Amyloid is a pathologic substance mostly consisting of proteins such as amylin, which can become deposited on different organs and tissues. In some degenerative diseases, such as Alzheimer's or Parkinson's, the formation of ordered amyloid fibers has been observed in places where cell death occurs. In patients with type-2 diabetes mellitus, islets of amyloid have been found within the islets of Langerhans, the collection of pancreatic cells with an endocrine function. These amyloid deposits are found in regions with cellular degeneration and have therefore been associated with the progression of the diabetes.
An IDIBAPS study published on the front page of Diabetologia (51(12):2252-62) by the team led by Dr. Anna Novials analyzes the mechanisms by which these amyloid fibers are associated with the death by apoptosis of pancreatic cells. The results show that abnormal concentrations of calcium play a key role in the toxicity induced by the amyloid. The hypothesis put forward in the article suggests that TRPV4, a channel to the cell surface that is sensitive to mechanical and osmotic changes, becomes activated in response to physical alterations caused by the aggregation of fibers around the cells. This would activate the process that leads to cell death by apoptosis: the entry of calcium into the cell, that the polarized nation of the membrane, and the activation of L-type calcium channels.