Effects of insulin and actin on phosphofructokinase activity and cellular distribution in skeletal muscle

Abstract

In this work, we report evidences that the association of phosphofructokinase and F-actin can be affected by insulin stimulation in rabbit skeletal muscle homogenates and that this association can be a mechanism of phosphofructokinase regulation. Through co-sedimentation techniques, we observed that on insulin-stimulated tissues, approximately 70% of phosphofructokinase activity is co-located in an actin-enriched fraction, against 28% in control. This phenomenon is accompanied by a 100% increase in specific phosphofructokinase activity in stimulated homogenates. Purified F-actin causes an increase of 230% in phosphofructokinase activity and alters its kinetic parameters. The presence of F-actin increases the affinity of phosphofructokinase for fructose 6-phosphate nevertheless, with no changes in maximum velocity (V max ). Here we propose that the modulation of cellular distribution of phosphofructokinase may be one of the mechanisms of control of glycolytic flux in mammalian muscle by insulin.

Metformin reverses hexokinase and phosphofructokinase downregulation and intracellular distribution in the heart of diabetic mice

“…The particulate PFK fraction is described as the fraction of PFK associated to f-actin, which is more active than the soluble enzyme (17). Several hormonal signals regulate the association of PFK to f-actin, such as epinephrine (20), serotonin (22,23), and insulin (21,36). Hence, metformin might increase PFK activity in the particulate fraction by sensitizing insulin action, such as proposed above for HK particulate fraction.…”

“…Both HK and PFK are subjected to multiple regulatory mechanisms, including allosteric regulation by metabolites and control by hormones (14,15,(18)(19)(20)(21)(22)(23). Moreover, these two enzymes, as others from glycolysis, are able to reversibly associate to intracellular ultrastructures, such as the mitochondria for HK and actin filaments (f-actin) for PFK, as part of their regulatory mechanism (15,17).…”

The Crystal Structures of Eukaryotic Phosphofructokinases from Baker's Yeast and Rabbit Skeletal Muscle

“…[7][8][9] It interacts with proteins of the cytoskeleton. 10,11 By contrast, Saccharomyces cerevisiae PFK (ScPFK) forms stable heterooctamers α 4 β 4 with a molecular mass of ∼ 800 kDa and a sedimentation coefficient 21S. 12,13 Both α and β subunits are homologous to each other and show an internal sequence duplication similar to that seen in mammalian PFKs.…”

Glucuronoxylomannan from Cryptococcus neoformans Down-regulates the Enzyme 6-Phosphofructo-1-kinase of Macrophages

“…For instance, if the intracellular concentration of F2,6BP rises, e.g. due to insulin signaling (62,75), GXM inhibitory effects would be supposedly less pronounced as F2,6BP favors the formation of tetramers counteracting the formation of FIGURE 6. Effects of GXM on PFK activity in the presence of different allosteric modulators of the enzyme.…”