Neutrophils, known primarily as key players in defense against invading pathogens, represent an essential component of both the innate and adaptive immunity. Continuous production of large quantities of neutrophils is ensured by a complex process termed granulopoiesis. In order to maintain a stable neutrophilic population, granulopoiesis requires to be tightly regulated. Moreover, impaired granulopoiesis may lead to aberrant bone marrow function and, ultimately, give rise to acute myeloid leukemia (AML). Despite decades of research, the mechanisms regulating granulopoiesis are still unclear. In particular, the CCAAT/enhancer binding protein (C/EBP) family of transcription factors plays a critical role in this process. C/EBPα acts as a master regulator of granulopoiesis mainly by orchestrating expression of its target genes, which will mediate granulocytic differentiation. Thus, characterization of novel C/EBPα target genes is critical for a better understanding of the molecular mechanisms that regulate granulopoiesis. Previously, we showed that another C/EBP member, CEBPG, is a direct target of C/EBPα. In the first part of the present work, we addressed the unknown role of C/EBPγ in granulopoiesis. We observed that Cebpg conditional knockout (KO) mice, which have the Cebpg gene ablated specifically...

No description available.

Mast cells contribute to the activities of innate and adaptive branches of the immune system. They participate in pro-inflammatory responses to a wide range of pathogens, such as parasites, bacteria, and other foreign agents. These beneficial properties are in contrast to the contribution of mast cells to certain pathologies, such as asthma, allergy, autoimmune disorders, anaphylaxis, and systemic mastocytosis. Thorough knowledge of mast cell biology in health and disease is critical for the development of new therapeutic approaches. However, molecular mechanisms that control mast cell development and function are still incompletely defined. Our preliminary data indicate that the transcription factor C/EBP is a key player in mast cell biology. Here, using in vitro and in vivo models, we determine how C/EBP regulates the commitment of hematopoietic progenitors towards mast cells, and modulates mast cells function. These efforts provide novel insights to the role of C/EBP in hematopoiesis, and contribute to a better understanding of the mechanisms governing mast cell biology. Key words Mast cells, C/EBP, transcription factors, bone marrow-derived mast cell cultures, mast cell development, Cebpg conditional knockout mice