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FADD deficiency impairs early hematopoiesis in the bone marrow.

ABSTRACT: Signal transduction mediated by Fas-associated death domain protein (FADD) represents a paradigm of coregulation of apoptosis and cellular proliferation. During apoptotic signaling induced by death receptors including Fas, FADD is required for the recruitment and activation of caspase 8. In addition, a death receptor-independent function of FADD is essential for embryogenesis. In previous studies, FADD deficiency in embryonic stem cells resulted in a complete lack of B cells and dramatically reduced T cell numbers, as shown by Rag1(-/-) blastocyst complementation assays. However, T-specific FADD-deficient mice contained normal numbers of thymocytes and slightly reduced peripheral T cell numbers, whereas B cell-specific deletion of FADD led to increased peripheral B cell numbers. It remains undetermined what impact an FADD deficiency has on hematopoietic stem cells and progenitors. The current study analyzed the effect of simultaneous deletion of FADD in multiple cell types, including bone marrow cells, by using the IFN-inducible Mx1-cre transgene. The resulting FADD mutant mice did not develop lymphoproliferation diseases, unlike Fas-deficient mice. Instead, a time-dependent depletion of peripheral FADD-deficient lymphocytes was observed. In the bone marrow, a lack of FADD led to a dramatic decrease in the hematopoietic stem cells and progenitor-enriched population. Furthermore, FADD-deficient bone marrow cells were defective in their ability to generate lymphoid, myeloid, and erythroid cells. Thus, the results revealed a temporal requirement for FADD. Although dispensable during lymphopoiesis post lineage commitment, FADD plays a critical role in early hematopoietic stages in the bone marrow.

SUBMITTER: Rosenberg S

PROVIDER: S-EPMC3119601 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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FADD deficiency impairs early hematopoiesis in the bone marrow.

Rosenberg Stephen S Zhang Haibing H Zhang Jianke J

Journal of immunology (Baltimore, Md. : 1950) 20101129 1

Signal transduction mediated by Fas-associated death domain protein (FADD) represents a paradigm of coregulation of apoptosis and cellular proliferation. During apoptotic signaling induced by death receptors including Fas, FADD is required for the recruitment and activation of caspase 8. In addition, a death receptor-independent function of FADD is essential for embryogenesis. In previous studies, FADD deficiency in embryonic stem cells resulted in a complete lack of B cells and dramatically red ...[more]

PMID: 21115735

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Project description:Endothelial progenitor cell (EPC)-based therapy has immense potential to promote cardiac neovascularization and attenuate ischemic injury. Functional benefits of EPCs and other adult stem cell therapies largely involve paracrine mechanisms and exosomes secreted by stem cells are emerging as pivotal paracrine entity of stem/progenitor cells. However, modest outcomes after EPC-/stem cell-based clinical trials suggest that stem cell/exosome function might be modulated by stimuli they encounter in ischemic tissues, including systemic inflammation. We hypothesized that EPCs under inflammatory stress might produce exosomes of altered and dysfunctional content, which may compromise EPC repair in ischemic heart disease. We have previously shown that EPCs obtained from interleukin-10 knockout (IL-10KO) mice (model mimicking systemic inflammation) display impaired angiogenic functions. Whether IL-10KO-EPC-derived exosomes inherit their parental dysfunctional phenotype and whether inflammatory environment alters the cargo of their secreted exosomes are not known. After cell expansion from IL-10KO and wild-type (WT) mice, we isolated exosomes and compared their functions in terms of effect on cell survival, proliferation, migration, and angiogenic capacity in vitro. WT-EPC-Exo treatment enhanced endothelial cell proliferation and tube formation, and inhibited apoptosis, whereas IL-10KO-Exo exhibited impaired or even detrimental effects, suggesting that the reparative capacity of WT-EPC-Exo is lost in exosomes derived from IL-10-KO-EPCs. Deep RNA sequencing and proteomic analyses to compare WT and IL-10KO-Exo revealed drastically altered exosome cargo. Importantly, IL-10KO-EPC-Exo were highly enriched in microRNAs and proteins that promote inflammation and apoptosis and inhibit angiogenesis. Through modulation of a specific enriched miRNA (miR-375), we partially rescued IL-10KO-EPC-Exo dysfunction. Thus, our study revealed that EPC exosomes display impaired function under inflammatory stimulus through changed exosome contents, and the dysfunction can be rescued by modulation of a specific target packed in exosomes.

Project description:RationaleEndothelial progenitor cell (EPC) survival and function in the injured myocardium is adversely influenced by hostile microenvironment such as ischemia, hypoxia, and inflammatory response, thereby compromising full benefits of EPC-mediated myocardial repair.ObjectiveWe hypothesized that interleukin-10 (IL-10) modulates EPC biology leading to enhanced survival and function after transplantation in the ischemic myocardium.Methods and resultsMyocardial infarction (MI)-induced mobilization of bone marrow EPC (Sca-1+Flk1+cells) into the circulation was significantly impaired in IL-10 knockout (KO) mice. Bone marrow transplantation to replace IL-10 KO marrow with wild-type (WT) marrow attenuated these effects. Impaired mobilization was associated with lower stromal cell-derived factor (SDF)-1 expression levels in the myocardium of KO mice. Interestingly, SDF-1 administration reversed mobilization defect in KO mice. In vitro, hypoxia-mediated increases in CXCR4 expression and cell survival were lower in IL-10-deficient EPCs. Furthermore, SDF-1-induced migration of WT EPCs was inhibited by AMD3100, an inhibitor of CXCR4. To further study the effect of IL-10 on in vivo EPC survival and engraftment into vascular structures, GFP-labeled EPC were injected intramyocardially after induction of MI, and the mice were treated with either saline or recombinant IL-10. The IL-10-treated group showed increased retention of transplanted EPCs in the myocardium and was associated with significantly reduced EPC apoptosis after MI. Interestingly, increased EPC retention and their association with the vascular structures was observed in IL-10-treated mice. Increased EPC survival and angiogenesis in the myocardium of IL-10-treated mice corroborated with improved left ventricular function, reduced infarct size, and fibrosis in the myocardium. In vitro, IL-10-induced increase in VEGF expression in WT EPC was abrogated by STAT3 inhibitor, suggesting IL-10 signals through STAT3 activation.ConclusionsTaken together, our studies demonstrate that MI-induced EPC mobilization was impaired in IL-10 KO mice and that IL-10 increases EPC survival and function possibly through activation of STAT3/VEGF signaling cascades, leading to attenuation of MI-induced left ventricular dysfunction and remodeling.

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FADD deficiency impairs early hematopoiesis in the bone marrow.

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FADD deficiency impairs early hematopoiesis in the bone marrow.

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