Which signaling cascade mediates insulin-stimulated glucose uptake in skeletal muscle and adipose tissue?

• A. IRS-1/PI3K/AKT Signaling Leading to GLUT4 Translocation
• B. cAMP/PKA Pathway
• C. MAPK/ERK Pathway
• D. JAK/STAT Pathway

Answer: (A)

Insulin’s rapid boost of glucose uptake in muscle and fat relies on the IRS-1/PI3K/AKT pathway, which drives GLUT4 to the cell surface. When insulin binds its receptor, IRS-1 gets phosphorylated and recruits PI3K, producing PIP3 that activates AKT. Activated AKT then promotes the movement of GLUT4-containing vesicles to the plasma membrane (via targets like AS160), increasing glucose entry into the cells.

This pathway is the main route for insulin-stimulated GLUT4 translocation, whereas the other options pertain to different cellular responses. The cAMP/PKA pathway typically handles glycogen breakdown and glucose production signals, not GLUT4 translocation. The MAPK/ERK pathway is more about growth and mitogenic signaling, with only indirect roles in metabolism. The JAK/STAT pathway is central to cytokine signaling, not the acute metabolic actions of insulin in skeletal muscle and adipose tissue.