title: Upregulation of β-cell genes and improved function in rodent islets following chronic glucokinase activation.
abstract: Glucokinase (GK) plays a critical role in controlling blood glucose; GK activators have been shown to stimulate insulin secretion acutely both in vitro and in vivo. Sustained stimulation of insulin secretion could potentially lead to β-cell exhaustion; this study examines the effect of chronic GK activation on β-cells. Gene expression and insulin secretion were measured in rodent islets treated in vitro with GKA71 for 72 h. Key β-cell gene expression was measured in rat, mouse and global GK heterozygous knockout mouse islets (gk(del/wt)). Insulin secretion, after chronic exposure to GKA71, was measured in perifused rat islets. GKA71 acutely increased insulin secretion in rat islets in a glucose-dependent manner. Chronic culture of mouse islets with GKA71 in 5 mmol/l glucose significantly increased the expression of insulin, IAPP, GLUT2, PDX1 and PC1 and decreased the expression of C/EBPβ compared with 5 mmol/l glucose alone. Similar increases were shown for insulin, GLUT2, IAPP and PC1 in chronically treated rat islets. Insulin mRNA was also increased in GKA71-treated gk(del/wt) islets. No changes in GK mRNA were observed. Glucose-stimulated insulin secretion was improved in perifused rat islets following chronic treatment with GKA71. This was associated with a greater insulin content and GK protein level. Chronic treatment of rodent islets with GKA71 showed an upregulation of key β-cell genes including insulin and an increase in insulin content and GK protein compared with glucose alone.
authors.affiliation: AstraZeneca Diabetes and Obesity Drug Discovery, CVGI iMED, 3S42C Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, UK.
authors.forename: D
authors.initials: D
authors.lastname: Gill
authors.forename: K J
authors.initials: KJ
authors.lastname: Brocklehurst
authors.forename: H W G
authors.initials: HW
authors.lastname: Brown
authors.forename: D M
authors.initials: DM
authors.lastname: Smith
mesh_terms: D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects*; D020536:Enzyme Activators / Q000494:pharmacology*; D057075:Enzyme Assays; D005941:Glucokinase / Q000737:chemistry / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000235:genetics / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051381:Rats; D017208:Rats, Wistar; D013450:Sulfones / Q000494:pharmacology*; D013830:Thiadiazoles / Q000494:pharmacology*; D046509:Tissue Culture Techniques; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000235:genetics*
chemical_list: C561743:3-(2-methoxy-1-methylethoxy)-5-(4-methylsulfonylphenoxy)-N-(3-methyl-1,2,4-thiadiazol-5-yl)benzamide; D020536:Enzyme Activators; D007328:Insulin; D013450:Sulfones; D013830:Thiadiazoles; D005941:Glucokinase; D005947:Glucose