Kidney denervation prevents the development of tubulointerstitial fibrosis, but the neuropeptide calcitonin gene-related peptide (CGRP) in the denervated kidneys restores the fibrotic feature through ...the upregulation of profibrogenic growth factors. CGRP is involved in aggravation of inflammation by increasing the number of circulating cells and chemotactic factors. However, it is not clear how CGRP contributes to the upregulation of profibrogenic factors during fibrogenesis. In both human and pig kidney proximal tubular cell lines, administration of 1 nM CGRP significantly increased the levels of transforming growth factor-β1 (TGF-β1) production and connective tissue growth factor (CTGF) expression at 6 and 24 h after the administration. Exogenous CGRP also increased the TGF-β1 and CTGF protein levels in the incubation media, indicating release of these proteins from the cells. Treatment with 100 nM CGRP receptor antagonist (CGRP
8-37
) for 24 h significantly inhibited the increase in intracellular levels and released levels of TGF-β1 and CTGF in CGRP-treated cells. Genetic inhibition of CGRP receptor using siRNA transfection also suppressed the increase in TGF-β1 production and release at 24 h after CGRP stimulation. Furthermore, treatment with a specific protein kinase C (PKC) inhibitor chelerythrine (1 thru 10 μM) markedly reduced the upregulation and release of TGF-β1 and CTGF 6 h after CGRP administration. Finally, inhibition of c-Jun N-terminal protein kinase (JNK) phosphorylation using 1 μM SP600125 prevented the increase in TGF-β1 and CTGF upregulation and release 6 h after CGRP administration. Consistent with the in vitro data, exogenous CGRP in denervated UUO kidneys upregulated and secreted TGF-β1 and CTGF in dependence on PKC activation and JNK phosphorylation. In conclusion, these data suggest that exogenous CGRP induces the upregulation and secretion of profibrogenic TGF-β1 and CTGF proteins through the CGRP receptor/PKC/JNK signaling pathway in kidney proximal tubular cells.
The mammalian gastrointestinal tract harbors a highly complex microbial community that comprises hundreds of different types of bacterial cells. The gastrointestinal microbiota plays an important ...role in the function of the host intestine. Most cancer patients undergoing pelvic irradiation experience side effects such as diarrhea; however, little is currently known about the effects of irradiation on the microorganisms colonizing the mucosal surfaces of the gastrointestinal tract. The aim of this study was to investigate the effects of gamma irradiation on the compositions of the large and small intestinal microbiotas. The gut microbiotas in control mice and mice receiving irradiation treatment were characterized by high-throughput sequencing of the bacterial 16S rRNA gene. Irradiation treatment induced significant alterations in the bacterial compositions of the large and small intestines at the genus level. Unexpectedly, irradiation treatment increased the number of operational taxonomic units in the small intestine but not the large intestine. In particular, irradiation treatment increased the level of the genera Alistipes in the large intestine and increased the level of the genus Corynebacterium in the small intestine. By contrast, compared with that in the corresponding control group, the level of the genera Prevotella was lower in the irradiated large intestine, and the level of the genera Alistipes was lower in the irradiated small intestine. Overall, the data presented here reveal the potential microbiological effects of pelvic irradiation on the gastrointestinal tracts of cancer patients.
•The gut microbiota in mice receiving irradiation was characterized by high-throughput sequencing method using 16S rRNA gene.•Gut microbial abundances showed that significant alterations in the both intestines affected by radiation.•Alistipes and Mucisprillum might be associated with gamma irradiation exposure and host gut health.
The kidney is a highly metabolic organ and uses high levels of ATP to maintain electrolyte and acid-base homeostasis and reabsorb nutrients. Energy depletion is a critical factor in development and ...progression of various kidney diseases including acute kidney injury (AKI), chronic kidney disease (CKD), and diabetic and glomerular nephropathy. Mitochondrial fatty acid β-oxidation (FAO) serves as the preferred source of ATP in the kidney and its dysfunction results in ATP depletion and lipotoxicity to elicit tubular injury and inflammation and subsequent fibrosis progression. This review explores the current state of knowledge on the role of mitochondrial FAO dysfunction in the pathophysiology of kidney diseases including AKI and CKD and prospective views on developing therapeutic interventions based on mitochondrial energy metabolism.
The contribution of p53 to kidney dysfunction, inflammation, and tubular cell death, hallmark features of ischemic renal injury (IRI), remains undefined. Here, we studied the role of proximal tubule ...cell (PTC)-specific p53 activation on the short- and long-term consequences of renal ischemia/reperfusion injury in mice. After IRI, mice with PTC-specific deletion of p53 (p53 knockout KO) had diminished whole-kidney expression levels of p53 and its target genes, improved renal function, which was shown by decreased plasma levels of creatinine and BUN, and attenuated renal histologic damage, oxidative stress, and infiltration of neutrophils and macrophages compared with wild-type mice. Notably, necrotic cell death was attenuated in p53 KO ischemic kidneys as well as oxidant-injured p53-deficient primary PTCs and pifithrin-α-treated PTC lines. Reduced oxidative stress and diminished expression of PARP1 and Bax in p53 KO ischemic kidneys may account for the decreased necrosis. Apoptosis and expression of proapoptotic p53 targets, including Bid and Siva, were also significantly reduced, and cell cycle arrest at the G2/M phase was attenuated in p53 KO ischemic kidneys. Furthermore, IRI-induced activation of TGF-β and the long-term development of inflammation and interstitial fibrosis were significantly reduced in p53 KO mice. In conclusion, specific deletion of p53 in the PTC protects kidneys from functional and histologic deterioration after IRI by decreasing necrosis, apoptosis, and inflammation and modulates the long-term sequelae of IRI by preventing interstitial fibrogenesis.
Kidney ischemia and reperfusion injury (IRI) is a significant contributor to acute kidney injury (AKI), characterized by tubular injury and kidney dysfunction. Salvador family WW domain containing ...protein 1 (SAV1) is a key component of the Hippo pathway and plays a crucial role in the regulation of organ size and tissue regeneration. However, whether SAV1 plays a role in kidney IRI is not investigated. In this study, we investigated the role of SAV1 in kidney injury and regeneration following IRI. A proximal tubule-specific knockout of
in kidneys (
) was generated, and wild-type and
mice underwent kidney IRI or sham operation. Plasma creatinine and blood urea nitrogen were measured to assess kidney function. Histological studies, including periodic acid-Schiff staining and immunohistochemistry, were conducted to assess tubular injury, SAV1 expression, and cell proliferation. Western blot analysis was employed to assess the Hippo pathway-related and proliferation-related proteins. SAV1 exhibited faint expression in the proximal tubules and was predominantly expressed in the connecting tubule to the collecting duct. At 48 h after IRI,
mice continued to exhibit severe kidney dysfunction, compared to attenuated kidney dysfunction in wild-type mice. Consistent with the functional data, severe tubular damage induced by kidney IRI in the cortex was significantly decreased in wild-type mice at 48 h after IRI but not in
mice. Furthermore, 48 h after IRI, the number of Ki67-positive cells in the cortex was significantly higher in wild-type mice than
mice. After IRI, activation and expression of Hippo pathway-related proteins were enhanced, with no significant differences observed between wild-type and
mice. Notably, at 48 h after IRI, protein kinase B activation (AKT) was significantly enhanced in
mice compared to wild-type mice. This study demonstrates that
deficiency in the kidney proximal tubule worsens the injury and delays kidney regeneration after IRI, potentially through the overactivation of AKT.
Cisplatin is a well-known chemotherapy medication used to treat numerous cancers. However, treatment with cisplatin in cancer therapy has major side effects, such as nephrotoxic acute kidney injury. ...Adult vertebrate kidneys are commonly used as models of cisplatin-induced nephrotoxic acute kidney injury. Embryonic zebrafish kidney is more simplified and is composed simply of two nephrons and thus is an excellent model for the investigation of cisplatin nephrotoxicity. Here, we developed a novel model to induce cisplatin nephrotoxicity in adult zebrafish and demonstrated that intraperitoneal injection of cisplatin caused a decline in kidney proximal tubular function based on fluorescein-labeled dextran uptake and alkaline phosphatase staining. We also showed that cisplatin induced histological injury of the kidney tubules, quantified by tubular injury scores on the periodic acid-Schiff-stained kidney sections. As shown in a mouse model of cisplatin-induced nephrotoxicity, the activation of poly(ADP-ribose) polymerase (PARP), an enzyme implicated in cisplatin-induced cell death, was markedly increased after cisplatin injection in adult zebrafish. Furthermore, pharmacological inhibition of PARP using a specific PARP inhibitor PJ 34 hydrochloride (PJ34) or 3-aminobenzamide ameliorated kidney proximal tubular functional and histological damages in cisplatin-injected adult zebrafish kidneys. Administration of a combination of PARP inhibitors PJ34 and 3-aminobenzamide additively protected renal function and histology in zebrafish and mouse models of cisplatin nephrotoxicity. In conclusion, these data suggest that adult zebrafish are not only suitable for drug screening and genetic manipulation but also useful as a simplified but powerful model to study the pathophysiology of cisplatin nephrotoxicity and establish new therapies for treating human kidney diseases.
Clear cell renal cell carcinoma (ccRCC) alters metabolic signals frequently, leading to mitochondrial dysfunction, such as increase of glycolysis and accumulation of lipid. Sirtuin3 (SIRT3) is a key ...factor for the regulation of both mitochondrial integrity and function. SIRT3 is downregulated and contributes in both cancer development and progression in ccRCC. The aim of this study is to investigate SIRT3-regulated mitochondrial biogenesis in ccRCC. SIRT3 overexpression alone reduced glucose uptake rate and enhanced membrane potential in mitochondria. ccRCC with overexpressed SIRT3 further improved the lethal effects when combined with anticancer drugs (Resveratrol, Everolimus and Temsirolimus). Cell viability was markedly decreased in a dose-dependent manner when treated with resveratrol or mTOR inhibitors in SIRT3 overexpressing ccRCC. In conclusion, SIRT3 improved mitochondrial functions in ccRCC through metabolic reprogramming. Mitochondrial reprogramming by SIRT3 regulation improves the sensitivity to anticancer drugs. The combination of SIRT3 and resveratrol functioned synergistically lethal effect in ccRCC.
Recently, kidney fibrosis following transplantation has become recognized as a main contributor of chronic allograft nephropathy. In transplantation, transient ischemia is an inescapable event. ...Reactive oxygen species (ROS) play a critical role in ischemia and reperfusion (I/R)-induced acute kidney injury, as well as progression of fibrosis in various diseases such as hypertension, diabetes, and ureteral obstruction. However, a role of ROS/oxidative stress in chronic kidney fibrosis following I/R injury remains to be defined. In this study, we investigated the involvement of ROS/oxidative stress in kidney fibrosis following kidney I/R in mice. Mice were subjected to 30 min of bilateral kidney ischemia followed by reperfusion on day 0 and then administered with either manganese (III) tetrakis(1-methyl-4-pyridyl) porphyrin (MnTMPyP, 5 mg/kg body wt ip), a cell permeable superoxide dismutase (SOD) mimetic, or 0.9% saline (vehicle) beginning at 48 h after I/R for 14 days. I/R significantly increased interstitial extension, collagen deposition, apoptosis of tubular epithelial cells, nitrotyrosine expression, hydrogen peroxide production, and lipid peroxidation and decreased copper-zinc SOD, manganese SOD, and glucose 6-phosphate dehydrogenase activities in the kidneys 16 days after the procedure. MnTMPyP administration minimized these postischemic changes. In addition, MnTMPyP administration significantly attenuated the increases of alpha-smooth muscle actin, PCNA, S100A4, CD68, and heat shock protein 47 expression following I/R. We concluded that kidney fibrosis develops chronically following I/R injury, and this process is associated with the increase of ROS/oxidative stress.
Tp53-induced glycolysis and apoptosis regulator (TIGAR) activation blocks glycolytic ATP synthesis by inhibiting phosphofructokinase-1 activity. Our data indicate that TIGAR is selectively induced ...and activated in renal outermedullary proximal straight tubules (PSTs) after ischemia-reperfusion injury in a p53-dependent manner. Under severe ischemic conditions, TIGAR expression persisted through 48 h postinjury and induced loss of renal function and histological damage. Furthermore, TIGAR upregulation inhibited phosphofructokinase-1 activity, glucose 6-phosphate dehydrogenase (G6PD) activity, and induced ATP depletion, oxidative stress, autophagy, and apoptosis. Small interfering RNA-mediated TIGAR inhibition prevented the aforementioned malevolent effects and protected the kidneys from functional and histological damage. After mild ischemia, but not severe ischemia, G6PD activity and NADPH levels were restored, suggesting that TIGAR activation may redirect the glycolytic pathway into gluconeogenesis or the pentose phosphate pathway to produce NADPH. The increased level of NADPH maintained the level of GSH to scavenge ROS, resulting in a lower sensitivity of PST cells to injury. Under severe ischemia, G6PD activity and NADPH levels were reduced during reperfusion; however, blockade of TIGAR enhanced their levels and reduced oxidative stress and apoptosis. Collectively, these results demonstrate that inhibition of TIGAR may protect PST cells from energy depletion and apoptotic cell death in the setting of severe ischemia-reperfusion injury. However, under low ischemic burden, TIGAR activation induces the pentose phosphate pathway and autophagy as a protective mechanism.
PDF
