Article

Diabetologia

, Volume 54, Issue 4, pp 819-827

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Per-arnt-sim (PAS) domain-containing protein kinase is downregulated in human islets in type 2 diabetes and regulates glucagon secretion

  • G. da Silva XavierAffiliated withSection of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London Email author 
  • , H. FarhanAffiliated withSection of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London
  • , H. KimAffiliated withSection of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London
  • , S. CaxariaAffiliated withSection of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London
  • , P. JohnsonAffiliated withNuffield Department of Surgical Sciences, Oxford University
  • , S. HughesAffiliated withNuffield Department of Surgical Sciences, Oxford University
  • , M. BuglianiAffiliated withDipartimento di Endocrinologia e Metabolismo, Unità Metabolica, Università di Pisa
  • , L. MarselliAffiliated withDipartimento di Endocrinologia e Metabolismo, Unità Metabolica, Università di Pisa
  • , P. MarchettiAffiliated withDipartimento di Endocrinologia e Metabolismo, Unità Metabolica, Università di Pisa
    • , F. BirzeleAffiliated withBoehringer Ingelheim Pharma, Target Discovery Research
    • , G. SunAffiliated withSection of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London
    • , R. ScharfmannAffiliated withINSERM U845, Centre de Recherche Croissance et Signalisation, Université Paris Descartes, Faculté de Médecine, Hôpital Necker
    • , J. RutterAffiliated withDivision of Endocrinology, University of Utah School of Medicine
    • , K. SiniakowiczAffiliated withSection on Islet Transplantation and Cell Biology, Research Division, Joslin Diabetes Center and the Department of Medicine, Harvard Medical School
    • , G. WeirAffiliated withSection on Islet Transplantation and Cell Biology, Research Division, Joslin Diabetes Center and the Department of Medicine, Harvard Medical School
    • , H. ParkerAffiliated withCambridge Institute for Medical Research and Department of Clinical Biochemistry, Addenbrooke’s Hospital
    • , F. ReimannAffiliated withCambridge Institute for Medical Research and Department of Clinical Biochemistry, Addenbrooke’s Hospital
    • , F. M. GribbleAffiliated withCambridge Institute for Medical Research and Department of Clinical Biochemistry, Addenbrooke’s Hospital
    • , G. A. RutterAffiliated withSection of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London Email author 

Abstract

Aims/hypothesis

We assessed whether per-arnt-sim (PAS) domain-containing protein kinase (PASK) is involved in the regulation of glucagon secretion.

Methods

mRNA levels were measured in islets by quantitative PCR and in pancreatic beta cells obtained by laser capture microdissection. Glucose tolerance, plasma hormone levels and islet hormone secretion were analysed in C57BL/6 Pask homozygote knockout mice (Pask −/−) and control littermates. Alpha-TC1-9 cells, human islets or cultured E13.5 rat pancreatic epithelia were transduced with anti-Pask or control small interfering RNAs, or with adenoviruses encoding enhanced green fluorescent protein or PASK.

Results

PASK expression was significantly lower in islets from human type 2 diabetic than control participants. PASK mRNA was present in alpha and beta cells from mouse islets. In Pask−/− mice, fasted blood glucose and plasma glucagon levels were 25 ± 5% and 50 ± 8% (mean ± SE) higher, respectively, than in control mice. At inhibitory glucose concentrations (10 mmol/l), islets from Pask−/− mice secreted 2.04 ± 0.2-fold (p < 0.01) more glucagon and 2.63 ± 0.3-fold (p < 0.01) less insulin than wild-type islets. Glucose failed to inhibit glucagon secretion from PASK-depleted alpha-TC1-9 cells, whereas PASK overexpression inhibited glucagon secretion from these cells and human islets. Extracellular insulin (20 nmol/l) inhibited glucagon secretion from control and PASK-deficient alpha-TC1-9 cells. PASK-depleted alpha-TC1-9 cells and pancreatic embryonic explants displayed increased expression of the preproglucagon (Gcg) and AMP-activated protein kinase (AMPK)-alpha2 (Prkaa2) genes, implying a possible role for AMPK-alpha2 downstream of PASK in the control of glucagon gene expression and release.

Conclusions/interpretation

PASK is involved in the regulation of glucagon secretion by glucose and may be a useful target for the treatment of type 2 diabetes.

Keywords

Αlpha cells Glucagon secretion Human islets of Langerhans Knockout mouse PASK