Project description:The P38α modulates proliferation, survival and differentiation of different kinds of celll. Here, we demonstrate that loss of P38α accelerates recovery from anemia in mice by promoting survival of erythroblasts. To identify gene expression changes in P38α+/- versus P38α-/- erythroblasts, we sorted erythroblasts from P38α+/- and P38α-/- mice during recovery from anemia and performed microarray analysis.
Project description:p38α MAP kinase plays an important tumor suppressor role, which is mediated by both its negative effect on cell proliferation and its pro-apoptotic activity. Surprisingly, most tumor suppressor mechanisms coordinated by p38α have been reported to occur at the post- translational level. This contrasts with the important role of p38α in the regulation of transcription and the profound changes in gene expression that normally occur during tumorigenesis. We have analyzed whole genome expression profiles of Ras-transformed wild- type and p38α-deficient cells and have identified 202 genes that are potentially regulated by p38α in transformed cells. Expression analysis has confirmed the regulation of these genes by p38α in tumors, and functional validation has identified several of them as likely mediators of the tumor suppressor effect of p38α on Ras-induced transformation. Interestingly, about 10% of the genes that are negatively regulated by p38α in transformed cells contribute to EGF receptor signalling. Our results suggest that inhibition of EGF receptor signalling by transcriptional targets of p38α is an important function of this signalling pathway in the context of tumor suppression. We have investigated how transcriptional regulation contributes to the tumor suppressor effect of p38α, by comparing whole-genome expression profiles of wild-type (WT) and p38α- deficient (p38α-/-) mouse embryo fibroblasts (MEFs) expressing oncogenic H-RasG12V
Project description:p38α MAP kinase plays an important tumor suppressor role, which is mediated by both its negative effect on cell proliferation and its pro-apoptotic activity. Surprisingly, most tumor suppressor mechanisms coordinated by p38α have been reported to occur at the post- translational level. This contrasts with the important role of p38α in the regulation of transcription and the profound changes in gene expression that normally occur during tumorigenesis. We have analyzed whole genome expression profiles of Ras-transformed wild- type and p38α-deficient cells and have identified 202 genes that are potentially regulated by p38α in transformed cells. Expression analysis has confirmed the regulation of these genes by p38α in tumors, and functional validation has identified several of them as likely mediators of the tumor suppressor effect of p38α on Ras-induced transformation. Interestingly, about 10% of the genes that are negatively regulated by p38α in transformed cells contribute to EGF receptor signalling. Our results suggest that inhibition of EGF receptor signalling by transcriptional targets of p38α is an important function of this signalling pathway in the context of tumor suppression.
Project description:There is considerable evidence that inhibition of p38α mitogen-activated protein kinase diminishes cardiac damage during myocardial ischemia. During myocardial ischemia p38α interacts with TAB1, a scaffold protein, which promotes p38α autoactivation; active p38α (pp38α) then trans-phosphorylates TAB1. Previously, we solved the X-ray structure of the p38α-TAB1(384-412) complex. Here we further characterize the interaction by resolving the structure of the pp38α-TAB1(1-438) complex in the active state. Based on this information we created a global knock-in mouse with substitution of four residues on TAB1 (V390A, Y392A, V408G, M409A) we show are required for docking onto p38α. Whereas ablating p38α or TAB1 results in early embryonal lethality, the TAB1 KI mice are viable, develop normally and have no appreciable alteration in their lymphocyte repertoire or myocardial transcriptional profile. Nonetheless, following in vivo regional myocardial ischemia, infarction volume is significantly reduced and the trans- phosphorylation of TAB1 is disabled. Unexpectedly, the activation of myocardial p38α during ischemia is only mildly attenuated in TAB1 KI hearts, an effect most likely due to the removal of the steric hindrance to MAP2K3 binding. We conclude that it is the phosphorylation of TAB1 by pp38α during ischemia that is associated with cardiac damage. The data reveal that it is possible to selectively inhibit signalling downstream of p38α to attenuate ischemic injury. Our findings validate the p38α-TAB1 complex as a therapeutic target that may circumvent the toxicity associated with ATP-competitive inhibitors of p38α.
Project description:Here, we describe the identification and characterization of p38α as a novel regulator of DUX4 expression in FSHD myotubes. By using multiple highly characterized, potent and specific inhibitors of p38α/β, we show a robust reduction of DUX4 expression, activity and cell death across FSHD1 and FSHD2 patient-derived lines. RNA-seq profiling reveals that a small number of genes are differentially expressed upon p38α/β inhibition, the vast majority of which are DUX4 target genes. Our results reveal a novel and apparently critical role for p38α in the aberrant activation of DUX4 in FSHD and support the potential of p38α/β inhibitors as effective therapeutics to treat FSHD at its root cause.
Project description:In response to elevated glucocorticoid levels, erythroid progenitors rapidly expand to produce large numbers of young erythrocytes. Previous work demonstrates hematopoietic changes in rodents exposed to various physical and psychological stressors, however, the effects of chronic psychological stress on erythropoiesis has not be delineated. We employed laboratory, clinical and genomic analyses of a murine model of chronic restraint stress (RST) to examine the influence of psychological stress on erythropoiesis. Mice exposed to RST demonstrated markers of early erythroid expansion involving the glucocorticoid receptor. In addition, these RST-exposed mice had increased numbers of circulating reticulocytes and increased erythropoiesis in primary and secondary erythroid tissues. Mice also showed increases in erythroid progenitor populations and elevated expression of the erythroid transcription factor KLF1 in these cells. Together this work describes some of the first evidence of psychological stress affecting erythroid homeostasis through glucocorticoid stimulation and begins to define the transcription factor pathway involved.
Project description:p38 MAPK is activated during CD8+ T cell primary response. p38 activation promotes effector CD8+ T cell terminal differentiation but represses MPEC formation. p38α/beta deficient mice possess a similar number of virus-specific effector CD8+ T cells as wildtype counterparts. Meanwhile p38α/beta deletion doesn’t influence the clearance of LCMV although it impairs the cytolytic activity of CD8+ T cells. Loss of p38α/beta significantly enhances IL-2-producing Tcm accumulation in mouse spleen with no impact on total memory CD8+ T cell numbers yet. And in line with this, more robust proliferation of memory CD8+ T cells in the secondary response and stronger antigen-specific killing ability in rechallenged mice are resulted from p38α/beta deficiency. These results establish a pivotal role for p38α/beta in skewing MPEC formation toward SLEC differentiation, as well as in suppressing Tcm formation, and thus affecting the recall response.
Project description:Hematopoietic stem cells (HSCs) and their progeny sustain lifetime hematopoiesis. Aging alters HSC function, number, and composition and increases risk of hematological malignancies, but how these changes occur in HSCs remains unclear. Signaling via p38MAPK has been proposed as a candidate mechanism underlying induction of HSC aging. Here, using genetic models of both chronological and premature aging, we describe a multimodal role for p38α, the major p38MAPK isozyme in hematopoiesis, in HSC aging. We report that p38α regulates differentiation bias and sustains transplantation capacity of HSCs in the early phase of chronological aging (from young to 1-year-old). However, p38α decreased HSC transplantation capacity in the late progression phase of chronological aging (from 1- to 2-years-old). Furthermore, co-deletion of p38α in mice deficient in Ataxia-telangiectasia mutated (Atm), a model of premature aging, exacerbated aging-related HSC phenotypes seen in Atm single mutant mice. Mechanistically, p38α makes a positive contribution to inflammation during the late phase aging, resulting in defects in 2-year-old HSCs. Overall, we propose multiple functions of p38MAPK, which both promotes and suppresses HSC aging context-dependently.
Project description:Hematopoietic stem cells (HSCs) and their progeny sustain lifetime hematopoiesis. Aging alters HSC function, number, and composition and increases risk of hematological malignancies, but how these changes occur in HSCs remains unclear. Signaling via p38MAPK has been proposed as a candidate mechanism underlying induction of HSC aging. Here, using genetic models of both chronological and premature aging, we describe a multimodal role for p38α, the major p38MAPK isozyme in hematopoiesis, in HSC aging. We report that p38α regulates differentiation bias and sustains transplantation capacity of HSCs in the early phase of chronological aging (from young to 1-year-old). However, p38α decreased HSC transplantation capacity in the late progression phase of chronological aging (from 1- to 2-years-old). Furthermore, co-deletion of p38α in mice deficient in Ataxia-telangiectasia mutated (Atm), a model of premature aging, exacerbated aging-related HSC phenotypes seen in Atm single mutant mice. Mechanistically, p38α makes a positive contribution to inflammation during the late phase aging, resulting in defects in 2-year-old HSCs. Overall, we propose multiple functions of p38MAPK, which both promotes and suppresses HSC aging context-dependently.
Project description:In absence of selenium, proerythroblasts exhibited delay in differentation into basophilic erythroblasts during phenylhydrazine induced stress erythropoiesis. This microarray project was aiming to explore gene expression patterns in erythroblasts in the function of selenium status.