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GLP-1 signalling compensates for impaired insulin signalling in regulating beta cell proliferation in ?IRKO mice.

ABSTRACT: We aimed to investigate potential interactions between insulin and glucagon-like peptide (GLP)-1 signalling pathways in the regulation of beta cell-cycle dynamics in vivo, in the context of the therapeutic potential of GLP-1 to modulate impaired beta cell function.Beta cell-specific insulin receptor knockout (?IRKO) mice, which exhibit beta cell dysfunction and an age-dependent decrease in beta cell mass, were treated with the dipeptidyl peptidase-4 inhibitor vildagliptin. Following this, glucose homeostasis and beta cell proliferation were evaluated and underlying molecular mechanisms were investigated.The sustained elevation in circulating GLP-1 levels, caused by treatment of the knockout mice with vildagliptin for 6 weeks, significantly improved glucose tolerance secondary to enhanced insulin secretion and proliferation of beta cells. Treating ?IRKO beta cell lines with the GLP-1 analogue, exendin-4, promoted Akt phosphorylation and protein expression of cyclins A, D1 and E two- to threefold, in addition to cyclin D2. Pancreases from the vildagliptin-treated ?IRKO mice exhibited increased cyclin D1 expression, while cyclin D2 expression was impaired.Activation of GLP-1 signalling compensates for impaired growth factor (insulin) signalling and enhances expression of cyclins to promote beta cell proliferation. Together, these data indicate the potential of GLP-1-related therapies to enhance beta cell proliferation and promote beneficial outcomes in models with dysfunctional beta cells.

SUBMITTER: Kawamori D

PROVIDER: S-EPMC5508991 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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GLP-1 signalling compensates for impaired insulin signalling in regulating beta cell proliferation in βIRKO mice.

Kawamori Dan D Shirakawa Jun J Liew Chong Wee CW Hu Jiang J Morioka Tomoaki T Duttaroy Alokesh A Burkey Bryan B Kulkarni Rohit N RN

Diabetologia 20170520 8

<h4>Aims/hypothesis</h4>We aimed to investigate potential interactions between insulin and glucagon-like peptide (GLP)-1 signalling pathways in the regulation of beta cell-cycle dynamics in vivo, in the context of the therapeutic potential of GLP-1 to modulate impaired beta cell function.<h4>Methods</h4>Beta cell-specific insulin receptor knockout (βIRKO) mice, which exhibit beta cell dysfunction and an age-dependent decrease in beta cell mass, were treated with the dipeptidyl peptidase-4 inhibi ...[more]

PMID: 28526921

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Project description:BackgroundObesity and diabetes mellitus are associated with an increased risk of pancreatic cancer. These associations may be secondary to consequences of peripheral insulin resistance, pancreatic β-cell dysfunction, or hyperglycemia itself. Hemoglobin A1c (HbA1c) is a measure of hyperglycemia, whereas plasma insulin and proinsulin are markers of peripheral insulin resistance, and the proinsulin to insulin ratio marks pancreatic β-cell dysfunction.MethodsThis was a prospective, nested case-control study of 449 case patients and 982 control subjects with prediagnostic blood samples and no diabetes history from five prospective US cohorts followed through 2008. Two or three control subjects were matched to each case patient by year of birth, cohort, smoking, and fasting status. Pancreatic cancer risk was assessed by prediagnostic HbA1c, insulin, proinsulin, and proinsulin to insulin ratio with multivariable-adjusted logistic regression. All P values were two-sided.ResultsThe highest vs lowest quintiles of HbA1c, insulin, and proinsulin were associated with with an increased risk for pancreatic cancer (odds ratio [OR] = 1.79; 95% confidence interval [CI] = 1.17 to 2.72, P trend = .04 for HbA1c; OR = 1.57; 95% CI = 1.08 to 2.30; Ptrend = .002 for insulin; and OR = 2.22; 95% CI = 1.50 to 3.29; P trend < .001 for proinsulin). Proinsulin to insulin ratio was not associated with pancreatic cancer risk. Results were similar across studies (all P heterogeneity > .29). In cancers developing 10 or more years after blood collection, the associations with insulin and proinsulin became stronger (highest vs lowest quintile, OR = 2.77; 95% CI = 1.28 to 5.99 for insulin and OR = 3.60; 95% CI = 1.68 to 7.72 for proinsulin). In mutually adjusted models including HbA1c, insulin, and proinsulin, only proinsulin remained statistically significant ( highest vs lowest quintile, OR = 2.55; 95% CI = 1.54 to 4.21; Ptrend < .001).ConclusionsAmong participants from five large prospective cohorts, circulating markers of peripheral insulin resistance, rather than hyperglycemia or pancreatic β-cell dysfunction, were independently associated with pancreatic cancer risk.

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GLP-1 signalling compensates for impaired insulin signalling in regulating beta cell proliferation in ?IRKO mice.

Publications

GLP-1 signalling compensates for impaired insulin signalling in regulating beta cell proliferation in βIRKO mice.

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