Renal Vascular Smooth Muscle Cells Research Articles

Preliminary Exploration of Potential Active Ingredients and Molecular Mechanisms of Yanggan Yishui Granules for Treating Hypertensive Nephropathy Using UPLC-Q-TOF/MS Coupled with Network Pharmacology and Molecular Docking Strategy.

Hypertensive nephropathy (HN) is a prevalent complication of hypertension and stands as the second primary reason for end-stage renal disease. Research in clinical settings has revealed that Yanggan Yishui Granule (YGYSG) has significant therapeutic effects on HN. However, the material basis and action mechanisms of YGYSG against HN remain unclear. Consequently, this study utilized a comprehensive method integrating ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS), network pharmacology, and molecular docking to delineate the active ingredients and potential therapeutic mechanisms of YGYSG for treating HN. Firstly, sixty distinct components were recognized in total as potential active ingredients in YGYSG by UPLC-Q-TOF/MS. Subsequently, the mechanisms of YGYSG against HN were revealed for the first time using network pharmacology. 23 ingredients played key roles in the complete network and were the key active ingredients, which could affect the renin-angiotensin system, fluid shear stress and atherosclerosis, HIF-1 signaling pathway, and AGE-RAGE signaling pathway in diabetic complications by regulating 29 key targets such as TNF, IL6, ALB, EGFR, ACE, and MMP2. YGYSG could treat HN through the suppression of inflammatory response and oxidative stress, attenuating the proliferation of renal vascular smooth muscle cells, lessening glomerular capillary systolic pressure, and ameliorating renal dysfunction and vascular damage through the aforementioned targets and pathways. Molecular docking results revealed that most key active ingredients exhibited a high affinity for binding to the key targets. This study pioneers in clarifying the bioactive compounds and molecular mechanisms of YGYSG against HN and offers scientific reference into the clinical application.

Calcineurin Is a Universal Regulator of Vessel Function-Focus on Vascular Smooth Muscle Cells.

Calcineurin, a serine/threonine phosphatase regulating transcription factors like NFaT and CREB, is well known for its immune modulatory effects and role in cardiac hypertrophy. Results from experiments with calcineurin knockout animals and calcineurin inhibitors indicate that calcineurin also plays a crucial role in vascular function, especially in vascular smooth muscle cells (VSMCs). In the aorta, calcineurin stimulates the proliferation and migration of VSMCs in response to vascular injury or angiotensin II administration, leading to pathological vessel wall thickening. In the heart, calcineurin mediates coronary artery formation and VSMC differentiation, which are crucial for proper heart development. In pulmonary VSMCs, calcineurin/NFaT signaling regulates the release of Ca2+, resulting in increased vascular tone followed by pulmonary arterial hypertension. In renal VSMCs, calcineurin regulates extracellular matrix secretion promoting fibrosis development. In the mesenteric and cerebral arteries, calcineurin mediates a phenotypic switch of VSMCs leading to altered cell function. Gaining deeper insights into the underlying mechanisms of calcineurin signaling will help researchers to understand developmental and pathogenetical aspects of the vasculature. In this review, we provide an overview of the physiological function and pathophysiology of calcineurin in the vascular system with a focus on vascular smooth muscle cells in different organs. Overall, there are indications that under certain pathological settings reduced calcineurin activity seems to be beneficial for cardiovascular health.

Interaction of Angiotensin II AT1 Receptors with Purinergic P2X Receptors in Regulating Renal Afferent Arterioles in Angiotensin II-Dependent Hypertension.

In angiotensin II (Ang II)-dependent hypertension, Ang II activates angiotensin II type 1 receptors (AT1R) on renal vascular smooth muscle cells, leading to renal vasoconstriction with eventual glomerular and tubular injury and interstitial inflammation. While afferent arteriolar vasoconstriction is initiated by the increased intrarenal levels of Ang II activating AT1R, the progressive increases in arterial pressure stimulate the paracrine secretion of adenosine triphosphate (ATP), leading to the purinergic P2X receptor (P2XR)-mediated constriction of afferent arterioles. Thus, the afferent arteriolar tone is maintained by two powerful systems eliciting the co-existing activation of P2XR and AT1R. This raises the conundrum of how the AT1R and P2XR can both be responsible for most of the increased renal afferent vascular resistance existing in angiotensin-dependent hypertension. Its resolution implies that AT1R and P2XR share common receptor or post receptor signaling mechanisms which converge to maintain renal vasoconstriction in Ang II-dependent hypertension. In this review, we briefly discuss (1) the regulation of renal afferent arterioles in Ang II-dependent hypertension, (2) the interaction of AT1R and P2XR activation in regulating renal afferent arterioles in a setting of hypertension, (3) mechanisms regulating ATP release and effect of angiotensin II on ATP release, and (4) the possible intracellular pathways involved in AT1R and P2XR interactions. Emerging evidence supports the hypothesis that P2X1R, P2X7R, and AT1R actions converge at receptor or post-receptor signaling pathways but that P2XR exerts a dominant influence abrogating the actions of AT1R on renal afferent arterioles in Ang II-dependent hypertension. This finding raises clinical implications for the design of therapeutic interventions that will prevent the impairment of kidney function and subsequent tissue injury.

Postinjury Inhibition of Endothelin‐1 Dependent Renal Vasoregulation Mitigates Rhabdomyolysis‐Induced Acute Kidney Injury

Rhabdomyolysis is a life‐threatening condition resulting from the breakdown of skeletal muscle fibers leading to the release of myoglobin into the blood. Increased circulating myoglobin can cause kidney damage, and acute kidney injury (AKI) occurs in 33‐50% of patients with myoglobinuria. Persistent constriction of the renal microvessels, which reduces renal blood flow (RBF) and glomerular filtration rate (GFR), contributes to rhabdomyolysis‐induced AKI. Since activation of G‐protein‐coupled receptors (GPCR) and ion channels regulate renal vascular resistance (RVR), rhabdomyolysis may likely modulate RVR via GPCR and vascular ion channel mechanisms. Pretreatment of rats with an endothelin receptor antagonist has been shown to alleviate rhabdomyolysis‐induced AKI. However, the downstream and upstream links between rhabdomyolysis and increased ET‐1 synthesis are unknown. The downstream effectors of ET‐1‐induced vasoconstriction are smooth muscle cell (SMC) Ca2+‐permeable ion channels. Yet, the ion channel mechanisms that trigger renal vasoconstriction in rhabdomyolysis‐induced AKI remain unknown. Also, most cases of rhabdomyolysis‐induced AKI cannot be predicted. Whether post‐injury inhibition of the vascular mechanisms of ET‐1 ameliorates, rhabdomyolysis‐induced AKI is unknown. This study investigates post‐injury renal production and vascular regulation of the ET system in rhabdomyolysis‐induced AKI. Six h of rhabdomyolysis increased peptidase endothelin converting enzyme (ECE‐1)‐dependent biosynthesis of ET‐1 in the kidneys. Rhabdomyolysis‐induced AKI was not sex‐dependent. At 24 h, rhabdomyolysis also increased renal reactive oxygen species (ROS), ECE‐1, and ET‐1 levels. Furthermore, ET‐1 activated rat renal vascular smooth muscle cell TRPC3 leading to a reduction in RBF and increased RVR. Protein expression levels of the ET receptors (ETA and ETB) and TRPC3 channels in renal microvessels were unaltered. However, postinjury inhibition of ECE1, ET Receptors, and TRPC3 mitigated rhabdomyolysis‐induced GFR impairment, renal hypoperfusion, AKI biomarker elevation, and morphological kidney damage. To further explore the role of TRPC3 ion channels in rhabdomyolysis‐induced AKI, we subjected TRPC3 knock‐out (KO) rats to rhabdomyolysis. Compared to their wild‐type counterparts, KO rats show protection against rhabdomyolysis‐induced AKI. Our findings suggest that ECE‐driven proteolytic ET‐1 production contributes to rhabdomyolysis‐induced AKI. Downstream, ET‐derived DAG activates renal vascular smooth muscle cell TRPC3 channels leading to extracellular calcium entry, vasoconstriction, increased RVR, and reduced GFR.

Qualitative analysis of two systems of nonlinear first‐order ordinary differential equations for biological systems

We consider two systems of nonlinear first‐order ordinary differential equations proposed to describe ‐levels in renal vascular smooth muscle cells and in liver cells. Initially, we present the models and its assumptions. We next investigate an approach to local solvability by Picard–Lindelöf 's Theorem. Further, we prove nonnegativity of the systems' possible solutions and we especially conclude global unique existence of the models' solutions by Gronwall‐type arguments and the concept of trapping regions. After finishing our theoretical part with some aspects of stability analysis, we provide evidence of our findings by some numerical experiments.

KV7.1 channel blockade inhibits neonatal renal autoregulation triggered by a step decrease in arterial pressure.

KV7 channels, the voltage-gated K+ channels encoded by KCNQ genes, mediate heterogeneous vascular responses in rodents. Postnatal changes in the functional expression of KV7 channels have been reported in rodent saphenous arteries, but their physiological function in the neonatal renal vascular bed is unclear. Here, we report that, unlike adult pigs, only KCNQ1 (KV7.1) out of the five members of KCNQ genes was detected in neonatal pig renal microvessels. KCNQ1 is present in fetal pig kidneys as early as day 50 of gestation, and the level of expression remains the same up to postnatal day 21. Activation of renal vascular smooth muscle cell (SMC) KV7.1 stimulated whole cell currents, inhibited by HMR1556 (HMR), a selective KV7.1 blocker. HMR did not change the steady-state diameter of isolated renal microvessels. Similarly, intrarenal artery infusion of HMR did not alter mean arterial pressure, renal blood flow, and renal vascular resistance in the pigs. An ∼20 mmHg reduction in mean arterial pressure evoked effective autoregulation of renal blood flow, which HMR inhibited. We conclude that 1) the expression of KCNQ isoforms in porcine renal microvessels is dependent on kidney maturation, 2) KV7.1 is functionally expressed in neonatal pig renal vascular SMCs, 3) a decrease in arterial pressure up to 20 mmHg induces renal autoregulation in neonatal pigs, and 4) SMC KV7.1 does not control basal renal vascular tone but contributes to neonatal renal autoregulation triggered by a step decrease in arterial pressure.NEW & NOTEWORTHY KV7.1 is present in fetal pig kidneys as early as day 50 of gestation, and the level of expression remains the same up to postnatal day 21. KV7.1 is functionally expressed in neonatal pig renal vascular smooth muscle cells (SMCs). A decrease in arterial pressure up to 20 mmHg induces renal autoregulation in neonatal pigs. Although SMC KV7.1 does not control basal renal vascular resistance, its inhibition blunts neonatal renal autoregulation engendered by a step decrease in arterial pressure.

Retraction

Retraction: "Activation of the Nrf2-ARE Signaling Pathway Prevents Hyperphosphatemia-Induced Vascular Calcification by Inducing Autophagy in Renal Vascular Smooth Muscle Cells," by Li Yao, Jian Wang, Bin-Yao Tian, Tian-Hua Xu, Zi-Tong Sheng, J Cell Biochem. 2017; 4708-4715: The above article, published online on 17 May 2017 in Wiley Online Library (https://onlinelibrary.wiley.com/doi/10.1002/jcb.26137) has been retracted by agreement between the the journal's Editor in Chief, Prof. Dr. Christian Behl, and Wiley Periodicals LLC. The retraction has been agreed following an investigation based on allegations raised by a third party. A detailed investigation revealed that several image elements of the experimental data were published elsewhere in a different scientific context. Thus, the editors consider the conclusions of this article to be invalid.

Activation of the renal GLP-1R leads to expression of Ren1 in the renal vascular tree.

The GLP‐1 receptor (GLP‐1R) in the kidney is expressed exclusively in vascular smooth muscle cells in arteries and arterioles. Downstream effects of the activation of the renal vascular GLP‐1R are elusive but may involve regulation of the renin‐angiotensin‐aldosterone system (RAAS). The expression of Ren1 in the mouse renal vasculature was investigated by in situ hybridization after a single subcutaneous dose of liraglutide, semaglutide and after repeated injections of liraglutide. Single and repeated exposure to GLP‐1R agonists induced expression of Ren1 in the renal vascular smooth muscle cell compartment compared with vehicle injected controls (p < .0001) for both semaglutide and liraglutide. The present data show a robust induction of Ren1 expression in the vascular smooth muscle cells of the kidney after single and repeated GLP‐1R activation and this renin recruitment may be involved in the effects of GLP‐1R agonist treatment on kidney disease.

The roles of collagen in chronic kidney disease and vascular calcification

The extracellular matrix component collagen is widely expressed in human tissues and participates in various cellular biological processes. The collagen amount generally remains stable due to intricate regulatory networks, but abnormalities can lead to several diseases. During the development of renal fibrosis and vascular calcification, the expression of collagen is significantly increased, which promotes phenotypic changes in intrinsic renal cells and vascular smooth muscle cells, thereby exacerbating disease progression. Reversing the overexpression of collagen substantially prevents or slows renal fibrosis and vascular calcification in a wide range of animal models, suggesting a novel target for treating patients with these diseases. Stem cell therapy seems to be an effective strategy to alleviate these two conditions. However, recent findings indicate that the natural pore structure of collagen fibers is sufficient to induce the inappropriate differentiation of stem cells and thereby exacerbate renal fibrosis and vascular calcification. A comprehensive understanding of the role of collagen in these diseases and its effect on stem cell biology will assist in improving the unmet requirements for treating patients with kidney disease.

SMIT (Sodium-Myo-Inositol Transporter) 1 Regulates Arterial Contractility Through the Modulation of Vascular Kv7 Channels.

The SMIT1 (sodium:myo-inositol transporter 1) regulates myo-inositol movement into cells and responses to hypertonic stimuli. Alteration of myo-inositol levels has been associated with several diseases, including hypertension, but there is no evidence of a functional role of SMIT1 in the vasculature. Recent evidence showed that in the nervous system SMIT1 interacted and modulated the function of members of the Kv7 family of voltage-gated potassium channels, which are also expressed in the vasculature where they regulate arterial contractility. Therefore, in this study, we evaluated whether SMIT1 was functionally relevant in arterial smooth muscle. Approach and Results: Immunofluorescence and polymerase chain reaction experiments revealed that SMIT1 was expressed in rat renal and mesenteric vascular smooth muscle cells. Isometric tension recordings showed that incubation of renal arteries with raffinose and myo-inositol (which increases SMIT1 expression) reduced the contractile responses to methoxamine, an effect that was abolished by preincubation with the pan-Kv7 blocker linopirdine and by molecular knockdown of Kv7.4 and Kv7.5. Knockdown of SMIT1 increased the contraction of renal arteries induced by methoxamine, impaired the response to the Kv7.2-Kv7.5 activator ML213 but did not interfere with the relaxant responses induced by openers of other potassium channels. Proximity ligation assay showed that SMIT1 interacted with heteromeric channels formed by Kv7.4 and Kv7.5 proteins in both renal and mesenteric vascular smooth muscle cells. Patch-clamp experiments showed that incubation with raffinose plus myo-inositol increased Kv7 currents in vascular smooth muscle cells. SMIT1 protein is expressed in vascular smooth muscle cells where it modulates arterial contractility through an association with Kv7.4/Kv7.5 heteromers.

Endothelins contribute to early renal insufficiency engendered by acute urinary tract obstruction in neonatal pigs

Urinary tract obstruction reduces kidney functions, which, if left uncorrected, may lead to irreversible renal loss, especially in infants. Despite the removal of obstruction, a decline in steady‐state renal blood flow (RBF) persists, vascular mechanisms of which are poorly understood. Urinary tract obstruction‐induced increase in the levels of vasoactive endothelin (ET)‐1 has been reported in humans and rodents. However, whether obstructive renal vasculopathy is associated with increased renal production of all ET isoforms (ET1‐3) remains unresolved. Also, the mechanisms that underlie ET‐induced renal vasoregulation in neonates are unclear. Here, we show that ET receptor (ETR)‐operated calcium entry via TRPC3 channels increases renal vascular resistance and reduces RBF in neonatal pigs. Acute unilateral urinary tract obstruction (UUO) in neonatal pigs increased peptidase endothelin converting enzyme 1 (ECE1)‐dependent renal production of ET1‐3 and diacylglycerol (DAG). Despite the removal of obstruction, acute UUO reduced kidney perfusion and caused an increase in renal vascular resistance (RVR) and the urinary levels of NGAL, the early predictive biomarker of acute kidney injury. The protein expression levels of ETRs (ETA and ETB) and TRPC3 channels in renal microvessels were unaltered in neonatal pigs subjected to acute UUO. However, pharmacological inhibition of ECE1, ETR, and TRPC3 mitigated acute UUO‐induced increase in RVR and urine NGAL in the pigs. These data suggest that increased ECE1 production and proteolytic processing of all big ETs to their vasoactive isoforms contribute to early neonatal renal insufficiency engendered by UUO. ET‐derived DAG activates renal vascular smooth muscle cell TRPC3 channels, leading to extracellular calcium entry, vasoconstriction, increased RVR and sustained hypoperfusionSupport or Funding InformationNIH/NIDDK: R01DK101668 and R56DK120595

A Mutation in γ-Adducin Impairs Autoregulation of Renal Blood Flow and Promotes the Development of Kidney Disease.

The genes and mechanisms involved in the association between diabetes or hypertension and CKD risk are unclear. Previous studies have implicated a role for γ-adducin (ADD3), a cytoskeletal protein encoded by Add3. We investigated renal vascular function in vitro and in vivo and the susceptibility to CKD in rats with wild-type or mutated Add3 and in genetically modified rats with overexpression or knockout of ADD3. We also studied glomeruli and primary renal vascular smooth muscle cells isolated from these rats. This study identified a K572Q mutation in ADD3 in fawn-hooded hypertensive (FHH) rats-a mutation previously reported in Milan normotensive (MNS) rats that also develop kidney disease. Using molecular dynamic simulations, we found that this mutation destabilizes a critical ADD3-ACTIN binding site. A reduction of ADD3 expression in membrane fractions prepared from the kidney and renal vascular smooth muscle cells of FHH rats was associated with the disruption of the F-actin cytoskeleton. Compared with renal vascular smooth muscle cells from Add3 transgenic rats, those from FHH rats had elevated membrane expression of BKα and BK channel current. FHH and Add3 knockout rats exhibited impairments in the myogenic response of afferent arterioles and in renal blood flow autoregulation, which were rescued in Add3 transgenic rats. We confirmed these findings in a genetic complementation study that involved crossing FHH and MNS rats that share the ADD3 mutation. Add3 transgenic rats showed attenuation of proteinuria, glomerular injury, and kidney fibrosis with aging and mineralocorticoid-induced hypertension. This is the first report that a mutation in ADD3 that alters ACTIN binding causes renal vascular dysfunction and promotes the susceptibility to kidney disease.

Pharmacological inhibition of TRPV4 channels protects against ischemia-reperfusion-induced renal insufficiency in neonatal pigs.

Renal vasoconstriction, an early manifestation of ischemic acute kidney injury (AKI), results in renal hypoperfusion and a rapid decline in kidney function. The pathophysiological mechanisms that underlie ischemia-reperfusion (IR)-induced renal insufficiency are poorly understood, but possibilities include alterations in ion channel-dependent renal vasoregulation. In the present study, we show that pharmacological activation of TRPV4 channels constricted preglomerular microvessels and elicited renal hypoperfusion in neonatal pigs. Bilateral renal ischemia followed by short-term reperfusion increased TRPV4 protein expression in resistance size renal vessels and TRPV4-dependent cation currents in renal vascular smooth muscle cells (SMCs). Selective TRPV4 channel blockers attenuated IR-induced reduction in total renal blood flow (RBF), cortical perfusion, and glomerular filtration rate (GFR). TRPV4 inhibition also diminished renal IR-induced increase in AKI biomarkers. Furthermore, the level of angiotensin II (Ang II) was higher in the urine of IR- compared with sham-operated neonatal pigs. IR did not alter renal vascular expression of Ang II type 1 (AT1) receptors. However, losartan, a selective AT1 receptor antagonist, ameliorated IR-induced renal insufficiency in the pigs. Blockade of TRPV4 channels attenuated Ang II-evoked receptor-operated Ca2+ entry and constriction in preglomerular microvessels. TRPV4 inhibition also blunted Ang II-induced increase in renal vascular resistance (RVR) and hypoperfusion in the pigs. Together, our data suggest that SMC TRPV4-mediated renal vasoconstriction and the ensuing increase in RVR contribute to early hypoperfusion and renal insufficiency elicited by renal IR in neonatal pigs. We propose that multimodal signaling by renal vascular SMC TRPV4 channels controls neonatal renal microcirculation in health and disease.

Intraluminal pressure triggers myogenic response via activation of calcium spark and calcium-activated chloride channel in rat renal afferent arteriole.

Myogenic contraction of renal arterioles is an important regulatory mechanism for renal blood flow autoregulation. We have previously demonstrated that integrin-mediated mechanical force increases the occurrence of Ca2+ sparks in freshly isolated renal vascular smooth muscle cells (VSMCs). To further test whether the generation of Ca2+ sparks is a downstream signal of mechanotransduction in pressure-induced myogenic constriction, the relationship between Ca2+ sparks and transmural perfusion pressure was investigated in intact VSMCs of pressurized rat afferent arterioles. Spontaneous Ca2+ sparks were found in VSMCs when afferent arterioles were perfused at 80 mmHg. The spark frequency was significantly increased when perfusion pressure was increased to 120 mmHg. A similar increase of spark frequency was also observed in arterioles stimulated with β1-integrin-activating antibody. Moreover, spark frequency was significantly higher in arterioles of spontaneous hypertensive rats at 80 and 120 mmHg. Spontaneous membrane current recorded using whole cell perforated patch in renal VSMCs showed predominant activity of spontaneous transient inward currents instead of spontaneous transient outward currents when holding potential was set close to physiological resting membrane potential. Real-time PCR and immunohistochemistry confirmed the expression of Ca2+-activated Cl- channel (ClCa) TMEM16A in renal VSMCs. Inhibition of TMEM16A with T16Ainh-A01 impaired the pressure-induced myogenic contraction in perfused afferent arterioles. Our study, for the first time to our knowledge, detected Ca2+ sparks in VSMCs of intact afferent arterioles, and their frequencies were positively modulated by the perfusion pressure. Our results suggest that Ca2+ sparks may couple to ClCa channels and trigger pressure-induced myogenic constriction via membrane depolarization.

Calcium Spark Activity is Modulated by Perfusion Pressure in Vascular Smooth Muscle of Afferent Arterioles

Myogenic response and tubuloglomerular feedback are the two primary mechanisms for renal blood flow autoregulation by regulating the afferent arteriolar vascular resistance. However, the mechanisms of mechanotransduction in pressure induced myogenic response are not well defined in afferent arterioles. We have previously demonstrated that integrin‐mediated mechanical force increases the occurrence of Ca2+ sparks in freshly isolated renal vascular smooth muscle cells (VSMCs). To test whether generation of Ca2+ sparks is a downstream signal of mechanotransduction in pressure induced myogenic constriction, the relationship between Ca2+ spark frequency and transmural perfusion pressure was investigated in intact VSMCs of afferent arterioles isolated from Sprague‐Dawley rats. Spontaneous Ca2+ sparks were found in VSMCs when afferent arterioles were perfused at 80 mmHg. The Ca2+ spark frequency was significantly increased when perfusion pressure was increased by 40 mmHg. Similar increase of Ca2+ spark frequency was also found when arterioles were stimulated with β1‐integrin activating antibody. Spontaneous membrane current recorded with whole cell perforated‐patch in renal VSMCs indicated that there were more spontaneous transient inward currents (STICs) than spontaneous transient outward currents (STOCs) when holding potential was set close to physiological resting membrane potential. These observations indicated that Ca2+ sparks activity might couple to Ca2+‐activated Cl− (ClCa) channel and trigger pressure induced myogenic constriction via membrane depolarization. Real‐time PCR and immunofluorescence confirmed the presence of the ClCa channel TMEM16A in renal VSMCs. Inhibition of TMEM16A with the specific antagonist T16Ainh‐A01 impaired pressure induced myogenic contraction in the perfused afferent arterioles. It is known that myogenic response is enhanced in spontaneously hypertensive rat (SHR). TMEM16A abundance and spontaneous Ca2+ sparks were more prevalent in renal arterioles of SHR than those of Sprague‐Dawley rats, which are consistent with notion that Ca2+ spark activity is part of the signal transduction process in myogenic response. In conclusion, Ca2+ sparks were detected in intact VSMCs of afferent arterioles for the first time and their frequencies were positively modulated by the perfusion pressure. The coupling Ca2+ sparks to ClCa might contribute to the mechanical signal transduction process in pressure induced myogenic constriction.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Retracted: Activation of the Nrf2‐ARE Signaling Pathway Prevents Hyperphosphatemia‐Induced Vascular Calcification by Inducing Autophagy in Renal Vascular Smooth Muscle Cells

This study investigates the effect of nuclear factor erythroid 2-related factor 2-antioxidant response element (Nrf2-ARE) signaling pathway in vascular calcification (VC) via inducing Autophagy in renal vascular smooth muscle cells (VSMCs). VSMCs were assigned into six experimental groups: the normal control, high phosphorus, si-negative control (si-NC), Nrf2-siRNA, over-expressed Nrf2, and negative control (NC) groups. RT-PCR was applied to detect the mRNA expressions of the desired Nrf2-ARE signaling pathway-related genes (Nrf2, NQO-1, HO-1, γ-GCS). The protein products of these genes: apoptosis-related genes (LC3I and LC3II), osteogenic marker proetins (Runt-related transcription factor 2) Runx2 and BMP2 were all detected by Western blotting. Autophagosomes in VSMCs were observed under a transmission electron microscope. We discovered an increased calcium ion concentration and upregulated Runx2, BMP2, Nrf2, HO-1, γ-GCS, NQO-1, and LC3II/LC3I expressions in the high phosphorous, si-NC and Nrf2-siRNA, and NC groups, compared with the normal control group. Compared to the high phosphorus and si-NC groups, higher levels of Runx2 and BMP2 but decreased Nrf2, HO-1, γ-GCS, NQO-1, and LC3II/LC3I expressions were detected in the Nrf2-siRNA group. The high phosphorus, si-NC and over-expressed Nrf2 experimental groups all had increased Nrf2, NQO-1, HO-1, γ-GCS, and LC3II/LC3I expressions as well as high numbers of autophagosomes compared with the normal control group. Finally, we detected a lower amount of autophagosomes presence and Nrf2, NQO-1, HO-1 γ-GCS, and LC3II/LC3 protein expression of Nrf2-siRNA group than that of the high phosphorus and si-NC groups. Activation of Nrf2-ARE signaling pathway may prevent hyperphosphatemia-induced VC by inducing autophagy in VSMCs. J. Cell. Biochem. 118: 4708-4715, 2017. © 2017 Wiley Periodicals, Inc.

Effects of Fetal and Neonatal Murine Peripheral Blood Mononuclear Cells Infusion on MicroRNA-145 Expression in Renal Vascular Smooth Muscle Cells in MRL/lpr Mice

For patients with refractory systemic lupus erythematosus, current medications are insufficient to control their condition, and new treatments are necessary. We aimed to evaluate the therapeutic effect of fetal and neonatal murine peripheral blood (FNPB) mononuclear cells and their impact on microRNA-145 (miR-145) in renal vascular smooth muscle cells (VSMCs) of MRL/lpr lupus-prone mice. MRL/lpr mice aged 20 weeks were randomized to 3 groups of 15 (control group, radiation group, infusion group). The renal tissues were subjected to pathological examination. In situ hybridization assay was applied to measure miR-145 expression in renal vessels of MRL/lpr mice. The infusion group had significantly better results for pathological renal tissue lesions than either the control or radiation group. In MRL/lpr mice, there was positive expression of miR-145 in renal VSMCs, although the expression of miR-145 was not discernible in renal vascular intima and adventitia. The miR-145 expression in renal VSMCs in the infusion group was significantly higher than in the control or radiation group, and higher in the radiation group than in the control group; however, the difference was not statistically significant. The increased expression of miR-145 in renal VSMCs might be one of the mechanisms supporting FNPB as a therapy for lupus nephritis; it also suggests that the miR-145 in renal vessels might be a new target for treatment of lupus nephritis.

RGS4 inhibits angiotensin II signaling and macrophage localization during renal reperfusion injury independent of vasospasm

Vascular inflammation is a major contributor to the severity of acute kidney injury. In the context of vasospasm-independent reperfusion injury we studied the potential anti-inflammatory role of the Gα-related RGS protein, RGS4. Transgenic RGS4 mice were resistant to 25 minute injury, although post-ischemic renal arteriolar diameter was equal to the wild type early after injury. A 10 minute unilateral injury was performed to study reperfusion without vasospasm. Eighteen hours after injury blood flow was decreased in the inner cortex of wild type mice with preservation of tubular architecture. Angiotensin II levels in the kidneys of wild type and transgenic mice were elevated in a sub-vasoconstrictive range 12 and 18 hours after injury. Angiotensin II stimulated pre-glomerular vascular smooth muscle cells (VSMC) to secrete the macrophage chemoattractant, RANTES; a process decreased by angiotensin II R2 (AT2) inhibition. However, RANTES increased when RGS4 expression was suppressed implicating Gα protein activation in an AT2-RGS4-dependent pathway. RGS4 function, specific to VSMC, was tested in a conditional VSMC-specific RGS4 knockout showing high macrophage density by T2 MRI compared to transgenic and non-transgenic mice after the 10 minute injury. Arteriolar diameter of this knockout was unchanged at successive time points after injury. Thus, RGS4 expression, specific to renal VSMC, inhibits angiotensin II-mediated cytokine signaling and macrophage recruitment during reperfusion, distinct from vasomotor regulation.

βENaC acts as a mechanosensor in renal vascular smooth muscle cells that contributes to renal myogenic blood flow regulation, protection from renal injury and hypertension.

Pressure-induced constriction (also known as the "myogenic response") is an important mechanodependent response in small renal arteries and arterioles. The response is initiated by vascular smooth muscle cell (VSMC) stretch due to an increase in intraluminal pressure and leads to vasoconstriction. The myogenic response has two important roles as a mechanism of local blood flow autoregulation and protection against systemic blood pressure-induced microvascular damage. However, the molecular mechanisms underlying initiation of myogenic response are unresolved. Although several molecules have been considered initiators of the response, our laboratory has focused on the role of degenerin proteins because of their strong evolutionary link to mechanosensing in the nematode. Our laboratory has addressed the hypothesis that certain degenerin proteins act as mechanosensors in VSMCs. This article discusses the importance of a specific degenerin protein, β Epithelial Na+ Channel (βENaC), in pressure-induced vasoconstriction, renal blood flow and susceptibility to renal injury. We propose that loss of the renal myogenic constrictor response delays the correction of renal blood flow that occurs with fluctuations in systemic pressure, which allows pressure swings to be transmitted to the microvasculature, thus increasing the susceptibility to renal injury and hypertension. The role of βENaC in myogenic regulation is independent of tubular βENaC and thus represents a non-tubular role for βENaC in renal-cardiovascular homeostasis.

α-Galactosidase A Knockout Mice: Progressive Organ Pathology Resembles the Type 2 Later-Onset Phenotype of Fabry Disease

Fabry disease is an X-linked lysosomal storage disease caused by deficient activity of α-galactosidase A and the resultant systemic accumulation of globotrioasylceramide (GL-3) and related glycolipids. α-Galactosidase A gene knockout (Gla KO) mice have no α-galactosidase A activity and progressively accumulate GL-3 in tissues and fluids, similarly to FD patients. The nature and temporal effects of the progressive substrate accumulation on tissue histology in these mice have not previously been characterized. Here, we report the pathology of young to old (3 to 17 months old) Gla KO mice and compare these changes with those in strain-matched control animals. Gla KO mice accumulated GL-3 in various tissues and fluids with age. Lysosomal GL-3 inclusions increased with age in multiple cell types, including renal epithelial, intestinal, and vascular smooth muscle cells, and neurons in trigeminal and dorsal root ganglia, as detected by light and electron microscopy. However, unlike the case for male FD patients with the type 1 classic phenotype, GL-3 inclusions were not detected in vascular endothelial cells or cardiomyocytes. The histological changes in Gla KO mice better resemble the type 2 later-onset phenotype observed in patients with residual α-galactosidase A activity. GL-3 accumulation in the small intestine and sensory ganglia of Gla KO mice provides a model for study of enteropathy and neuropathy in Fabry disease.