The role of reduced glucose transporter content and glucose metabolism in the immature secretory responses of fetal rat pancreatic islets

Diabetologia ◽  
1994 ◽  
Vol 37 (2) ◽  
pp. 134-140 ◽  
Author(s):  
S. J. Hughes
2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Masataka YOKOYAMA ◽  
Yoshio KOBAYASHI ◽  
Tohru MINAMINO

Cellular senescence is a state of irreversible growth arrest induced by various stresses such as oncogenic stimuli. This response is controlled by negative regulators of the cell cycle like the p53 tumor suppressor protein. Accumulating evidence has suggested a role of p53 activation in various age-associated conditions including atherosclerosis, heart failure and diabetes. Here we show that endothelial p53 activation plays a pathological role in the regulation of endothelial function and glucose metabolism under diabetic conditions. Endothelial expression of p53 was markedly up-regulated in a streptozotocin-induced diabetes model. Endothelial function such as acetylcholine-dependent vasodilatation was markedly impaired in this model. Although hyperglycemia was not altered, impairment of endothelial function was significantly improved in mice with endothelial cell-specific p53 deficiency. In same way, p53 was markedly activated in ischemic vessels, and endothelial p53 deficiency enhanced ischemia-induced angiogenesis. Mechanistically, endothelial p53 up-regulated the expression of PTEN that negatively regulated the Akt-eNOS pathway, and therefore disruption of p53 improved endothelial dysfunction. We also found that endothelial p53 was markedly activated, and the Akt-eNOS pathway was attenuated in a diet-induced obesity model. Disruption of endothelial p53 activation improved dietary inactivation of eNOS that up-regulated the expression of PGC-1α in skeletal muscle, thereby increasing mitochondrial biogenesis and oxygen consumption. Inhibition of endothelial p53 also improved dietary impairment of glucose transport into skeletal muscle by up-regulating endothelial expression of glucose transporter 1. Consequently, mice with endothelial cell-specific p53 deficiency fed a high-calorie diet showed improvement of insulin sensitivity and less fat accumulation compared with control littermates. These results indicate that endothelial p53 negatively regulates endothelium-dependent vasodilatation, ischemia-induced angiogenesis, and mitochondrial biogenesis by inhibiting the Akt-eNOS pathway and suggest that inhibition of endothelial p53 could be a novel therapeutic target in diabetic patients.


2007 ◽  
Vol 193 (3) ◽  
pp. 367-381 ◽  
Author(s):  
Anthony J Weinhaus ◽  
Laurence E Stout ◽  
Nicholas V Bhagroo ◽  
T Clark Brelje ◽  
Robert L Sorenson

Glucokinase activity is increased in pancreatic islets during pregnancy and in vitro by prolactin (PRL). The underlying mechanisms that lead to increased glucokinase have not been resolved. Since glucose itself regulates glucokinase activity in β-cells, it was unclear whether the lactogen effects are direct or occur through changes in glucose metabolism. To clarify the roles of glucose metabolism in this process, we examined the interactions between glucose and PRL on glucose metabolism, insulin secretion, and glucokinase expression in insulin 1 (INS-1) cells and rat islets. Although the PRL-induced changes were more pronounced after culture at higher glucose concentrations, an increase in glucose metabolism, insulin secretion, and glucokinase expression occurred even in the absence of glucose. The presence of comparable levels of insulin secretion at similar rates of glucose metabolism from both control and PRL-treated INS-1 cells suggests the PRL-induced increase in glucose metabolism is responsible for the increase in insulin secretion. Similarly, increases in other known PRL responsive genes (e.g. the PRL receptor, glucose transporter-2, and insulin) were also detected after culture without glucose. We show that the upstream glucokinase promoter contains multiple STAT5 binding sequences with increased binding in response to PRL. Corresponding increases in glucokinase mRNA and protein synthesis were also detected. This suggests the PRL-induced increase in glucokinase mRNA and its translation are sufficient to account for the elevated glucokinase activity in β-cells with lactogens. Importantly, the increase in islet glucokinase observed with PRL is in line with that observed in islets during pregnancy.


Diabetologia ◽  
1992 ◽  
Vol 35 (10) ◽  
pp. 924-931 ◽  
Author(s):  
E. Strandell ◽  
S. Sandler ◽  
C. Boitard ◽  
D. L. Eizirik

1982 ◽  
Vol 206 (1) ◽  
pp. 97-102 ◽  
Author(s):  
P Thams ◽  
K Capito ◽  
C J Hedeskov

The effects of Ca2+-calmodulin on adenylate cyclase activity in EGTA-washed, 27000 g particulate fractions of mouse and rat pancreatic islets were studied. Ca2+ (10 microM)-calmodulin (1 microM) stimulated adenylate cyclase activity 53.1 +/- 5.2 (N = 6)% in the particulate fraction of rat islets. Trifluoperazine (50 microM), a specific inhibitor of calmodulin, inhibited the Ca2+-calmodulin activation of the adenylate cyclase activity of this fraction of rat islets. These results confirm previous reports dealing with Ca2+-Calmodulin and rat islet adenylate cyclase [Valverde, Vandermeers. Anjaneyulu & Malaisse (1979) Science 206, 225-227; Sharp, Wiedenkeller, Kaelin, Siegel & Wollheim (1980) Diabetes 29, 74-77]. In contrast, however, Ca2+ (1-100 microM)-calmodulin (1-10 microM) did not stimulate the adenylate cyclase activity in the EGTA-washed particulate fraction of mouse islets, and trifluoperazine (50 microM) did not inhibit the adenylate cyclase activity of this fraction of mouse islets, although some remaining calmodulin [0.18 +/- 0.05 (n = 3) microgram/mg of protein] could be demonstrated. GTP (10 microM) enhanced islet adenylate cyclase activity considerably, but did not confer any sensitivity towards Ca2+-calmodulin on mouse islet adenylate cyclase. The results question the role of calmodulin in the Ca2+-dependent rise in cyclic AMP evoked by glucose in pancreatic islets.


Diabetologia ◽  
2006 ◽  
Vol 49 (12) ◽  
pp. 2930-2938 ◽  
Author(s):  
N. Sasaki ◽  
M. Iwase ◽  
Y. Uchizono ◽  
U. Nakamura ◽  
H. Imoto ◽  
...  

2021 ◽  
Vol 55 (2) ◽  
pp. 193-205

Yes-associated protein (YAP) is one of the Hippo pathway's two effectors, a pathway associated with organ size control. Research on YAP has focused on its oncogenic potential. However, in cancer cells, aside from inducing growth, YAP was also found to regulate glucose metabolism. Therefore, we aimed to explore YAP's control of glucose metabolism and whether these findings are translatable to physiological conditions. We conducted a systematic review of the MEDLINE database through PubMed in April 2020 and repeated the search in September 2020. We found that YAP induced the transcriptional activity of most genes associated with glucose metabolism from enzymes to transport proteins. In glycolysis and gluconeogenesis, YAP upregulated all enzymes except for enolase and pyruvate kinase. Multiple research has also shown YAP's ability to regulate the expression of glucose transporter of the GLUT family. Additionally, glucose concentration, hypoxia, and hormones such as insulin and glucagon regulate YAP activity and depend on YAP to exert their biological activity. In this review, we have shown that YAP is a central regulator of glucose metabolism, controlling both enzymes and proteins involved in glucose transport. YAP is also situated strategically in several pathways controlling glucose and was found to mediate their effects. If these results were consistent in physiological conditions and across glucose-associated metabolic disturbances, then YAP may become a prospective therapeutic target.


Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1568 ◽  
Author(s):  
Min-Hsun Kuo ◽  
Wen-Wei Chang ◽  
Bi-Wen Yeh ◽  
Yeh-Shiu Chu ◽  
Yueh-Chun Lee ◽  
...  

Breast cancer brain metastasis commonly occurs in one-fourth of breast cancer patients and is associated with poor prognosis. Abnormal glucose metabolism is found to promote cancer metastasis. Moreover, the tumor microenvironment is crucial and plays an active role in the metabolic adaptations and survival of cancer cells. Glucose transporters are overexpressed in cancer cells to increase glucose uptake. The glucose transporter 3 (GLUT3) is a high-affinity glucose transporter that is highly expressed in mammalian neurons. GLUT3 is also overexpressed in several malignant brain tumors. However, the role of GLUT3 in breast cancer brain metastasis remains unknown. The results of the present study demonstrated that GLUT3 is highly overexpressed in brain metastatic breast cancers and mediates glucose metabolic reprogramming. Furthermore, knockdown of cAMP-response element binding protein (CREB) could directly regulate GLUT3 expression in brain metastatic breast cancer cells. Notably, we verified and provided a novel role of GLUT3 in mediating glucose metabolism and assisting breast cancer cells to survive in the brain to promote brain metastasis.


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