RESUMO
Mechanisms governing the distinct temporal dynamics that characterize post-natal angiogenesis and lymphangiogenesis elicited by cutaneous wounds and inflammation remain unclear. RhoB, a stress-induced small GTPase, modulates cellular responses to growth factors, genotoxic stress and neoplastic transformation. Here we show, using RhoB null mice, that loss of RhoB decreases pathological angiogenesis in the ischaemic retina and reduces angiogenesis in response to cutaneous wounding, but enhances lymphangiogenesis following both dermal wounding and inflammatory challenge. We link these unique and opposing roles of RhoB in blood versus lymphatic vasculatures to the RhoB-mediated differential regulation of sprouting and proliferation in primary human blood versus lymphatic endothelial cells. We demonstrate that nuclear RhoB-GTP controls expression of distinct gene sets in each endothelial lineage by regulating VEZF1-mediated transcription. Finally, we identify a small-molecule inhibitor of VEZF1-DNA interaction that recapitulates RhoB loss in ischaemic retinopathy. Our findings establish the first intra-endothelial molecular pathway governing the phased response of angiogenesis and lymphangiogenesis following injury.
Assuntos
Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo , Linfangiogênese , Neovascularização Patológica , Doenças Retinianas/fisiopatologia , Proteína rhoB de Ligação ao GTP/fisiologia , Animais , Animais Recém-Nascidos , Linhagem da Célula/genética , Proteínas de Ligação a DNA , Células Endoteliais/patologia , Células Endoteliais/fisiologia , Feminino , Regulação da Expressão Gênica , Inflamação/genética , Inflamação/fisiopatologia , Linfangiogênese/genética , Masculino , Camundongos , Neovascularização Patológica/genética , Doenças Retinianas/genética , Doenças Retinianas/patologia , Fatores de Transcrição , Cicatrização/genética , Cicatrização/fisiologia , Proteína rhoB de Ligação ao GTP/genéticaRESUMO
OBJECTIVE: Multipotent germline stem (mGS) cells derived from neonatal mouse testis, similar to embryonic stem (ES) cells, differentiate into various types of somatic cells in vitro and produce teratomas after inoculation into mice. In the present work, we examined mGS cells for hematopoietic progenitor potential in vitro and in vivo. MATERIALS AND METHODS: mGS cells were differentiated on OP9 stromal cells and induced into Flk1(+) cells. Flk1(+) cells were sorted and replated on OP9 stromal cells with various cytokines and emerging hematopoietic cells were analyzed for lineage marker expression by fluorescein-activated cell sorting, progenitor activity by colony assay, and stem cell transplantation assay. RESULTS: mGS cells, like ES cells, produce hematopoietic progenitors, including both primitive and definitive erythromyeloid, megakaryocyte, and B- and T-cell lineages via Flk1(+) progenitors. When transplanted into the bone marrow (BM) of nonobese diabetic/severe combined immunodeficient (NOD/SCID) gammac(null) mice directly, mGS-derived green fluorescent protein (GFP)-positive cells were detected 4 months later in the BM and spleen. GFP(+) donor cells were also identified in the Hoechst33342 side population, a feature of hematopoietic stem cells. However, these mGS-derived hematopoietic cells did not proliferate in vivo, even after exposure to hematopoietic stressors, such as 5-fluorouracil (5FU) injection or serial transplantation. CONCLUSION: mGS cells produced multipotent hematopoietic progenitor cells with myeloid and lymphoid lineage potential in vitro and localized in the BM after intra-BM injection but, like ES cells, failed to expand or show stem cell repopulating ability in vivo.