytic capacity that cells can mount and that this regulatory part is self-employed of AKT, SGK or mTOR. Open in a separate window Number 1 Inhibition of AKT does not phenocopy the effects of PI3K inhibition on glycolysis. A, B. PI3K-, but not AKT- or mTOR-inhibitors decrease the cytosolic NADH/NAD+ percentage Rabbit Polyclonal to 5-HT-2B and glycolysis in MCF10A cells. The NADH/NAD+ percentage (A) was identified in.
MCF-10A were treated as with Fig
