Rab5 is a GTPase protein that is involved in intracellular membrane trafficking. It functions by binding to various effector proteins and regulating cellular responses, including the formation of transport vesicles an...Rab5 is a GTPase protein that is involved in intracellular membrane trafficking. It functions by binding to various effector proteins and regulating cellular responses, including the formation of transport vesicles and their fusion with the cellular membrane. Rab5 has been reported to play an important role in the development of the zebrafish embryo;however, its role in axonal regeneration in the central nervous system remains unclear. In this study, we established a zebrafish Mauthner cell model of axonal injury using single-cell electroporation and two-photon axotomy techniques. We found that overexpression of Rab5 in single Mauthner cells promoted marked axonal regeneration and increased the number of intra-axonal transport vesicles. In contrast, treatment of zebrafish larvae with the Rab kinase inhibitor CID-1067700markedly inhibited axonal regeneration in Mauthner cells. We also found that Rab5 activated phosphatidylinositol 3-kinase(PI3K) during axonal repair of Mauthner cells and promoted the recovery of zebrafish locomotor function. Additionally, rapamycin, an inhibitor of the mechanistic target of rapamycin downstream of PI3K, markedly hindered axonal regeneration. These findings suggest that Rab5 promotes the axonal regeneration of injured zebrafish Mauthner cells by activating the PI3K signaling pathway.展开更多
BACKGROUND Diabetic nephropathy(DN)is a leading cause of chronic kidney disease and endstage renal disease,and is a significant global healthcare burden.Although proximal tubular epithelial cells(PTECs)and podocytes a...BACKGROUND Diabetic nephropathy(DN)is a leading cause of chronic kidney disease and endstage renal disease,and is a significant global healthcare burden.Although proximal tubular epithelial cells(PTECs)and podocytes are involved in DN progression,the specific molecular interactions between these cells are not well understood.AIM To elucidate the role of interleukin-6(IL-6)/Rab5 signaling in mediating crosstalk between PTECs and podocytes,and to evaluate the protective effects of nicotinamide mononucleotide(NMN)against DN progression.METHODS We utilized in vitro and in vivo models to investigate the pathogenesis of DN.In vitro,human PTECs and murine podocytes were cultured under high-glucose conditions,and IL-6 neutralizing antibodies or NMN treatments were applied.Podocyte injury was assessed by measurements of nephrin endocytosis,Rab5 activity,cytoskeletal organization,cell adhesion,and cell-spreading assays.In vivo,DN was induced in mice using streptozotocin,and mice then received NMN,insulin,or both treatments over an 8-week period.Renal tissues were analyzed histologically,ultrastructurally,and immunochemically,and urinary albumin excretion was measured to assess renal function.Statistical analyses were conducted using one-way ANOVA and Tukey's test.RESULTS High-glucose conditions induced the epithelial-mesenchymal transition(EMT)in PTECs,increased IL-6 secretion,and activated Rab5 signaling in podocytes,leading to increased nephrin endocytosis and podocyte injury.Blocking IL-6 significantly attenuated these effects.NMN treatment of diabetic mice markedly reduced podocyte injury,glomerular hypertrophy,foot-process effacement,and urinary albumin excretion.Mechanistically,NMN suppressed the EMT and IL-6 secretion by PTECs,inhibited Rab5 activation in podocytes,and prevented nephrin endocytosis,thereby preserving the cytoskeletal integrity and function of podocytes.CONCLUSION Our findings reveal a novel pathogenic mechanism of DN in which IL-6 released from glucose-stressed PTECs activates Rab5 signaling in podocytes,followed by nephrin endocytosis and structural injury of podocytes.Importantly,NMN treatment effectively disrupted this pathological pathway of intercellular communication,and provided significant protection against DN progression.These results suggest that NMN supplementation and targeting the IL-6/Rab5 signaling axis has promise as a therapeutic strategy for managing DN.展开更多
基金supported by the Research Funds of the Center for Advanced Interdisciplinary Science and Biomedicine of IHM,No.QYZD20220002the National Natural Science Foundation of China,No.82071357a grant from the Ministry of Science and Technology of China,No.2019YFA0405600 (all to BH)。
文摘Rab5 is a GTPase protein that is involved in intracellular membrane trafficking. It functions by binding to various effector proteins and regulating cellular responses, including the formation of transport vesicles and their fusion with the cellular membrane. Rab5 has been reported to play an important role in the development of the zebrafish embryo;however, its role in axonal regeneration in the central nervous system remains unclear. In this study, we established a zebrafish Mauthner cell model of axonal injury using single-cell electroporation and two-photon axotomy techniques. We found that overexpression of Rab5 in single Mauthner cells promoted marked axonal regeneration and increased the number of intra-axonal transport vesicles. In contrast, treatment of zebrafish larvae with the Rab kinase inhibitor CID-1067700markedly inhibited axonal regeneration in Mauthner cells. We also found that Rab5 activated phosphatidylinositol 3-kinase(PI3K) during axonal repair of Mauthner cells and promoted the recovery of zebrafish locomotor function. Additionally, rapamycin, an inhibitor of the mechanistic target of rapamycin downstream of PI3K, markedly hindered axonal regeneration. These findings suggest that Rab5 promotes the axonal regeneration of injured zebrafish Mauthner cells by activating the PI3K signaling pathway.
基金Supported by Hubei Provincial Natural Science Foundation,No.2023AFB732and Scientific Research Project of Hubei Provincial Health Commission,No.WJ2023M053.
文摘BACKGROUND Diabetic nephropathy(DN)is a leading cause of chronic kidney disease and endstage renal disease,and is a significant global healthcare burden.Although proximal tubular epithelial cells(PTECs)and podocytes are involved in DN progression,the specific molecular interactions between these cells are not well understood.AIM To elucidate the role of interleukin-6(IL-6)/Rab5 signaling in mediating crosstalk between PTECs and podocytes,and to evaluate the protective effects of nicotinamide mononucleotide(NMN)against DN progression.METHODS We utilized in vitro and in vivo models to investigate the pathogenesis of DN.In vitro,human PTECs and murine podocytes were cultured under high-glucose conditions,and IL-6 neutralizing antibodies or NMN treatments were applied.Podocyte injury was assessed by measurements of nephrin endocytosis,Rab5 activity,cytoskeletal organization,cell adhesion,and cell-spreading assays.In vivo,DN was induced in mice using streptozotocin,and mice then received NMN,insulin,or both treatments over an 8-week period.Renal tissues were analyzed histologically,ultrastructurally,and immunochemically,and urinary albumin excretion was measured to assess renal function.Statistical analyses were conducted using one-way ANOVA and Tukey's test.RESULTS High-glucose conditions induced the epithelial-mesenchymal transition(EMT)in PTECs,increased IL-6 secretion,and activated Rab5 signaling in podocytes,leading to increased nephrin endocytosis and podocyte injury.Blocking IL-6 significantly attenuated these effects.NMN treatment of diabetic mice markedly reduced podocyte injury,glomerular hypertrophy,foot-process effacement,and urinary albumin excretion.Mechanistically,NMN suppressed the EMT and IL-6 secretion by PTECs,inhibited Rab5 activation in podocytes,and prevented nephrin endocytosis,thereby preserving the cytoskeletal integrity and function of podocytes.CONCLUSION Our findings reveal a novel pathogenic mechanism of DN in which IL-6 released from glucose-stressed PTECs activates Rab5 signaling in podocytes,followed by nephrin endocytosis and structural injury of podocytes.Importantly,NMN treatment effectively disrupted this pathological pathway of intercellular communication,and provided significant protection against DN progression.These results suggest that NMN supplementation and targeting the IL-6/Rab5 signaling axis has promise as a therapeutic strategy for managing DN.
