scholarly journals Long- But Not Short-Term Adult-Onset, Isolated GH Deficiency in Male Mice Leads to Deterioration of β-Cell Function, Which Cannot Be Accounted for by Changes in β-Cell Mass

Endocrinology ◽  
2014 ◽  
Vol 155 (3) ◽  
pp. 726-735 ◽  
Author(s):  
Jose Cordoba-Chacon ◽  
Manuel D. Gahete ◽  
Naveen K. Pokala ◽  
David Geldermann ◽  
Maria Alba ◽  
...  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Idil I. Aigha ◽  
Essam M. Abdelalim

Abstract Understanding the biology underlying the mechanisms and pathways regulating pancreatic β cell development is necessary to understand the pathology of diabetes mellitus (DM), which is characterized by the progressive reduction in insulin-producing β cell mass. Pluripotent stem cells (PSCs) can potentially offer an unlimited supply of functional β cells for cellular therapy and disease modeling of DM. Homeobox protein NKX6.1 is a transcription factor (TF) that plays a critical role in pancreatic β cell function and proliferation. In human pancreatic islet, NKX6.1 expression is exclusive to β cells and is undetectable in other islet cells. Several reports showed that activation of NKX6.1 in PSC-derived pancreatic progenitors (MPCs), expressing PDX1 (PDX1+/NKX6.1+), warrants their future commitment to monohormonal β cells. However, further differentiation of MPCs lacking NKX6.1 expression (PDX1+/NKX6.1−) results in an undesirable generation of non-functional polyhormonal β cells. The importance of NKX6.1 as a crucial regulator in MPC specification into functional β cells directs attentions to further investigating its mechanism and enhancing NKX6.1 expression as a means to increase β cell function and mass. Here, we shed light on the role of NKX6.1 during pancreatic β cell development and in directing the MPCs to functional monohormonal lineage. Furthermore, we address the transcriptional mechanisms and targets of NKX6.1 as well as its association with diabetes.


2008 ◽  
Vol 28 (9) ◽  
pp. 2971-2979 ◽  
Author(s):  
Yutaka Shigeyama ◽  
Toshiyuki Kobayashi ◽  
Yoshiaki Kido ◽  
Naoko Hashimoto ◽  
Shun-ichiro Asahara ◽  
...  

ABSTRACT Recent studies have demonstrated the importance of insulin or insulin-like growth factor 1 (IGF-1) for regulation of pancreatic β-cell mass. Given the role of tuberous sclerosis complex 2 (TSC2) as an upstream molecule of mTOR (mammalian target of rapamycin), we examined the effect of TSC2 deficiency on β-cell function. Here, we show that mice deficient in TSC2, specifically in pancreatic β cells (βTSC2−/− mice), manifest increased IGF-1-dependent phosphorylation of p70 S6 kinase and 4E-BP1 in islets as well as an initial increased islet mass attributable in large part to increases in the sizes of individual β cells. These mice also exhibit hypoglycemia and hyperinsulinemia at young ages (4 to 28 weeks). After 40 weeks of age, however, the βTSC2−/− mice develop progressive hyperglycemia and hypoinsulinemia accompanied by a reduction in islet mass due predominantly to a decrease in the number of β cells. These results thus indicate that TSC2 regulates pancreatic β-cell mass in a biphasic manner.


Endocrinology ◽  
2015 ◽  
Vol 157 (2) ◽  
pp. 624-635 ◽  
Author(s):  
Joon Ha ◽  
Leslie S. Satin ◽  
Arthur S. Sherman

Abstract Type 2 diabetes (T2D) is generally thought to result from the combination of 2 metabolic defects, insulin resistance, which increases the level of insulin required to maintain glucose within the normal range, and failure of insulin-secreting pancreatic β-cells to compensate for the increased demand. We build on a mathematical model pioneered by Topp and colleagues to elucidate how compensation succeeds or fails. Their model added a layer of slow negative feedback to the classic insulin-glucose loop in the form of a slow, glucose-dependent birth and death law governing β-cell mass. We add to that model regulation of 2 aspects of β-cell function on intermediate time scales. The model quantifies the relative contributions of insulin action and insulin secretion defects to T2D and explains why prevention is easier than cure. The latter is a consequence of a threshold separating the normoglycemic and diabetic states (bistability), which also underlies the success of bariatric surgery and acute caloric restriction in rapidly reversing T2D. The threshold concept gives new insight into “Starling's Law of the Pancreas,” whereby insulin secretion is higher for prediabetics and early diabetics than for normal individuals.


2008 ◽  
Vol 8 (2_suppl) ◽  
pp. S19-S25 ◽  
Author(s):  
Baptist Gallwitz

The clinical course of type 2 diabetes mellitus is characterised by a progressive decline in β -cell mass. The changing β-cell mass reflects a shifting balance between β-cell neogenesis, islet neogenesis and β-cell apoptosis. In persons with diabetes, administration of exogenous glucagon-like peptide-1 (GLP-1) improves glucose sensitivity and insulin synthesis and may help increase β cell mass. As the effects of GLP-1 on the β cell are becoming better understood at both the molecular and cellular levels, it has become possible to develop therapies with the potential to harness and sustain the positive effects of endogenous GLP-1 in patients with type 2 diabetes. Data from in vitro, preclinical and phase II studies show promising results with GLP-1 analogues in improving β-cell function in patients with type 2 diabetes. For example, in vitro models have shown the GLP-1 analogue liraglutide inhibits β-cell apoptosis in isolated neonatal rat islets. In vitro, animal models demonstrate increasing β-cell mass with liraglutide administration. Results from a recently completed phase II clinical trial with liraglutide in patients with type 2 diabetes demonstrate that daily treatment markedly improves β -cell function as shown by an increased first-phase insulin response and secretory capacity and a decreased proinsulin:insulin ratio. Now, phase III trials continue to bear out the potential for liraglutide for treatment of patients with type 2 diabetes.Br J Diabetes Vasc Dis 2008;8 (Suppl 2): S19-S25


1988 ◽  
Vol 77 (6) ◽  
pp. 852-859 ◽  
Author(s):  
G. DAHLQUIST ◽  
L. BLOM ◽  
B. PERSSON ◽  
M. WALLENSTEEN ◽  
S. WALL

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