Effector and Naturally Occurring Regulatory T Cells Display No Abnormalities in Activation Induced Cell Death in NOD Mice

BACKGROUND: Disturbed peripheral negative regulation might contribute to evolution of autoimmune insulitis in type 1 diabetes. This study evaluates the sensitivity of naïve/effector (Teff) and regulatory T cells (Treg) to activation-induced cell death mediated by Fas cross-linking in NOD and wild-type mice. PRINCIPAL FINDINGS: Both effector (CD25(-), FoxP3(-)) and suppressor (CD25(+), FoxP3(+)) CD4(+) T cells are negatively regulated by Fas cross-linking in mixed splenocyte populations of NOD, wild type mice and FoxP3-GFP trangeneess. Proliferation rates and sensitivity to Fas cross-linking are dissociated in Treg cells: fast cycling induced by IL-2 and CD3/CD28 stimulation improve Treg resistance to Fas-ligand (FasL) in both strains. The effector and suppressor CD4(+) subsets display balanced sensitivity to negative regulation under baseline conditions, IL-2 and CD3/CD28 stimulation, indicating that stimulation does not perturb immune homeostasis in NOD mice. Effective autocrine apoptosis of diabetogenic cells was evident from delayed onset and reduced incidence of adoptive disease transfer into NOD.SCID by CD4(+)CD25(-) T cells decorated with FasL protein. Treg resistant to Fas-mediated apoptosis retain suppressive activity in vitro. The only detectable differential response was reduced Teff proliferation and upregulation of CD25 following CD3-activation in NOD mice. CONCLUSION: These data document negative regulation of effector and suppressor cells by Fas cross-linking and dissociation between sensitivity to apoptosis and proliferation in stimulated Treg. There is no evidence that perturbed AICD in NOD mice initiates or promotes autoimmune insulitis

Apoptosis of Purified CD4+ T Cell Subsets Is Dominated by Cytokine Deprivation and Absence of Other Cells in New Onset Diabetic NOD Mice

BACKGROUND: Regulatory T cells (Treg) play a significant role in immune homeostasis and self-tolerance. Excessive sensitivity of isolated Treg to apoptosis has been demonstrated in NOD mice and humans suffering of type 1 diabetes, suggesting a possible role in the immune dysfunction that underlies autoimmune insulitis. In this study the sensitivity to apoptosis was measured in T cells from new onset diabetic NOD females, comparing purified subsets to mixed cultures. PRINCIPAL FINDINGS: Apoptotic cells are short lived in vivo and death occurs primarily during isolation, manipulation and culture. Excessive susceptibility of CD25(+) T cells to spontaneous apoptosis is characteristic of isolated subsets, however disappears when death is measured in mixed splenocyte cultures. In variance, CD25(-) T cells display balanced sensitivity to apoptosis under both conditions. The isolation procedure removes soluble factors, IL-2 playing a significant role in sustaining Treg viability. In addition, pro- and anti-apoptotic signals are transduced by cell-to-cell interactions: CD3 and CD28 protect CD25(+) T cells from apoptosis, and in parallel sensitize naïve effector cells to apoptosis. Treg viability is modulated both by other T cells and other subsets within mixed splenocyte cultures. Variations in sensitivity to apoptosis are often hindered by fast proliferation of viable cells, therefore cycling rates are mandatory to adequate interpretation of cell death assays. CONCLUSIONS: The sensitivity of purified Treg to apoptosis is dominated by cytokine deprivation and absence of cell-to-cell interactions, and deviate significantly from measurements in mixed populations. Balanced sensitivity of naïve/effector and regulatory T cells to apoptosis in NOD mice argues against the concept that differential susceptibility affects disease evolution and progression

NMR solution structure of the major G-quadruplex structure formed in the human BCL2 promoter region

BCL2 protein functions as an inhibitor of cell apoptosis and has been found to be aberrantly expressed in a wide range of human diseases. A highly GC-rich region upstream of the P1 promoter plays an important role in the transcriptional regulation of BCL2. Here we report the NMR solution structure of the major intramolecular G-quadruplex formed on the G-rich strand of this region in K(+) solution. This well-defined mixed parallel/antiparallel-stranded G-quadruplex structure contains three G-tetrads of mixed G-arrangements, which are connected with two lateral loops and one side loop, and four grooves of different widths. The three loops interact with the core G-tetrads in a specific way that defines and stabilizes the overall G-quadruplex structure. The loop conformations are in accord with the experimental mutation and footprinting data. The first 3-nt loop adopts a lateral loop conformation and appears to determine the overall folding of the BCL2 G-quadruplex. The third 1-nt double-chain-reversal loop defines another example of a stable parallel-stranded structural motif using the G(3)NG(3) sequence. Significantly, the distinct major BCL2 promoter G-quadruplex structure suggests that it can be specifically involved in gene modulation and can be an attractive target for pathway-specific drug design

Metal distribution in marine sediment along the Doha Bay, Qatar.

Concentrations of 25 heavy metals (Ag, Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Sr, V, Zn and Hg) in surface sediments along the Doha Bay from 10 transects each with five stations were studied. Significant differences were observed in metal concentrations between the sampling locations and durations. Higher concentrations were observed in areas where there are a lot of anthropological activities. The distribution of selected metals was presented in contour maps showing the variation between the two periods. In order to further study particle size effect on metal uptake, two different grinding times were administered on four randomly selected samples and the results showed no significant difference on the analysis in the inductively coupled plasma-optical emission spectrometry (ICP-OES) instrument. The overall results of metal analyses were within the international standards criteria, and the results were comparable to the previous studies conducted around Qatar

Hematopoietic RIPK1 deficiency results in bone marrow failure caused by apoptosis and RIPK3-mediated necroptosis

Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) is recruited to the TNF receptor 1 to mediate proinflammatory signaling and to regulate TNF-induced cell death. RIPK1 deficiency results in postnatal lethality, but precisely why Ripk1(−/−) mice die remains unclear. To identify the lineages and cell types that depend on RIPK1 for survival, we generated conditional Ripk1 mice. Tamoxifen administration to adult RosaCreER(T2)Ripk1(fl/fl) mice results in lethality caused by cell death in the intestinal and hematopoietic lineages. Similarly, Ripk1 deletion in cells of the hematopoietic lineage stimulates proinflammatory cytokine and chemokine production and hematopoietic cell death, resulting in bone marrow failure. The cell death reflected cell-intrinsic survival roles for RIPK1 in hematopoietic stem and progenitor cells, because Vav-iCre Ripk1(fl/fl) fetal liver cells failed to reconstitute hematopoiesis in lethally irradiated recipients. We demonstrate that RIPK3 deficiency partially rescues hematopoiesis in Vav-iCre Ripk1(fl/fl) mice, showing that RIPK1-deficient hematopoietic cells undergo RIPK3-mediated necroptosis. However, the Vav-iCre Ripk1(fl/fl) Ripk3(−/−) progenitors remain TNF sensitive in vitro and fail to repopulate irradiated mice. These genetic studies reveal that hematopoietic RIPK1 deficiency triggers both apoptotic and necroptotic death that is partially prevented by RIPK3 deficiency. Therefore, RIPK1 regulates hematopoiesis and prevents inflammation by suppressing RIPK3 activation

Whole-tree water balance and indicators for short-term drought stress in non-bearing 'Barnea' olives

Drainage-weighing lysimetersallowedmonitoringofwaterbalancecomponentsofnon-bearingolive (Olea europaea cv Barnea)treesovera3-monthperiodincludingshort-termeventsofcontrolledbut severe waterstress.Theobjectiveofthestudywastoevaluateavarietyofsoilandplant-basedwater status anddroughtstressmonitoringmethodsonthebasisoftree-scaleevapotranspiration(ET).As the treesenteredintoandrecoveredfromwaterstress,meteorologicaldata,actualET(ETa), soilwater content andchangesinleafturgorpressurewerecontinuouslymonitored.Additionally,middaymea- surements ofstemwaterpotential,stomatalconductance,canopytemperature,andquantumyieldof PSII photochemistrywereconducted.Diurnal(dawntodusk)measurementsofalltheaboveweremade hourly ondaysofmaximumstress.Shootelongationratewasmeasuredforperiodsofstressandrecovery. Quantum yieldofPSIIphotochemistry,stomatalconductance,andstemwaterpotentialallsuccessfully indicated reductionsinwhole-treewaterconsumptionbeginningatmoderatestresslevels.Thesemea- sured parametersfullyrecoveredtothelevelsofnon-stressedtreessoonafterwaterapplicationwas renewed. Shootelongationwasreduced25–30%forthe10-dayperiodduringandfollowingdroughtand recovered thereaftertolevelsofnon-stressedtrees.Whole-treeETa was reducedbyasmuchas20%even following fullrecoveryoftheleaflevelparameters,suggestingreducedcanopysizeandgrowthduetothe stress period.Non-destructive,continuous(turgorpressure)andremotelysensed(canopytemperature) methods showedpromisingpotentialformonitoringeffectsofwaterstress,inspiteoftechnologicaland data interpretationchallengesrequiringfurtherattention