RESUMEN
Lymphangiogenesis plays a crucial role during development, in cancer metastasis and in inflammation. Activation of VEGFR-3 (also known as FLT4) by VEGF-C is one of the main drivers of lymphangiogenesis, but the transcriptional events downstream of VEGFR-3 activation are largely unknown. Recently, we identified a wave of immediate early transcription factors that are upregulated in human lymphatic endothelial cells (LECs) within the first 30 to 80â min after VEGFR-3 activation. Expression of these transcription factors must be regulated by additional pre-existing transcription factors that are rapidly activated by VEGFR-3 signaling. Using transcription factor activity analysis, we identified the homeobox transcription factor HOXD10 to be specifically activated at early time points after VEGFR-3 stimulation, and to regulate expression of immediate early transcription factors, including NR4A1. Gain- and loss-of-function studies revealed that HOXD10 is involved in LECs migration and formation of cord-like structures. Furthermore, HOXD10 regulates expression of VE-cadherin, claudin-5 and NOS3 (also known as e-NOS), and promotes lymphatic endothelial permeability. Taken together, these results reveal an important and unanticipated role of HOXD10 in the regulation of VEGFR-3 signaling in lymphatic endothelial cells, and in the control of lymphangiogenesis and permeability.
Asunto(s)
Proteínas de Homeodominio/genética , Neoplasias/genética , Miembro 1 del Grupo A de la Subfamilia 4 de Receptores Nucleares/genética , Factores de Transcripción/genética , Factor C de Crecimiento Endotelial Vascular/genética , Receptor 3 de Factores de Crecimiento Endotelial Vascular/genética , Línea Celular , Permeabilidad de la Membrana Celular/genética , Movimiento Celular/genética , Células Endoteliales/metabolismo , Células Endoteliales/patología , Regulación Neoplásica de la Expresión Génica , Humanos , Linfangiogénesis/genética , Metástasis de la Neoplasia , Neoplasias/patología , Transducción de Señal , Factor C de Crecimiento Endotelial Vascular/biosíntesis , Receptor 3 de Factores de Crecimiento Endotelial Vascular/biosíntesisRESUMEN
VEGF-C/VEGFR-3 signaling plays a central role in lymphatic development, regulating the budding of lymphatic progenitor cells from embryonic veins and maintaining the expression of PROX1 during later developmental stages. However, how VEGFR-3 activation translates into target gene expression is still not completely understood. We used cap analysis of gene expression (CAGE) RNA sequencing to characterize the transcriptional changes invoked by VEGF-C in LECs and to identify the transcription factors (TFs) involved. We found that MAFB, a TF involved in differentiation of various cell types, is rapidly induced and activated by VEGF-C. MAFB induced expression of PROX1 as well as other TFs and markers of differentiated LECs, indicating a role in the maintenance of the mature LEC phenotype. Correspondingly, E14.5 Mafb(-/-) embryos showed impaired lymphatic patterning in the skin. This suggests that MAFB is an important TF involved in lymphangiogenesis.