ABSTRACT
During the early thymus colonization, Notch signaling activation on hematopoietic progenitor cells (HPCs) drives proliferation and T cell commitment. Although these processes are driven by transcription factors such as HOXB4 and GATA3, there is no evidence that Notch directly regulates their transcription. To evaluate the role of NOTCH and TNF signaling in this process, human CD34+ HPCs were cocultured with OP9-DL1 cells, in the presence or absence of TNF. The use of a Notch signaling inhibitor and a protein synthesis inhibitor allowed us to distinguish primary effects, mediated by direct signaling downstream Notch and TNF, from secondary effects, mediated by de novo synthesized proteins. A low and physiologically relevant concentration of TNF promoted T lymphopoiesis in OP9-DL1 cocultures. TNF positively modulated the expression of both transcripts in a Notch-dependent manner; however, GATA3 induction was mediated by a direct mechanism, while HOXB4 induction was indirect. Induction of both transcripts was repressed by a GSK3ß inhibitor, indicating that activation of canonical Wnt signaling inhibits rather than induces their expression. Our study provides novel evidences of the mechanisms integrating Notch and TNF-alpha signaling in the transcriptional induction of GATA3 and HOXB4. This mechanism has direct implications in the control of self-renewal, proliferation, commitment, and T cell differentiation.
Subject(s)
GATA3 Transcription Factor/metabolism , Homeodomain Proteins/metabolism , Lymphopoiesis , Receptors, Notch/metabolism , Signal Transduction , T-Lymphocytes/metabolism , Transcription Factors/metabolism , Tumor Necrosis Factor-alpha/metabolism , Animals , Basic Helix-Loop-Helix Transcription Factors/genetics , Basic Helix-Loop-Helix Transcription Factors/metabolism , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cell Line , Cell Lineage/genetics , GATA3 Transcription Factor/genetics , Gene Expression Regulation , Homeodomain Proteins/genetics , Humans , Lymphopoiesis/genetics , Mice , NF-kappa B/metabolism , Protein Subunits/genetics , Protein Subunits/metabolism , Signal Transduction/genetics , Transcription Factor HES-1/genetics , Transcription Factor HES-1/metabolism , Transcription Factors/geneticsABSTRACT
Mesenchymal stromal cells (MSCs) are cultured cells that can give rise to mature mesenchymal cells under appropriate conditions and secrete a number of biologically relevant molecules that may play an important role in regenerative medicine. Evidence indicates that pericytes (PCs) correspond to mesenchymal stem cells in vivo and can give rise to MSCs when cultured, but a comparison between the gene expression profiles of cultured PCs (cPCs) and MSCs is lacking. We have devised a novel methodology to isolate PCs from human adipose tissue and compared cPCs to MSCs obtained through traditional methods. Freshly isolated PCs expressed CD34, CD140b, and CD271 on their surface, but not CD146. Both MSCs and cPCs were able to differentiate along mesenchymal pathways in vitro, displayed an essentially identical surface immunophenotype, and exhibited the ability to suppress CD3(+) lymphocyte proliferation in vitro. Microarray expression data of cPCs and MSCs formed a single cluster among other cell types. Further analyses showed that the gene expression profiles of cPCs and MSCs are extremely similar, although MSCs differentially expressed endothelial cell (EC)-specific transcripts. These results confirm, using the power of transcriptomic analysis, that PCs give rise to MSCs and suggest that low levels of ECs may persist in MSC cultures established using traditional protocols.
Subject(s)
Adipose Tissue/cytology , Mesenchymal Stem Cells/metabolism , Pericytes/metabolism , Transcriptome , Adolescent , Adult , Antigens, CD/genetics , Antigens, CD/metabolism , Cell Differentiation , Cells, Cultured , Female , Humans , Male , Mesenchymal Stem Cells/cytology , Middle Aged , Pericytes/cytology , Primary Cell Culture/methodsABSTRACT
Ischemia-reperfusion injury is a common early event in kidney transplantation and contributes to a delay in organ function. Acute tubular necrosis, impaired kidney function and organ leukocyte infiltration are the major findings. The therapeutic potential of stem cells has been the focus of recent research as these cells possess capabilities such as self-renewal, multipotent differentiation and aid in regeneration after organ injury. FTY720 is a new synthetic compound that has been associated with preferential migration of blood lymphocytes to peripheral lymph nodes instead of inflammatory sites. Bone marrow stem cells (BMSC) and/or FTY720 were used as therapy to promote recovery of tubule cells and avoid inflammation at the renal site, respectively. Mice were submitted to renal ischemia-reperfusion injury and were either treated with two doses of FTY720, 10x10(6) BMSC, or both in order to compare the therapeutic effect with non-treated and control animals. Renal function and structure were investigated as were cell numbers in peripheral blood and spleen. Activation and apoptosis markers were also evaluated in splenocytes using flow cytometry. We found that the combined therapy (FTY720+BMSC) was associated with more significant changes in renal function and structure after ischemia-reperfusion injury when compared with the other groups. Also a decrease at cell numbers and prevention of spleen cells activation and apoptosis was observed. In conclusion, in our model it was not possible to demonstrate the potential of stem cells alone or in combination with FTY720 to promote early kidney recovery after ischemia-reperfusion injury.
