Bestrophin3 Deficiency in Vascular Smooth Muscle Cells Activates MEKK2/3-MAPK Signaling to Trigger Spontaneous Aortic Dissection.

BACKGROUND: Aortic dissection (AD) is a fatal cardiovascular disorder without effective medications due to unclear pathogenic mechanisms. Bestrophin3 (Best3), the predominant isoform of bestrophin family in vessels, has emerged as critical for vascular pathological processes. However, the contribution of Best3 to vascular diseases remains elusive. METHODS: Smooth muscle cell-specific and endothelial cell-specific Best3 knockout mice (Best3SMKO and Best3ECKO, respectively) were engineered to investigate the role of Best3 in vascular pathophysiology. Functional studies, single-cell RNA sequencing, proteomics analysis, and coimmunoprecipitation coupled with mass spectrometry were performed to evaluate the function of Best3 in vessels. RESULTS: Best3 expression in aortas of human AD samples and mouse AD models was decreased. Best3SMKO but not Best3ECKO mice spontaneously developed AD with age, and the incidence reached 48% at 72 weeks of age. Reanalysis of single-cell transcriptome data revealed that reduction of fibromyocytes, a fibroblast-like smooth muscle cell cluster, was a typical feature of human ascending AD and aneurysm. Consistently, Best3 deficiency in smooth muscle cells decreased the number of fibromyocytes. Mechanistically, Best3 interacted with both MEKK2 and MEKK3, and this interaction inhibited phosphorylation of MEKK2 at serine153 and MEKK3 at serine61. Best3 deficiency induced phosphorylation-dependent inhibition of ubiquitination and protein turnover of MEKK2/3, thereby activating the downstream mitogen-activated protein kinase signaling cascade. Furthermore, restoration of Best3 or inhibition of MEKK2/3 prevented AD progression in angiotensin II-infused Best3SMKO and ApoE-/- mice. CONCLUSIONS: These findings unveil a critical role of Best3 in regulating smooth muscle cell phenotypic switch and aortic structural integrity through controlling MEKK2/3 degradation. Best3-MEKK2/3 signaling represents a novel therapeutic target for AD.

Vascular smooth muscle-specific LRRC8A knockout ameliorates angiotensin II-induced cerebrovascular remodeling by inhibiting the WNK1/FOXO3a/MMP signaling pathway.

Hypertensive cerebrovascular remodeling involves the enlargement of vascular smooth muscle cells (VSMCs), which activates volume-regulated Cl- channels (VRCCs). The leucine-rich repeat-containing family 8 A (LRRC8A) has been shown to be the molecular identity of VRCCs. However, its role in vascular remodeling during hypertension is unclear. In this study, we used vascular smooth muscle-specific LRRC8A knockout (CKO) mice and an angiotensin II (Ang II)-induced hypertension model. The results showed that cerebrovascular remodeling during hypertension was ameliorated in CKO mice, and extracellular matrix (ECM) deposition was reduced. Based on the RNA-sequencing analysis of aortic tissues, the level of matrix metalloproteinases (MMPs), such as MMP-9 and MMP-14, were reduced in CKO mice with hypertension, which was further verified in vivo by qPCR and immunofluorescence analysis. Knockdown of LRRC8A in VSMCs inhibited the Ang II-induced upregulation of collagen I, fibronectin, and matrix metalloproteinases (MMPs), and overexpression of LRRC8A had the opposite effect. Further experiments revealed an interaction between with-no-lysine (K)-1 (WNK1), which is a "Cl--sensitive kinase", and Forkhead transcription factor O3a (FOXO3a), which is a transcription factor that regulates MMP expression. Ang II induced the phosphorylation of WNK1 and downstream FOXO3a, which then increased the expression of MMP-2 and MMP-9. This process was inhibited or potentiated when LRRC8A was knocked down or overexpressed, respectively. Overall, these results demonstrate that LRRC8A knockout in vascular smooth muscle protects against cerebrovascular remodeling during hypertension by reducing ECM deposition and inhibiting the WNK1/FOXO3a/MMP signaling pathway, demonstrating that LRRC8A is a potential therapeutic target for vascular remodeling-associated diseases such as stroke.

Endophilin A2 protects against renal fibrosis by targeting TGF-ß/Smad signaling.

Renal fibrosis underlies all forms of end-stage kidney disease. Endophilin A2 (EndoA2) plays a role in nephrotic syndrome; however, its effect on renal fibrosis remains unknown. Here, we demonstrate that EndoA2 protects against kidney interstitial fibrosis via the transforming growth factor-ß (TGF-ß)/Smad signaling pathway. Mouse kidneys with fibrosis or kidney biopsy specimens from patients with fibrotic nephropathy had lower levels of EndoA2 protein expression than that in kidneys without fibrosis. In vivo overexpression of EndoA2 with the endophilin A2 transgene (EndoA2Tg ) notably prevented renal fibrosis, decreased the protein expression of profibrotic molecules, suppressed tubular injury, and reduced apoptotic tubular cells in the obstructed kidney cortex of mice with unilateral ureteral obstruction (UUO). In vivo and in vitro overexpression of EndoA2 markedly inhibited UUO- or TGF-ß1-induced phosphorylation of Smad2/3 and tubular epithelial cells dedifferentiation. Furthermore, EndoA2 was co-immunoprecipitated with the type II TGF-ß receptor (TßRII), thus inhibiting the binding of the type I TGF-ß receptor (TßRI) to TßRII. These findings indicate that EndoA2 mitigates renal fibrosis, at least partially, via modulating the TGF-ß/Smad signaling. Targeting EndoA2 may be a new potential therapeutic strategy for treatment of renal fibrosis.

Macrophage NFATc3 prevents foam cell formation and atherosclerosis: evidence and mechanisms.

AIMS: Our previous study demonstrated that Ca2+ influx through the Orai1 store-operated Ca2+ channel in macrophages contributes to foam cell formation and atherosclerosis via the calcineurin-ASK1 pathway, not the classical calcineurin-nuclear factor of activated T-cell (NFAT) pathway. Moreover, up-regulation of NFATc3 in macrophages inhibits foam cell formation, suggesting that macrophage NFATc3 is a negative regulator of atherogenesis. Hence, this study investigated the precise role of macrophage NFATc3 in atherogenesis. METHODS AND RESULTS: Macrophage-specific NFATc3 knockout mice were generated to determine the effect of NFATc3 on atherosclerosis in a mouse model of adeno-associated virus-mutant PCSK9-induced atherosclerosis. NFATc3 expression was decreased in macrophages within human and mouse atherosclerotic lesions. Moreover, NFATc3 levels in peripheral blood mononuclear cells from atherosclerotic patients were negatively associated with plaque instability. Furthermore, macrophage-specific ablation of NFATc3 in mice led to the atherosclerotic plaque formation, whereas macrophage-specific NFATc3 transgenic mice exhibited the opposite phenotype. NFATc3 deficiency in macrophages promoted foam cell formation by potentiating SR-A- and CD36-meditated lipid uptake. NFATc3 directly targeted and transcriptionally up-regulated miR-204 levels. Mature miR-204-5p suppressed SR-A expression via canonical regulation. Unexpectedly, miR-204-3p localized in the nucleus and inhibited CD36 transcription. Restoration of miR-204 abolished the proatherogenic phenotype observed in the macrophage-specific NFATc3 knockout mice, and blockade of miR-204 function reversed the beneficial effects of NFATc3 in macrophages. CONCLUSION: Macrophage NFATc3 up-regulates miR-204 to reduce SR-A and CD36 levels, thereby preventing foam cell formation and atherosclerosis, indicating that the NFATc3/miR-204 axis may be a potential therapeutic target against atherosclerosis.

MicroRNA-302a promotes neointimal formation following carotid artery injury in mice by targeting PHLPP2 thus increasing Akt signaling.

The excessive proliferation and migration of smooth muscle cells (SMCs) play an important role in restenosis following percutaneous coronary interventions. MicroRNAs are able to target various genes and involved in the regulation of diverse cellular processes including cell growth and proliferation. In this study we investigated whether and how MicroRNAs regulated vascular SMC proliferation and vascular remodeling following carotid artery injury in mice. We showed that carotid artery injury-induced neointimal formation was remarkably ameliorated in microRNA (miR)-302 heterozygous mice and SMC-specific miR-302 knockout mice. In contrast, delivery of miR-302a adenovirus to the injured carotid artery enhanced neointimal formation. Upregulation of miR-302a enhanced the proliferation and migration of mouse aorta SMC (MASMC) in vitro by promoting cell cycle transition, whereas miR-302a inhibition caused the opposite results. Moreover, miR-302a promoted Akt activation by corporately decreasing Akt expression and increasing Akt phosphorylation in MASMCs. Application of the Akt inhibitor GSK690693 (5 µmol/L) counteracted the functions of miR-302a in promoting MASMC proliferation and migration. We further revealed that miR-302a directly targeted at the 3' untranslated region of PH domain and leucine rich repeat protein phosphatase 2 (PHLPP2) and negatively regulated PHLPP2 expression. Restoration of PHLPP2 abrogated the effects of miR-302a on Akt activation and MASMC motility. Furthermore, knockdown of PHLPP2 largely abolished the inhibition of neointimal formation that was observed in miR-302 heterozygous mice. Our data demonstrate that miR-302a exacerbates SMC proliferation and restenosis through increasing Akt signaling by targeting PHLPP2.

Reduced intracellular chloride concentration impairs angiogenesis by inhibiting oxidative stress-mediated VEGFR2 activation.

Chloride (Cl-) homeostasis is of great significance in cardiovascular system. Serum Cl- level is inversely associated with the mortality of patients with heart failure. Considering the importance of angiogenesis in the progress of heart failure, this study aims to investigate whether and how reduced intracellular Cl- concentration ([Cl-]i) affects angiogenesis. Human umbilical endothelial cells (HUVECs) were treated with normal Cl- medium or low Cl- medium. We showed that reduction of [Cl-]i (from 33.2 to 16.18 mM) inhibited HUVEC proliferation, migration, cytoskeleton reorganization, tube formation, and subsequently suppressed angiogenesis under basal condition, and VEGF stimulation or hypoxia treatment. Moreover, VEGF-induced NADPH-mediated reactive oxygen species (ROS) generation and VEGFR2 axis activation were markedly attenuated in low Cl- medium. We revealed that lowering [Cl-]i inhibited the expression of the membrane-bound catalytic subunits of NADPH, i.e., p22phox and Nox2, and blunted the translocation of cytosolic regulatory subunits p47phox and p67phox, thereby restricting NADPH oxidase complex formation and activation. Furthermore, reduced [Cl-]i enhanced ROS-associated protein tyrosine phosphatase 1B (PTP1B) activity and increased the interaction of VEGFR2 and PTP1B. Pharmacological inhibition of PTP1B reversed the effect of lowering [Cl-]i on VEGFR2 phosphorylation and angiogenesis. In mouse hind limb ischemia model, blockade of Cl- efflux using Cl- channel inhibitors DIDS or DCPIB (10 mg/kg, i.m., every other day for 2 weeks) significantly enhanced blood flow recovery and new capillaries formation. In conclusion, decrease of [Cl-]i suppresses angiogenesis via inhibiting oxidase stress-mediated VEGFR2 signaling activation by preventing NADPH oxidase complex formation and promoting VEGFR2/PTP1B association, suggesting that modulation of [Cl-]i may be a novel therapeutic avenue for the treatment of angiogenic dysfunction-associated diseases.

Inhibition of Orai1-mediated Ca2+ entry limits endothelial cell inflammation by suppressing calcineurin-NFATc4 signaling pathway.

Orai1-dependent Ca2+ entry plays an essential role in inflammatory response through regulating T cell and macrophage activation and neutrophil infiltration. However, whether Orai1 Ca2+ entry contributes to endothelial activation, one of the early steps of vascular inflammation, remains elusive. In the present study, we observed that knockdown of Orai1 reduced, whereas overexpression of Orai1 potentiated, TNFα-induced expression of adhesion molecules such as ICAM-1 and VCAM-1 in HUVECs, and subsequently blocked adhesion of monocyte to HUVECs. In vivo, Orai1 downregulation attenuated TNFα-induced ICAM-1 and VCAM-1 expression in mouse aorta and the levels of pro-inflammatory cytokines in the serum. In addition, Orai1 knockdown also dramatically decreased the expression of pro-inflammatory cytokines and neutrophil infiltration in the lung after TNFα treatment, and thus protected lung tissue injury. Notably, among all isoforms of nuclear factor of activated T cells (NFATs), TNFα only triggered NFATc4 nuclear accumulation in HUVECs. Knockdown of Orai1 or inhibition of calcineurin prevented TNFα-induced NFATc4 nuclear translocation and reduced ICAM-1 and VCAM-1 expression in HUVECs. Overexpression of NFATc4 further enhanced ICAM-1 and VCAM-1 expression induced by TNFα. Our study demonstrates that Orai1-Ca2+-calcineurin-NFATc4 signaling is an essential inflammatory pathway required for TNFα-induced endothelial cell activation and vascular inflammation. Therefore, Orai1 may be a potential therapeutic target for treatment of inflammatory diseases.

Ca2+/Calmodulin-Dependent Protein Kinase II γ-Dependent Serine727 Phosphorylation Is Required for TMEM16A Ca2+-Activated Cl- Channel Regulation in Cerebrovascular Cells.

BACKGROUND: TMEM16A is a critical component of Ca2+-activated chloride channels (CaCCs) and mediates basilar arterial smooth muscle cell (BASMC) proliferation in hypertensive cerebrovascular remodeling. CaMKII is a negative regulator of CaCC, and four CaMKII isoforms (α, ß, γ and δ) are expressed in vasculature; however, it is unknown which and how CaMKII isoforms affect TMEM16A-associated CaCC and BASMC proliferation.Methods and Results:Patch clamp and small interfering RNA (siRNA) knockdown of different CaMKII isoforms revealed that only CaMKIIγ inhibited native Ca2+-activated chloride currents (ICl.Ca) in BASMCs. The TMEM16A overexpression evoked TMEM16A Cl-current and inhibited angiotensin II (Ang II)-induced proliferation in BASMCs. The co-immunoprecipitation and pull-down assay indicated an interaction between CaMKIIγ and TMEM16A protein. TMEM16A Cl-current was modulated by CaMKIIγ phosphorylation at serine residues in TMEM16A. Serine525 and Serine727 in TMEM16A were mutated to alanine, and only mutation at Ser727 (S727A) reversed the CaMKIIγ inhibition of the TMEM16A Cl-current. Phosphomimetic mutation S727D markedly decreased TMEM16A Cl-current and reversed TMEM16A-mediated suppression of BASMC proliferation, mimicking the inhibitory effects of CaMKIIγ on TMEM16A. A significant increase in CaMKIIγ isoform content was observed in parallel to the decrease of TMEM16A and ICl.Cain basilar artery proliferative remodeling in Ang II-infused mice. CONCLUSIONS: Serine 727 phosphorylation in TMEM16A by CaMKIIγ provides a new mechanism for regulating TMEM16A CaCC activity and Ang II-induced BASMC proliferation.

The oxidized phospholipid POVPC impairs endothelial function and vasodilation via uncoupling endothelial nitric oxide synthase.

Endothelial dysfunction is an early stage of atherosclerosis. We recently have shown that 25-hydroxycholesterol found in atherosclerotic lesions could impair endothelial function and vasodilation by uncoupling and inhibiting endothelial nitric oxide synthase (eNOS). 1-Palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC), the oxidation product of oxidized low-density lipoprotein, is another proinflammatory lipid and has also been found in atherosclerotic lesions. However, whether POVPC promotes atherosclerosis like 25-hydroxycholesterol remains unclear. The purpose of this study was to explore the effects of POVPC on endothelial function and vasodilation. Human umbilical vein endothelial cells (HUVECs) were incubated with POVPC. Endothelial cell proliferation, migration and tube formation were measured. Nitric oxide (NO) production and superoxide anion generation (O2-) were determined. The expression and phosphorylation of endothelial nitric oxide synthase (eNOS), AKT, PKC-ßII and P70S6K as well as the association of eNOS and heat shock protein 90 (HSP90) were detected by immunoblotting and immunoprecipitation. Endothelial cell apoptosis was monitored by TUNEL staining. The expression of Bcl-2, Bax, and Cleaved Caspase 3 were detected by immunoblotting. Finally, aortic ring from C57BL6 mice were isolated and treated with POVPC and the endothelium-dependent vasodilation was evaluated. POVPC significantly inhibited HUVECs proliferation, migration, tube formation, decreased NO production but increased O2- generation. POVPC inhibited the phosphorylation of Akt and eNOS at Ser1177, increased activation of PKC-ßII, P70S6K and the phosphorylation of eNOS at Thr495, reduced the association of HSP90 with eNOS. Meanwhile, POVPC induced endothelial cell apoptosis by inhibiting Bcl-2 expression, increasing Bax and cleaved caspase-3 expressions as well as caspase-3 activity and impaired endothelium-dependent vasodilation. These data demonstrated that POVPC impaired endothelial function by uncoupling and inhibiting eNOS as well as by inducing endothelial cell apoptosis. Therefore, POVPC may play an important role in the development of atherosclerosis and may be considered as a potential therapeutic target for atherosclerosis.

Inhibition of Orai1-mediated Ca2+ entry enhances chemosensitivity of HepG2 hepatocarcinoma cells to 5-fluorouracil.

Increasing evidence supports that activation of store-operated Ca2+ entry (SOCE) is implicated in the chemoresistance of cancer cells subjected to chemotherapy. However, the molecular mechanisms underlying chemoresistance are not well understood. In this study, we aim to investigate whether 5-FU induces hepatocarcinoma cell death through regulating Ca2+ -dependent autophagy. [Ca2+ ]i was measured using fura2/AM dye. Protein expression was determined by Western blotting and immunohistochemistry. We found that 5-fluorouracil (5-FU) induced autophagic cell death in HepG2 hepatocarcinoma cells by inhibiting PI3K/AKT/mTOR pathway. Orai1 expression was obviously elevated in hepatocarcinoma tissues. 5-FU treatment decreased SOCE and Orai1 expressions, but had no effects on Stim1 and TRPC1 expressions. Knockdown of Orai1 or pharmacological inhibition of SOCE enhanced 5-FU-induced inhibition of PI3K/AKT/mTOR pathway and potentiated 5-FU-activated autophagic cell death. On the contrary, ectopic overexpression of Orai1 antagonizes 5-FU-induced autophagy and cell death. Our findings provide convincing evidence to show that Orai1 expression is increased in hepatocarcinoma tissues. 5-FU can induce autophagic cell death in HepG2 hepatocarcinoma cells through inhibition of SOCE via decreasing Orai1 expression. These findings suggest that Orai1 expression is a predictor of 5-FU sensitivity for hepatocarcinoma treatment and blockade of Orai1-mediated Ca2+ entry may be a promising strategy to sensitize hepatocarcinoma cells to 5-FU treatment.

Inhibition of Orai1 Store-Operated Calcium Channel Prevents Foam Cell Formation and Atherosclerosis.

OBJECTIVE: To determine the role of orai1 store-operated Ca(2+) entry in foam cell formation and atherogenesis. APPROACH AND RESULTS: Acute administration of oxidized low-density lipoprotein (oxLDL) activates an orai1-dependent Ca(2+) entry in macrophages. Chelation of intracellular Ca(2+), inhibition of orai1 store-operated Ca(2+) entry, or knockdown of orai1 dramatically inhibited oxLDL-induced upregulation of scavenger receptor A, uptake of modified LDL, and foam cell formation. Orai1-dependent Ca(2+) entry induces scavenger receptor A expression and foam cell formation through activation of calcineurin but not calmodulin kinase II. Activation of nuclear factor of activated T cells is not involved in calcineurin signaling to foam cell formation. However, oxLDL dephosohorylates and activates apoptosis signal-regulating kinase 1 in macrophages. Orai1 knockdown prevents oxLDL-induced apoptosis signal-regulating kinase 1 activation. Knockdown of apoptosis signal-regulating kinase 1, or inhibition of its downstream effectors, JNK and p38 mitogen-activated protein kinase, reduces scavenger receptor A expression and foam cell formation. Notably, orai1 expression is increased in atherosclerotic plaques of apolipoprotein E(-/-) mice fed with high-cholesterol diet. Knockdown of orai1 with adenovirus harboring orai1 siRNA or inhibition of orai1 Ca(2+) entry with SKF96365 for 4 weeks dramatically inhibits atherosclerotic plaque development in high-cholesterol diet feeding apolipoprotein E(-/-) mice. In addition, inhibition of orai1 Ca(2+) entry prevents macrophage apoptosis in atherosclerotic plaque. Moreover, the expression of inflammatory genes in atherosclerotic lesions and the infiltration of myeloid cells into the aortic sinus plaques are decreased after blocking orai1 signaling. CONCLUSIONS: Orai1-dependent Ca(2+) entry promotes atherogenesis possibly by promoting foam cell formation and vascular inflammation, rendering orai1 Ca(2+) channel a potential therapeutic target against atherosclerosis.

Blockade of Orai1 Store-Operated Calcium Entry Protects against Renal Fibrosis.

Evidence supports an important role of Ca2+ release-activated Ca2+ channel protein 1 (Orai1)-mediated Ca2+ entry in the development of renal fibrosis, a common pathologic feature of CKDs that lead to ESRD, but the molecular mechanisms remain unclear. We determined the role of Orai1 calcium channel in renal fibrosis induced by high-fat diet and by unilateral ureteral obstruction. Mouse kidneys with fibrosis had higher levels of Orai1 protein expression than did kidneys without fibrosis. In vivo knockdown of Orai1 with adenovirus harboring Orai1-short hairpin RNA or inhibition of Orai1 with SKF96365 dramatically prevented renal fibrosis and significantly decreased protein expression of fibronectin, α­smooth muscle actin, and TGF­ß1 in the kidney cortex of ApoE-/- mice on a high-fat diet and in the obstructed kidneys of mice with unilateral ureteral obstruction. Compared with kidney biopsy specimens of patients with glomerular minimal change disease, those of patients with fibrotic nephropathy had higher expression levels of Orai1. In cultured human proximal tubule epithelial cells (HK2), knockdown of Orai1 Ca2+ channel with adenovirus-Orai1-short hairpin RNA markedly inhibited TGF-ß1-induced intracellular Ca2+ influx and phosphorylation of smad2/3. Knockdown or blockade of the Orai1 Ca2+ channel in HK2 cells also prevented epithelial-to-mesenchymal transition induced by TGF­ß1. In conclusion, blockade of the Orai1 Ca2+ channel prevented progression of renal fibrosis in mice, likely by suppressing smad2/3 phosphorylation and TGF-ß1-induced epithelial-to-mesenchymal transition. These results render the Orai1 Ca2+ channel a potential therapeutic target against renal fibrosis.

Endophilin A2 protects H2O2-induced apoptosis by blockade of Bax translocation in rat basilar artery smooth muscle cells.

BACKGROUND: Apoptosis plays a central role in maintaining the normal cell number and tissue homeostasis. Endophilins are a family of evolutionarily conserved proteins that have the critical role in endocytosis. Here, we determined whether endophilin A2 (EndoII) contributes to hydrogen peroxide (H2O2)-induced apoptosis in rat basilar artery smooth muscle cells (BASMCs) and the underlying mechanisms. METHODS AND RESULTS: By using small interference RNA (siRNA) and EndoII overexpression strategy, we found that EndoII siRNA knockdown reduced cell viability and promoted H2O2-induced cell apoptosis, evidenced by loss of mitochondrial membrane potential, release of cytochrome c, and activation of caspase-9, 3 and poly (ADP-ribose) polymerase (PARP). In contrast, EndoII overexpression showed opposite effects and inhibited H2O2-induced BASMCs apoptosis. Further studies revealed that there was a direct interaction between EndoII and Bax. Upon H2O2-induced apoptosis, the association of EndoII with Bax were significantly decreased, while the interaction of Bax/tBid were increased, accompanied by a translocation of Bax from cytosol to mitochondria. Knockdown of EndoII did not affect the expression of Bax, but further promoted the binding of Bax with tBid and favored the accumulation of Bax to mitochondria as well as Bax activation; whereas EndoII overexpression produced the opposite effects. In addition, EndoII siRNA aggravated, but EndoII overexpression alleviated, the reduction of Bcl-2 expression in H2O2-treated cells. CONCLUSIONS: These data suggested a role of EndoII in protecting BASMCs apoptosis induced by H2O2, possibly by inhibiting the addressing of Bax to mitochondria. Targeting on EndoII may be a new strategy to treat apoptosis-associated diseases.

Reduction of Intracellular Chloride Concentration Promotes Foam Cell Formation.

BACKGROUND: Previous work has demonstrated that the volume-regulated chloride channel is activated during foam cell formation, and inhibition of chloride movement prevents intracellular lipid accumulation. However, the mechanism explaining how chloride movement promotes foam cell formation is not clear. METHODS AND RESULTS: Foam cell formation was determined by Oil Red O staining. Western blotting and co-immunoprecipitation were used to examine protein expression and protein-protein interaction. [Cl(-)]iwas measured using 6-methoxy-N-ethylquinolinium iodide dye. The results showed that [Cl(-)]iwas decreased in monocytes/macrophages from patients with hypercholesterolemia and from apoE(-/-)mice fed with a high-fat diet. Lowering [Cl(-)]iupregulated scavenger receptor A (SR-A) expression, increased the binding and uptake of oxLDL, enhanced pro-inflammatory cytokine production and subsequently accelerated foam cell formation in macrophages from humans and mice. In addition, low Cl(-)solution stimulated the activation of JNK and p38 mitogen-activated protein kinases. Inhibition of JNK and p38 blocked Cl(-)reduced medium-induced SR-A expression and lipid accumulation. In contrast, reduction of [Cl(-)]ipromoted the interaction of SR-A with caveolin-1, thus facilitating caveolin-1-dependent SR-A endocytosis. Moreover, disruption of caveolae attenuated SR-A internalization, JNK and p38 activation, and ultimately prevented SR-A expression and foam cell formation stimulated by low Cl(-)medium. CONCLUSIONS: This data provide strong evidence that reduction of [Cl(-)]iis a critical contributor to intracellular lipid accumulation, suggesting that modulation of [Cl(-)]iis a novel avenue to prevent foam cell formation and atherosclerosis.

ClC-3 deficiency prevents atherosclerotic lesion development in ApoE-/- mice.

BACKGROUND: Recent evidence suggested that ClC-3, encoding Cl(-) channel or Cl(-)/H(+) antiporter, plays a critical role in regulation of a variety of physiological functions. However, remarkably little is known about whether ClC-3 is involved in atherosclerosis. This study aims to establish the involvement and direct role of ClC-3 in atherogenesis and underlying mechanisms by using ClC-3 and ApoE double null mice. METHODS AND RESULTS: After a 16-week western-type high-fat diet, the ClC-3(+/+)ApoE(-/-) mice developed widespread atherosclerotic lesions in aorta. However, the lesion size was significantly reduced in aorta of ClC-3(-/-)ApoE(-/-) mice. Compared with the ClC-3(+/+) controls, there was significantly decreased ox-LDL binding and uptake in isolated peritoneal macrophages from ClC-3(-/-) mice. Moreover, the expression of scavenger receptor SR-A, but not CD36, was significantly decreased in both ClC-3(-/-) peritoneal macrophages and aortic lesions from ClC-3(-/-)ApoE(-/-) mice. These findings were further confirmed in ox-LDL-treated RAW264.7 macrophages, which showed that silence of ClC-3 inhibited SR-A expression, ox-LDL accumulation and foam cell formation, whereas overexpression of ClC-3 produced the opposite effects. In addition, ClC-3 siRNA significantly inhibited, whereas ClC-3 overexpression increased, the phosphorylation of JNK/p38 MAPK in ox-LDL-treated RAW264.7 foam cells. Pretreatment with JNK or p38 inhibitor abolished ClC-3-induced increase in SR-A expression and ox-LDL uptake. Finally, the increased JNK/p38 phosphorylation and SR-A expression induced by ClC-3 could be mimicked by reduction of [Cl(-)]i by low Cl(-) solution. CONCLUSIONS: Our findings demonstrated that ClC-3 deficiency inhibits atherosclerotic lesion development, possibly via suppression of JNK/p38 MAPK dependent SR-A expression and foam cell formation.

ClC-3 chloride channel/antiporter defect contributes to inflammatory bowel disease in humans and mice.

BACKGROUND: ClC-3 channel/antiporter plays a critical role in a variety of cellular activities. ClC-3 has been detected in the ileum and colon. OBJECTIVE: To determine the functions of ClC-3 in the gastrointestinal tract. DESIGN: After administration of dextran sulfate sodium (DSS) or 2,4,6-trinitrobenzenesulfonic acid (TNBS), intestines from ClC-3-/- and wild-type mice were examined by histological, cellular, molecular and biochemical approaches. ClC-3 expression was determined by western blot and immunostaining. RESULTS: ClC-3 expression was reduced in intestinal tissues from patients with UC or Crohn's disease and from mice treated with DSS. Genetic deletion of ClC-3 increased the susceptibility of mice to DSS- or TNBS-induced experimental colitis and prevented intestinal recovery. ClC-3 deficiency promoted DSS-induced apoptosis of intestinal epithelial cells through the mitochondria pathway. ClC-3 interacts with voltage-dependent anion channel 1, a key player in regulation of mitochondria cytochrome c release, but DSS treatment decreased this interaction. In addition, lack of ClC-3 reduced the numbers of Paneth cells and impaired the expression of antimicrobial peptides. These alterations led to dysfunction of the epithelial barrier and invasion of commensal bacteria into the mucosa. CONCLUSIONS: A defect in ClC-3 may contribute to the pathogenesis of IBD by promoting intestinal epithelial cell apoptosis and Paneth cell loss, suggesting that modulation of ClC-3 expression might be a new strategy for the treatment of IBD.

Dual action of macrophage miR-204 confines cyclosporine A-induced atherosclerosis.

BACKGROUND AND PURPOSE: Atherosclerosis induced by cyclosporine A (CsA), an inhibitor of the calcineurin/nuclear factor of activated T cells (NFAT) pathway, is a major concern after organ transplantation. However, the atherosclerotic mechanisms of CsA remain obscure. We previously demonstrated that calcineurin/NFAT signalling inhibition contributes to atherogenesis via suppressing microRNA-204 (miR-204) transcription. We therefore hypothesised that miR-204 is involved in the development of CsA-induced atherosclerosis. EXPERIMENTAL APPROACH: ApoE-/- mice with macrophage-miR-204 overexpression were generated to determine the effects of miR-204 on CsA-induced atherosclerosis. Luciferase reporter assays and chromatin immunoprecipitation sequencing were performed to explore the targets mediating miR-204 effects. KEY RESULTS: CsA alone did not significantly affect atherosclerotic lesions or serum lipid levels. However, it exacerbated high-fat diet-induced atherosclerosis and hyperlipidemia in C57BL/6J and ApoE-/- mice, respectively. miR-204 levels decreased in circulating monocytes and plaque lesions during CsA-induced atherosclerosis. The upregulation of miR-204 in macrophages inhibited CsA-induced atherosclerotic plaque formation but did not affect serum lipid levels. miR-204 limited the CsA-induced foam cell formation by reducing the expression of the scavenger receptors SR-BII and CD36. SR-BII was post-transcriptionally regulated by mature miR-204-5p via 3'-UTR targeting. Additionally, nuclear-localised miR-204-3p prevented the CsA-induced binding of Ago2 to the CD36 promoter, suppressing CD36 transcription. SR-BII or CD36 expression restoration dampened the beneficial effects of miR-204 on CsA-induced atherosclerosis. CONCLUSION AND IMPLICATIONS: Macrophage miR-204 ameliorates CsA-induced atherosclerosis, suggesting that miR-204 may be a potential target for the prevention and treatment of CsA-related atherosclerotic side effects.

High-density lipoprotein regulates angiogenesis by affecting autophagy via miRNA-181a-5p.

We previously demonstrated that normal high-density lipoprotein (nHDL) can promote angiogenesis, whereas HDL from patients with coronary artery disease (dHDL) is dysfunctional and impairs angiogenesis. Autophagy plays a critical role in angiogenesis, and HDL regulates autophagy. However, it is unclear whether nHDL and dHDL regulate angiogenesis by affecting autophagy. Endothelial cells (ECs) were treated with nHDL and dHDL with or without an autophagy inhibitor. Autophagy, endothelial nitric oxide synthase (eNOS) expression, miRNA expression, nitric oxide (NO) production, superoxide anion (O2•-) generation, EC migration, and tube formation were evaluated. nHDL suppressed the expression of miR-181a-5p, which promotes autophagy and the expression of eNOS, resulting in NO production and the inhibition of O2•- generation, and ultimately increasing in EC migration and tube formation. dHDL showed opposite effects compared to nHDL and ultimately inhibited EC migration and tube formation. We found that autophagy-related protein 5 (ATG5) was a direct target of miR-181a-5p. ATG5 silencing or miR-181a-5p mimic inhibited nHDL-induced autophagy, eNOS expression, NO production, EC migration, tube formation, and enhanced O2•- generation, whereas overexpression of ATG5 or miR-181a-5p inhibitor reversed the above effects of dHDL. ATG5 expression and angiogenesis were decreased in the ischemic lower limbs of hypercholesterolemic low-density lipoprotein receptor null (LDLr-/-) mice when compared to C57BL/6 mice. ATG5 overexpression improved angiogenesis in ischemic hypercholesterolemic LDLr-/- mice. Taken together, nHDL was able to stimulate autophagy by suppressing miR-181a-5p, subsequently increasing eNOS expression, which generated NO and promoted angiogenesis. In contrast, dHDL inhibited angiogenesis, at least partially, by increasing miR-181a-5p expression, which decreased autophagy and eNOS expression, resulting in a decrease in NO production and an increase in O2•- generation. Our findings reveal a novel mechanism by which HDL affects angiogenesis by regulating autophagy and provide a therapeutic target for dHDL-impaired angiogenesis.

The PTM profiling of CTCF reveals the regulation of 3D chromatin structure by O-GlcNAcylation.

CCCTC-binding factor (CTCF), a ubiquitously expressed and highly conserved protein, is known to play a critical role in chromatin structure. Post-translational modifications (PTMs) diversify the functions of protein to regulate numerous cellular processes. However, the effects of PTMs on the genome-wide binding of CTCF and the organization of three-dimensional (3D) chromatin structure have not been fully understood. In this study, we uncovered the PTM profiling of CTCF and demonstrated that CTCF can be O-GlcNAcylated and arginine methylated. Functionally, we demonstrated that O-GlcNAcylation inhibits CTCF binding to chromatin. Meanwhile, deficiency of CTCF O-GlcNAcylation results in the disruption of loop domains and the alteration of chromatin loops associated with cellular development. Furthermore, the deficiency of CTCF O-GlcNAcylation increases the expression of developmental genes and negatively regulates maintenance and establishment of stem cell pluripotency. In conclusion, these results provide key insights into the role of PTMs for the 3D chromatin structure.