Project description:Single cell RNAseq analysis of kidneys from P0 mouse demonstrated that expression of Vegfc by podocytes and mesangial cells is dispensable for glomerular development.
Project description:Microvascular dysfunction is a key driver of kidney disease. Pathophysiological changes in the kidney vasculature are regulated by vascular endothelial growth factor receptors (VEGFRs), supporting them as potential therapeutic targets. The tyrosine kinase receptor VEGFR-3, encoded by FLT4 and activated by the ligands VEGF-C and VEGF-D, is best known for its role in lymphangiogenesis. Therapeutically targeting VEGFR-3 to modulate lymphangiogenesis has been proposed as a strategy to treat kidney disease. However, outside the lymphatics, VEGFR-3 is also expressed in blood vascular endothelial cells in several tissues including the kidney. Here, we show that Vegfr-3 is expressed in fenestrated microvascular beds within the developing and adult mouse kidney, which include the glomerular capillary loops. We found that expression levels of VEGFR-3 are dynamic during glomerular capillary loop development, with the highest expression observed during endothelial cell migration into the S-shaped glomerular body. We developed a conditional knockout mouse model for Vegfr-3 and found that loss of Vegfr-3 resulted in a striking glomerular phenotype characterized by aneurysmal dilation of capillary loops, absence of mesangial structure, abnormal interendothelial cell junctions, and poor attachment between glomerular endothelial cells and the basement membrane. In addition, we demonstrated that expression of the VEGFR-3 ligand VEGF-C by podocytes and mesangial cells is dispensable for glomerular development. Instead, VEGFR-3 in glomerular endothelial cells attenuates VEGFR-2 phosphorylation. Together, the results of our study support a VEGF-C-independent functional role for VEGFR-3 in the kidney microvasculature outside of lymphatic vessels, which has implications for clinical therapies that target this receptor.NEW & NOTEWORTHY Targeting VEGFR-3 in kidney lymphatics has been proposed as a method to treat kidney disease. However, expression of VEGFR-3 is not lymphatic-specific. We demonstrated developmental expression of VEGFR-3 in glomerular endothelial cells, with loss of Vegfr-3 leading to malformation of glomerular capillary loops. Furthermore, we showed that VEGFR-3 attenuates VEGFR-2 activity in glomerular endothelial cells independent of paracrine VEGF-C signaling. Together, these data provide valuable information for therapeutic development targeting these pathways.
Project description:We have used a chimeric VEGFR-2 in which the extracellular domain of mouse VEGFR-2 was replaced with the extracellular domain of human CSF-1 receptor. VEGFR-2 was immunoprecipitated with anti-VEGFR-2 antibody from PAE cells ectopically expressing VEGFR-2. The immunoprecipitated proteins were eluted and separated on SDS-PAGE, followed by in-gel chymotrypsin or trypsin digestion. The digested samples were analyzed by nano LC/MS/MS on a Thermo Fisher LTQ Orbitrap XL. The LC-MS/MS data were analyzed using Proteome Discoverer (Thermo Fisher Scientific; Version 1.3.0.339). MS/MS search was carried out using Sequest search algorithm against the sequence of target mouse protein from the UniProtKB database. Search parameters included chymotrypsin as the enzyme with four missed cleavage allowed; methylation at lysine and arginine, phosphorylation of serine, threonine, and tyrosine, alkylation at cysteine, and oxidation of methionine were set as dynamic modifications. Precursor and fragment mass tolerance were set to 5 ppm and 0.8 Da, respectively. The false discovery rate was calculated by enabling the peptide sequence analysis using a decoy database. High confidence peptide identifications were obtained by setting a target false discovery rate threshold of 1% at the peptide level.
Project description:Melanoma growth is driven by malignant melanoma initiating cells (MMIC) identified by expression of the ATP-binding cassette (ABC) member, ABCB5. ABCB5+ melanoma subpopulations have been shown to overexpress the vasculogenic differentiation markers CD144 (VE-cadherin) and TIE-1 and are associated with CD31-negative vasculogenic mimicry (VM), an established biomarker associated with increased patient mortality. Here we identify a critical role for VEGFR-1 signaling in ABCB5+ MMIC-dependent VM and tumor growth. Global gene expression analyses, validated by mRNA and protein determinations, revealed preferential expression of VEGFR-1 on ABCB5+ tumor cells purified from clinical melanomas and established melanoma lines. In vitro, VEGF induced in a VEGFR-1-dependent manner expression of CD144 in ABCB5+ subpopulations that constitutively expressed VEGFR-1, but not in ABCB5- bulk populations that were predominantly VEGFR-1-negative. In vivo, melanomaspecific shRNA-mediated knockdown of VEGFR-1 blocked the development of ABCB5+ VM morphology and inhibited ABCB5+ VM-associated production of the secreted melanoma mitogen, laminin. Moreover, melanoma-specific VEGFR-1 knockdown markedly inhibited tumor growth (by >90%). Our results demonstrate that VEGFR-1 function in MMIC regulates VM and associated laminin production, and show that this function represents one mechanism through which MMIC promote tumor growth.
Project description:Retinal microvessels (RMVs) and brain microvessels (BMVs) were isolated from diabetic and nondiabetic rats. RNA were extracted, amplified and processed on Affymetrix rat 2.0 microarray Chips. Differently expressed genes (DEGs) between diabetic RMVs and nondiabetic RMVs, and between diabetic BMVs and nondiabetic BMVs were analyzed. Using these DEGs, we analyzed and compared the diabetic effects on the gene expression profiles in retinal microvasculature and brain microvasculature. In the brain microvasculature multiple compensatory mechanisms exists, serving to protect brain tissue from diabetic insults, whereas these mechanisms are not activated in the retinal microvasculature.
Project description:Melanoma growth is driven by malignant melanoma initiating cells (MMIC) identified by expression of the ATP-binding cassette (ABC) member, ABCB5. ABCB5+ melanoma subpopulations have been shown to overexpress the vasculogenic differentiation markers CD144 (VE-cadherin) and TIE-1 and are associated with CD31-negative vasculogenic mimicry (VM), an established biomarker associated with increased patient mortality. Here we identify a critical role for VEGFR-1 signaling in ABCB5+ MMIC-dependent VM and tumor growth. Global gene expression analyses, validated by mRNA and protein determinations, revealed preferential expression of VEGFR-1 on ABCB5+ tumor cells purified from clinical melanomas and established melanoma lines. In vitro, VEGF induced in a VEGFR-1-dependent manner expression of CD144 in ABCB5+ subpopulations that constitutively expressed VEGFR-1, but not in ABCB5- bulk populations that were predominantly VEGFR-1-negative. In vivo, melanomaspecific shRNA-mediated knockdown of VEGFR-1 blocked the development of ABCB5+ VM morphology and inhibited ABCB5+ VM-associated production of the secreted melanoma mitogen, laminin. Moreover, melanoma-specific VEGFR-1 knockdown markedly inhibited tumor growth (by >90%). Our results demonstrate that VEGFR-1 function in MMIC regulates VM and associated laminin production, and show that this function represents one mechanism through which MMIC promote tumor growth. Microarray analyses were performed on purified ABCB5+ (n=5) and ABCB5- (n=5) cell subsets derived from the established human melanoma cell lines G3361 and A375 and from three distinct clinical melanoma specimen. Total RNA was extracted, processed and hybridized onto Affymetrix human HG-U133Plus2 GeneChip microarrays (Affymetrix, Santa Clara, CA).
Project description:Glomerular endothelial cells were cultured in normal condition and treated or not with microvesicles derived from endothelial progenitor cells. mRNA profiling of glomerular endothelial cells , treated with MVs, was analyzed after normalization with mRNA profiling of untreated cells.