Metabolically stressed kidney is in part characterized by infiltrating macrophages and macrophage-derived TGF-β1 that promote the synthesis of various ECM molecules. TGF-β1 strongly enhances the expression of the ge...Metabolically stressed kidney is in part characterized by infiltrating macrophages and macrophage-derived TGF-β1 that promote the synthesis of various ECM molecules. TGF-β1 strongly enhances the expression of the gene TGFBI that encodes a cell-adhesion class, proapoptotic ECM protein called BIGH3. We hypothesized that in a diabetic environment a relationship between infiltrating macrophages, macrophage-derived TGF-β1, and BIGH3 protein promotes renal cell death. To investigate this hypothesis, we used our mouse model of diabetic complications. Mice on a high-fat diet developed hypercholesterolemia, and exposure to streptozotocin rendered hypercholesterolemic mice diabetic. Immunohistochemical images show increased macrophage infiltration and BIGH3 protein in the kidney cortices of hypercholesterolemic and diabetic mice. Macrophages induced a two-fold increase in BIGH3 expression and an 86% increase in renal proximal tubule epithelial cell apoptosis. TGF-β1 antibody and TGF-β1 receptor chemical antagonist blocked macrophage-induced apoptosis. BIGH3 antibody completely blocked apoptosis that was induced by TGF-β1, and blocked apoptosis induced by exogenous recombinant BIGH3. These results uncover a distinctive interplay of macrophage-derived TGF-β1, BIGH3 protein, and apoptosis, and indicate that BIGH3 is central in a novel pathway that promotes diabetic nephropathy. Macrophage TGF-β1 and BIGH3 are identified as prediabetic biomarkers, and potential therapeutic targets for intervention in prediabetic and diabetic individuals.展开更多
Numerous studies have demonstrated a relationship between the extracellular matrix protein BIGH3 and variations in the malignant properties of different cancer cell types, including osteosarcoma cells. BIGH3 protein c...Numerous studies have demonstrated a relationship between the extracellular matrix protein BIGH3 and variations in the malignant properties of different cancer cell types, including osteosarcoma cells. BIGH3 protein can suppress and promote tumor growth, even on the same cancer cell type, indicating that contextual cues regulate BIGH3-mediated divergent outcomes. We employed a multicellular tumor spheroid model to study the effects of BIGH3 with respect to physical and molecular features of three-dimensional tumor growth. The results demonstrated that exogenous recombinant BIGH3 blocked the development of multicellular large tumor spheroids so that only small spheroids formed. The effect was dependent on the BIGH3 concentration in the growth medium and the time of incubation of BIGH3 with the osteosarcoma cells in the spheroid model. TGF-β1 signaling induced multicellular tumor spheroids to synthesize a greater quantity of BIGH3 relative to non-treated spheroids. The TGF-β1-mediated increase in BIGH3 protein antagonized the development of multicellular large spheroids. Anti-BIGH3 antibody, and an inhibitor of TGF-β1 signaling, blocked the antagonistic effect induced through TGF-β1 stimulation and BIGH3 protein expression, resulting in the formation of multicellular large spheroids. Immunohistochemistry detected BIGH3 at cell bodies within the spheroid stroma, suggesting osteosarcoma cell-surface proteins bind BIGH3. Flow cytometry demonstrates that osteosarcoma cells interact with soluble BIGH3, and solid-phase cell adhesion assays show that osteosarcoma adhesion to BIGH3 substratum is mediated by integrin α4β1. However, anti-α4 antibody did not attenuate the BIGH3-mediated antagonism toward formation of multicellular large spheroids. We conclude that TGFβ1 and BIGH3 suppress the development of large osteosarcoma tumors.展开更多
文摘Metabolically stressed kidney is in part characterized by infiltrating macrophages and macrophage-derived TGF-β1 that promote the synthesis of various ECM molecules. TGF-β1 strongly enhances the expression of the gene TGFBI that encodes a cell-adhesion class, proapoptotic ECM protein called BIGH3. We hypothesized that in a diabetic environment a relationship between infiltrating macrophages, macrophage-derived TGF-β1, and BIGH3 protein promotes renal cell death. To investigate this hypothesis, we used our mouse model of diabetic complications. Mice on a high-fat diet developed hypercholesterolemia, and exposure to streptozotocin rendered hypercholesterolemic mice diabetic. Immunohistochemical images show increased macrophage infiltration and BIGH3 protein in the kidney cortices of hypercholesterolemic and diabetic mice. Macrophages induced a two-fold increase in BIGH3 expression and an 86% increase in renal proximal tubule epithelial cell apoptosis. TGF-β1 antibody and TGF-β1 receptor chemical antagonist blocked macrophage-induced apoptosis. BIGH3 antibody completely blocked apoptosis that was induced by TGF-β1, and blocked apoptosis induced by exogenous recombinant BIGH3. These results uncover a distinctive interplay of macrophage-derived TGF-β1, BIGH3 protein, and apoptosis, and indicate that BIGH3 is central in a novel pathway that promotes diabetic nephropathy. Macrophage TGF-β1 and BIGH3 are identified as prediabetic biomarkers, and potential therapeutic targets for intervention in prediabetic and diabetic individuals.
文摘Numerous studies have demonstrated a relationship between the extracellular matrix protein BIGH3 and variations in the malignant properties of different cancer cell types, including osteosarcoma cells. BIGH3 protein can suppress and promote tumor growth, even on the same cancer cell type, indicating that contextual cues regulate BIGH3-mediated divergent outcomes. We employed a multicellular tumor spheroid model to study the effects of BIGH3 with respect to physical and molecular features of three-dimensional tumor growth. The results demonstrated that exogenous recombinant BIGH3 blocked the development of multicellular large tumor spheroids so that only small spheroids formed. The effect was dependent on the BIGH3 concentration in the growth medium and the time of incubation of BIGH3 with the osteosarcoma cells in the spheroid model. TGF-β1 signaling induced multicellular tumor spheroids to synthesize a greater quantity of BIGH3 relative to non-treated spheroids. The TGF-β1-mediated increase in BIGH3 protein antagonized the development of multicellular large spheroids. Anti-BIGH3 antibody, and an inhibitor of TGF-β1 signaling, blocked the antagonistic effect induced through TGF-β1 stimulation and BIGH3 protein expression, resulting in the formation of multicellular large spheroids. Immunohistochemistry detected BIGH3 at cell bodies within the spheroid stroma, suggesting osteosarcoma cell-surface proteins bind BIGH3. Flow cytometry demonstrates that osteosarcoma cells interact with soluble BIGH3, and solid-phase cell adhesion assays show that osteosarcoma adhesion to BIGH3 substratum is mediated by integrin α4β1. However, anti-α4 antibody did not attenuate the BIGH3-mediated antagonism toward formation of multicellular large spheroids. We conclude that TGFβ1 and BIGH3 suppress the development of large osteosarcoma tumors.
