Induction of insulin secretion in engineered liver cells by nitric oxide

BACKGROUND: Type 1 Diabetes Mellitus results from an autoimmune destruction of the pancreatic beta cells, which produce insulin. The lack of insulin leads to chronic hyperglycemia and secondary complications, such as cardiovascular disease. The currently approved clinical treatments for diabetes mellitus often fail to achieve sustained and optimal glycemic control. Therefore, there is a great interest in the development of surrogate beta cells as a treatment for type 1 diabetes. Normally, pancreatic beta cells produce and secrete insulin only in response to increased blood glucose levels. However in many cases, insulin secretion from non-beta cells engineered to produce insulin occurs in a glucose-independent manner. In the present study we engineered liver cells to produce and secrete insulin and insulin secretion can be stimulated via the nitric oxide pathway. RESULTS: Expression of either human insulin or the beta cell specific transcription factors PDX-1, NeuroD1 and MafA in the Hepa1-6 cell line or primary liver cells via adenoviral gene transfer, results in production and secretion of insulin. Although, the secretion of insulin is not significantly increased in response to high glucose, treatment of these engineered liver cells with L-arginine stimulates insulin secretion up to three-fold. This L-arginine-mediated insulin release is dependent on the production of nitric oxide. CONCLUSION: Liver cells can be engineered to produce insulin and insulin secretion can be induced by treatment with L-arginine via the production of nitric oxide

Calpain Inhibition Attenuates Adipose Tissue Inflammation and Fibrosis in Diet-Induced Obese Mice

Adipose tissue macrophages have been proposed as a link between obesity and insulin resistance. However, the mechanisms underlying these processes are not completely defined. Calpains are calcium-dependent neutral cysteine proteases that modulate cellular function and have been implicated in various inflammatory diseases. To define whether activated calpains influence diet-induced obesity and adipose tissue macrophage accumulation, mice that were either wild type (WT) or overexpressing calpastatin (CAST Tg), the endogenous inhibitor of calpains were fed with high (60% kcal) fat diet for 16 weeks. CAST overexpression did not influence high fat diet-induced body weight and fat mass gain throughout the study. Calpain inhibition showed a transient improvement in glucose tolerance at 5 weeks of HFD whereas it lost this effect on glucose and insulin tolerance at 16 weeks HFD in obese mice. However, CAST overexpression significantly reduced adipocyte apoptosis, adipose tissue collagen and macrophage accumulation as detected by TUNEL, Picro Sirius and F4/80 immunostaining, respectively. CAST overexpression significantly attenuated obesity-induced inflammatory responses in adipose tissue. Furthermore, calpain inhibition suppressed macrophage migration to adipose tissue in vitro. The present study demonstrates a pivotal role for calpains in mediating HFD-induced adipose tissue remodeling by influencing multiple functions including apoptosis, fibrosis and inflammation

Protective role of <it>Scoparia dulcis </it>plant extract on brain antioxidant status and lipidperoxidation in STZ diabetic male Wistar rats

<p>Abstract</p> <p>Background</p> <p>The aim of the study was to investigate the effect of aqueous extract of <it>Scoparia dulcis </it>on the occurrence of oxidative stress in the brain of rats during diabetes by measuring the extent of oxidative damage as well as the status of the antioxidant defense system.</p> <p>Methods</p> <p>Aqueous extract of <it>Scoparia dulcis </it>plant was administered orally (200 mg/kg body weight) and the effect of extract on blood glucose, plasma insulin and the levels of thiobarbituric acid reactive substances (TBARS), hydroperoxides, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and reduced glutathione (GSH) were estimated in streptozotocin (STZ) induced diabetic rats. Glibenclamide was used as standard reference drug.</p> <p>Results</p> <p>A significant increase in the activities of plasma insulin, superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and reduced glutathione was observed in brain on treatment with 200 mg/kg body weight of <it>Scoparia dulcis </it>plant extract (SPEt) and glibenclamide for 6 weeks. Both the treated groups showed significant decrease in TBARS and hydroperoxides formation in brain, suggesting its role in protection against lipidperoxidation induced membrane damage.</p> <p>Conclusions</p> <p>Since the study of induction of the antioxidant enzymes is considered to be a reliable marker for evaluating the antiperoxidative efficacy of the medicinal plant, these findings suggest a possible antiperoxidative role for <it>Scoparia dulcis </it>plant extract. Hence, in addition to antidiabetic effect, <it>Scoparia dulcis </it>possess antioxidant potential that may be used for therapeutic purposes.</p

Induction of insulin secretion in engineered liver cells by nitric oxide-5

<p><b>Copyright information:</b></p><p>Taken from "Induction of insulin secretion in engineered liver cells by nitric oxide"</p><p>http://www.biomedcentral.com/1472-6793/7/11</p><p>BMC Physiology 2007;7():11-11.</p><p>Published online 17 Oct 2007</p><p>PMCID:PMC2121102.</p><p></p>el A) or a combination of PDX-1, NeuroD1 and MafA adenoviruses (panel B). After incubation on 1 mM glucose for about 16 h, the cells were transferred to KRB buffer containing 1 mM glucose in the presence or absence of 20 mM L-arginine and 100 μM L-NNA. Insulin secretion in the media was measured in three independent experiments and is expressed as fold difference of insulin secretion of 1 mM glucose incubated cells

Induction of insulin secretion in engineered liver cells by nitric oxide-4

<p><b>Copyright information:</b></p><p>Taken from "Induction of insulin secretion in engineered liver cells by nitric oxide"</p><p>http://www.biomedcentral.com/1472-6793/7/11</p><p>BMC Physiology 2007;7():11-11.</p><p>Published online 17 Oct 2007</p><p>PMCID:PMC2121102.</p><p></p>ndividually or in combination was determined using a mouse insulin ELISA kit. After incubation with the corresponding adenoviruses, the cells were incubated first over night with 1 mM glucose and then transferred to KRB buffer containing 25 mM glucose. Total insulin secretion is expressed as μU/ml * 10cells. B. Hepa1-6 cells expressing all three transcription factors, PDX-1, NeuroD1 and MafA were incubated for 1 h in KRB buffer containing 1 mM glucose with or without 20 mM L-arginine and 100 μM L-NNA. The amount insulin in the media was quantified by an insulin ELISA assay. The data are averages of five (n = 5) independent experiments

Induction of insulin secretion in engineered liver cells by nitric oxide-6

<p><b>Copyright information:</b></p><p>Taken from "Induction of insulin secretion in engineered liver cells by nitric oxide"</p><p>http://www.biomedcentral.com/1472-6793/7/11</p><p>BMC Physiology 2007;7():11-11.</p><p>Published online 17 Oct 2007</p><p>PMCID:PMC2121102.</p><p></p>sulin or control adenovirus, after treatment with 1 or 25 mM glucose for 1 h. Total insulin secretion is expressed as μU/ml * 10cells

Induction of insulin secretion in engineered liver cells by nitric oxide-0

<p><b>Copyright information:</b></p><p>Taken from "Induction of insulin secretion in engineered liver cells by nitric oxide"</p><p>http://www.biomedcentral.com/1472-6793/7/11</p><p>BMC Physiology 2007;7():11-11.</p><p>Published online 17 Oct 2007</p><p>PMCID:PMC2121102.</p><p></p>sulin or control adenovirus, after treatment with 1 or 25 mM glucose for 1 h. Total insulin secretion is expressed as μU/ml * 10cells

Induction of insulin secretion in engineered liver cells by nitric oxide-1

<p><b>Copyright information:</b></p><p>Taken from "Induction of insulin secretion in engineered liver cells by nitric oxide"</p><p>http://www.biomedcentral.com/1472-6793/7/11</p><p>BMC Physiology 2007;7():11-11.</p><p>Published online 17 Oct 2007</p><p>PMCID:PMC2121102.</p><p></p>rred to 1 mM glucose with or without 20 mM L-arginine in the presence or absence of the NOS inhibitor L-NNA (100 μM) for 1 h. The amount of secreted insulin in the medium was determined and is expressed as fold difference, where insulin secretion on 1 mM glucose was set as 1-fold. Values are expressed as means ± SD for n = 5 in each group. B. Effect of NO donor sodium nitroprusside (SNP) on insulin secretion in Hepa1-6 cells. Insulin secretion in Hepa1-6 cells incubated with the human insulin adenovirus was measured after incubation of cells with 1 mM glucose, with or without 20 mM L-arginine or 100 μM SNP for 1 h (n = 3)

Identification of glucose-regulated miRNAs from pancreatic β cells reveals a role for miR-30d in insulin transcription

MicroRNAs (miRNAs) are small noncoding ribonucleotides that bind mRNAs and function mainly as translational repressors in mammals. MicroRNAs have been implicated to play a role in many diseases, including diabetes. Several reports indicate an important function for miRNAs in insulin production as well as insulin secretion. We have recently carried out a screen in the pancreatic β-cell line MIN6 to identify miRNAs with altered abundance in response to changes in glucose concentrations. This screen resulted in identification of 61 glucose-regulated miRNAs from a total of 108 miRNAs detectable in MIN6 cells. Many of the identified miRNAs, including miR-124a, miR-107, and miR-30d were up-regulated in the presence of high glucose. Only a few of the miRNAs, including miR-296, miR-484, and miR-690 were significantly down-regulated by high glucose treatment. Interestingly, we found that overexpression of miR-30d, one of the miRNAs up-regulated by glucose, increased insulin gene expression, while inhibition of miR-30d abolished glucose-stimulated insulin gene transcription. Overexpression or inhibition of miR-30d did not have any effect on insulin secretion. These data suggest that the putative target genes of miR-30d may be negative regulators of insulin gene expression

Comparison of plants used for skin and stomach problems in Trinidad and Tobago with Asian ethnomedicine

RefereedThis paper provides a preliminary evaluation of fifty-eight ethnomedicinal plants used in Trinidad and Tobago for skin problems, stomach problems, pain and internal parasites for safety and possible efficacy. Thirty respondents, ten of whom were male were interviewed from September 1996 to September 2000 on medicinal plant use for health problems. The respondents were obtained by snowball sampling, and were found in thirteen different sites, 12 in Trinidad and one in Tobago. The uses are compared to those current in Asia. Bambusa vulgaris, Bidens alba, Jatropha curcas, Neurolaena lobata, Peperomia rotundifolia and Phyllanthus urinaria are possibly efficacous for stomach problems, pain and internal parasites. Further scientific study of these plants is warranted