Differential expression of the glutamate transporter GLT-1 in pancreas

J Histochem Cytochem. 2012 Feb;60(2):139-51. doi: 10.1369/0022155411430095. Epub 2011 Nov 22.

Abstract

The glutamate uptake transporter GLT-1 is best understood for its critical role in preventing brain seizures. Increasing evidence argues that GLT-1 also modulates, and is modulated by, metabolic processes that influence glucose homeostasis. To investigate further the potential role of GLT-1 in these regards, the authors examined GLT-1 expression in pancreas and found that mature multimeric GLT-1 protein is stably expressed in the pancreas of wild-type, but not GLT-1 knockout, mice. There are three primary functional carboxyl-terminus GLT-1 splice variants, called GLT-1a, b, and c. Brain and liver express all three variants; however, the pancreas expresses GLT-1a and GLT-1b but not GLT-1c. Quantitative real time-PCR further revealed that while GLT-1a is the predominant GLT-1 splice variant in brain and liver, GLT-1b is the most abundant splice variant expressed in pancreas. Confocal microscopy and immunohistochemistry showed that GLT-1a and GLT-1b are expressed in both islet β- and α-cells. GLT-1b was also expressed in exocrine ductal domains. Finally, glutamine synthetase was coexpressed with GLT-1 in islets, which suggests that, as with liver and brain, one possible role of GLT-1 in the pancreas is to support glutamine synthesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Excitatory Amino Acid Transporter 2 / deficiency
  • Excitatory Amino Acid Transporter 2 / genetics*
  • Excitatory Amino Acid Transporter 2 / metabolism
  • Gene Expression Profiling
  • Immunohistochemistry
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Microscopy, Confocal
  • Pancreas / cytology
  • Pancreas / metabolism*
  • Real-Time Polymerase Chain Reaction

Substances

  • Excitatory Amino Acid Transporter 2
  • Slc1a2 protein, mouse