Question

explain the different biological roles of insulin on the podocyte , muscle cell, and neurons

include the mesangial cells, glomerular endothelial cells, proximal tubular cell , distal tubular cell

Answer 1

Podocyte

They are insulin sensitive cells and are involved in glucose uptake into the cell by GLUT 1 and GLUT 4.

The insulin binding on insulin receptor triggers autophosphorylation of insulin receptor substrate (IRS) protein 1 and 2 this masks SH2 domain and activates Ras MAP kinase. PI3K is activated by p85 which activated Akt pathway . These lead to contraction in the podocyte by release of Ca

The IRS 2 is responsible for translocation of GLUT 4 to plasma membrane and glucose uptake by podocyte

Skeletal muscle

In the skeletal also it causes uptake of glucose via GLUT 4 by similar action mentioned above

Similarly insulin induces contraction in the skeletal muscle by activation of MAO kinase by IRS 2

Neurons have GLUT 1 and GLUT 3 which on the attachment of insulin to insulin receptor are translocated by mechanism explained above and help in glucose uptake by neuron

Mesangial cells insulin causes rearrangement in the cytoskeleton of mesangium

Insulin causes release of NO from endothelial cells

Proximal tubules

Insulin induces reabsorption of sodium and water by both proximal and distal tubukes

Distal tubes also reabsorb Mg under influence of insulin

It inhibits gluconeogenesis in the proximal tubules

No is released by distal tubules via insulin