Beta Cell

2022-05-02: reference:

Beta Cell #

• Located in the Pancreas, where they are the sole site of human insulin synthesis, where it is then stored (and proteolyzed from pro-insulin) in vesicles.

• When Glucose arrives through GLUT2,closes ATP-sensitive Potassium Channels ($K_{ir}6.x$), depolarizing it (Kir brings K+ into the cell doe wtf?) - which opens VGCCs, and the Ca2+ influx acivates insulin exocytosis.

  • Not GLUT4. In mice, it’s GLUT2. In humans, GLUT3 is >5x capacity, and greater affinity than GLUT1, which is still more than GLUT2.

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• Hypoxia-inducible factor-1α regulates β cell function in mouse and human islets

  • Decreased levels of HIF-1α impaired glucose-stimulated ATP generation and β cell function (thus impaired insulin secretion and concomitant glucose intolerance)
  • Removing iron by chelation improved HIF-1α activity and β cell function. This improved insulin secretion and glucose tolerance.
  • Insulin increases HIF-1α activity in liver, muscle, breast/prostate carcinoma, retinal epithelial-derived cells etc. in its usual PI3K-Akt-dependent manner. It itself contains Insulin Receptors, which serves as negative feedback for developing Insulin Resistance.