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Sulprostone is a potent prostaglandin E

Insulin receptor substrate-2 (Irs2) integrates insulin-like signals with glucose and cAMP agonists to regulate beta-cell growth, function, and survival. This study investigated whether increased Irs2 concentration in beta-cells could reduce beta-cell destruction and the incidence of type 1 diabetes in nonobese diabetic (NOD) mice. NOD mice were intercrossed with C57BL/6 mice overexpressing Irs2 specifically in beta-cells to create NOD(Irs2) mice. After backcrossing NOD(Irs2) mice for 12 generations, glucose homeostasis and diabetes incidence were compared against NOD littermates. Compared with 12-wk-old NOD mice, the progression of severe insulitis was reduced and islet mass was increased in NOD(Irs2) mice. Moreover, the risk of diabetes decreased 50% in NOD(Irs2) mice until the experiment was terminated at 40 wk of age. Nondiabetic NOD(Irs2) mice displayed better glucose tolerance than nondiabetic NOD mice throughout the duration of the study and up to the age of 18 months. The effect of Irs2 to increase islet mass and improve glucose tolerance raised the possibility that NOD(Irs2) mice might have an increased capacity to respond to anti-CD3 antibody, which can induce remission of overt diabetes in some NOD mice. Anti-CD3 antibody injections restored glucose tolerance in newly diabetic NOD and NOD(Irs2) mice; however, anti-CD3-treated NOD(Irs2) mice were less likely than NOD mice to relapse during the experimental period because they displayed 10-fold greater beta-cell mass and mitogenesis. In conclusion, increased Irs2 attenuated the progression of beta-cell destruction, promoted beta-cell mitogenesis, and reduced diabetes incidence in NOD(Irs2) mice.

The human GH family consists of five genes, including the placental chorionic somatomammotropins (CS), within a single locus on chromosome 17. Based on nuclease sensitivity, the entire GH/CS locus is accessible in pituitary chromatin, yet only GH-N is expressed. Previously, we reported a P sequence element (263P) capable of repressing placental CS-A promoter activity in transfected pituitary (GC) cells, and our data indicated a possible role for nuclear factor-1 (NF-1) and regulatory factor X1 in this repression. In this study we show the formation of two independent pituitary complexes in vitro: a repressor complex containing NF-1 and a nonfunctional complex containing regulatory factor X1. In vitro repressor function is stabilized by the presence of P sequence element C (PSE-C), downstream of the previously characterized PSE-A and PSE-B. Repressor function is also dependent on an intact Pit-1 binding site in the CS-A promoter. EMSAs with PSE-C reveal binding of the hepatocyte nuclear factor-3/forkhead (HNF-3/fkh) family of transcription factors in rat pituitary GC cells. This observation is extended to human pituitary tissue, where HNF-3alpha's association with P sequences is confirmed by chromatin immunoprecipitation. Furthermore, protein-protein interactions between HNF-3alpha and NF-1 family members are demonstrated. These results identify HNF-3alpha as an additional member of the pituitary P sequence regulatory complex, implicating it in tissue-specific expression of the human GH/CS family.

The human GH family consists of five genes, including the placental chorionic somatomammotropins (CS), within a single locus on chromosome 17. Based on nuclease sensitivity, the entire GH/CS locus is accessible in pituitary chromatin, yet only GH-N is expressed. Previously, we reported a P sequence element (263P) capable of repressing placental CS promoter activity in transfected pituitary (GC) cells. Regions of protein binding within 263P include P sequence elements A and B (PSE-A and PSE-B), and we reported nuclear factor-1 (NF-1) recognition of PSE-B. We now provide evidence for multiple interactions on PSE-A, including binding of the regulatory factor X (RFX) family. Disruption of the RFX site within 263P blunts repressor activity in transfected GC cells; however, repression is only abolished when both PSE-A/RFX and PSE-B/NF-1 sites are mutated. The capacity of RFX and NF-1 to participate in a novel common complex is further suggested by coimmunoprecipitation of RFX1 and epitope-tagged NF-1 family members. Finally, we confirm the association of NF-1 and RFX1 with P sequences in human pituitary tissue by chromatin immunoprecipitation. Taken together, our data suggest that an inverse relationship exists between 263P and CS promoter histone hyperacetylation and the association of these factors in vivo.

We have used a previously unavailable model of pancreatic development, derived in vitro from human embryonic stem cells, to capture a time-course of gene, miRNA and histone modification levels in pancreatic endocrine cells. We investigated whether it is possible to better understand, and hence control, the biological pathways leading to pancreatic endocrine formation by analysing this information and combining it with the available scientific literature to generate models using a casual reasoning approach. We show that the embryonic stem cell differentiation protocol is highly reproducible in producing endocrine precursor cells and generates cells that recapitulate many aspects of human embryonic pancreas development, including maturation into functional endocrine cells when transplanted into recipient animals. The availability of whole genome gene and miRNA expression data from the early stages of human pancreatic development will be of great benefit to those in the fields of developmental biology and diabetes research. Our causal reasoning algorithm suggested the involvement of novel gene networks, such as NEUROG3/E2F1/KDM5B and SOCS3/STAT3/IL-6, in endocrine cell development We experimentally investigated the role of the top-ranked prediction by showing that addition of exogenous IL-6 could affect the expression of the endocrine progenitor genes NEUROG3 and NKX2.2.