Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UNIPROT:P01275 (glucagon)
26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

beta-Cell transplantation is viewed as a cure for type 1 diabetes; however, it is limited by the number of pancreas donors. Human stem cells offer the promise of an abundant source of insulin-producing cells, given the existence of methods for manipulating their differentiation. We have previously demonstrated that the expression of the beta-cell transcription factor pancreatic duodenal homeobox 1 (PDX-1) in human fetal liver cells activates multiple aspects of the beta-cell phenotype. These cells, termed FH-B-TPN cells, produce insulin, release insulin in response to physiological glucose levels, and replace beta-cell function in diabetic immunodeficient mice. However, they deviate from the normal beta-cell phenotype by the lack of expression of a number of beta-cell genes, the expression of non-beta-cell genes, and a lower insulin content. Here we aimed to promote differentiation of FH-B-TPN cells toward the beta-cell phenotype using soluble factors. Cells cultured with activin A in serum-free medium upregulated expression of NeuroD and Nkx2.2 and downregulated paired box homeotic gene 6 (PAX-6). Glucokinase and prohormone convertase 1/3 were also upregulated, whereas pancreatic polypeptide and glucagon as well as liver markers were downregulated. Insulin content was increased by up to 33-fold, to approximately 60% of the insulin content of normal beta-cells. The cells were shown to contain human C-peptide and release insulin in response to physiological glucose levels. Cell transplantation into immunodeficient diabetic mice resulted in the restoration of stable euglycemia. The cells continued to express insulin in vivo, and no cell replication was detected. Thus, the manipulation of culture conditions induced a significant and stable differentiation of FH-B-TPN cells toward the beta-cell phenotype, making them excellent candidates for beta-cell replacement in type 1 diabetes.
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PMID:Differentiation of human liver-derived, insulin-producing cells toward the beta-cell phenotype. 1612 44

We induced partial beta-cell loss within the pancreas of neonatal rats using streptozotocin (STZ) to better characterize the mechanisms leading to beta-cell regeneration postnatally. Rats were administered either STZ (70 mg/kg) or buffer alone on postnatal d 4, and the endocrine pancreas was examined between 4 and 40 d later. STZ-treated rats showed an approximately 60% loss of existing beta-cells and a moderate hyperglycemia (<15 mm glucose), with levels returning to near-control values after 20 d. Within preexisting islets, there was increased cell proliferation in both insulin- and glucagon-positive cells at 8 d as well as alpha-cell hyperplasia. These were associated with increased pancreatic content and circulating levels of glucagon. Pancreatic levels of glucagon-like polypeptide-1 (GLP-1) were increased 8 d after STZ compared with control values, and the GLP-1/glucagon ratio changed in favor of GLP-1. Administration of a GLP-1 receptor antagonist, GLP-1-(9-39), resulted in decreased recovery of beta-cells after STZ and worse glucose tolerance. Atypical glucagon-positive cells were found within islets that colocalized pancreatic duodenal homeobox-1 or glucose transporter-2. Pancreatic levels of insulin mRNA did not return to control values until 40 d after STZ. Insulin-positive cells were found after 8 d that colocalized glucagon and GLP-1. The model shows that the pancreas of the young rat can rapidly regenerate a loss of beta-cells, and this is associated with hyperplasia of alpha-cells with an altered phenotype of increased GLP-1 synthesis. The target cells of GLP-1 probably include immature beta-cells that coexpress proglucagon.
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PMID:Ontogeny of regeneration of beta-cells in the neonatal rat after treatment with streptozotocin. 1648 29

The ATP-sensitive K(+) channel (K(ATP) channel) in pancreatic beta-cells is a critical regulator in insulin secretion. We previously reported that transgenic mice expressing a dominant-negative form (Kir6.2G132S) of Kir6.2, a subunit of the K(ATP) channel, specifically in beta-cells develop severe hyperglycemia in adults (8 weeks of age). In this study, we conducted a long-term investigation of the phenotype of these transgenic mice. Surprisingly, hyperglycemia was spontaneously improved with concomitant improvement of pancreatic insulin content in the transgenic mice at >25 weeks of age. Insulin-positive cells and pancreatic duodenal homeobox 1 (PDX1)-positive cells both were clearly increased in the older compared with the younger transgenic mice. Interestingly, cells labeled with the lectin Dolichos biflorus agglutinin (DBA), a potential indicator of uncommitted pancreatic epithelial/ductal cells, were detected in the islets of the transgenic mice but not in those of wild-type mice. In addition, a subset of the DBA-labeled cells was positive for PDX1, insulin, glucagon, somatostatin, or pancreatic polypeptide. Moreover, some of the DBA-labeled cells were also positive for a proliferating cell marker. These results show that the Kir6.2G132S transgenic mouse is a useful model for studying beta-cell regeneration and that DBA-labeled cells participate in the process.
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PMID:Spontaneous recovery from hyperglycemia by regeneration of pancreatic beta-cells in Kir6.2G132S transgenic mice. 1680 60

Type 1 diabetes is caused by the destruction of pancreatic beta-cells by T cells of the immune system. Islet transplantation is a promising therapy for diabetes mellitus. Bone marrow stem cells (BMSC) have the capacity to differentiate into various cell lineages including endocrine cells of the pancreas. To investigate the conditions that allow BMSC to differentiate into insulin-producing cells, a novel in vitro method was developed by using the histone deacetylase inhibitor, trichostatin A (TSA). BMSC, cultured in presence of TSA, differentiated into islet-like clusters under appropriate culture conditions. These islet-like clusters were similar to the cells of the islets of the pancreas. The islet-like clusters showed endocrine gene expression typical for pancreatic beta-cell development and function, such as insulin (I and II), glucagon, somatostatin, GLUT-2, pancreatic duodenal homeobox-1 (PDX-1), and Pax 4. Immunocytochemistry confirmed islet-like clusters contained pancreatic hormones. The colocalization of insulin and C-peptide was also observed. Enzyme-linked immunosorbent assay analysis demonstrated that insulin secretion was regulated by glucose. Western blot analysis demonstrated the presence of stored insulin. Electron microscopy of the islet-like cells revealed an ultrastructure similar to that of pancreatic beta-cells, which contain insulin granules within secretory vesicles. These findings suggest that histone-deacetylating agents could allow the differentiation of BMSC into insulin-producing beta-cells.
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PMID:Chromatin-remodeling factors allow differentiation of bone marrow cells into insulin-producing cells. 1699 May 88

Epidermal growth factor receptor (EGF-R) signaling is essential for proper fetal development and growth of pancreatic islets, and there is also evidence for its involvement in beta-cell signal transduction in the adult. To study the functional roles of EGF-R in beta-cell physiology in postnatal life, we have generated transgenic mice that carry a mutated EGF-R under the pancreatic duodenal homeobox-1 promoter (E1-DN mice). The transgene was expressed in islet beta- and delta-cells but not in alpha-cells, as expected, and it resulted in an approximately 40% reduction in pancreatic EGF-R, extracellular signal-related kinase, and Akt phosphorylation. Homozygous E1-DN mice were overtly diabetic after the age of 2 weeks. The hyperglycemia was more pronounced in male than in female mice. The relative beta-cell surface area of E1-DN mice was highly reduced at the age of 2 months, while alpha-cell surface area was not changed. This defect was essentially postnatal, since the differences in beta-cell area of newborn mice were much smaller. An apparent explanation for this is impaired postnatal beta-cell proliferation; the normal surge of beta-cell proliferation during 2 weeks after birth was totally abolished in the transgenic mice. Heterozygous E1-DN mice were glucose intolerant in intraperitoneal glucose tests. This was associated with a reduced insulin response. However, downregulation of EGF-R signaling had no influence on the insulinotropic effect of glucagon-like peptide-1 analog exendin-4. In summary, our results show that even a modest attenuation of EGF-R signaling leads to a severe defect in postnatal growth of the beta-cells, which leads to the development of diabetes.
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PMID:Downregulation of EGF receptor signaling in pancreatic islets causes diabetes due to impaired postnatal beta-cell growth. 1713 Apr 73

Islet cell replacement is considered as the optimal treatment for type I diabetes. However, the availability of human pancreatic islets for transplantation is limited. Here, we show that human bone marrow-derived mesenchymal stem cells (hMSCs) could be induced to differentiate into functional insulin-producing cells by introduction of the pancreatic duodenal homeobox-1 (PDX-1). Recombinant adenoviral vector was used to deliver PDX-1 gene into hMSCs. After being infected with Ad-PDX-1, hMSCs were successfully induced to differentiate into insulin-secreting cells. The differentiated PDX-1+ hMSCs expressed multiple islet-cell genes including neurogenin3 (Ngn3), insulin, GK, Glut2, and glucagon, produced and released insulin/C-peptide in a weak glucose-regulated manner. After the differentiated PDX-1+ hMSCs were transplanted into STZ-induced diabetic mice, euglycemia can be obtained within 2 weeks and maintained for at least 42 days. These findings validate the hMSCs model system as a potential basis for enrichment of human beta cells or their precursors, and a possible source for cell replacement therapy in diabetes.
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PMID:Generation of insulin-producing cells from PDX-1 gene-modified human mesenchymal stem cells. 1722 89

Previous studies describe a unique culture method for the commitment of murine embryonic stem cells to early endocrine pancreata. In this report, early pancreatic-like beta-cell progenitors were enriched and a colony assay devised to allow these progenitors to differentiate into insulin-expressing colonies in vitro. An embryonic stem cell line with enhanced green fluorescent protein (EGFP) inserted into one allele of neurogenin 3 (Ngn3), a marker for pancreatic endocrine progenitors, was differentiated. During the late stage of culture, 20-30% of cells were Ngn3-EGFP(+). Gene expression profiling using the PancChip microarray platform demonstrated that Ngn3-EGFP(+) cells differentially express endocrine-related genes. A novel semisolid culture method was developed to support the formation of individual insulin/C-peptide-expressing colonies from dissociated single cells. Approximately 0.1-0.6% of Ngn3-EGFP(+) cells gave rise to insulin-expressing colonies, a three- to fivefold enrichment of beta-cell-like progenitors, or insulin-expressing colony-forming units (ICFUs), compared with nonsorted cells. All of the single colonies expressed insulin II, while 69% coexpressed insulin I and 44% coexpressed glucagon. Some single colonies expressed insulin I, insulin II, and Pdx-1 (pancreatic duodenal homeobox-1), but not glucagon. In other colonies, glucagon expression overlapped with C-peptide II in double immunostaining analysis, suggesting heterogeneity among the ICFUs and their resulting colonies. Together, these results demonstrate that progenitors that have the potential to give rise to insulin-expressing cells can be derived from murine embryonic stem cells.
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PMID:Insulin-expressing colonies developed from murine embryonic stem cell-derived progenitors. 1739 39

Ultrasound-targeted microbubble destruction (UTMD) was used to direct betacellulin (BTC) and pancreatic duodenal homeobox-1 (PDX1) to rat pancreas 48 h after islet destruction by streptozotocin (STZ). Sprague-Dawley rats were rendered diabetic by STZ injection. Controls included normal rats, STZ only without UTMD, and UTMD with DsRed reporter gene. Blood glucose increased dramatically in all rats 48 h after STZ, and continued to rise after UTMD with BTC alone. Blood glucose declined from day 3 to day 10 after UTMD with PDX1, but remained elevated (261+/-8 mg/dl). However, in rats treated with both BTC and PDX1, blood glucose remained below 200 mg/dl throughout day 10. This was accompanied by normalization of blood insulin and C-peptide. Histology demonstrated islet-like clusters of glucagon-staining cells in the rats treated with BTC and PDX1, but these clusters disappeared by 30 days after UTMD treatment. Although regeneration of insulin-producing islets was not seen, diabetes was reversed for up to 15 days after a single UTMD treatment by ectopic insulin production by pancreatic acinar cells. These cells co-expressed amylase and insulin and demonstrated several beta-cell markers by reverse transcription-PCR. Gene therapy by UTMD can reverse diabetes in vivo in adult rats by restoring pancreatic insulin production.
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PMID:Reversal of streptozotocin-induced diabetes in rats by gene therapy with betacellulin and pancreatic duodenal homeobox-1. 1746 Jul 16

Generation of new beta-cells from the adult pancreas or the embryonic stem cells is being pursued by research groups worldwide. Success will be dependent on confirmation of true beta-cell phenotype evidenced by capacity to process and store proinsulin. The aim of these studies was to robustly determine endocrine characteristics of the AR42J rat pancreatic acinar cell line before and after in vitro transdifferentiation. beta-cell phenotypic marker expression was characterised by RT-PCR, immunostaining, western blotting, ELISA and in human preproinsulin transgene over-expression studies in wild-type AR42J cells and after culture on Matrigel basement membrane matrix with and without growth/differentiation factor supplementation. Pancreatic duodenal homeobox 1 (PDX1), forkhead box transcription factor a2 (Foxa2), glucokinase, pancreatic polypeptide and low-level insulin gene transcription in wild-type AR42J cells were confirmed by RT-PCR. Culture on Matrigel-coated plates and supplementation of medium with glucagon-like peptide 1 induced expression of the beta-cell Glut 2 with maintained expression of insulin and PDX1. Increased biosynthesis and secretion of proinsulin were confirmed by immunocytochemical staining and sensitive ELISA. Absence of the regulated secretory pathway was demonstrated by undetectable prohormone convertase expression. In addition, inability to process and store endogenous proinsulin or human proinsulin translated from a constitutively over-expressed preproinsulin transgene was confirmed. The importance of robust phenotypic characterisation at the protein level in attempted beta-cell transdifferentiation studies has been confirmed. Rodent and human sensitive/specific differential proinsulin/insulin ELISA in combination with human preproinsulin over-expression enables detailed elucidatation of core endocrine functions of proinsulin processing and storage in putative new beta-cells.
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PMID:Inability to process and store proinsulin in transdifferentiated pancreatic acinar cells lacking the regulated secretory pathway. 1818 Mar 15

Islet-like cells derived from embryonic stem (ES) cells may be a promising therapeutic option for future diabetes treatment. Here, we demonstrated a five-stage protocol with adding exendin-4 instead of nicotinamide finally could generate islet-like cells from human embryonic stem (ES) cells. Immunofluorescence analysis revealed a high percentage of c-peptide positive cells in the derivation. However, in addition to insulin/c-peptide, most cells also coexpressed PDX-1 (pancreas duodenum homeobox-1), glucagon, somatostatin or pancreatic polypeptide. Insulin and other pancreatic beta-cell-specific genes were all present in the differentiated cells. Insulin secretion could be detected and increased significantly by adding KCL in high glucose concentration in vitro. Furthermore, subcutaneous transplantation of scaffolds seeded with the islet-like cells or cell transplantation under kidney capsules for further differentiation in vivo could improve 6h fasted blood glucose levels and diabetic phenotypes in streptozotocin-induced diabetic SCID mice. More interestingly, blood vessels of host origin, characterized by mouse CD31 immunostaining, invaded the cell-scaffold complexes. This work reveals a five-stage protocol with adding exendin-4 may be an effective protocol on the differentiation of human ES cells into islet-like cells, and suggests scaffolds can serve as vehicles for islet-like cell transplantation.
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PMID:The reversal of hyperglycaemia in diabetic mice using PLGA scaffolds seeded with islet-like cells derived from human embryonic stem cells. 1913 50


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