Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glucose and amino acid starvation of cells in culture generally enhances their sensitivity to oxidative stress. This is explained by compensatory autophagocytosis, which results in increased amounts of lysosomal low-molecular-weight, redox-active iron, due to the degradation of metallo-proteins, with a potential increase in iron-catalyzed, intralysosomal oxidative reactions. Such reactions diminish the stability of lysosomal membranes, with resultant leakage of hydrolytic enzymes into the cytosol and ensuing cellular degeneration, often of apoptotic type. However, starvation of NIT insulinoma cells, which are normally remarkably sensitive to oxidative stress, actually attenuated the sensitivity to such stress. We found that starved NIT cells rapidly synthesized ferritin. Moreover, ferritin was found to be autophagocytosed, and the lysosomes were stabilized, as assayed by the acridine orange relocation test. We hypothesize that compensatory autophagocytosis during starvation increases the cytosolic pool of redox-active iron, as a reflection of enhanced transportation of low-molecular-weight iron from autophagic lysosomes to the cytosol, resulting in ferritin induction. The newly formed ferritin would, in turn, become autophagocytosed and bind redox-active lysosomal iron in a non-redox-active form. We also suggest that the proposed mechanism may be a way for oxidative stress-sensitive cells to compensate partly for their failing capacity to degrade hydrogen peroxide before it leaks into the acidic vacuolar apparatus and induces intralysosomal oxidative stress. The insulin-producing beta cell may belong to this type of cells.
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PMID:Starvation-induced autophagocytosis paradoxically decreases the susceptibility to oxidative stress of the extremely oxidative stress-sensitive NIT insulinoma cells. 975 30

Amyloid-containing islets of Langerhans from the pancreas of 75 diabetics and one case of an amyloid-containing insulinoma were investigated. By light and electron microscopy, amyloid deposits were observed between the B cells and adjacent capillaries. The cytoplasm of B cells and extracellular amyloid display immunohistological binding of anti-insulin antibody. Correspondingly, ferritin-labeled anti-insulin antibody was found by electron microscopy on and between the amyloid fibrils. Insulin or proinsulin (or a protein closely related to insulin) thus appears to be a component of the protein which constitutes the amyloid. The molecular weight and mode of deposition of this form of amyloid are in agreement with other amyloidoses of the hormonal type (AH-type).
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PMID:The influence of insulin on local amyloidosis of the islets of Langerhans and insulinoma. 1878 62