Endothelial KCa3.1 and KCa2.3 Mediate S1P (Sphingosine-1-Phosphate)-Dependent Vasodilation and Blood Pressure Homeostasis.

BACKGROUND: S1P (sphingosine-1-phosphate) has been reported to possess vasodilatory properties, but the underlying pathways are largely unknown. METHODS: Isolated mouse mesenteric artery and endothelial cell models were used to determine S1P-induced vasodilation, intracellular calcium, membrane potentials, and calcium-activated potassium channels (KCa2.3 and KCa3.1 [endothelial small- and intermediate-conductance calcium-activated potassium channels]). Effect of deletion of endothelial S1PR1 (type 1 S1P receptor) on vasodilation and blood pressure was evaluated. RESULTS: Mesenteric arteries subjected to acute S1P stimulation displayed a dose-dependent vasodilation response, which was attenuated by blocking endothelial KCa2.3 or KCa3.1 channels. In cultured human umbilical vein endothelial cells, S1P stimulated immediate membrane potential hyperpolarization following activation of KCa2.3/KCa3.1 with elevated cytosolic Ca2+. Further, chronic S1P stimulation enhanced expression of KCa2.3 and KCa3.1 in human umbilical vein endothelial cells in dose- and time-dependent manners, which was abolished by disrupting either S1PR1-Ca2+ signaling or downstream Ca2+-activated calcineurin/NFAT (nuclear factor of activated T-cells) signaling. By combination of bioinformatics-based binding site prediction and chromatin immunoprecipitation assay, we revealed in human umbilical vein endothelial cells that chronic activation of S1P/S1PR1 promoted NFATc2 nuclear translocation and binding to promoter regions of KCa2.3 and KCa3.1 genes thus to upregulate transcription of these channels. Deletion of endothelial S1PR1 reduced expression of KCa2.3 and KCa3.1 in mesenteric arteries and exacerbated hypertension in mice with angiotensin II infusion. CONCLUSIONS: This study provides evidence for the mechanistic role of KCa2.3/KCa3.1-activated endothelium-dependent hyperpolarization in vasodilation and blood pressure homeostasis in response to S1P. This mechanistic demonstration would facilitate the development of new therapies for cardiovascular diseases associated with hypertension.

Quantitative interactome proteomics identifies a proteostasis network for GABAA receptors.

Gamma-aminobutyric acid type A (GABAA) receptors are the primary inhibitory neurotransmitter-gated ion channels in the mammalian central nervous system. Maintenance of GABAA receptor protein homeostasis (proteostasis) in cells utilizing its interacting proteins is essential for the function of GABAA receptors. However, how the proteostasis network orchestrates GABAA receptor biogenesis in the endoplasmic reticulum is not well understood. Here, we employed a proteomics-based approach to systematically identify the interactomes of GABAA receptors. We carried out a quantitative immunoprecipitation-tandem mass spectrometry analysis utilizing stable isotope labeling by amino acids in cell culture. Furthermore, we performed comparative proteomics by using both WT α1 subunit and a misfolding-prone α1 subunit carrying the A322D variant as the bait proteins. We identified 125 interactors for WT α1-containing receptors, 105 proteins for α1(A322D)-containing receptors, and 54 overlapping proteins within these two interactomes. Our bioinformatics analysis identified potential GABAA receptor proteostasis network components, including chaperones, folding enzymes, trafficking factors, and degradation factors, and we assembled a model of their potential involvement in the cellular folding, degradation, and trafficking pathways for GABAA receptors. In addition, we verified endogenous interactions between α1 subunits and selected interactors by using coimmunoprecipitation in mouse brain homogenates. Moreover, we showed that TRIM21 (tripartite motif containing-21), an E3 ubiquitin ligase, positively regulated the degradation of misfolding-prone α1(A322D) subunits selectively. This study paves the way for understanding the molecular mechanisms as well as fine-tuning of GABAA receptor proteostasis to ameliorate related neurological diseases such as epilepsy.

Drug-coated balloon for treatment of non-atherosclerotic renal artery stenosis-a multi-center study.

INTRODUCTION: Renal artery stenosis (RAS) is a significant reason for secondary hypertension. Impaired renal function and subsequent cardiopulmonary dysfunction could also occur. Patients of non-atherosclerotic RAS has a relatively young age and long life expectancy. Revascularization with percutaneous transluminal angioplasty (PTA) is a viable treatment option. However, restenosis is unavoidable which limits its use. Drug-coated balloon (DCB) has been proven to be effective in restenosis prevention in femoropopliteal arterial diseases and in patients with renal artery stenosis. And PTA for Renal artery fibromuscular dysplasia is safe and clinically successful. Therefore, we could speculate that DCB might have potential efficacy in non-atherosclerotic RAS treatment. METHODS AND ANALYSIS: This will be a randomized multi-center-controlled trial. Eighty-four eligible participants will be assigned randomly in a 1:1 ratio to the control group (plain old balloon, POB) and the experimental group (DCB). Subjects in the former group will receive balloon dilatation alone, and in the latter group will undergo the DCB angioplasty. The DCB used in this study will be a paclitaxel-coated balloon (Orchid, Acotec Scientific Holdings Limited, Beijing, China). Follow-up visits will be scheduled 1, 3, 6, 9, and 12 months after the intervention. Primary outcomes will include controlled blood pressure and primary patency in the 9-month follow-up. Secondary outcomes will include technical success rate, complication rate, and bail-out stenting rate. TRIAL REGISTRATION: ClinicalTrials.gov (number NCT05858190). Protocol version V.4 (3 May 2023).

Ant-Neointimal Formation Effects of SLC6A6 in Preventing Vascular Smooth Muscle Cell Proliferation and Migration via Wnt/ß-Catenin Signaling.

Vascular smooth muscle cells (VSMCs) play an important role in the pathogenesis of vascular remolding, such as atherosclerosis and restenosis. Solute carrier family 6 member 6 (SLC6A6) is a transmembrane transporter that maintains a variety of physiological functions and is highly expressed in VSMCs. However, its role on VSMCs during neointimal formation remains unknown. In this study, mRNA and protein levels of SLC6A6 were examined using models of VSMC phenotype switching in vivo and in vitro and human artery samples with or without atherosclerosis. SLC6A6 gain- and loss-of-function approaches were performed by adenovirus infection or small interfering RNA (siRNA) transfection, respectively. Reactive oxygen species (ROS), proliferation, migration, and phenotype-related proteins of VSMCs were measured. Vascular stenosis rate and related genes were assessed in a rat vascular balloon injury model overexpressing SLC6A6. SLC6A6 was downregulated in dedifferentiated VSMCs, atherosclerotic vascular tissues, and injured vascular tissues. SLC6A6 suppressed VSMC proliferation and migration, while increasing contractile VSMC proteins. Mechanistically, SLC6A6 overexpression reduced ROS production and inhibited the Wnt/ß-catenin pathway. Furthermore, SLC6A6 overexpression suppressed neointimal formation in vivo. Collectively, overexpression of SLC6A6 suppresses neointimal formation by inhibiting VSMC proliferation and migration via Wnt/ß-catenin signaling and maintaining the VSMC contractile phenotype.

Rationale and design for the study of recombinant human hepatocyte growth factor plasmid in the treatment of patients with chronic limb-threatening ischemia (HOPE CLTI): Randomized, placebo-controlled, double-blind, phase III clinical trials.

BACKGROUND: Although patients with CLTI have benefited from the rapid development of endovascular techniques, many patients are considered unsuitable for revascularization procedures. A previous phase II clinical trial has suggested that recombinant human hepatocyte growth factor plasmid (NL003) can salvage limbs during the treatment of patients with CLTI. However, the safety and efficacy of this drug need to be evaluated in a larger cohort. STUDY DESIGN: HOPE CLTI is a multicenter, randomized, double-blind, placebo-controlled phase III clinical study to evaluate the efficacy and safety of intramuscular injection of NL003 in CLTI patients. This study consisted of 22 trials: HOPE CLTI-1, which includes patients with rest pain (Rutherford stage 4), and HOPE CLTI-2, which includes patients with limb ulcers (Rutherford stage 5). In both trials, patients are randomized with a 2:1 ratio of intramuscular injection of NL003 to placebo. The primary endpoint of HOPE CLTI-1 is the complete pain relief rate. The primary endpoint of HOPE CLTI-2 is the complete ulcer healing rate. The safety endpoint was assessed based on adverse events after injection of NL003. Enrollment began in July 2019. The HOPE CLTI-1 trial aims to complete the randomization of at least 300 patients, while the HOPE CLTI-2 trial aims to enroll at least 240 patients. Both trials are organized such that patients will be followed for 6 months after the first intramuscular injection. CONCLUSIONS: HITOP CLTI, which is comprised of 2 multicenter, double-blind, placebo-controlled phase III clinical trials, aims to evaluate the efficacy and safety of the intramuscular administration of NL003 in patients with CLTI.

C-reactive Protein, Free Fatty Acid, and Uric Acid as Predictors of Adverse Events after Endovascular Revascularization of Arterial Femoropopliteal Occlusion Lesions.

OBJECTIVES: This study aimed to investigate the relationship between pre-procedure high-sensitivity C-reactive protein (hsCRP), free fatty acid (FFA), and uric acid (UA) levels and post-procedure mortality and morbidity of endovascular revascularization of arterial femoropopliteal occlusion lesions. METHODS: This was a retrospective review of clinical data retrieved from a prospectively held database in Peking Union Medical College Hospital. A total of 71 Patients who underwent endovascular treatment (EVT) for femoropopliteal occlusive disease between January 1, 2014 and November 1, 2017, were included in this study. Endpoints were defined as major adverse limb events (MALE; target vessel revascularization, amputation, or disease progression) and major adverse cardiovascular events (MACE; stroke, myocardial infarction, or all-cause death) during the entire follow-up period. Univariate and multivariate Cox proportional hazards regression models were used to evaluate the relationship of elevated biomarker levels (hsCRP, FFA and UA, measured by immunoturbidimetry assay, enzymatic assay and enzymatic assay, respectively) to MALE and MACE outcomes. RESULTS: Seventy-one patients (72 limbs) with sufficient follow-up information were included in the analysis. The mean age was 69.7 ± 8.6 years; 21.1% were female. The Rutherford class of target limbs were ≥ 3. The median follow-up was 36 (range 18-59 months). Univariate analyses revealed that patients with elevated hsCRP levels had an increased risk of MALE (hazard ratio [HR], 2.682; 95% confidence interval [CI], 1.281-5.617, P = 0.009). High FFA levels were associated with an increased risk of MALE (HR, 2.658; 95% CI, 1.075-6.573; P = 0.034). Multivariate analyses demonstrated that elevated hsCRP values (HR, 4.015; 95% CI, 1.628-10.551; P = 0.003) and FFA value (HR, 3.034; 95% CI, 1.102-8.354; P = 0.032) were both significantly associated with increased MALE. Elevated UA levels predicted MACE in the presence of confounders (HR, 11.446; 95% CI, 1.367-95.801 P = 0.023). CONCLUSION: Pre-procedure hsCRP and FFA levels could serve as predictors of adverse events after EVT in patients with arterial femoropopliteal occlusive disease. The role of UA in MACE may warrant further investigation, because the correlation is not as powerful as the other two in the study.

A systematic review and meta-analysis on the association between C-reactive protein levels and adverse limb events after revascularization in patients with peripheral arterial disease.

OBJECTIVE: Patients with peripheral arterial disease (PAD) are predisposed to postprocedure adverse limb events (ALE). Previous single-center studies investigating the relationship between baseline C-reactive protein (CRP) levels and postprocedure ALE have reported inconsistent results. Therefore, we performed a systematic review and meta-analysis of reported data to determine the association between CRP levels and the occurrence of postprocedure ALE in patients with PAD. METHODS: Studies investigating the association between the CRP levels and postprocedure ALE (ie, target vessel revascularization, amputation, restenosis, disease progression, composite endpoint of any of these ALE) were identified in the Medline, EMBASE, and Cochrane databases. Meta-analyses of the reported hazard ratios (HRs) were conducted using an inverse variance-weighted random effects model. Subgroup analyses were performed to determine the differences in outcomes between open surgery and endovascular treatment. Pooled estimates are reported as HRs to compare higher and lower CRP levels and odds ratio or relative risk per unit increase in logeCRP (natural logarithm C-reactive protein). RESULTS: A total of eight studies involving 1460 participants were included in our meta-analysis. Patients with higher baseline CRP levels had a greater risk of ALE (HR, 1.09; 95% confidence interval, 1.00-1.18; P = .04) compared with those with lower baseline CRP levels. The pooled estimate of odds ratio and relative risk for ALE was 2.25 (95% confidence interval, 1.49-3.41; P < .01) per unit increase in logeCRP. Subgroup analyses found no significant differences in the pooled estimates in studies of open surgery vs endovascular treatment. CONCLUSIONS: Our results have demonstrated that high baseline CRP levels are predictive of ALE in patients with PAD after lower limb revascularization.

An indirect comparison by Bayesian network meta-analysis of drug-coated devices versus saphenous vein graft bypass in femoropopliteal arterial occlusive disease.

OBJECTIVE: To compare the efficacy and safety between drug-coated devices (DCDs) and bypass surgery with saphenous vein graft (BSV) in femoropopliteal arterial occlusive disease. METHODS: A Bayesian network meta-analysis and indirect comparison were performed. Randomized controlled trials of BSV, bypass surgery with prosthetic graft, bare metal stents, endoluminal bypass (covered stent), percutaneous transluminal angioplasty, and DCDs treating femoropopliteal arterial occlusive disease were collected. The primary end point was target lesion revascularization/target vessel revascularization, and secondary end points were all-cause mortality, limb salvage, and early complications (PROSPERO registry number: CRD42019136530). RESULTS: Forty-two trials and 6867 patients were included. The comparison of DCDs and BSV revealed no significant difference in the 1-year target lesion revascularization/target vessel revascularization (DCDs vs BSV: odds ratio [OR], 0.60; 95% credible interval [CrI], 0.16-2.39). Total early complications from BSV were significantly higher than those from DCDs (DCDs vs BSV: OR, 0.14; 95% CrI, 0.05-0.45), and the main complications of BSV were not death related. There was also no significant difference in systemic early complications (DCDs vs BSV: OR, 0.19; 95% CrI, 0.00-7.82) and 1-year amputation rate (DCDs vs BSV: OR, 2.81; 95% CrI, 0.16-89.53). The 30-day (DCDs vs BSV: OR, 0.38; 95% CrI, 0.00-110.46), 1-year (DCDs vs BSV: OR, 0.96; 95% CrI, 0.24-3.29), 2-year (DCDs vs BSV: OR, 1.60; 95% CrI, 0.64-4.95), and 5-year all-cause mortality rates (DCDs vs BSV: OR, 2.05; 95% CrI, 0.92-4.39) showed no significant differences between DCDs and BSV, although there was a noticeable tendency toward significant results of a higher 5-year mortality rate. CONCLUSIONS: There is no significant difference between DCDs and BSV in short-term efficacy or short- and long-term mortality. Despite traditional BSV remaining the gold standard, DCDs provide a reasonable alternative therapy. In addition, the DCDs have a lower short-term morbidity associated with the procedure at the cost of the possible risk of higher long-term mortality. Clinical trials with more validity are required for a direct comparison between BSV and DCDs.

Potential Role of Melatonin as an Adjuvant for Atherosclerotic Carotid Arterial Stenosis.

Carotid artery stenosis (CAS) is an atherosclerotic disease characterized by a narrowing of the artery lumen and a high risk of ischemic stroke. Risk factors of atherosclerosis, including smoking, hypertension, hyperglycemia, hyperlipidemia, aging, and disrupted circadian rhythm, may potentiate atherosclerosis in the carotid artery and further reduce the arterial lumen. Ischemic stroke due to severe CAS and cerebral ischemic/reperfusion (I/R) injury after the revascularization of CAS also adversely affect clinical outcomes. Melatonin is a pluripotent agent with potent anti-inflammatory, anti-oxidative, and neuroprotective properties. Although there is a shortage of direct clinical evidence demonstrating the benefits of melatonin in CAS patients, previous studies have shown that melatonin may be beneficial for patients with CAS in terms of reducing endothelial damage, stabilizing arterial plaque, mitigating the harm from CAS-related ischemic stroke and cerebral I/R injury, and alleviating the adverse effects of the related risk factors. Additional pre-clinical and clinical are required to confirm this speculation.

Endovascular Aortic Repair Is a Viable Strategy for Treatment of Primary Infected Abdominal Aortic Aneurysm.

BACKGROUND: Infected abdominal aortic aneurysm (IAAA) is rare, and information is limited whether endovascular aortic repair (EVAR) can be considered a permanent treatment or is a temporary fix preceding open surgery. This retrospective study reviewed the short- and long-term outcomes of open surgery, emergent EVAR, and elective EVAR in the treatment of primary IAAA. METHODS: Between January 2008 and January 2017, 16 men and 3 women (aged 60.7 y; range 30-76 y) with IAAA were treated with emergent open repair, emergent EVAR, or elective EVAR, after adjunctive antibiotic therapy. Demographics, aneurysm anatomy, clinical presentations, laboratory tests, details of aneurysm repair, morbidity, mortality, and postoperative outcomes of these patients were reviewed. RESULTS: Positive microbial cultures were obtained in 12 patients. Six and 3 patients underwent emergent EVAR and open repair, respectively. Ten patients who completed the full antibiotic regimen received elective EVAR. The mean follow-up duration was 28.8 mo (range, 1.5-96 mo). The 30-day mortality rates of the emergent EVAR, open repair, and elective EVAR groups were 16.7% (1/6), 0%, and 0%, respectively; the 1-year survival rates were 16.7% (1/6), 100% (1/1), and 88.9% (8/9). Reduction in the blood erythrocyte sedimentation rate (ESR) during the first week of antibiotic treatment was inversely related to aneurysm rupture and correlated with patients' post-EVAR survival time. CONCLUSIONS: Elective EVAR for IAAA had acceptable short- and long-term outcomes. Patients' response to initial antibiotic treatment may help facilitate management. Less than 0.130 reduction in ESR during the first week of antibiotic treatment may indicate risk of aneurysm rupture.

Cigarette smoke exposure impairs lipid metabolism by decreasing low-density lipoprotein receptor expression in hepatocytes.

BACKGROUND: Cigarette smoke (CS) exposure impairs serum lipid profiles and the function of vascular endothelial cells, which accelerates the atherosclerosis. However, the precise mechanism and effect on the expression of low-density lipoprotein receptor (LDLR) in the liver by CS exposure is still unclear. METHODS: In this study, adult male C57BL/6 J mice were divided into three groups, with one group being exposed to CS for 6 weeks. HepG2 cells were treated with CS extract at concentrations of 1, 2.5, 5, and 10%. RESULTS: The serum levels of total cholesterol (TC), triglycerides (TGs), and low-density lipoprotein cholesterol (LDL-C) for the CS-exposure group were significantly higher than those in the control group (P < 0.05). Moreover, CS exposure decreased the LDLR expression in the hepatocytes and promoted inflammation in the blood vessel walls. Melatonin was intraperitoneally injected at 10 mg/kg/d for 6 weeks alongside CS exposure, and this significantly decreased the levels of TC, TGs, and LDL-C and decreased the expression of intercellular adhesion molecule-1 and the infiltration of cluster determinant 68-cells. In vitro, CS extract prepared by bubbling CS through phosphate-buffered saline decreased the LDLR expression in HepG2 cells in a time- and concentration-dependent manner, and this effect was prevented by pretreatment with 100 µM melatonin. CONCLUSIONS: In conclusion, CS exposure impaired lipid metabolism and decreased LDLR expression in hepatocytes, and these effects could be prevented by melatonin supplementation. These findings implied that melatonin has the potential therapeutic applicability in the prevention of lipid metabolic disorder in smokers.

[Genomics-based Biomarkers for Diseases:A Bibliometric Analysis Based on Web of Science].

Objective To analyze the research hotspots and trends of biomarkers for diseases based on genomics and thus provide basis for the future studies in this field. Method Based on the Web of Science,we analyzed the genomics-based biomarkers for diseases in literature published between 2006 and 2018 in terms of country and institutions,knowledge base,research hotspots,and trends by using bibliometric methods and CiteSpace software. Results A total of 998 articles were retrieved.The total number of articles has shown an upward trend and reached a peak of 112 in 2017 and 2018.Most articles(n=477)were from the United States,follwed by China(n=93).Nature,P Natl Acad Sci USA,PLoS One,Science,and New Engl J Med are core journals in this field.Keywords co-occurrence analysis identified four research hotspots:disease research,research method and technology,research level,and application purpose. Conclusion Research in functional genomics,cancer immunotherapy,genome-wide association and multi-omics techniques,personalized medicine,and precision medicine are research hotspots and frontiers in this field.

Melatonin attenuates smoking-induced hyperglycemia via preserving insulin secretion and hepatic glycogen synthesis in rats.

Epidemiology survey indicated that cigarette smoking is a risk factor of diabetes. However, the precise mechanisms remain to be clarified. In this study, we found that smoking caused metabolic malfunctions on pancreas and liver in experimental animal model. These were indicated by hyperglycemia, increased serum hemoglobin A1c level and decreased insulin secretion, inhibition of liver glycogen synthase (LGS), and hepatic glycogen synthesis. Mechanistic studies revealed that all these alterations were caused by the inflammatory reaction and reactive oxygen species (ROS) induced by the smoking. Melatonin treatment significantly preserved the functions of both pancreas and liver by reducing ß cell apoptosis, CD68-cell infiltration, ROS production, and caspase-3 expression. The siRNA-knockdown model identified that the protective effects of melatonin were mediated by melatonin receptor-2 (MT2). This study uncovered potentially underlying mechanisms related to the association between smoking and diabetes. In addition, it is, for first time, to report that melatonin effectively protects against smoking-induced glucose metabolic alterations and the signal transduction pathway of melatonin is mainly mediated by its MT2 receptor. These observations provide solid evidence for the clinically use of melatonin to reduce smoking-related diabetes, and the therapeutic regimens are absent currently.

A Legendre-Galerkin spectral method for constructing atmospheric acoustic normal modes.

A Legendre-Galerkin spectral method is applied to the construction of atmospheric acoustic normal modes above level ground, represented by a complex impedance. A search in the complex plane for modal eigenvalues is replaced by a complex symmetric matrix eigenvalue problem. The Legendre-Galerkin spectral method projects the acoustic normal modes onto an orthogonal basis of Legendre polynomials. The matrix eigenvalue problem can be solved by readily available, public domain, software. Prior knowledge of the location of a set of nearby real eigenvalues is unnecessary since the complex symmetric matrix formulation embodies an approximation of all of the physical constraints of the problem. The normal modes are used to compute the acoustic field, due to a harmonic point source in the atmosphere, including a group of discrete modes radiating into the upper atmosphere, usually associated with the continuous spectrum. The validity of the acoustic field calculation is tested in a comparison with the fast field program and interpreted, with aid of the normal modes, in a downward-refracting atmosphere.

Grp94 Protein Delivers γ-Aminobutyric Acid Type A (GABAA) Receptors to Hrd1 Protein-mediated Endoplasmic Reticulum-associated Degradation.

Proteostasis maintenance of γ-aminobutyric acid type A (GABAA) receptors dictates their function in controlling neuronal inhibition in mammalian central nervous systems. However, as a multisubunit, multispan, integral membrane protein, even wild type subunits of GABAA receptors fold and assemble inefficiently in the endoplasmic reticulum (ER). Unassembled and misfolded subunits undergo ER-associated degradation (ERAD), but this degradation process remains poorly understood for GABAA receptors. Here, using the α1 subunits of GABAA receptors as a model substrate, we demonstrated that Grp94, a metazoan-specific Hsp90 in the ER lumen, uses its middle domain to interact with the α1 subunits and positively regulates their ERAD. OS-9, an ER-resident lectin, acts downstream of Grp94 to further recognize misfolded α1 subunits in a glycan-dependent manner. This delivers misfolded α1 subunits to the Hrd1-mediated ubiquitination and the valosin-containing protein-mediated extraction pathway. Repressing the initial ERAD recognition step by inhibiting Grp94 enhances the functional surface expression of misfolding-prone α1(A322D) subunits, which causes autosomal dominant juvenile myoclonic epilepsy. This study clarifies a Grp94-mediated ERAD pathway for GABAA receptors, which provides a novel way to finely tune their function in physiological and pathophysiological conditions.

Combining valosin-containing protein (VCP) inhibition and suberanilohydroxamic acid (SAHA) treatment additively enhances the folding, trafficking, and function of epilepsy-associated γ-aminobutyric acid, type A (GABAA) receptors.

GABAA receptors are the primary inhibitory ion channels in the mammalian central nervous system. The A322D mutation in the α1 subunit results in its excessive endoplasmic reticulum-associated degradation at the expense of plasma membrane trafficking, leading to autosomal dominant juvenile myoclonic epilepsy. Presumably, valosin-containing protein (VCP)/p97 extracts misfolded subunits from the endoplasmic reticulum membrane to the cytosolic proteasome for degradation. Here we showed that inhibiting VCP using Eeyarestatin I reduces the endoplasmic reticulum-associated degradation of the α1(A322D) subunit without an apparent effect on its dynamin-1 dependent endocytosis and that this treatment enhances its trafficking. Furthermore, coapplication of Eeyarestatin I and suberanilohydroxamic acid, a known small molecule that promotes chaperone-assisted folding, yields an additive restoration of surface expression of α1(A322D) subunits in HEK293 cells and neuronal SH-SY5Y cells. Consequently, this combination significantly increases GABA-induced chloride currents in whole-cell patch clamping experiments than either chemical compound alone in HEK293 cells. Our findings suggest that VCP inhibition without stress induction, together with folding enhancement, represents a new strategy to restore proteostasis of misfolding-prone GABAA receptors and, therefore, a potential remedy for idiopathic epilepsy.

Saccharothrix stipae sp. nov., an actinomycete isolated from the rhizosphere of Stipa grandis.

An actinomycete, strain D34T, was isolated from a soil sample collected from the rhizosphere of Stipa grandis at Yunwu Mountain in Ningxia, north-west China. Strain D34T showed highest 16S rRNA gene sequence similarity to Saccharothrix espanaensis DSM 44229T (99.0 %), Saccharothrix texasensis NRRL B-16107T (98.7 %) and Saccharothrix variisporea NRRL B-16296T (98.6 %). The strain contained meso-diaminopimelic acid, alanine, glycine and glutamic acid as major cell-wall amino acids. Mannose, rhamnose and galactose were the characteristic whole-cell sugars. The fatty acid profile consisted predominantly of iso-C15 : 0, iso-C16 : 0, iso-C16 : 1, C17 : 1ω6c, anteiso-C17 : 0 and anteiso-C15 : 0. The phospholipid profile included phosphatidylethanolamine (typical of phospholipid pattern type II). Furthermore, a combination of some physiological and biochemical properties and low DNA-DNA relatedness values indicated that strain D34T was differentiated from members of closely related species. On the basis of these phenotypic, genotypic and chemotaxonomic data, strain D34T represents a novel species of the genus Saccharothrix, for which the name Saccharothrix stipae sp. nov. is proposed. The type strain is D34T ( = JCM 30560T = ACCC19714T).

Micromonospora nickelidurans sp. nov., isolated from soil from a nickel-mining site.

An actinomycete, strain K55T, was isolated from a composite soil sample from a nickel mine,collected from Yueyang, Shaanxi Province, PR China. Strain K55T showed 16S rRNA gene sequence similarities of 98.73 %­98.51 % to species of the genus Micromonospora, including Micromonospora haikouensis 232617T, Micromonospora coxensis 2-30-b(28)T, Micromonospora wenchangensis 2602GPT1-05T, Micromonospora matsumotoense IMSNU22003T, Micromonospora maoerensis NEAU-MES19T, and Micromonospora humi P0402T. This strain harboured meso-diaminopimelic acid, alanine and glycine as the major cell-wall amino acids, xylose and glucose as the characteristic whole-cell sugars, and iso-C15 : 0(20.53 %),iso-C17 : 0 (12.74 %), iso-C16 : 0 (12.15 %), anteiso-C17 : 0 (7.97 %), C17 : 1ω8c(7.49 %) and C17 : 0 (6.63 %) as the dominant fatty acids. The major menaquinones were MK-10(H4) and MK-10(H6). The phospholipid profile comprised phosphatidylethanolamine,diphosphatidylglycerol, phosphatidylinositol, phosphatidylglycerol and unknown phosphoglycolipids. The DNA G+C content was 71.4 mol%. A comprehensive analysis ofseveral physiological and biochemical traits and DNA­DNA relatedness indicated that strainK55T was different from closely related species. These phenotypic, genotypic and chemotaxonomic data suggest that strain K55T represents a novel species of the genus Micromonospora, for which the name Micromonospora nickelidurans sp. nov., is proposed. The type strain is K55T (5JCM 30559T5ACCC19713T).

Using pharmacological chaperones to restore proteostasis.

Normal organismal physiology depends on the maintenance of proteostasis in each cellular compartment to achieve a delicate balance between protein synthesis, folding, trafficking, and degradation while minimizing misfolding and aggregation. Defective proteostasis leads to numerous protein misfolding diseases. Pharmacological chaperones are cell-permeant small molecules that promote the proper folding and trafficking of a protein via direct binding to that protein. They stabilize their target protein in a protein-pharmacological chaperone state, increasing the natively folded protein population that can effectively engage trafficking machinery for transport to the final destination for function. Here, as regards the application of pharmacological chaperones, we focus on their capability to promote the folding and trafficking of lysosomal enzymes, G protein coupled receptors (GPCRs), and ion channels, each of which is presently an important drug target. Pharmacological chaperones hold great promise as potential therapeutics to ameliorate a variety of protein misfolding diseases.

Hsp47 promotes biogenesis of multi-subunit neuroreceptors in the endoplasmic reticulum.

Protein homeostasis (proteostasis) deficiency is an important contributing factor to neurological and metabolic diseases. However, how the proteostasis network orchestrates the folding and assembly of multi-subunit membrane proteins is poorly understood. Previous proteomics studies identified Hsp47 (Gene: SERPINH1), a heat shock protein in the endoplasmic reticulum lumen, as the most enriched interacting chaperone for gamma-aminobutyric type A (GABAA) receptors. Here, we show that Hsp47 enhances the functional surface expression of GABAA receptors in rat neurons and human HEK293T cells. Furthermore, molecular mechanism study demonstrates that Hsp47 acts after BiP (Gene: HSPA5) and preferentially binds the folded conformation of GABAA receptors without inducing the unfolded protein response in HEK293T cells. Therefore, Hsp47 promotes the subunit-subunit interaction, the receptor assembly process, and the anterograde trafficking of GABAA receptors. Overexpressing Hsp47 is sufficient to correct the surface expression and function of epilepsy-associated GABAA receptor variants in HEK293T cells. Hsp47 also promotes the surface trafficking of other Cys-loop receptors, including nicotinic acetylcholine receptors and serotonin type 3 receptors in HEK293T cells. Therefore, in addition to its known function as a collagen chaperone, this work establishes that Hsp47 plays a critical and general role in the maturation of multi-subunit Cys-loop neuroreceptors.