Inhibitory effect and mechanism of PKD1 gene-specific knockout on myocardial injury in mice with septic cardiomyopathy

WANG Haibo; LIU Xintong; HUANG Zhixin; LIU Guangjiao; TAN Xiaojin

doi:10.3969/j.issn.1002-266X.2025.05.012

Abstract：Objective To investigate the inhibitory effect and mechanism of protein kinase D1(PKD1)gene-specif-ic knockout in cardiomyocytes on myocardial injury in mice with septic cardiomyopathy(SCM).Methods Twenty-six male mice were randomly divided into four groups:sham group(n=4),model group(n=9),knockout sham group(n=4),and knockout model group(n=9).The PKD1 gene was knocked out in the latter two groups using the Cre-loxP recombina-tion system.Two months later,the model and knockout model groups underwent cecal ligation and puncture(CLP)to es-tablish SCM.At 24 h after CLP,echocardiography was performed to assess myocardial injury indicators[heart weight to tibia length ratio(HW/TL),left ventricular end-systolic diameter(LVIDs),left ventricular end-systolic volume(LVESV),left ventricular ejection fraction(LVEF),and left ventricular fractional shortening(LVFS)].Hematoxylin-eo-sin staining was used to observe myocardial histopathology.Western blotting was performed to detect PKD1,signal trans-ducer and activator of transcription 3(STAT3),and STAT3 phosphorylation at Tyr705(STAT3 Tyr705)in cardiomyocytes and their nuclei,cytoplasm,and mitochondria.Real-time fluorescent quantitative reverse transcription PCR(qRT-PCR)was used to measure PKD1 and suppressor of cytokine signaling 3(SOCS3)mRNA expression in the myocardial tissues.Results There was no significant difference in HW/TL among the groups(P>0.05).Compared with the sham group,the model group exhibited higher LVIDs and LVESV but lower LVEF and LVFS(all P<0.05).In contrast,the knockout model group showed lower LVIDs and LVESV but higher LVEF and LVFS than the model group(all P<0.05).At 24 h af-ter CLP,the model group displayed significant myocardial fiber disruption,cellular edema,necrosis,and neutrophil infil-tration,whereas the knockout model group exhibited improved histopathology.No significant differences were observed in STAT3 protein expression in the nuclei,cytoplasm,or mitochondria among the groups(all P>0.05).Compared with the sham group,the model group had higher STAT3 Tyr705 protein expression in the nuclei and cytoplasm(P<0.05).Howev-er,the knockout model group showed lower STAT3 Tyr705 expression in the nuclei but higher expression in the cytoplasm than the model group(all P<0.05).Additionally,SOCS3 mRNA expression was higher in the model group than in the sham group(P<0.05),whereas the knockout model group had lower nuclear SOCS3 mRNA expression than the model group(P<0.05).Conclusion PKD1 knockout may inhibit myocardial injury in SCM mice by inhibiting STAT3 phos-phorylation in cardiomyocyte nuclei and reducing SOCS3 mRNA expression.