Suppression of Pdx-1 perturbs proinsulin processing, insulin secretion and GLP-1 signalling in INS-1 cells

Autor: P. A. Antinozzi, Claes B. Wollheim, M. Iezzi, Sten Theander, Haiyan Wang, Philippe A. Halban, Benoit R. Gauthier
Rok vydání: 2004
Předmět:
Time Factors
Adenosine Triphosphate/metabolism
Endocrinology
Diabetes and Metabolism
medicine.medical_treatment
Prohormone
Gene Expression
Homeodomain Proteins/genetics/metabolism/ physiology
Trans-Activators/genetics/metabolism/ physiology
Adenosine Triphosphate
Gene Expression/drug effects/genetics
Glucokinase
Insulin Secretion
Cyclic AMP
Receptors
Glucagon
Cyclic AMP/metabolism
Exocytosis/physiology
Insulin
Proinsulin
ddc:616
Regulation of gene expression
Human Growth Hormone
Signal Transduction/ physiology
Human Growth Hormone/genetics/secretion
Mitochondria
Gene Expression Regulation
Neoplastic
Doxycycline
Proprotein Convertases
Beta cell
Insulin/ secretion
Glycolysis
hormones
hormone substitutes
and hormone antagonists
medicine.drug
Signal Transduction
medicine.medical_specialty
endocrine system
RNA
Messenger/genetics/metabolism
Glucokinase/genetics
Calcium Signaling/physiology
Biology
Transfection
digestive system
Exocytosis
Glucagon-Like Peptide-1 Receptor
Doxycycline/pharmacology
Proinsulin/ metabolism
Receptors
Glucagon/genetics/ physiology
Receptors
Fibroblast Growth Factor/genetics
Islets of Langerhans
Internal medicine
Cell Line
Tumor
Mitochondria/metabolism
Internal Medicine
medicine
Animals
Secretion
Calcium Signaling
RNA
Messenger
Receptor
Fibroblast Growth Factor
Type 1
Transcription factor
Glucagon-like peptide 1 receptor
Homeodomain Proteins
Dose-Response Relationship
Drug
Islets of Langerhans/drug effects/metabolism
Receptor Protein-Tyrosine Kinases/genetics
Receptor Protein-Tyrosine Kinases
Receptors
Fibroblast Growth Factor
Rats
Endocrinology
Glucose
Gene Expression Regulation
Neoplastic/drug effects
Mutation
Trans-Activators
Glucose/metabolism/pharmacology
Proprotein Convertases/genetics
Zdroj: Diabetologia, Vol. 48, No 4 (2005) pp. 720-731
ISSN: 0012-186X
Popis: AIMS/HYPOTHESIS: Mutations in genes encoding HNF-4alpha, HNF-1alpha and IPF-1/Pdx-1 are associated with, respectively, MODY subtypes-1, -3 and -4. Impaired glucose-stimulated insulin secretion is the common primary defect of these monogenic forms of diabetes. A regulatory circuit between these three transcription factors has also been suggested. We aimed to explore how Pdx-1 regulates beta cell function and gene expression patterns. METHODS: We studied two previously established INS-1 stable cell lines permitting inducible expression of, respectively, Pdx-1 and its dominant-negative mutant. We used HPLC for insulin processing, adenovirally encoded aequorin for cytosolic [Ca2+], and transient transfection of human growth hormone or patch-clamp capacitance recordings to monitor exocytosis. RESULTS: Induction of DN-Pdx-1 resulted in defective glucose-stimulated and K+-depolarisation-induced insulin secretion in INS-1 cells, while overexpression of Pdx-1 had no effect. We found that DN-Pdx-1 caused down-regulation of fibroblast growth factor receptor 1 (FGFR1), and consequently prohormone convertases (PC-1/3 and -2). As a result, DN-Pdx-1 severely impaired proinsulin processing. In addition, induction of Pdx-1 suppressed the expression of glucagon-like peptide 1 receptor (GLP-1R), which resulted in marked reduction of both basal and GLP-1 agonist exendin-4-stimulated cellular cAMP levels. Induction of DN-Pdx-1 did not affect glucokinase activity, glycolysis, mitochondrial metabolism or ATP generation. The K+-induced cytosolic [Ca2+] rise and Ca2+-evoked exocytosis (membrane capacitance) were not abrogated. CONCLUSIONS/INTERPRETATION: The severely impaired proinsulin processing combined with decreased GLP-1R expression and cellular cAMP content, rather than metabolic defects or altered exocytosis, may contribute to the beta cell dysfunction induced by Pdx-1 deficiency.
Databáze: OpenAIRE
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