Regulation of secretory granule pH in insulin-secreting cells

Linda S. Tompkins, Kevin D. Nullmeyer, Sean M. Murphy, Craig S. Weber, Ron Lynch

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Luminal acidification is important for the maturation of secretory granules, yet little is known regarding the regulation of pH within them. A pH-sensitive green fluorescent protein (EGFP) was targeted to secretory granules in RIN1046-38 insulinoma cells by using a construct in which the EGFP gene was preceded by the nucleotide sequence for human growth hormone. Stimulatory levels of glucose doubled EGFP secretion from cell cultures, and potentiators of glucose-induced insulin secretion enhanced EGFP release. Thus this targeted EGFP is useful for population measurements of secretion. However, less than ∼4% of total cell EGFP was released after 1.5 h of stimulation. Consequently, when analyzed in single cells, fluorescence of the targeted EGFP acts as an indicator of pH within secretory granules. Glucose elicited a decrease in granule pH, whereas inhibitors of the V-type H+-ATPase increased pH and blocked the glucose effect. Granule pH also was modified by effectors of the protein kinase A pathway, with activation eliciting granule alkalinization, suggesting that potentiation of peptide release by cAMP may involve regulated changes in secretory granule pH.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume283
Issue number2 52-2
StatePublished - 2002

Fingerprint

Secretory Vesicles
Insulin-Secreting Cells
Green Fluorescent Proteins
Insulin
Glucose
Proton-Translocating ATPases
Human Growth Hormone
Acidification
Cyclic AMP-Dependent Protein Kinases
Cell culture
Nucleotides
Genes
Fluorescence
Chemical activation
Vacuolar Proton-Translocating ATPases
Insulinoma
Peptides
Cell Culture Techniques

Keywords

  • cAMP
  • Green fluorescent protein
  • Insulin secretion
  • Protein kinase A
  • V-type H ATPase

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

Cite this

Tompkins, L. S., Nullmeyer, K. D., Murphy, S. M., Weber, C. S., & Lynch, R. (2002). Regulation of secretory granule pH in insulin-secreting cells. American Journal of Physiology - Cell Physiology, 283(2 52-2).

Regulation of secretory granule pH in insulin-secreting cells. / Tompkins, Linda S.; Nullmeyer, Kevin D.; Murphy, Sean M.; Weber, Craig S.; Lynch, Ron.

In: American Journal of Physiology - Cell Physiology, Vol. 283, No. 2 52-2, 2002.

Research output: Contribution to journalArticle

Tompkins, LS, Nullmeyer, KD, Murphy, SM, Weber, CS & Lynch, R 2002, 'Regulation of secretory granule pH in insulin-secreting cells', American Journal of Physiology - Cell Physiology, vol. 283, no. 2 52-2.
Tompkins, Linda S. ; Nullmeyer, Kevin D. ; Murphy, Sean M. ; Weber, Craig S. ; Lynch, Ron. / Regulation of secretory granule pH in insulin-secreting cells. In: American Journal of Physiology - Cell Physiology. 2002 ; Vol. 283, No. 2 52-2.
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