Dual regulatory role for phosphatase and tensin homolog in specification of intestinal endocrine cell subtypes

AIM: To investigate the impact of phosphatase and tensin homolog (Pten) in the specification of intestinal enteroendocrine subpopulations.METHODS: Using the Cre/loxP system, a mouse with conditional intestinal epithelial Pten deficiency was generated. Pten mutant mice and controls were sacrificed and small intestines collected for immunofluorescence and quantitative real-time polymerase chain reaction. Blood was collected on 16 h fasted mice by cardiac puncture. Enzyme-linked immunosorbent assay was used to measure blood circulating ghrelin, somatostatin (SST) and glucose-dependent insulinotropic peptide (GIP) levels.RESULTS: Results show an unexpected dual regulatory role for epithelial Pten signalling in the specification/differentiation of enteroendocrine cell subpopulations in the small intestine. Our data indicate that Pten positively regulates chromogranin A (CgA) expressing subpopulations, including cells expressing secretin, ghrelin, gastrin and cholecystokinin (CCK). In contrast, Pten negatively regulates the enteroendocrine subtype specification of non-expressing CgA cells such as GIP and SST expressing cells.CONCLUSION: The present results demonstrate that Pten signalling favours the enteroendocrine progenitor to specify into cells expressing CgA including those producing CCK, gastrin and ghrelin.     

Conserved role for autophagy in Rho1-mediated cortical remodeling and blood cell recruitment

Dynamic regulation of cell shape underlies many developmental and immune functions. Cortical remodeling is achieved under the central control of Rho GTPase pathways that modulate an exquisite balance in the dynamic assembly and disassembly of the cytoskeleton and focal adhesions. Macroautophagy (autophagy), associated with bulk cytoplasmic remodeling through lysosomal degradation, has clearly defined roles in cell survival and death. Moreover, it is becoming apparent that proteins, organelles, and pathogens can be targeted for autophagic clearance by selective mechanisms, although the extent and roles of such degradation are unclear. Here we report a conserved role for autophagy specifically in the cortical remodeling of Drosophila blood cells (hemocytes) and mouse macrophages. Continuous autophagy was required for integrin-mediated hemocyte spreading and Rho1-induced cell protrusions. Consequently, hemocytes disrupted for autophagy were impaired in their recruitment to epidermal wounds. Cell spreading required ref(2)P, the Drosophila p62 multiadaptor, implicating selective autophagy as a novel mechanism for modulating cortical dynamics. These results illuminate a specific and conserved role for autophagy as a regulatory mechanism for cortical remodeling, with implications for immune cell function.     

XRCC1和XPD单核苷酸多态性与非小细胞肺癌铂类药物化疗敏感性的关系

目的研究X线修复交叉互补基因1（XRCC1）和着色性干皮病基因（XPD）单核苷酸多态性与老年晚期非小细胞肺癌（NSCLC）铂类药物化疗敏感性关系。方法应用聚合酶链反应结舍限制性片段长度多态性（PCR-RFLP）的方法检测81例以铂类药物为主要化疗方案的NSCLC患者XRCC1 Arg399Gln和XPD Lys751Gin基因型多态性，采用非条件Logistic回归分析不同基因型与化疗疗效的关系。结果81例患者化疗总有效率为35．8％，其中完全缓解（CR）、部分缓解（PR）、稳定（SD）和进展（PD）患者分别为0、29、31、21例。携带至少1个XRCC1 399Arg等位基因的患者化疗敏感性是携带Gln／Gln基因型患者的4.52倍（OR=4．52，95％CI=1.11—18．38）。未发现XPD Lys751Gin遗传多态与化疗敏感性相关。结论XRCC1 Arg399Gln多态可能与晚期NSCLC铂类药物化疗敏感性有关。     

Progression to type 1 diabetes in islet cell antibody-positive relatives in the European Nicotinamide Diabetes Intervention Trial: the role of additional immune, genetic and metabolic markers of risk

Aims/hypothesis To examine the role of additional immune, genetic and metabolic risk markers in determining risk of diabetes in islet cell antibody (ICA)-positive individuals with a family history of type 1 diabetes recruited into the European Nicotinamide Diabetes Intervention Trial.Methods Five hundred and forty-nine first-degree relatives with confirmed ICA levels ≥20 Juvenile Diabetes Foundation units (mean age 15.9 years; interquartile range 10.4–33.7 years) were recruited from 20 countries. OGTTs and IVGTTs were performed at baseline, antibodies to glutamate decarboxylase (GADA), protein tyrosine phosphatase (IA–2A) and insulin (IAA) were determined by RIA, and HLA class II genotyping was performed by PCR of sequence-specific oligonucleotides.Results One hundred and fifty-nine participants developed diabetes within 5 years. Univariate analysis showed that the cumulative risk of development of diabetes within 5 years varied according to age, relationship to the proband, positivity for IAA, IA–2A and GADA, number and combination of islet antibodies, HLA class II genotype, baseline glucose tolerance, and first-phase insulin secretion, but not gender or incidence of childhood type 1 diabetes in the background population. Children aged ≤10 years had a 59% risk of diabetes within 5 years, compared with 11% in those ≥25 years (p<0.0001). Using multivariate analysis, independent determinants were age, first-phase insulin response, baseline glucose tolerance and number of additional antibody markers, but not antibody type or genotype. Individuals <25 years with two or more additional antibodies at baseline had a 62% risk of diabetes within 5 years and these combined criteria identified 81% of the cases in the whole cohort.Conclusions/interpretation We suggest that screening and recruitment for future intervention trials should be limited to family members aged <25 years, and should be based on islet autoantibodies alone.See Appendix for ENDIT Group.     

The role of IL‐1β in reduced IL‐7 production by stromal and epithelial cells: a model for impaired T‐cell numbers in the gut during HIV‐1 infection

Abstract. Thang PH, Ruffin N, Brodin D, Rethi B, Cam PD, Hien NT, Lopalco L, Vivar N, Chiodi F (Karolinska Institutet, Stockholm, Sweden; National Institute of Hygiene and Epidemiology, Hanoi, Vietnam; San Raffaele Scientific Institute, Milan, Italy). The role of IL‐1β in reduced IL‐7 production by stromal and epithelial cells: a model for impaired T‐cell numbers in the gut during HIV‐1 infection. J Intern Med 2010; 268 : 181–193. Objectives. Interleukin (IL)‐7 is a key cytokine in T‐cell homeostasis. Stromal cells, intestinal epithelial cells and keratinocytes are known to produce this cytokine. The mechanisms and cellular factors regulating IL‐7 production are still unclear. We assessed whether IL‐1β and interferon (IFN)‐γ, cytokines produced during inflammatory conditions, may impact on IL‐7 production. Design. We used human intestinal epithelial cells (DLD‐1 cell line) and bone marrow stromal cells (HS27 cell line), known to produce IL‐7; IL‐7 production was evaluated at the mRNA and protein levels. To assess whether treatment of HS27 cells with IL‐1β and/or IFN‐γ leads to changes in the gene expression of cytokines, Toll‐like receptors (TLRs) and chemokines, we analysed gene expression profiles using the whole‐genome microarray Human Gene 1.0 ST. Results. We found that IFN‐γ enhanced the expression of IL‐7 mRNA (P < 0.001) in both cell lines. IL‐1β treatment led to a significant down‐regulation (P < 0.001) of IL‐7 mRNA expression in both cell lines. The IL‐7 concentration in supernatants collected from treated DLD‐1 and HS27 cell cultures reflected the trend of IL‐7 mRNA levels. The gene profiles revealed dramatic changes in expression of cytokines and their receptors (IL‐7/IL‐7Rα; IL‐1α,IL‐1β/IL‐1R1; IFN‐γ/IFN‐γR1), of IFN regulatory factors (IRF‐1 and 2), of TLRs and of important chemo‐attractants for T cells. The microarray results were verified by additional methods. Conclusions. Our results are discussed in the setting of inflammation and T‐cell survival in the gut compartment during HIV‐1 infection where stromal and epithelial cells may produce factors that contribute to impaired IL‐7 homeostasis and homing of T cells.