Cardiac-targeted PIASy gene silencing mediates deSUMOylation of caveolin-3 and prevents ischemia/reperfusion-induced Na_(v)1.5 downregulation and ventricular arrhythmias

Background:Abnormal myocardial voltage-gated sodium channel 1.5(Nav1.5)expression and function cause lethal ventricular arrhythmias during myocardial ischemia–reperfusion(I/R).Protein inhibitor of activated STAT Y(PIASy)-mediated caveolin-3(Cav-3)small ubiquitin-related modifier(SUMO)modification affects Cav-3 binding to the Nav1.5.PIASy activity is increased after myocardial I/R,but it is unclear whether this is attributable to plasma membrane Nav1.5 downregulation and ventricular arrhythmias.Methods:Using recombinant adeno-associated virus subtype 9(AAV9),rat cardiac PIASy was silenced using intraventricular injection of PIASy short hairpin RNA(shRNA).After two weeks,rat hearts were subjected to I/R and electrocardiography was performed to assess malignant arrhythmias.Tissues from peri-infarct areas of the left ventricle were collected for molecular biological measurements.Results:PIASy was upregulated by I/R(P<0.01),with increased SUMO2/3 modification of Cav-3 and reduced membrane Nav1.5 density(P<0.01).AAV9-PIASy shRNA intraventricular injection into the rat heart down-regulated PIASy after I/R,at both mRNA and protein levels(P<0.05 vs.Scramble-shRNA+I/R group),decreased SUMO-modified Cav-3 levels,enhanced Cav-3 binding to Nav1.5,and prevented I/R-induced decrease of Nav1.5 and Cav-3co-localization in the intercalated disc and lateral membrane.PIASy silencing in rat hearts reduced I/R-induced fatal arrhythmias,which was reflected by a modest decrease in the duration of ventricular fibrillation(VF;P<0.05 vs.Scramble-shRNA+I/R group)and a significantly reduced arrhythmia score(P<0.01 vs.Scramble-shRNA+I/R group).The anti-arrhythmic effects of PIASy silencing were also evidenced by decreased episodes of ventricular tachycardia(VT),sustained VT and VF,especially at the time 5–10 min after ischemia(P<0.05 vs.Scramble-shRNA+IR group).Using in vitro human embryonic kidney 293 T(HEK293T)cells and isolated adult rat cardiomyocyte models exposed to hypoxia/reoxygenation(H/R),we confirmed that increased PIASy promoted Cav-3 modification by SUMO2/3 and Nav1.5/Cav-3 dissociation after H/R.Mutation of SUMO consensus lysine sites in Cav-3(K38R or K144R)altered the membrane expression levels of Nav1.5 and Cav-3 before and after H/R in HEK293T cells.Conclusions:I/R-induced cardiac PIASy activation increased Cav-3 SUMOylation by SUMO2/3 and dysregulated Nav1.5-related ventricular arrhythmias.Cardiac-targeted PIASy silencing mediated Cav-3 deSUMOylation and partially prevented I/R-induced Nav1.5 downregulation in the plasma membrane of cardiomyocytes,and subsequent ventricular arrhythmias in rats.PIASy was identified as a potential therapeutic target for life-threatening arrhythmias in patients with ischemic heart diseases.

Electroacupuncture alleviates postoperative pain through inhibiting neuroinflammation via stimulator of interferon genes/type-1 interferon pathway

Objective This work explores the impact of electroacupuncture(EA)on acute postoperative pain(APP)and the role of stimulator of interferon genes/type-1 interferon(STING/IFN-1)signaling pathway modulation in the analgesic effect of EA in APP rats.Methods The APP rat model was initiated through abdominal surgery and the animals received two 30 min sessions of EA at bilateral ST36(Zusanli)and SP6(Sanyinjiao)acupoints.Mechanical,thermal and cold sensitivity tests were performed to measure the pain threshold,and electroencephalograms were recorded in the primary somatosensory cortex to identify the effects of EA treatment on APP.Western blotting and immunofluorescence were used to examine the expression and distribution of proteins in the STING/IFN-1 pathway as well as neuroinflammation.A STING inhibitor(C-176)was administered intrathecally to verify its role in EA.Results APP rats displayed mechanical and thermal hypersensitivities compared to the control group(P<0.05).APP significantly reduced the amplitude ofθ,αandγoscillations compared to their baseline values(P<0.05).Interestingly,expression levels of proteins in the STING/IFN-1 pathway were downregulated after inducing APP(P<0.05).Further,APP increased pro-inflammatory factors,including interleukin-6,tumor necrosis factor-αand inducible nitric oxide synthase,and downregulated anti-inflammatory factors,including interleukin-10 and arginase-1(P<0.05).EA effectively attenuated APP-induced painful hypersensitivities(P<0.05)and restored theθ,αandγpower in APP rats(P<0.05).Meanwhile,EA distinctly activated the STING/IFN-1 pathway and mitigated the neuroinflammatory response(P<0.05).Furthermore,STING/IFN-1 was predominantly expressed in isolectin-B4-or calcitonin-gene-related-peptide-labeled dorsal root ganglion neurons and superficial laminae of the spinal dorsal horn.Inhibition of the STING/IFN-1 pathway by intrathecal injection of C-176 weakened the analgesic and anti-inflammatory effects of EA on APP(P<0.05).Conclusion EA can generate robust analgesic and anti-inflammatory effects on APP,and these effects may be linked to activating the STING/IFN-1 pathway,suggesting that STING/IFN-1 may be a target for relieving APP.