“
“Foxp3+ T regulatory (Treg) cells can be induced to produce interleukin (IL)-17 by in vitro exposure to proinflammatory cytokines, Caspase inhibitor drawing into question their functional stability at sites of inflammation.

Unlike their splenic counterparts, Treg cells from the inflamed central nervous system (CNS-Treg cells) during EAE resisted conversion to IL-17 production when exposed to IL-6. We show that the highly activated phenotype of CNS-Treg cells includes elevated expression of the Th1-associated molecules CXCR3 and T-bet, but reduced expression of the IL-6 receptor α chain (CD126) and the signaling chain gp130. We found a lack of IL-6 receptor on all CNS CD4+ T cells, which was reflected by an absence of both classical and trans-IL-6 signaling in CNS CD4+ LY2157299 chemical structure cells, compared with their splenic counterparts. We propose that extinguished responsiveness to IL-6 (via down-regulation of CD126 and gp130) stabilizes the regulatory phenotype of activated Treg cells at sites of autoimmune inflammation. Foxp3+ Treg

cells are primary mediators of peripheral tolerance and have shown therapeutic potential in models of organ-specific autoimmune disease [[1]]. However, Treg cells have also been reported to produce interleukin (IL)-17 when stimulated in vitro in the presence of inflammatory cytokines [[2, 3]], suggesting that Treg cells can adapt to an inflammatory environment by acquiring certain effector characteristics. Here, we tested whether Treg cells isolated from a site of autoimmune inflammation could be driven toward an effector phenotype. We used the experimental autoimmune check details encephalomyelitis (EAE) model wherein Foxp3+ Treg cells accumulate in the inflamed central nervous system (CNS). Unlike their splenic counterparts, CNS-Treg cells resisted conversion into an IL-17-secreting population. This resistance was attributable to a reduction in IL-6 responsiveness due to the fact that

CNS-Treg cells lacked expression of both chains of the IL-6 receptor, CD126, and gp130. We therefore reveal a key mechanism allowing Treg cells that are active in sites of inflammation to maintain a commitment to an antiinflammatory role. We fluorescence-activated cell sorter (FACS)-sorted Treg (GFP+) and non-Treg (GFP−) CD4+ cells from the spleen and CNS of Foxp3-GFP mice with EAE and assessed their cytokine production profile. CNS Foxp3− T cells showed production of IL-2 and a broad range of effector cytokines (IL-4, IL-5, IL-17, IFN-γ, TNF-α, and GM-CSF) in response to anti-CD3+anti-CD28 stimulation. In contrast, Foxp3+ cells from the CNS showed no production of these effector cytokines, with only low-level production of IL-10 being evident (Fig. 1A). We next tested FACS-sorted GFP+ (Foxp3+) CNS-Treg cells under in vitro exposure to a well-characterized IL-17-promoting cocktail.

The IL-17E-mediated Th2 responses are inhibited in the absence of either chain.71,74,98 In agreement with

the pre-clinical data signifying a role in Th2 biology, elevated expression of IL-17RB is detected in human asthmatic lung tissue, and the 5661G-A polymorphism within the IL-17RB gene, has been identified to be protective against asthma.64,107 Database mining for proteins homologous to IL-17RA led to the identification of IL-17RC.97 Biochemical analyses demonstrate high-affinity find more interactions between IL-17RC–IL-17A and IL-17RC–IL-17F.66 There have been no reports of IL-17RC binding to other IL-17 family members. Similar to IL-17RA, IL-17RC expression is elevated in patients with RA, emphasizing the selleckchem role of this pathway in autoimmune disease pathology.94,95 Intriguingly, alternative splice variants of IL-17RC have been detected in prostrate cancer tumours, but the function of these proteins is unclear.108,109 The function of IL-17RC has only been reported in the context of IL-17A and IL-17F biology.

In agreement with the essential role for IL-17RC in IL-17A and IL-17F responses, genetic deletion or antibody-mediated blockade of this chain abrogates IL-17A and IL-17F responses such as pro-inflammatory cytokine induction.11,110 Similar to the il17ra−/− mice, il17rc−/−mice display delayed onset and milder disease in the MOG-EAE model, and increased susceptibility to fungal infections.111,112 The biology of these IL-17R family members, which were also identified through database searches, is unknown. Interleukin-17RD was detected in endothelial cells and epithelial

cells (Table 2).113 Similar to IL-17RB and IL-17RC, IL-17RD has also been demonstrated to co-localize and complex with IL-17RA.114 Biochemical data suggest that this interaction mediates IL-17A function, as mutations within the cytoplasmic domain Ibrutinib mw of IL-17RD prevent IL-17A induction of the 24p3 luciferase reporter.114 Other studies suggest that this receptor may have inhibitory effects, as over-expression suppresses fibroblast growth factor-mediated Ras and phosphatidyl inositol 3-kinase signalling. The significance of IL-17RD in vivo remains to be determined. Likewise, the biology of IL-17RE is undetermined. It has been reported that IL-17C binds to IL-17RE, although the import of this interaction is not understood.7 The specific cellular populations that are IL-17RE+ have not been defined.115 Although multiple splice variants of the IL-17RE gene have been identified, the biological significance of these isoforms is unknown.115 A role in MAPK activation has been detected, but further studies are required to understand the significance of this observation. Although substantial efforts have elucidated the biological functions of this unique family, there is still much to be discovered. In particular, the significance of the newer family members in host defence and inflammation needs to be addressed.

Importantly, GP283-vaccinated PKO mice survive the LCMV infection but viral titers in these mice were only transiently reduced suggesting that sterilizing CD8+ T-cell-mediated immunity was not achieved. Therefore, our results suggested that vaccination of perforin-deficient hosts (and perhaps FHL patients)

against either dominant or subdominant epitopes may not be beneficial but rather could potentially cause harmful outcome for the hosts. In addition, exhaustion of immunodominant NP118-specfic memory CD8+ T cells following primary LCMV infection of BALB/c PKO mice is thought to limit cytokine dysregulation and establish chronic infection. Whether secondary GP283-specific memory CD8+ T cells following LCMV challenge will also undergo exhaustion after EPZ-6438 order massive primary response

and the impact on the chronic infection by LCMV remain to be elucidated. BALB/c-PKO mice (H-2d MHC; 8–16 weeks of age) [[12, 27]] were maintained by brother–sister mating under specific pathogen-free conditions until initiation of experiments. Following LCMV infection PKO mice were monitored daily for weight loss. Mice that lost ≥30% of their starting weight Tamoxifen solubility dmso were euthanized per Institutional Animal Care and Use Committee (IACUC) guidelines. Animal experiments were approved by The University of Iowa IACUC. Peptide-coated splenic DC were generated as described [[52]]. Attenuated (actA-deficient) LM strains DP-L1942 (att LM) [[53]], XFL303actA- (att LM-NP118) [[54]], and att LM-CS252 [[55]] are resistant to streptomycin and were used as described [[16]]. The Armstrong strain of LCMV was prepared

as described [[12]]. Viral titers in homogenates of spleen were determined by plaque assay on VERO cells as described [[56]]. Naïve female PKO mice were immunized with 1 × 107 CFU att LM-NP118 and the memory time point (day 100) spleen cells were analyzed for the frequency and phenotype of NP118-specific CD8+ T cells via FACS. For adoptive very transfer experiment, groups of naïve PKO mice received splenocytes from memory mice containing the indicated numbers of NP118-specific memory CD8+ T cells 1 day before LCMV-Arm infection. The magnitude of the epitope-specific CD8+ T-cell response was determined either by intracellular IFN-γ staining (ICS) after 5–6 h incubation in brefeldin A, in the presence or absence of 200 nM of indicated peptide or MHC class I tetramer staining as described [[57]]. ICS from blood was done in the presence of peptide-coated P815 cells. We used antibodies with the indicated specificity and with appropriate combination of fluorochromes: IFN-γ (clone XMG1.2, eBioscience), CD8 (53-6.7, BD), Thy1.2 (53-2.1, BD), TNF (MP6-XT22, eBioscience), CD127 (A7R34, eBioscience), CD43 (1B11, BD), CD27 (LG.

0404, Wilcoxon p=0.0280; progression-free survival: Log-Rank p=0.0225; Wilcoxon p=0.0136). In vitro assays revealed increased proliferation and migration of medulloblastoma cell lines after PAX8 siRNA knockdown. In summary, high PAX8 expression is linked to better prognosis in

medulloblastomas potentially by suppressing both proliferative and migratory properties of MB cells. The distinct spatio-temporal expression pattern of PAX8 during brain development might contribute to the understanding of distinct MB subtype histogenesis. “
“Cerebral amyloid angiopathy (CAA) represents the deposition of amyloid β protein (Aβ) in the meningeal and intracerebral Selleckchem PF 2341066 vessels. It is often observed as an accompanying lesion of Alzheimer’s disease (AD) or in the brain of elderly individuals even in the absence of dementia. CAA is largely age-dependent. In subjects with severe CAA a higher frequency of Napabucasin cell line vascular lesions has been reported. The goal of our study was to define the frequency and distribution of CAA in a 1-year autopsy population (91 cases) from the Department of Internal Medicine, Rehabilitation, and Geriatrics, Geneva. Five brain

regions were examined, including the hippocampus, and the inferior temporal, frontal, parietal and occipital cortex, using an antibody against Aβ, and simultaneously assessing the severity of AD-type pathology with Braak stages for neurofibrillary tangles identified with an anti-tau antibody. In parallel, the relationships of CAA with vascular brain Endonuclease lesions were established. CAA was present in 53.8% of the studied population, even in cases without AD (50.6%). The strongest correlation was seen between CAA and age,

followed by the severity of amyloid plaques deposition. Microinfarcts were more frequent in cases with CAA; however, our results did not confirm a correlation between these parameters. The present data show that CAA plays a role in the development of microvascular lesions in the ageing brain, but cannot be considered as the most important factor in this vascular pathology, suggesting that other mechanisms also contribute importantly to the pathogenesis of microvascular changes. “
“Glioblastomas display marked phenotypic and molecular heterogeneity. The expression of the PTEN protein in glioblastomas also shows great intratumour heterogeneity, but the significance of this heterogeneity has so far received little attention. We conducted a comparative study on paraffin and frozen samples from 60 glioblastomas. Based on PTEN immunostaining, paraffin glioblastomas were divided into positive (homogeneous staining) and both positive and negative (heterogeneous staining) tumours. DNA was extracted from manually microdissected samples from representative areas, and from frozen samples taken randomly from the same tumours.

Since there is a lack of data, we aimed to define the expression pattern and cellular source of TNFRSF9 in human gliomas. GSK2126458 price We investigated TNFRSF9 expression in normal human CNS tissue and glioma

specimens using immunohistochemistry, immunofluorescence and western blotting techniques. Our results show that TNFRSF9 is considerably upregulated in human gliomas when compared to normal brain tissue. In addition, our data provides evidence for an immune cell-independent de novo expression pattern of TNFRSF9 in mainly non-neoplastic reactive astrocytes and excludes classic immunological cell types, namely lymphocytes and microglia as the source of TNFRSF9. Moreover, TNFRSF9 is predominantly expressed in a perivascular and peri-tumoral distribution with significantly higher expression in IDH1 mutant gliomas. Our findings provide a novel, TNFRSF9-positive, reactive astrocytic phenotype and challenge the therapeutic suitability of TNFRSF9 as a promising target for human gliomas. “
“Uranium olfactory uptake after intranasal exposure raises some concerns for people potentially exposed to airborne radionuclide contamination as the brain could be a direct target for these contaminants. A model of nasal instillation was used to elucidate the transport

mechanisms of uranium to the brain and to map its localization. Increasing concentrations of depleted uranium containing solutions were instilled in the nasal cavity of adult male rats. Uranium concentrations RG-7388 supplier were measured using inductively coupled plasma-mass spectrometry (ICP-MS) 4 h after instillation. Olfactory neuroepithelium cytoarchitecture was

studied using immunohistochemistry experiments. Secondary ion mass spectrometry (SIMS) microscopy Dynein was performed to localize uranium in the olfactory system. ICP-MS analyses showed a frontal accumulation of uranium in the olfactory bulbs associated with a smaller increase in more caudal brain regions (frontal cortex, hippocampus and cerebellum). Uranium concentrations in the olfactory bulbs do not reach a saturation point. Olfactory nerve bundle integrity is not affected by uranium as revealed by immunohistochemistry. SIMS microscopy allowed us to show that uranium localization is mainly restricted to the olfactory neuroepithelium and around olfactory nerve bundles. It is subsequently detected in the olfactory nerve layer of the olfactory bulb. These results suggest the existence of a transcellular passage from the mucosa to the perineural space around axon bundles. Uranium bypasses the blood brain barrier and is conveyed to the brain via the cerebrospinal fluid along the olfactory nerve. Future studies might need to integrate this new contamination route to assess uranium neurotoxicity after nasal exposure. “
“We present a rare case of primary T-cell lymphoblastic lymphoma of the pituitary gland. A 58-year-old woman presented with headaches, right-sided ptosis and cranial nerve III palsy.

Overall, our results hint at the importance of monoubiquitination of AVM-associated proteins throughout the A. phagocytophilum infection cycle in promyelocytic HL-60 cells as well as endothelial cells, as a comparable degree of ubiquitination of the AVM was observed for infected RF/6A cells. Considerably, fewer ApVs of infected ISE6 cells exhibited ubiquitination than infected mammalian cells. Either AVM ubiquitination does not play a prominent role in A. phagocytophilum infection of ISE6 cells or association of ubiquitinated proteins with the AVM may be temporally regulated during infection of ISE6

cells. By accruing monoubiquitinated mTOR inhibitor proteins that localize and direct traffic to endocytic compartments, A. phagocytophilum conceivably camouflages its vacuolar membrane as a means for avoiding lysosomal targeting. Support for this possibility comes from the precedent that the ApV selectively recruits Rab GTPases that are predominantly associated with recycling endosomes while concomitantly GDC-0199 manufacturer blocking recruitment of Rabs that are important for lysosomal delivery. Tetracycline treatment of infected cells culminates in the dissociation of recycling endosome-associated Rabs with the concomitant association of the lysosomal markers Rab7

and LAMP-1 (Huang et al., 2010a). Confocal microscopic analysis of fixed cells reveals that no more than 52.6% ± 4.2% or 61.0% ± 6.2% ApVs in HL-60 cells or RF/6A cells, respectively, are positive for ubiquitin at any time point examined. A highly similar trend occurs when one examines the percentages of ApVs to which GFP-tagged recycling endosome-associated Rab GTPases localize (Huang et al., 2010a). Ubiquitin machinery, like Rab GTPases, dynamically cycles on- and off-target organelle membranes (Grabbe et al., 2011; Segev, 2011). Thus, examining fixed A. phagocytophilum-infected cells provides a snapshot of the AVMs that are monoubiquitinated or have associated Rab GTPases at the instant at which preservative was added. Celecoxib Several bacterial effectors have been shown to exploit the host cell’s ubiquitination system to diversify or regulate their biological functions. Several effectors secreted by intracellular bacterial pathogens

mimic the activities of E3 ubiquitin ligases to spatially or temporally regulate host or bacterial proteins (Kubori & Galan, 2003; Kubori et al., 2010). Alternatively, the ubiquitination of other bacterial effectors regulates their activities and subcellular localization rather than serve as a signal for their proteasomal degradation (Marcus et al., 2002; Knodler et al., 2009; Patel et al., 2009). As AVM monoubiquitination is bacterial protein synthesis-dependent, it is plausible that A. phagocytophilum encodes one or more effectors that either may recruit monoubiquitinated host proteins to the AVM or may be monoubiquitinated themselves. To date, only three A. phagocytophilum-encoded AVM proteins – APH_1387, APH_0032, and AptA – have been identified (Huang et al.

It has been also shown that the accumulation of NK cells in CNS is CX3CL1-mediated process [21, 54]. Investigation on this pathway in AD could reveal new insight in disease pathogenesis. However, it should be noted that these results are related to MS and its experimental models that have immunopathologic features similar but not the same to AD. On the other side, there is little data regarding the protective or pathogenic mechanisms of NK cells in autoimmune neuroinflammatory diseases. It has been suggested that NK cells may stimulate autoreactive TH1cells

by IFN-γ secretion [55, 56]. It has been also supposed that NK cells may exert their protective function through direct lysing of dendritic cells and TH1cells or through secretion of immunoregulatory cytokines such PLX3397 as IL-10 and TGF-β in autoimmune diseases [57, 58]. What factors assign the pathogenic or protective behaviour of NK cells in various neurologic autoimmune diseases is still elusive. However, we think that the microenvironment status in which NK cells are involved could be an important factor for exerting their role as pathogenic and/or protective cells. Regarding the data provided in AD, we can suppose several environmental factors in which NK cells may be managed for exerting different functions. For example,

IL-12 that is produced by activated blood monocytes, macrophages and glial cells can stimulate NK cells for IFN-γ secretion and triggers the TH1 response in the acute phase selleckchem of AD [59]. Interestingly, a positive correlation has been recently reported between IL-12 and T cell levels in CSF of AD patients [59]. Moreover, NK cells expressing

CD4 can migrate towards the CD4-specific chemotactic factor IL-16 [60]. It should CYTH4 be noted that IL-16 is a growth factor for resting CD4+ cells that stimulates the secretion of inflammatory cytokines, such as IL-1β, IL-6 and TNF-α. Moreover, it can increase intracellular Ca+ or inositol-(1,4,5)-triphosphatase and translocation of the PKC [59]. Surprisingly, the signalling pathway that regulates NK lytic function induces activation of PKC and MAPK [61]. Additionally, the recent studies have demonstrated the high levels of IL-16, IL-18 and TGF-β1 mRNA expression in monocyte-macrophages of the peripheral blood of AD patients which are correlated with disease progression in AD patients [59]. IL-18 is a member of the IL-1 family that is expressed by macrophages and DCs and it can induce secretion of TH1 cytokines, which it synergistically acts with IL-12. It is reported that, IL-18 and IL-18 receptor mRNA expression have been observed in the brain of rats [59]. Increase in TGF-β levels was also reported in AD [59]. On the other side, NK cells can be as a source of both latent and active TGF-β [57]. IL-2 can upregulate the production of active TGF-β [57]. The combination of IL-2 and TNF-α has additive effects on TGF-β [57].

E.A., Kokron, M.C., and de Camargo, M.M., personal

communication). Interestingly, the EBV-immortalized cells https://www.selleckchem.com/products/BAY-73-4506.html from the patient with slower rescue of ER homeostasis also present slower growth rate in vitro. We are currently investigating whether this corresponds to a defect on the IRE1α/cyclin A axis described by Thorpe and collaborators [100]. Their work showed that IRE1α controls the production of cyclin A. In our specific case, the slower rate of activation of IRE1α could result in lower availability of cyclin A, and lower rates of cell division. The ER stress is defined by accumulation of misfolded/unfolded proteins within the ER lumen in association with the cell’s failure at coping with this protein overload. The UPR pathway has evolved with the role of initiating mechanisms that will restore the ER homeostasis. Upon ER stress, the UPR pathways increases protein folding by increasing the synthesis of ER chaperones; contributes to attenuation of protein overload by decreasing protein translation rates and Ibrutinib research buy increasing degradation of misfolded proteins, and activates a definitive solution to the ER stress by triggering the apoptosis programme. By this definition, any stimulus that activates protein synthesis and/or inhibits protein degradation is a potential ER stressor. ER stress, by its turn, also has the ability to potentiate those

same triggers that caused ER stress, providing an amplification loop that the cell must keep under control in order to regain homeostasis. For example, at the same time that ER stress triggers inflammation and helps sustained production of TNF-α and IL-6, it also provides protection against the damage caused by reactive

species produced by the inflammatory responses [66]. The UPR pathway influences directly the innate compartment. Some PRRs agonists showed synergic effect with ER stressors over the production of type I IFNs [66]. The UPR has been Bcl-w involved in acute phase responses [68], as well as in maintenance of NKT cells [73], and plasmacytoid dendritic cells [71]. The UPR pathway has been more extensively studied in B cells, where it plays a role in the differentiation programme. The differentiation process that transforms B cells into plasma cells require the activation of the UPR in a more complex and multi-layered manner as compared to pharmacological induction of ER stress. Firstly, the IRE1/XBP-1 and ATF6 axis of UPR are activated during the plasmacytic differentiation programme while the PERK arm is shut down [91, 96, 97]. Secondly, activation of the IRE1/XBP-1 branch in B cells appears to be independent of the presence of misfolded protein [90]. IRE1α is found activated prior to Ig synthesis [91] and elevated levels of transcripts for XBP-1 and ER chaperones are found before translation of Ig chains [87].

It is interesting to note that CTLA-4-Ig inhibits the systemic

inflammatory response, as suggested by a reduced buy KPT-330 concentration of the acute-phase proteins SAP and haptoglobin levels in the blood. This may imply that CTLA-4-Ig affects systemic levels of the inflammatory cytokines IL-6, IL-1β and TNF-α, which are thought to stimulate the production of these acute-phase proteins from the liver, but this needs to be investigated further. To our knowledge, this is the first study to show that CTLA-4-Ig causes a reduced level of systemic inflammation markers in the CHS model but is in accordance with data from rheumatoid arthritis patients, where treatment with CTLA-4-Ig results in reduced serum levels of the acute-phase protein C-reactive protein (CRP) [35]. Our adoptive transfer study suggests that CTLA-4-Ig mainly mediates an immunosuppressive effect during the sensitization phase. This is in accordance with the fact that CTLA-4 is a negative regulator of T cell activation and thereby works primarily to dampen the inflammation during the activation phase. However, we cannot exclude that CTLA-4-Ig can modulate more subtle aspects of the secondary challenge response (e.g. chemokine or cytokine

profiles). In conclusion, our study shows that CTLA-4-Ig treatment suppresses inflammation measured by several different parameters, including reduced ear swelling, reduced activation of effector T cells in selleck kinase inhibitor the skin-draining Tau-protein kinase lymph node after sensitization, reduced infiltration of activated T cells into the

inflamed ear after challenge, a decreased detection of certain cytokines and chemokines in the inflamed tissue and – on a systemic level – reduced serum levels of acute-phase proteins. Furthermore, our results suggest that CTLA-4-Ig mediates its effect primarily during the sensitization phase of CHS and is dispensable during the challenge phase. A. D. C. and C. H. are employees of Novo Nordisk A/S. Figure S1. Cytotoxic T lymphocyte antigen-4 (CTLA-4)-immunoglobulin (Ig) binds to dendritic cells (DCs) and down-regulates CD86 on both DCs and B cells in the draining lymph node after sensitization with dinitrofluorobenzene (DNFB). Groups of mice were treated with either CTLA-4-Ig or isotype control and sensitized with 0·5% DNFB the following day. Lymph node cells from the draining lymph node were stained with anti-human IgG1 and analysed by flow cytometry at days 3, 4 and 5 after sensitization for detection of binding of CTLA-4-Ig on lymph node cells. (A) %hIgG1+ cells of DCs gated as CD19–T cell receptor (TCR)-β–major histocompatibility complex II (MHC)II+CD11c+ cells 3, 4 and 5 days after sensitization. (B) %CD86+ cells of DCs. (C) Median fluorescence intensity (MFI) of CD86 phycoerythrin (PE) on CD19–MHCII+CD11C+ cells. (D) %hIgG1+ cells of B cells gated as CD19+ cells.

Together, these results identify Bcl11b as a central regulator of genes associated with T-cell maturation at the DP stage. The phenotype of the Lck-Cre-excised

mutants recapitulated that of mice with a germline disruption 25. These mice exhibited a severe differentiation block in DN cells, accompanied by a dramatic reduction in thymic cellularity, consistent with a role of Bcl11b in the survival of immature thymocytes 25. Importantly, loss of Bcl11b either in the germline (Bcl11bL−/L) or in the DN1-DN2 cells (Bcl11bL2/L2−Lckcre/+) preferentially affected the αβ T-cell lineage while appearing to spare γδ T cells. In both cases, a large percentage of Bcl11b-null cells expressed TCRγδ, most notably in the CD8+ population. TCRγδ expression might reflect impaired TCRβ rearrangement 25, and subsequent attempts by the selleck developing thymocyte to use a surrogate route of differentiation. Alternatively, Bcl11b may play a more active Roscovitine molecular weight role in the cell-fate choice between the αβ and the γδ lineages. This possibility

is supported by the strong upregulation of TCRγ transcripts in Bcl11b-deleted DP cells (>100× compared to WT, Supporting Information Table S1), suggesting a possible role of Bcl11b in repressing TCRγ expression. Note, however, that DP cells from Lck-Cre- (or CD4-Cre-) deleted mice did not exhibit surface TCRγδ expression (Supporting Information Fig. 7). As previously reported 26, disruption of the Bcl11b locus in DP cells resulted in a block in the differentiation into CD4+ and CD8+ SP cells. In addition, we observed a loss of canonical NKT cells in CD4-Cre-deleted mice, a T-cell population that has also been shown to differentiate from DP cells 43. However, the block in

T-cell differentiation in our mice appeared less severe than that reported by Albu et al. 26 – while we observed CD3hi (Fig. 2B) cell populations that were at least partially engaged into an SP differentiation process, such cells were apparently not as abundant in the mice described by these authors 26. These differences may possibly be attributed to differences in the timing of the deletion, as different CD4-Cre deleter lines were used in both studies, and/or genetic background differences. The large-scale changes in Orotidine 5′-phosphate decarboxylase the gene expression program of DP cells appear to be at the heart of the mutant phenotype. In addition to the large number of genes encoding transcription factors that are dysregulated in DP cells from Bcl11bdp−/− mice (see above), Bcl11b also regulates expression of a variety of genes that play key roles in signaling cascades during T-cell differentiation (e.g. IL7R (up), Lck (down), Notch1 (up), and Jak1 (up)), and in ubiquitous pathways, such as ERK and PI3K/AKT (Supporting Information Fig. 5). Thus, Bcl11b appears to function as a master transcriptional regulator that is required for the harmonious interplay of numerous signaling cascades and transcriptional networks in DP thymocytes.