PubMed Health⌕ Search

Biomedical subjects

Yoram Groner

Publications and source records attributed to Yoram Groner.

At least 19 recordsLinked to original sources
PubMed2007

RUN-CBFbeta interaction in C. elegans: computational prediction and experimental verification.

The Runt domain proteins are eukaryotic transcription factors that regulate major developmental pathways. All members of this family contain a highly-conserved sequence-specific DNA binding domain: the Runt domain (RD). Structural and biochemical studies have shown that the Runt domain undergoes a conformational transition upon binding to DNA and that this process is regulated by an unrelated partner protein CBFbeta that enhances the DNA binding affinity of RD. Most of the reported studies on the Runt domain transcription factors were performed on proteins from mammals and Drosophila whereas very little has been known about the C. elegans RD protein, RUN, which provides the simplest model system for understanding the function of this class of transcription factors. We performed computational studies on RD domains from various species including C. elegans, Drosophila, and human, using the atom-atom contact surface area scoring method. The scoring analysis indicates that the DNA binding regulation of the C. elegans RD protein (CeRD) occurs via its interaction with a CBFbeta-like partner, as found for the human proteins, whereas a different mode of regulation may occur in the Drosophila system. Sequence, secondary structure and fold analyses of a putative CBFbeta protein identified in the C. elegans genome, CeCBFbeta, sharing a 22% identity with the human protein, predict a similar structure of this protein to that of the human CBFbeta protein. We produced the C. elegans proteins CeRD and CeCBFbeta in bacteria and confirmed their physical interaction as well as cross interactions with the corresponding human proteins. We also confirmed the structural similarity of CBFbeta and CeCBFbeta by circular dichroism analysis. The combined results suggest that a similar mechanism of regulation operates for the human and the C. elegans RD proteins despite the low sequence identity between their CBFbeta proteins and the evolutionary distance between the two systems.

Amino Acid Sequence↗
PubMed2006

Transcription factors T-bet and Runx3 cooperate to activate Ifng and silence Il4 in T helper type 1 cells.

Cell differentiation involves activation and silencing of lineage-specific genes. Here we show that the transcription factor Runx3 is induced in T helper type 1 (T(H)1) cells in a T-bet-dependent manner, and that both transcription factors T-bet and Runx3 are required for maximal production of interferon-gamma (IFN-gamma) and silencing of the gene encoding interleukin 4 (Il4) in T(H)1 cells. T-bet does not repress Il4 in Runx3-deficient T(H)2 cells, but coexpression of Runx3 and T-bet induces potent repression in those cells. Both T-bet and Runx3 bind to the Ifng promoter and the Il4 silencer, and deletion of the silencer decreases the sensitivity of Il4 to repression by either factor. Our data indicate that cytokine gene expression in T(H)1 cells may be controlled by a feed-forward regulatory circuit in which T-bet induces Runx3 and then 'partners' with Runx3 to direct lineage-specific gene activation and silencing.

Animals↗
PubMed2006

Runx3 regulates dendritic epidermal T cell development.

The Runx3 transcription factor regulates development of T cells during thymopoiesis and TrkC sensory neurons during dorsal root ganglia neurogenesis. It also mediates transforming growth factor-beta signaling in dendritic cells and is essential for development of skin Langerhans cells. Here, we report that Runx3 is involved in the development of skin dendritic epidermal T cells (DETCs); an important component of tissue immunoregulation. In developing DETCs, Runx3 regulates expression of the alphaEbeta7 integrin CD103, known to affect migration and epithelial retention of DETCs. It also regulates expression of IL-2 receptor beta (IL-2Rbeta) that mediates cell proliferation in response to IL-2 or IL-15. In the absence of Runx3, the reduction in CD103 and IL-2Rbeta expression on Runx3(-/-) DETC precursors resulted in impaired cell proliferation and maturation, leading to complete lack of skin DETCs in Runx3(-/-) mice. The data demonstrate the requirement of Runx3 for DETCs development and underscore the importance of CD103 and IL-2Rbeta in this process. Of note, while Runx3(-/-) mice lack both DETCs and Langerhans cells, the two most important components of skin immune surveillance, the mice did not develop skin lesions under pathogen-free (SPF) conditions.

Animals↗
PubMed2006

Runx2 inhibits chondrocyte proliferation and hypertrophy through its expression in the perichondrium.

The perichondrium, a structure made of undifferentiated mesenchymal cells surrounding growth plate cartilage, regulates chondrocyte maturation through poorly understood mechanisms. Analyses of loss- and gain-of-function models show that Twist-1, whose expression in cartilage is restricted to perichondrium, favors chondrocyte maturation in a Runx2-dependent manner. Runx2, in turn, enhances perichondrial expression of Fgf18, a regulator of chondrocyte maturation. Accordingly, compound heterozygous embryos for Runx2 and Fgf18 deletion display the same chondrocyte maturation phenotype as Fgf18-null embryos. This study identifies a transcriptional basis for the inhibition of chondrocyte maturation by perichondrium and reveals that Runx2 fulfills antagonistic functions during chondrogenesis.

Animals↗
PubMed2006

RUNX3 negatively regulates CD36 expression in myeloid cell lines.

CD36 is a member of the scavenger receptor type B family implicated in the binding of lipoproteins, phosphatidylserine, thrombospondin-1, and the uptake of long-chain fatty acids. On mononuclear phagocytes, recognition of apoptotic cells by CD36 contributes to peripheral tolerance and prevention of autoimmunity by impairing dendritic cell (DC) maturation. Besides, CD36 acts as a coreceptor with TLR2/6 for sensing microbial diacylglycerides, and its deficiency leads to increased susceptibility to Staphylococcus aureus infections. The RUNX3 transcription factor participates in reprogramming DC transcription after pathogen recognition, and its defective expression leads to abnormally accelerated DC maturation. We present evidence that CD36 expression is negatively regulated by the RUNX3 transcription factor during myeloid cell differentiation and activation. In molecular terms, RUNX3 impairs the activity of the proximal regulatory region of the CD36 gene in myeloid cells through in vitro recognition of two functional RUNX-binding elements. Moreover, RUNX3 occupies the CD36 gene proximal regulatory region in vivo, and its overexpression in myeloid cells results in drastically diminished CD36 expression. The down-regulation of CD36 expression by RUNX3 implies that this transcription factor could impair harmful autoimmune responses by contributing to the loss of pathogen- and apoptotic cell-recognition capabilities by mature DCs.

Animals↗
PubMed2006

Dynamic expression of Runx1 in skin affects hair structure.

The three mammalian Runx transcription factors, some of which are known to be involved in human genetic diseases and cancer, are pivotal players in embryo development and function as key regulators of cell fate determination and organogenesis. Here, we report the expression of Runx1 during the development of hair and other skin appendages in the mouse and describe the effect of Runx1 on the structural hair output. In hair follicles, where the three Runx proteins are expressed, Runx1 expression is most prominent in both mesenchymal and epithelial compartments. The epithelial expression includes the hair keratin forming layers of the hair shaft and the bulge, where interestingly, Runx1 is co-expressed with keratin 15, a putative hair follicle stem cell marker. In the hair mesenchyme, during early stages of hair morphogenesis, Runx1 is expressed in a discrete dermal sub-epithelial layer, while at later stages it is found in a hair cycle dependent pattern in the dermal papilla. To elucidate the function of Runx1 in the hair follicle we have generated a Runx1 epidermal conditional knockout and found that the mutant mice display a remarkable structural deformation of the zigzag hair type. The data delineate Runx1 as a novel specific marker of several hair follicle cell types and sheds light on its role in hair morphogenesis and differentiation.

Animals↗
PubMed2006

Groucho/transducin-like Enhancer-of-split (TLE)-dependent and -independent transcriptional regulation by Runx3.

Regulation of gene expression by tissue-specific transcription factors involves both turning on and turning off transcription of target genes. Runx3, a runt-domain transcription factor, regulates cell-intrinsic functions by activating and repressing gene expression in sensory neurons, dendritic cells (DC), and T cells. To investigate the mechanism of Runx3-mediated repression in an in vivo context, we generated mice expressing a mutant Runx3 lacking the C-terminal VWRPY, a motif required for Runx3 interaction with the corepressor Groucho/transducin-like Enhancer-of-split (TLE). In contrast with Runx3(-/-) mice, which displayed ataxia due to the death of dorsal root ganglia TrkC neurons, Runx3(VWRPY-/-) mice were not ataxic and had intact dorsal root ganglia neurons, indicating that ability of Runx3 to tether Groucho/TLE is not essential for neurogenesis. In the DC compartment, the mutant protein Runx3(VWRPY-) promoted normally developed skin Langerhans cells but failed to restrain DC spontaneous maturation, indicating that this latter process involves Runx3-mediated repression through recruitment of Groucho/TLE. Moreover, in CD8(+) thymocytes, Runx3(VWRPY-) up-regulated alphaE/CD103-like WT Runx3, whereas unlike wild type, it failed to repress alphaE/CD103 in CD8(+) splenocytes. Thus, in CD8-lineage T cells, Runx3 regulates alphaE/CD103 in opposing regulatory modes and recruits Groucho/TLE to facilitate the transition from activation to repression. Runx3(VWRPY-) also failed to mediate the epigenetic silencing of CD4 gene in CD8(+) T cells, but normally regulated other pan-CD8(+) T cell genes. These data provide evidence for the requirement of Groucho/TLE for Runx3-mediated epigenetic silencing of CD4 and pertain to the mechanism through which other Runx3-regulated genes are epigenetically silenced.

Amino Acid Sequence↗
PubMed2006

The Runx1/AML1 transcription factor selectively regulates development and survival of TrkA nociceptive sensory neurons.

Neural crest cells (NCCs) can adopt different neuronal fates. In NCCs, neurogenin-2 promotes sensory specification but does not specify different subclasses of sensory neurons. Understanding the gene cascades that direct Trk gene activation may reveal mechanisms generating sensory diversity, because different Trks are expressed in different sensory neuron subpopulations. Here we show in chick and mouse that the Runt transcription factor Runx1 promotes axonal growth, is selectively expressed in neural crest-derived TrkA(+) sensory neurons and mediates TrkA transactivation in migratory NCCs. Inhibition of Runt activity depletes TrkA expression and leads to neuronal death. Moreover, Runx1 overexpression is incompatible with multipotency in the migratory neural crest but does not induce expression of pan-neuronal genes. Instead, Runx1-induced neuronal differentiation depends on an existing neurogenin2 proneural gene program. Our data show that Runx1 directs, in a context-dependent manner, key aspects of the establishment of the TrkA(+) nociceptive subclass of neurons.

Animals↗
PubMed2005

Accelerated chemokine receptor 7-mediated dendritic cell migration in Runx3 knockout mice and the spontaneous development of asthma-like disease.

The Runx3 transcription factor is a key regulator of lineage-specific gene expression in several developmental pathways and could also be involved in autoimmunity. We report that, in dendritic cells (DC), Runx3 regulates TGFbeta-mediated transcriptional attenuation of the chemokine receptor CCR7. When Runx3 is lost, i.e., in Runx3 knockout mice, expression of CCR7 is enhanced, resulting in increased migration of alveolar DC to the lung-draining lymph nodes. This increased DC migration and the consequent accumulation of activated DC in draining lymph nodes is associated with the development of asthma-like features, including increased serum IgE, hypersensitivity to inhaled bacterial lipopolysaccharide, and methacholine-induced airway hyperresponsiveness. The enhanced migration of DC in the knockout mice could be blocked in vivo by anti-CCR7 antibodies and by the drug Ciglitazone, known to inhibit CCR7 expression. The data indicate that Runx3 transcriptionally regulates CCR7 and that, when absent, the dysregulated expression of CCR7 in DC plays a role in the etiology of asthmatic conditions that recapitulate clinical symptoms of the human disease. Interestingly, human RUNX3 resides in a region of chromosome 1p36 that contains susceptibility genes for asthma and hypersensitivity against environmental antigens. Thus, mutations in RUNX3 may be associated with increased sensitivity to asthma development.

Animals↗
PubMed2005

Runx3 is involved in hair shape determination.

Transcriptional regulators of the Runx family play critical roles in normal organ development and, when mutated, lead to genetic diseases and cancer. Runx3 functions during cell lineage decisions in thymopoiesis and neurogenesis and mediates transforming growth factor-beta signaling in dendritic cells. Here, we study the function of Runx3 in the skin and its appendages, primarily the hair follicle, during mouse development. Runx3 is expressed predominantly in the dermal compartment of the hair follicles as they form and during the hair cycle, as well as in the nail and sweat gland skin appendages. Distinct expression is also detected periodically in isolated cells of the epidermis and in melanocytes, populating the hair bulb. Runx3-deficient mice display a perturbation of the normal hair coat, which we show to be due to hair type and hair shape changes. Thus, one of the functions of Runx3 in skin may be to regulate the formation of the epithelial derived structural hair by affecting dermal to epidermal interactions.

Animals↗
PubMed2004

Loss of Runx3 function in leukocytes is associated with spontaneously developed colitis and gastric mucosal hyperplasia.

RUNX transcription factors are key regulators of lineage-specific gene expression and might be involved in autoimmune diseases. Runx3 plays a role during the development of sensory neurons and T cells and regulates transforming growth factor beta (TGF-beta) signaling in dendritic cells. Here, we report that at 4 weeks of age, Runx3 knockout (KO) mice spontaneously develop inflammatory bowel disease (IBD) characterized by leukocyte infiltration, mucosal hyperplasia, formation of lymphoid clusters, and increased production of IgA. Additionally, at a considerably older age (8 months), the KO mice also develop progressive hyperplasia of the gastric mucosa associated with disturbed epithelial differentiation and cellular hyaline degeneration. Analysis of cytokines in the colonic mucosa of Runx3 KO mice revealed a mixed T helper 1/T helper 2 response. By using immunohistochemistry and RNA in situ hybridization, Runx3 expression in the gastrointestinal tract is detected in lymphoid and myeloid populations but not in the epithelium. The data indicate that loss of leukocytic cell-autonomous function of Runx3 results in IBD and gastric lesion in the KO mice. IBD in humans is viewed as a complex genetic disorder. Several susceptibility loci were identified on different human chromosomes including the chromosomal region 1p36 where RUNX3 resides. It is thus tempting to speculate that mutations in RUNX3 may constitute an IBD risk factor in humans.

Animals↗
PubMed2004

Structure and regulated expression of mammalian RUNX genes.

The RUNX are key regulators of lineage-specific gene expression in major developmental pathways. The expression of RUNX genes is tightly regulated, leading to a highly specific spatio/temporal expression pattern and to distinct phenotypes of gene knockouts. This review highlights the extensive structural similarities between the three mammalian RUNX genes and delineates how regulation of their expression at the levels of transcription and translation are orchestrated into the unique RUNX expression pattern.

Animals↗
PubMed2004

Runx3 regulates mouse TGF-beta-mediated dendritic cell function and its absence results in airway inflammation.

Runx3 transcription factor regulates cell lineage decisions in thymopoiesis and neurogenesis. Here we report that Runx3 knockout (KO) mice develop spontaneous eosinophilic lung inflammation associated with airway remodeling and mucus hypersecretion. Runx3 is specifically expressed in mature dendritic cells (DC) and mediates their response to TGF-beta. In the absence of Runx3, DC become insensitive to TGF-beta-induced maturation inhibition, and TGF-beta-dependent Langerhans cell development is impaired. Maturation of Runx3 KO DC is accelerated and accompanied by increased efficacy to stimulate T cells and aberrant expression of beta2-integrins. Lung alveoli of Runx3 KO mice accumulate DC characteristic of allergic airway inflammation. Taken together, abnormalities in DC function and subset distribution may constitute the primary immune system defect, which leads to the eosinophilic lung inflammation in Runx3 KO mice. These data may help elucidate the molecular mechanisms underlying the pathogenesis of allergic airway inflammation in humans.

Animals↗
PubMed2004

Functional and morphological alterations in compound transgenic mice overexpressing Cu/Zn superoxide dismutase and amyloid precursor protein [correction].

Down's syndrome (DS), the phenotypic manifestation of trisomy 21, involves overexpression of chromosome 21-encoded genes. The gene for amyloid precursor protein (APP), known to be involved in AD pathology, resides on chromosome 21 along with the gene for Cu/Zn superoxide dismutase (SOD1), a key enzyme in the metabolism of oxygen free radicals. We investigated the consequences of a combined increase in APP and SOD1, in a double-transgenic (tg)-APP-SOD1 mouse. These mice expressed severe impairment in learning, working and long-term memory. Expression of long-term potentiation in hippocampal slices was impaired in both tg-SOD and tg-APP-SOD mice, but not in tg-APP mice, indicating that increased APP by itself did not affect in vitro synaptic plasticity. In tg-APP-SOD mice, membrane-bound high molecular weight APP species accumulated while APP cleavage products did not increase and levels of secreted APP were unchanged. Severe morphological damage, including lipofuscin accumulation and mitochondria abnormalities, were found in aged tg-APP-SOD but not in the other mice. Thus, a combined elevation of the two chromosome 21 genes in tg-APP-SOD mice induced age-dependent alterations in morphological and behavioural functions.

Age Factors↗
PubMed2004

[Mouse whole mount RNA in situ hybridization: an effective technique for analyzing gene expression].

OBJECTIVE: To set up a method of analyzing gene expression profile from mouse whole embryos. METHODS: Mouse whole mount RNA in situ hybridization(WM-ISH) of E10.5-E14 embryos was carried out by using digoxigenin-labeled Runx1 and Runx3 RNA probes and their expression profile was observed by detecting the existence and status of corresponding mRNAs in the embryonic tissues. RESULTS: Clear hybridization signals were observed in different tissues and organs hybridized by Runx1 or Runx3 RNA probe. Different probes and ages of embryos had need of their own optimal proteinase K treatment conditions. CONCLUSION: Mouse whole mount RNA in situ hybridization is an effective method of analyzing gene expression. It is useful for revealing whole gene expression profile and has a great potentiality in the era of functional genomics. It provides an alternative method of studies on gene expression which is at least as good as LacZ staining and immunohistochemistry. The key factor of the success to mouse whole mount RNA in situ hybridization is whether the proteinase K treatment conditions are optimal or not.

Animals↗
PubMed2003

RUNX/AML and C/EBP factors regulate CD11a integrin expression in myeloid cells through overlapping regulatory elements.

The CD11a/CD18 (leukocyte function-associated antigen 1 [LFA-1]) integrin mediates critical leukocyte adhesive interactions during immune and inflammatory responses. The CD11a promoter directs CD11a/CD18 integrin expression, and its activity in lymphoid cells depends on a functional RUNX1/AML-1-binding site (AML-110) within the MS7 sequence. We now report that MS7 contains a C/EBP-binding site (C/EBP-100), which overlaps with AML-110 and is bound by C/EBP factors in myeloid cells. C/EBP and RUNX/AML factors compete for binding to their respective cognate elements and bind to the CD11a promoter MS7 sequence in a cell lineage- and differentiation-dependent manner. In myeloid cells MS7 is primarily recognized by C/EBP factors in proliferating cells whereas RUNX/AML factors (especially RUNX3/AML-2) bind to MS7 in differentiated cells. RUNX3/AML-2 binding to the CD11a promoter correlates with increased RUNX3/AML-2 protein levels and enhanced CD11a/CD18 cell surface expression. The relevance of the AML-110 element is underscored by the ability of AML-1/ETO to inhibit CD11a promoter activity, thus explaining the low CD11a/CD18 expression in t(8;21)-containing myeloid leukemia cells. Therefore, the expression of the CD11a/CD18 integrin in myeloid cells is determined through the differential occupancy of the CD11a proximal promoter by transcription factors implicated in the pathogenesis of myeloid leukemia.

Binding Sites↗
PubMed2003

Runx3 and Runx1 are required for CD8 T cell development during thymopoiesis.

The RUNX transcription factors are important regulators of lineage-specific gene expression. RUNX are bifunctional, acting both as activators and repressors of tissue-specific target genes. Recently, we have demonstrated that Runx3 is a neurogenic transcription factor, which regulates development and survival of proprioceptive neurons in dorsal root ganglia. Here we report that Runx3 and Runx1 are highly expressed in thymic medulla and cortex, respectively, and function in development of CD8 T cells during thymopoiesis. Runx3-deficient (Runx3 KO) mice display abnormalities in CD4 expression during lineage decisions and impairment of CD8 T cell maturation in the thymus. A large proportion of Runx3 KO peripheral CD8 T cells also expressed CD4, and in contrast to wild-type, their proliferation ability was largely reduced. In addition, the in vitro cytotoxic activity of alloimmunized peritoneal exudate lymphocytes was significantly lower in Runx3 KO compared with WT mice. In a compound mutant mouse, null for Runx3 and heterozygous for Runx1 (Runx3-/-;Runx1+/-), all peripheral CD8 T cells also expressed CD4, resulting in a complete lack of single-positive CD8+ T cells in the spleen. The results provide information on the role of Runx3 and Runx1 in thymopoiesis and suggest that both act as transcriptional repressors of CD4 expression during T cell lineage decisions.

Animals↗