Overexpression of dominant-negative mutant hepatocyte nuclear fctor-1 alpha in pancreatic beta-cells causes abnormal islet architecture with decreased expression of E-cadherin, reduced beta-cell proliferation, and diabetes.

One subtype of maturity-onset diabetes of the young (MODY)-3 results from mutations in the gene encoding hepatocyte nuclear factor (HNF)-1 alpha. We generated transgenic mice expressing a naturally occurring dominant-negative form of human HNF-1 alpha (P291fsinsC) in pancreatic beta-cells. A progressive hyperglycemia with age was seen in these transgenic mice, and the mice developed diabetes with impaired glucose-stimulated insulin secretion. The pancreatic islets exhibited abnormal architecture with reduced expression of glucose transporter (GLUT2) and E-cadherin. Blockade of E-cadherin-mediated cell adhesion in pancreatic islets abolished the glucose-stimulated increases in intracellular Ca(2+) levels and insulin secretion, suggesting that loss of E-cadherin in beta-cells is associated with impaired insulin secretion. There was also a reduction in beta-cell number (50%), proliferation rate (15%), and pancreatic insulin content (45%) in 2-day-old transgenic mice and a further reduction in 4-week-old animals. Our findings suggest various roles for HNF-1 alpha in normal glucose metabolism, including the regulation of glucose transport, beta-cell growth, and beta-cell-to-beta-cell communication.

Giant intrasellar arachnoid cyst manifesting as adrenal insufficiency due to hypothalamic dysfunction--case report--.

A 67-year-old man first noticed loss of pubic and axillary hair in 1992 and then a visual field defect in 2001. He experienced loss of consciousness attributed to hyponatremia in April 2002. Magnetic resonance imaging showed a giant intrasellar cystic mass, 40 mm in diameter, that had compressed the optic chiasm. The patient complained of chronic headache, and neurological examination revealed bitemporal hemianopsia. Preoperative endocrinological examination indicated adrenal insufficiency, and hypothyroidism due to hypothalamic dysfunction. The patient underwent endonasal transsphenoidal surgery. The cyst membrane was opened and serous fluid was drained. Histological examination identified the excised cyst membrane as arachnoid membrane. The patient's headaches resolved postoperatively, but the bitemporal hemianopsia and endocrinological function were unchanged. This arachnoid cyst associated with hypothalamic dysfunction might have been caused by an inflammatory episode in the suprasellar region.

Successful use of 111In-pentetrotide scintigraphy for localizing ectopic adrenocorticotropin-producing bronchial carcinoid tumor in a patient with Cushing's syndrome.

A 34-year-old man was diagnosed with clinical Cushing's syndrome based on circadian fluctuation of plasma adrenocorticotropin and serum cortisol levels and Liddle's-method. The presence of ectopic adrenocorticotropin production was suspected. Urine 5-hydroxyindoleaceturic acid level was high. Chest computed-tomography scan revealed a mass in the right upper lung. 111In-pentetrotide scintigraphy demonstrated marked accumulation in the right upper lung. We suspected an adrenocorticotropin-producing bronchial carcinoid. Plasma adrenocorticotropin and serum cortisol levels decreased immediately following resection of the tumor. Adrenocorticotropin production by tumor cells was confirmed by immunohistochemistry. This case indicates 111In-pentetrotide scintigraphy could be successfully used to identify and localize ectopic adrenocorticotropin-producing bronchial carcinoid.

Regenerative and therapeutic effects of heparin-binding epidermal growth factor-like growth factor on diabetes by gene transduction through retrograde pancreatic duct injection of adenovirus vector.

OBJECTIVES: In the adult pancreas, pre-existing beta cells, stem cells, and endocrine progenitor cells residing in the duct lining are considered important sources for beta-cell regeneration. A member of the epidermal growth factor (EGF) family, heparin binding (HB)-EGF, may promote this process. We examined whether HB-EGF gene transduction into duct cells could promote beta-cell regeneration. METHODS: We administered an HB-EGF adenovirus vector construct to male Institute of Cancer Research mice by retrograde injection through the pancreatic duct. We also performed HB-EGF gene transduction into cultured duct cells. RESULTS: On immunohistochemical and histomorphometric analysis of the experimental group, insulin-positive cells differentiated from duct cells, and the 5-bromo-2-deoxyuridine labeling index of beta cells was significantly increased. beta-cell mass was also increased, and the glucose tolerance of diabetic mice was improved at 12 weeks after injection. Using cultured pancreatic duct cells, we confirmed that HB-EGF gene transduction induced both insulin gene expression and insulin production by these cells. CONCLUSIONS: These results indicate that HB-EGF gene transduction into adult pancreatic duct cells not only promotes the proliferation of pre-existing beta cells but also leads to beta-cell differentiation from duct cells, and the resulting increase in beta-cell mass improves glucose tolerance.

Beta cell neogenesis from ducts and phenotypic conversion of residual islet cells in the adult pancreas of glucose intolerant mice induced by selective alloxan perfusion.

The aim of this study was to clarify the pattern of beta cell neogenesis in the alloxan-perfused, beta cells-depleted segment of glucose intolerant mice induced by selective alloxan perfusion. First, duct cells proliferated in the perfused segment, then cells co-expressing multiple islet hormones and transcription factors such as PDX-1, Nkx2.2, Isl1, and Pax6 were observed in duct cells, and newly formed islet-like cell clusters (ICCs) containing beta cells were recognized. In residual beta cell-depleted islets, glucagon or somatostatin and PDX-1 double-positive immature endocrine cells were recognized. Glucagon or somatostatin, insulin and PDX-1 triple-positive cells then appeared and these cells appeared to undergo terminal differentiation into beta cells. In conclusion, we demonstrated at least two different processes of beta cell neogenesis, i.e., formation of new ICCs from ductal epithelium and redifferentiation of residual non-beta islet cells in this model. In addition, transcription factors that appear in the processes of endocrine cell development may also play essential roles during beta cell neogenesis from duct cells.

Analysis of expression profiles of islet-associated transcription and growth factors during beta-cell neogenesis from duct cells in partially duct-ligated mice.

INTRODUCTION: Beta-cell neogenesis from pancreatic duct cells has been reported to occur in duct-ligated rat. Nevertheless, detailed process of this phenomenon has not been clarified. AIMS AND METHODOLOGY: To clarify the mechanism of beta-cell neogenesis, a partial pancreatic duct ligation mouse model was created. Proliferation of duct cells, beta-cell neogenesis, and expression of transcription factors and differentiation/growth factors were studied by immunohistochemistry, cDNA array, and RT-PCR methods. RESULTS: In the duct-ligated portion of the pancreas, newly formed islet-like cell clusters (ICCs) were observed arising from the ducts on day 7 and afterward. Transcription factors, such as pancreatic and duodenal homeobox gene-1 (PDX-1), paired box factor 6 (Pax6), islet1 and Nkx2.2-positive cells, and protein gene product 9.5 (PGP9.5) were also induced in duct lining cells. By cDNA microarray analysis, expression of insulin-like growth factor-1 (IGF-1) and transforming growth factor beta1 (TGF-beta1) were above control levels on day 5, and RT-PCR showed an increase from day 5 to day 28. IGF-1 and activin A-positive cells were detected in ducts. In addition, expression of betacellulin (BTC), heparin-binding epidermal growth factor-like growth factor (HB-EGF), and TGF-alpha were also increased from day 3 or 5. CONCLUSION: These findings suggest that beta-cell or endocrine precursors are localized among duct lining cells. Induction of several islet cell-associated transcription factors and differentiation and/or growth factors may play important roles during beta-cell neogenesis in this model.