T-cell Specific Transcription Factor Research Articles

In silico optimization of peptides that inhibit Wnt/β-catenin signaling

The Wnt/β-catenin signaling pathway causes transcriptional activation through the interaction between β-catenin and T cell-specific transcription factor (TCF) and regulates a wide variety of cellular responses, including proliferation, differentiation and cell motility. Excessive transcriptional activation of the Wnt/β-catenin pathway is implicated in developing or exacerbating various cancers. We have recently reported that liver receptor homolog-1 (LRH-1)-derived peptides inhibit the β-catenin/TCF interaction. In addition, we developed a cell-penetrating peptide (CPP)-conjugated LRH-1-derived peptide that inhibits the growth of colon cancer cells and specifically inhibits the Wnt/β-catenin pathway. Nonetheless, the inhibitory activity of the CPP-conjugated LRH-1-derived peptide was unsatisfactory (ca. 20 μM), and improving the bioactivity of peptide inhibitors is required for their in vivo applications. In this study, we optimized the LRH-1-derived peptide using in silico design to enhance its activity further. The newly designed peptides showed binding affinity toward β-catenin comparable to the parent peptide. In addition, the CPP-conjugated stapled peptide, Penetratin-st6, showed excellent inhibition (ca. 5 μM). Thus, the combination of in silico design by MOE and MD calculations has revealed that logical molecular design of PPI inhibitory peptides targeting β-catenin is possible. This method can be also applied to the rational design of peptide-based inhibitors targeting other proteins.

Development of a penetratin-conjugated stapled peptide that inhibits Wnt/β-catenin signaling

Wnt/β-catenin pathway triggers the formation of a complex between β-catenin and T cell-specific transcription factor (TCF), which induces transcriptional activation. Excessive transcriptional activation of this pathway is associated with the development, cause, and deterioration of various cancers. Therefore, the Wnt/β-catenin pathway is an attractive drug target for cancer therapeutics and small molecule- and peptide-based protein–protein interaction (PPI) inhibitors have been developed. However, peptide-based PPI inhibitors generally have low cell-membrane permeability because of their large molecular size. To improve cell-membrane permeability, conjugating cell-penetrating peptides (CPPs) to PPI-inhibiting peptides is a useful method for developing intracellularly targeted PPI inhibitors. In this study, we focused on the interaction between β-catenin and liver receptor homologue-1 (LRH-1) and designed and synthesized a series of LRH-1-derived peptides to develop inhibitors against Wnt/β-catenin signaling. The results showed that a penetratin-conjugated LRH-1-derived peptide (Penetratin-st7) predominantly inhibited DLD-1 cell growth at 20 μM treatment via inhibition of the Wnt signaling pathway. This result suggests that Penetratin-st7 is one of promising PPI inhibitors between TCF and β-catenin.

Targeting the Wnt Signaling Pathway in Liver Fibrosis for Drug Options: An Update

Liver fibrosis is a life-threatening disease, with challenging morbidity and mortality for healthcare systems worldwide. It imparts an enormous economic burden to societies, making continuous research and informational updates about its pathogenesis and treatment crucial. This review′s focus is on the current knowledge about the Wnt signaling pathway, serving as an important pathway in liver fibrosis development and activation of hepatic stellate cells (HSCs). Two types of Wnt pathways are distinguished, namely the ß-catenin-dependent canonical and non-canonical Ca2+ or planar cell polarity (PCP)-dependent pathway. The dynamic balance of physiologically healthy liver and hepatocytes is disturbed by repeated liver injuries. Activation of the ß-catenin Wnt pathway prevents the regeneration of hepatocytes by the replacement of extracellular matrix (ECM), leading to the appearance of scar tissue and the formation of regenerated nodular hepatocytes, lacking the original function of healthy hepatocytes. Therefore, liver function is reduced due to the severely advanced disease. Selective inhibition of ß-catenin inhibits inflammatory processes (since chemokines and pro-inflammatory cytokines are produced during Wnt activation), reduces growth of activated HSCs and reduces collagen synthesis and angiogenesis, thereby reducing the progression of liver fibrosis in vivo. While the canonical Wnt pathway is usually inactive in a physiologically healthy liver, it shows activity during cell regeneration or renewal and in certain pathophysiological conditions, such as liver diseases and cancer. Targeted blocking of some of the basic components of the Wnt pathway is a therapeutic approach. These include the frizzled transmembrane receptor (Fz) receptors using the secreted frizzled-related protein family (sFRP), Fz-coreceptors low-density LRP 5/6 through dickkopf-related protein 1 (DKK1) or niclosamide, glycogen kinase-3 beta (GSK-3β) using SB-216763, cyclic-AMP response element-binding protein (CBP) using PRI-724 and ICG-001, the lymphoid enhancer binding factor (LEF)/T cell-specific transcription factor (TCF) system as well as Wnt inhibitory factor 1 (WIF1) and miR-17-5p using pinostilbene hydrate (PSH). Significant progress has been made in inhibiting Wnt and thus stopping the progression of liver fibrosis by diminishing key components for its action. Comprehending the role of the Wnt signaling pathway in liver fibrosis may lead to discovery of novel targets in liver fibrosis therapeutic strategies’ development.

Potentiating Effects of Sorafenib and Tacrolimus Causing Acute Pancreatitis Secondary to Grade IV Hypertriglyceridemia: Case Report

Background. Hypertriglyceridemia (HTG) is the third most common cause of acute pancreatitis. With HTG's severely elevated (>1000 mg/dL), the risk increases to 20 %. Common causes of HTG include familial disorders, metabolic disorders, drug induced, diet, or lipodystrophic disorders. Currently, tacrolimus is known to induce HTG as an AE. However, little is known pertaining to interactions between tacrolimus and sorafenib resulting in a synergistic effect. Interestingly, these drugs have been reported to directly induced pancreatitis through unclear mechanisms. Case report A 68 yo patient male with AML s/p chemotherapy + allogeneic bone marrow transplant was admitted for acute pancreatitis and found to have elevated triglycerides (TG). Prior tacrolimus, levels were as low as 74; afterwards they increased to 250. After starting Sorafenib, he was incidentally found to have HTG of 1805. 1week later patient presented to an OSH with TG of 1961. Sorafenib was held, Tacrolimus continued, and he was prescribed Fenofibrate for which he never filled the prescription. Patient followed up with his PCP for abdominal pain. Although his labs showed a steady reduction of TG, he was subsequently admitted to the hospital for repeat acute pancreatitis. Serial labs showed a steady decline in TG. Patient symptoms improved and he was discharged on tacrolimus + fenofibrates. Sorafenib continued to be held, an alternative therapy was recommended Discussion Tacrolimus is an immunosuppressant that causes inhibition and blocking of T-cell specific transcription factor. A main adverse effects (AE) is HTG. Sorafenib is a tyrosine kinase receptor inhibitor; AEs include myelosuppression and endocrinopathies. few publications discuss drug interactions between sorafenib and tacrolimus. Some report higher toxicity when combing sorafenib and tacrolimuslike drugs (i.e. temsirolimus). This implies a possible interaction between tacrolimus and sorafenib with increased toxicity + HTG causing pancreatitis. The actual mechanism remains unknown. Conclusion Although the mechanism of interaction remains unknown, Tacrolimus alone is known to lead to mild-moderate HTG. The potentiating effects of sorafenib have not been evaluated. The correlation between sorafenib and tacrolimus usage and severe HTG has not been made, caution should be used when considering prescribing these to your patients. Additional research is needed to further clarity.

Wnts Promote Synaptic Assembly Through T-Cell Specific Transcription Factors in Caenorhabditis elegans.

Synapses are specialized neuronal connections essential for neuronal function. Defects in synaptic assembly or maintenance usually lead to various neurological disorders. Synaptic assembly is regulated by secreted molecules such as Wnts. Wnts are a large family of conserved glycosylated signaling molecules involved in many aspects of neural development and maintenance. However, the molecular mechanisms by which Wnts regulate synaptic assembly remain elusive due to the large number of ligands/receptors, the diversity of signaling cascades and the complexity of the nervous system. In this study, through genetic manipulation, we uncover that C. elegans Wnt-2 (CWN-2) is required for synaptic development. The CWN-2 signal is required during both embryonic and postembryonic development, in the nervous system and intestine, for promoting synaptic assembly. Furthermore, we provide genetic evidence for CWN-2 promoting synaptogenesis through the Frizzled receptor (FZD) CFZ-2, the Dishevelled (DVL) DSH-2, the β-catenin SYS-1 and the only T-cell specific transcription factor POP-1/TCF. Importantly, it is the first time to report the requirement of a TCF for presynaptic assembly. These findings expand our understanding of the synaptogenic mechanisms and may provide therapeutic insights into Wnt-related neurological disorders.

MiR-150-Mediated Foxo1 Regulation Programs CD8+ T Cell Differentiation

MicroRNA (miR)-150 is a developmental regulator of several immune-cell types, but its role in CD8+ Tcells is largely unexplored. Here, we show that miR-150 regulates the generation of memory CD8+ Tcells. After acute virus infection, miR-150 knockout (KO) mice exhibited an accelerated differentiation of CD8+ Tcells into memory cells and improved production of effector cytokines. Additionally, miR-150 KO CD8+ Tcells displayed an enhanced recall response and improved protection against infections with another virus and bacteria. We found that forkhead box O1 (Foxo1) and Tcell-specific transcription factor 1 (TCF1) are upregulated during the early activation phase in miR-150 KO CD8+ Tcells and that miR-150 directly targets and suppresses Foxo1. These results suggest that miR-150-mediated suppression of Foxo1 regulates the balance between effector and memory cell differentiation, which might aid in the development of improved vaccines and Tcell therapeutics.

Directly reprogramming fibroblasts into adipogenic, neurogenic and hepatogenic differentiation lineages by defined factors.

The reprogramming of adult cells into pluripotent cells or directly into alternative adult cell types represents a great potential technology for regenerative medicine. In the present study, the potential of key developmental adipogenic, neurogenic and hepatogenic regulators to reprogram human fibroblasts into adipocytes, neurocytes and hepatocytes was investigated. The results demonstrated that direct reprogramming of octamer-binding transcription factor 4 (Oct4) and CCAAT-enhancer-binding protein (C/EBP)β activated C/EBPα and peroxisome proliferator-activated receptor-γ expression, inducing the conversion of fibroblasts into adipocytes. Similarly, direct reprogramming of the transcription factors sex determining region-box 2, trans-acting T-cell specific transcription factor (GATA-3) and neurogenic differentiation 1 in fibroblasts may induce neurogenic differentiation through hemagglutinating virus of Japan envelope (HVJ-E) transfection. Moreover, hepatogenic differentiation was induced by combining the direct reprogramming of Oct4, GATA-3, hepatocyte nuclear factor 1 homeobox α and forkhead box protein A2 in fibroblasts. These results demonstrate that specific transcription factors and reprogramming factors are able to directly reprogram fibroblasts into adipogenic, neurogenic and hepatogenic differentiation lineages by HVJ-E transfection.

MiR-449 overexpression inhibits papillary thyroid carcinoma cell growth by targeting RET kinase-β-catenin signaling pathway.

Papillary thyroid carcinoma (PTC) is the most common thyroid cancer and represent approximately 80% of all thyroid cancers. The present study is aimed to investigate the role of microRNA (miR)-449 in the progression of PTC. Our results revealed that miR-449 was underexpressed in the collected PTC specimens compared with non-cancerous PTC tissues. Overexpression of miR-449 induced a cell cycle arrest at G0/G1 phase and inhibited PTC cell growth invitro. Further studies revealed that RET proto-oncogene (RET) is a novel miR-449 target, due to miR-449 bound directly to its 3'-untranslated region and miR-449 mimic reduced the protein expression of RET. Similar to the effects of miR-449 overexpression, RET downregulation inhibited cell growth, whereas RET overexpression reversed the inhibitive effect of miR-449 mimic. Furthermore, miR-449 overexpression inhibited the nuclear translocation of β-catenin and reduced the expression of several downstream genes, including c-Myc, cyclinD1, T cell-specific transcription factor (TCF) and lymphoid enhancer-binding factor 1 (LEF-1), and inactivated the β-catenin pathway in TPC-1 cells. Moreover, overexpression of β-catenin prevented miR-449-reduced cell cycle arrest and cell viability. In xenograft animal experiments, miR-449 overexpression effectively suppressed the tumor growth of PTC. Taken together, our research indicated that miR-449 functions as an anti-oncogene by targeting RET, and that miR-449 overexpression inhibited the growth of PTC by inactivating the β-catenin pathway. Thus, miR-449 may serve as a potential therapeutic strategy for the treatment of PTC.

Aggressive papillary tumor of endolymphatic sac: case report of a rare neoplasia

Aggressive papillary endolymphatic sac tumor (ELST) is a rare neoplasm, occasionally related to von Hippel-Lindau disease, characterized by locally aggressive growth with temporal bone destruction. The authors report a case of ELST in a female patient exhibiting fifth through eighth cranial nerve paralysis. Computed tomography (CT) revealed a large lytic process involving the right temporal bone. The patient underwent surgical resection. At microscopy, a neoplastic process was identified exhibiting monomorphic columnar cells with mild atypias, arranged in a papillary pattern. The lesion exhibited positivity for A31/AE3, epithelial membrane antigen (EMA), and vimentin; and negativity for synaptophysin, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), thyroglobulin, transthyretin, chromogranin, thyroid transcription factor 1 (TTF-1), trans-acting T-cell specific transcription factor GATA-3, and intestinal transcription factor CDX-2. The diagnosis of ELST was then established. Six years after surgical resection, lesion recurrence was observed.

R-spondin1 arguments hepatic fibrogenesis in vivo and in vitro

BackgroundThe development of liver fibrosis is the key stage toward a number of mortal complications of liver diseases, including cirrhosis and hepatocellular carcinoma. Canonical Wnt pathway is crucial in diverse biological processes and mediates the progression and regression of liver fibrosis. As a potent Wnt pathway agonist, roof plate-specific spondin-1 (R-spondin1) protein's role in the hepatic fibrosis has not been well elucidated. The purpose of this study was to investigate whether R-spondin1 contributed to hepatic stellate cells (HSC) activation, the key event in liver fibrogenesis. Materials and methodsTissue microarrays of human fibrotic liver samples, hepatocellular carcinoma samples, and normal hepatic tissue samples were constructed and immunostained for R-spondin1. Protein expression and transcriptional level of freshly isolated mice HSC were analyzed by Western blot assay and real-time polymerase chain reaction, respectively. Exogenous stimulation with recombinant R-spondin1 and Dickkopf-1 was performed to investigate the functionality. Nuclear β-catenin level and T-cell specific transcription factor activity were analyzed, and HSC proliferation was tested by Methyl-Thiazol-Tetrazolium bromide assay. ResultsOverexpression of R-spondin1 was observed in both fibrotic liver tissues and culture-activated HSC. Coculture with recombinant R-spondin1 induced a dose-dependent increase in both the transcription factor activity and the protein level of α-smooth muscle actin, collagen I, and nuclear β-catenin. Additionally, Dickkopf-1 repressed R-spondin1's effect on HSC. ConclusionsThese findings suggested that R-spondin1 might argument liver fibrogenesis by enhancing the canonical Wnt pathway.

Macrophage and T-cell fate control: insights from tracking transcription factor dynamics in single cells

Hematopoietic stem and progenitor cells employ circuits of regulatory genes to integrate developmental signals and stabilize fate choices. These progenitors show considerable cell-to-cell heterogeneity in their fate choices; thus, to better understand how regulatory genes control fate decisions, we tracked their levels in single progenitors over time using timelapse live-cell imaging. We examined two hematopoietic fate transitions: 1) macrophage differentiation, driven by the up-regulation of the myeloid transcription factor PU.1; and 2) T-cell fate commitment, controlled by the activation of the T-cell specific transcription factor Bcl11b. In our study of macrophage differentiation, we found that cell cycle length acts as critical mediator in the positive feedback circuit controlling differentiation (Kueh et al. 2013). By following PU.1 regulation in single cells containing a knock-in PU.1-GFP reporter, we found that developing macrophages lengthen their cell cycles to promote stable PU.1 accumulation, and that PU.1 itself promotes cell cycle lengthening, completing a positive feedback loop that stabilizes its own expression. Mathematical modeling furthered showed that this cell cycle feedback circuit robustly stabilizes a slow-dividing differentiated state. In our studies on T-cell fate commitment, we found that Notch signaling – the primary driver of development – enhances the frequency of all-or-none Bcl11b gene activation to promote commitment. By analyzing progenitors from mice containing a knock-in Bcl11b-YFP reporter, we found that uncommitted (Bcl11b-DN2A) progenitors can activate Bcl11b transcription and undergo fate commitment in the absence of Notch signaling, and that Notch signaling does not modulate the level of Bcl11b transcription, but instead increases the rate at which progenitors switch Bcl11b to an actively expressing state. These results reveal insights into how signaling pathways activate regulatory gene expression to instruct cell fate.

Low Expression Of BCL11B Predicts Poor Overall Survival In Adult Standard Risk T-ALL

▪ IntroductionAlthough risk stratification, detection of minimal residual disease (MRD) and implementation of novel therapeutic agents have improved outcome in acute lymphoblastic leukemia (ALL), survival in adult T-ALL patients still remains unsatisfactory. Therefore, new prognostic markers and potential therapeutic targets are warranted. BCL11B, a key player in normal T-cell development, has recently gained interest due to its high mutation rate (9-16%) in T-ALL. We investigated the frequency of BCL11B mutations, expression levels and the prognostic value in a large uniformly treated cohort of adult T-ALL. Patients and methodsWe analyzed bone marrow (BM) samples of 201 adult T-ALL patients sent to the reference laboratory of the German Multicenter Study Group for Adult ALL (GMALL). BCL11B expression was determined in 195 patients by qRT-PCR, BCL11B mutations were assessed in 178 patients by Sanger sequencing of exon 4 (including all 6 zink finger [ZF] domains). Low expression of BCL11B was defined by expression levels in the lowest quartile (BCL11Blow), high expression by levels in the three remaining quartiles (BCL11Bhigh). Samples had previously been characterized for expression of BAALC, IGFBP7, MN1, WT1, GATA3, ERG as well as for the mutations status of NOTCH1, WT1, and TCR rearrangements. Clinical data were available for 169 patients enrolled on the GMALL trials. We generated BCL11B associated gene expression profiles (GEP) derived from an independent set of 86 T-ALL patients enrolled in the Microarrays Innovations in LEukemia multicenter study. ResultsBCL11B was aberrantly expressed in adult T-ALL with significantly higher expression levels in thymic compared to early T-ALL (0.6 vs. 0.3, P=0.01). Expression of genes associated with a prognostic impact (BAALC, IGFBP7, ERG) or/and T-cell stage dependent expression profile (GATA3, IGFBP7) showed that BCL11Blow (n=49) had higher MN1 (1.6 vs, 0.3, P=0.01), IGFBP7 (1.3 vs. 0.5, P=0.02), and lower GATA3 expression (2.1 vs. 5.7, P<0.01) compared to BCL11Bhigh patients (n=146). This maturation stage specific expression of BCL11B was stressed by a higher rate of TCR rearrangement in BCL11Bhigh patients (73% vs. 27%, P=0.005) and further underlined by the BCL11B derived GEP linking low BCL11B to an immature molecular signature characterized by high expression of BAALC, IGFBP7, FLT3, CD34. Regarding clinical characteristics, low BCL11B expression was associated with a poor prognosis (5-year overall survival (OS): low 35% (n=40) vs. high 53% (n=129), P=0.02) in the overall T-ALL cohort. In the standard risk group of thymic T-ALL (n=102), BCL11Blow identified patients with an unexpected poor outcome (5-year OS: 20%, n=18) compared to BCL11Bhigh (62%, n=84, P<0.001). In addition, BCL11Blow thymic T-ALL patients showed a lower remission rate (5 years: 38% vs. 72%, P=0.02).BCL11B mutations were found in 24 of the 178 (13.5 %) T-ALL patients. In 9 patients, mutations resulted in frame shifts, whereas the remaining, except for a single one, missense mutations were located in the ZF domains: three resulting in introduction of a stop codon. BCL11B mutations were enriched in the mature immunophenotype (thymic: 20%, mature: 8%, early: 3%, P=0.03). No differences were observed in mRNA levels for BAALC, IGFBP7, MN1, WT1, GATA3, ERG, but patients with BCL11B mutations were less frequently assigned to the BCL11Blow group compared to those with high expression (5% vs. 95%, P=0.02). Regarding the clinical characteristics, BCL11B mutations had no prognostic impact regarding OS, neither in the total T-ALL cohort (5-year OS: 56% vs. 48%, n.s.) nor in the thymic T-ALL subgroup (5-year OS: 65% vs. 51%, n.s). ConclusionOur data confirmingly show a high frequency of BCL11B mutations (13.5%) in the so far largest cohort of adult T-ALL patients. As loss of function mutations were restricted to functional ZF domains and recurrently occurred in thymic T-ALL, these data stress a potential pathogenetic role of BCL11B as T-cell specific transcription factor. Importantly, low expression was associated with poor prognosis; in particular in the standard risk group of thymic T-ALL, BCL11Blow is a novel marker that identifies patients with an unacceptable poor prognosis. These findings might help to improve risk stratification in a significant proportion of adult T-ALL patients, which fail to standard therapy despite the favourable immunophenotypic characteristics. Disclosures:No relevant conflicts of interest to declare.

A T-Cell Specific Element Activates the TAL1 Oncogene Via an Interchromosomal Interaction During Leukemogenesis

AbstractAbstract 3507T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignant disease of thymocytes that mainly affects children and has very poor prognosis with high rates of relapse. A prominent feature observed in 60% of T-ALL childhood patients is the ectopic expression of a key hematopoietic transcription factor TAL1/SCL. Although several enhancers has been identified to play an important role in normal hematopoietic differentiation, the histone modification patterns and chromatin organization over the whole TAL1 locus reveled that none of them is active in T-ALL cell lines such as Jurkat and Rex cells. It remains currently unknown how TAL1 is activated in the majority of T-ALL patients lacking the TAL1 locus rearrangements. To understand the molecular mechanism underlying regulation of the TAL1 oncogene in leukemic T-cells, we employed circularized chromosome conformation capture (4C) methodology to identify new regulatory elements that activate TAL1 specifically in T-ALL leukemia. Using the TAL1 promoter 1a as the bait, we discovered that the TAL1 promoter 1a interacts with the TIL16 element (TAL1 interacting locus in chromosome 16) that is located at ∼15 Kb downstream of T-cell specific CD2BP2 gene in T-ALL cell line Jurkat, but not in erythroid progenitor K562 cells. The CD2BP2 protein is a cellular adapter protein that was originally identified as a binding partner of the T cell adhesion protein CD2 in the context of T cell signaling. The TIL16 element contains the bind sites for several transcription factors that are important for hematopoiesis such as C-Maf, Pax5, HoxA7 and USF2. The inter-chromosomal interaction between the TIL16 and the TAL1 promoter 1a was further confirmed by chromosome conformation capture (3C) assay in three TAL1 over-expressing T-ALL cell lines, Jurkat, REX and Molt4, but not in K562 cells. Recent genome wide study has correlates H3K4 mono- or dimethyl marks with distal enhancers while trimethyl H3K4 is enriched in promoters of active genes. To further test if the TIL16 acts as T-cell specific enhancer for TAL1 activation in T-ALL cells, we carried out ChIP-seq and ChIP analysis in CD4 T cells, Jurkat, and K562 cells. We found that the TIL16 element is specifically marked by H3K4me1 in Jurkat and CD4+ T-cells but not in K562 cells. The enrichment of H3K4me1 is correlated with the binding of c-Maf, a T-cell specific transcription factor. To further test whether the TIL16 element contributes to transcription activity, a DNA fragments containing the TIL16 element were cloneed into SV40 minimal promoter driven luciferase reporter and introduced into K562 and several T-ALL cell lines. Compared to the pGL3-SV40 vector that showed only minimal luciferase activity, the 1 Kb TIL element specifically activated transcription of the luciferase reporter in T-ALL cells, but not in erythroid progenitor K562 cells suggesting that the TIL16 element functions as a T-cell specific TAL1 enhancer. Thus, our data revealed a novel epigenetic mechanism by which the TAL1 oncogene is ectopically activated in T-cell leukemia. Disclosures:No relevant conflicts of interest to declare.

The relationship between the Wnt/β‐catenin and TGF‐β/BMP signals in the intervertebral disc cell

Degeneration of the lumbar intervertebral disc (IVD) is a cause of low back pain. In osteoarthritis patients, an increase in β-catenin accumulation has been reported. However, the molecular mechanisms involved in IVD remain unclear. In the present study, we examined the relationship of Wnt/β-catenin and transforming growth factor-β (TGF-β)/bone morphogenetic protein (BMP) signals in the IVDs. We found that treatment of nucleus pulposus (NP) cells with the Wnt/β-catenin activator lithium chloride (LiCl) results in the increased expression of β-catenin mRNA and protein, and cell proliferation is decreased due to the activation of the Wnt/β-catenin signals through the suppression of c-myc and cyclin-D1. In addition, T-cell-specific transcription factor (TCF) promoter activity was found to increase the following stimulation with LiCl alone, and was further increased when BMP2 was added, in comparison to the control group. We further observed the effects of treatment with PD98059, a specific inhibitor of the mitogen-activated protein kinase pathway, on TCF promoter activity in NP cells. These effects were largely attenuated by PD98059. Moreover, when transfected IVDs were co-transfected with R-Smad expression plasmids, there was a significant decrease in TCF reporter activity. We thereafter evaluated the effects of increased Wnt/β-catenin activity on the transcriptional activity of the Smad binding element (SBE). As a result, LiCl suppressed the activity of SBE reporter activity. The present study demonstrates for the first time that there are opposing effects between the Wnt/β-catenin and TGF-β/BMP signals in IVDs, which is consistent with the Wnt/β-catenin signals contributing to the pathogenesis of IVD degeneration.

Advances in pediatric asthma in 2009: Gaining control of childhood asthma

This year's summary will focus on recent advances in pediatric asthma as reported in Journal of Allergy and Clinical Immunology publications in 2009. New National Asthma Education and Prevention Program asthma guidelines were released in 2007, with a particular emphasis on asthma control. Now that we have worked with the principals of the guidelines for 2 years, new insights are reported on how to implement the guidelines into clinical practice. This year's report will focus on gaps in management that need to be addressed, including health disparities, methods to improve asthma management through opportunities available in school-based asthma programs, and more information on the development of asthma in childhood. This information brings us closer to the point of managing children with controllable asthma and understanding reasons why asthma is not controlled in the remaining children. If we can close these gaps through better communication, improvements in the health care system, and new insights into treatment, we will move closer to better methods to intervene early in the course of the disease and induce clinical remission as quickly as possible in most children.

Wnt/β-Catenin Signaling Suppresses Rapsyn Expression and Inhibits Acetylcholine Receptor Clustering at the Neuromuscular Junction

The dynamic interaction between positive and negative signals is necessary for remodeling of postsynaptic structures at the neuromuscular junction. Here we report that Wnt3a negatively regulates acetylcholine receptor (AChR) clustering by repressing the expression of Rapsyn, an AChR-associated protein essential for AChR clustering. In cultured myotubes, treatment with Wnt3a or overexpression of beta-catenin, the condition mimicking the activation of the Wnt canonical pathway, inhibited Agrin-induced formation of AChR clusters. Moreover, Wnt3a treatment promoted dispersion of AChR clusters, and this effect was prevented by DKK1, an antagonist of the Wnt canonical pathway. Next, we investigated possible mechanisms underlying Wnt3a regulation of AChR clustering in cultured muscle cells. Interestingly, we found that Wnt3a treatment caused a decrease in the protein level of Rapsyn. In addition, Rapsyn promoter activity in cultured muscle cells was inhibited by the treatment with Wnt3a or beta-catenin overexpression. Forced expression of Rapsyn driven by a promoter that is not responsive to Wnt3a prevented the dispersing effect of Wnt3a on AChR clusters, suggesting that Wnt3a indeed acts to disperse AChR clusters by down-regulating the expression of Rapsyn. The role of Wnt/beta-catenin signaling in dispersing AChR clusters was also investigated in vivo by electroporation of Wnt3a or beta-catenin into mouse limb muscles, where ectopic Wnt3a or beta-catenin caused disassembly of postsynaptic apparatus. Together, these results suggest that Wnt/beta-catenin signaling plays a negative role for postsynaptic differentiation at the neuromuscular junction, probably by regulating the expression of synaptic proteins, such as Rapsyn.

Regulatory T cells: hypes and limitations

In recent years there has been increased interest in understanding the physiology and function of regulatory T cells. In this review we focus on the characterization of regulatory T-cell subsets and their potential therapeutic use in organ transplantation. Regulatory T cells can play an instrumental role in the establishment of operational tolerance to allografts. The level of expression and the extent of posttranslational acetylation of the regulatory T-cell specific transcription factor Foxp3 are important modulators of their suppressive activity. Low expression of CD127 can be used as a novel marker to define pure regulatory T-cell populations and the expression of CD45RA on CD4CD25 regulatory T cells characterizes a population with a more stable phenotype upon expansion in vitro. Interleukin-35 is a recently discovered immunosuppressive cytokine secreted by CD4CD25 regulatory T cells. Although the presence of allospecific memory T cells in the pretransplant period and the use of immunosuppressants might interfere with the effectiveness of regulatory T-cell-based therapies, encouraging results indicate that the immunosuppressive drug rapamycin does not affect the expansion and function of regulatory T cells and could be included in a combined therapy. Important advances have been made towards establishing regulatory T cells as a viable therapy in transplantation and the first clinical trials using human regulatory T cells are currently underway. There are, however, important limitations and safety issues that have to be addressed before this therapy can be fully translated into the clinic.

Drosophila Wnt/Fz Pathways

Wnts [also known as Wingless (Wg)] are a family of conserved signaling molecules involved in a plethora of fundamental developmental and cell biological processes, such as cell proliferation, differentiation, and cell polarity. Dysregulation of the pathway can be detrimental, because several components are tumorigenic when mutated and are associated with hepatic, colorectal, breast, and skin cancers. First identified in the fruit fly Drosophila melanogaster as a gene family responsible for patterning the embryonic epidermis, the Wnt gene family, including Wg, encode secreted glycoproteins that activate receptor-mediated signaling pathways leading to numerous transcriptional and cellular responses. The main function of the canonical Wg pathway is to stabilize the cytoplasmic pool of a key mediator, beta-catenin [beta-catenin, known as Armadillo (Arm) in fruit flies], which is otherwise degraded by the proteasome pathway. Initially identified as a key player in stabilizing cell-cell adherens junctions, Arm is now known to also act as a transcription factor by forming a complex with the lymphoid enhancer factor (LEF)/T cell-specific transcription factor (TCF) family of high mobility group (HMG)-box transcription factors. Upon Wnt/Wg stimulation, stabilized Arm translocates to the nucleus, where, together with LEF/TCF transcription factors, it activates downstream target genes that regulate numerous cell biological processes.

Comparative Microarray Analysis of Gene Expression During Activation of Human Peripheral Blood T Cells and Leukemic Jurkat T Cells

Activation of T cells involves a complex cascade of signal transduction pathways linking T-cell receptor engagement at the cell membrane to the transcription of multiple genes within the nucleus. The T-cell leukemia–derived cell line Jurkat has generally been used as a model system for the activation of T cells. However, genome-wide comprehensive studies investigating the activation status, and thus the appropriateness, of this cell line for this purpose have not been performed. We sought to compare the transcriptional profiles of phenotypically purified human CD2+ T cells with those of Jurkat T cells during T-cell activation, using cDNA microarrays containing 6912 genes. About 300 genes were up-regulated by more than 2-fold during activation of both peripheral blood (PB) T cells and Jurkat T cells. The number of down-regulated genes was significantly lower than that of up-regulated genes. Only 79 genes in PB T cells and 37 genes in Jurkat T cells were down-regulated by more than 2-fold during activation. Comparison of gene expression during activation of Jurkat and PB T cells revealed a common set of genes that were up-regulated, such as Rho GTPase-activating protein 1, SKP2, CDC25A, T-cell specific transcription factor 7, cytoskeletal proteins, and signaling molecules. Genes that were commonly down-regulated in both PB T cells and Jurkat T cells included CDK inhibitors (p16, p19, p27), proapoptotic caspases, and the transcription factors c-fos and jun-B. After activation, 71 genes in PB T cells and only 3 genes in Jurkat T cells were up-regulated 4-fold or more. Of these up-regulated genes and expressed sequence tags, 44 were constitutively expressed at high levels in nonactivated Jurkat cells. Quantitative real-time RT-PCR analysis confirmed our microarray data. Our findings indicate that although there is significant overlap in the activation-associated transcriptional profiles in PB T cells compared with Jurkat T cells, there is a subset of genes showing differential expression patterns during the activation of the two cell types.

A polymorphism in the TCF7 gene, C883A, is associated with type 1 diabetes.

Type 1 diabetes is an autoimmune disease with a Th1 phenotype in which insulin-producing beta-cells in the pancreas are destroyed. The T-cell-specific transcription factor TCF7 activates genes involved in immune regulation and is a candidate locus for genetic susceptibility to type 1 diabetes. A nonsynonymous single nucleotide polymorphism (SNP) (Pro to Thr) in the TCF7 gene, C883A, was examined in samples from 282 Caucasian multiplex type 1 diabetic families. HLA-DRB1 and -DQB1 genotypes were previously determined for these samples, allowing data stratification based on HLA-associated risk. The transmission disequilibrium test showed significant overtransmission of the A allele from fathers (64.1%, P < 0.007) and nonsignificant overtransmission (57.4%, P < 0.06) of the A allele to patients who do not carry the highest-risk HLA-DR3/DR4 genotype. Elliptical sib pair analysis showed significant associations of the A allele with type 1 diabetes in paternal transmissions (P < 0.03), transmissions to male children (P < 0.04), and in the non-DR3/DR4 group (P < 0.04). These data also suggest that TCF7 C883A may affect age of disease onset. Analysis of genotype data from surrounding SNPs suggests that this TCF7 polymorphism may itself represent a risk factor for type 1 diabetes.