Molecular physiology of amylin

Abstract

Amylin is a 37-amino acid peptide first isolated, purified, and characterized from the amyloid deposits in the pancrease of type 2 diabetics. It is synthesized and secreted primarily from pancreatic beta cells along with insulin. The ability of amylin to potently reduce insulin-stimulated incorporation of glucose into glycogen in skeletal muscle requires both an intact 2Cys-7Cys disulfide bond and a COOH-terminal amide. Amylin has structural and functional relationships to two other messenger proteins, calcitonin and CGRP. Amylin has relatively potent calcitonin-like activity on bone metabolism and weaker CGRP-like activity on the vasculature. CGRP is a slightly weaker agonist than amylin for metabolic responses. Although rat calcitonins are weak, teleost fish calcitonins are very potent agonists for amylin's metabolic effects. This group of peptides appears to act on a family of related G protein-coupled receptors; several variant calcitonin receptors have recently been cloned and expressed. These receptors appear to be coupled to adenylyl cyclase in many instances; recent evidence supports the view that amylin's effects on skeletal muscle occur, at least in large part, through activation of the cAMP pathway.

High-protein diet selectively reduces fat mass and improves glucose tolerance in Western-type diet-induced obese rats

“…On the contrary, the increase of GIP (also known as glucose-dependent insulinotropic peptide) was higher in the Western-type diet/high-protein diet group compared with the Western-type diet/standard diet group. Because both hormones are involved in glucose homeostasis (41,51) and affect insulin release and signaling, these changes may contribute to the observed beneficial effect of a high-protein diet on glucose tolerance in diet-induced obese rats. In addition, diet-induced obese rats switched to a high-protein diet displayed a higher dark feeding phase-related fold-change increase of PP and PYY compared with the standard diet/standard diet group, which may contribute to the anorexigenic effect of a high-protein diet.…”

Adsorption of Biological Molecules to a Solid Support for Scanning Probe Microscopy

“…Amylin, a 37-aminoacid peptide (Cooper, 1994), is cosecreted with insulin from pancreatic b-cells in response to nutrient stimuli. It has structural relationships to two other messenger proteins, calcitonin and CGRP (Pittner et al, 1994). Human amylin is cytotoxic at concentrations above 1-10 µM.…”

Identification of a Novel -99A>T IAPP Gene Mutation in A North Indian Type-2-Diabetes Patient with Hypertension

“…Immunolocalisation studies of its secretory granules confirmed that amylin is synthesised in, and probably co-secreted from the ß-cells of the Islets of Langerhans [2]. Apart from its pathological role in type-2-diabetes [3,4], amylin also plays a vital role in glycemic regulation by various mechanisms like delaying gastric emptying, stimulating satiety centre in hypothalamus, thereby delaying the rate of appearance of glucose in blood and preventing post-prandial spikes in blood glucose levels [5]. The human amylin gene IAPP which encodes the complete polypeptide is located in short arm of chromosome12; (12p12.1).…”