Glutamate inhibits protein phosphatases and promotes insulin exocytosis in pancreatic beta-cells
2005 (English)In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 328, no 2, 601-7 p.Article in journal (Refereed) Published
In human type 2 diabetes mellitus, loss of glucose-sensitive insulin secretion from the pancreatic beta-cell is an early pathogenetic event, but the mechanisms involved in glucose sensing are poorly understood. A messenger role has been postulated for L-glutamate in linking glucose stimulation to sustained insulin exocytosis in the beta-cell, but the precise nature by which L-glutamate controls insulin secretion remains elusive. Effects of L-glutamate on the activities of ser/thr protein phosphatases (PPase) and Ca(2+)-regulated insulin exocytosis in INS-1E cells were investigated. Glucose increases L-glutamate contents and promotes insulin secretion from INS-1E cells. L-glutamate also dose-dependently inhibits PPase enzyme activities analogous to the specific PPase inhibitor, okadaic acid. L-glutamate and okadaic acid directly and non-additively promote insulin exocytosis from permeabilized INS-1E cells in a Ca(2+)-independent manner. Thus, an increase in phosphorylation state, through inhibition of protein dephosphorylation by glucose-derived L-glutamate, may be a novel regulatory mechanism linking glucose sensing to sustained insulin exocytosis.
Place, publisher, year, edition, pages
2005. Vol. 328, no 2, 601-7 p.
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
IdentifiersURN: urn:nbn:se:uu:diva-248860DOI: 10.1016/j.bbrc.2005.01.024ISI: 000227075700035PubMedID: 15694391OAI: oai:DiVA.org:uu-248860DiVA: diva2:801053