Yang Liuqing, Ahammed Md Salim, Wu Penglong, Sternburg Jack O, Liu Jinbao, Wang Xuejun
Division of Basic Biomedical Sciences, Sanford School of Medicine of The University of South Dakota Vermillion, SD 57069, USA.
Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, State Key Lab of Respiratory Disease, School of Basic Medical Sciences, Affiliated Cancer Hospital of Guangzhou Medical University Guangzhou 511436, Guangdong, P. R. China.
Am J Cardiovasc Dis. 2024 Apr 15;14(2):90-105. doi: 10.62347/NSWR6869. eCollection 2024.
Proteasome activation by the cAMP-dependent protein kinase (PKA) was long suggested and recent studies using both cell cultures and genetically engineered mice have established that direct phosphorylation of RPN6/PSMD11 at Serine14 (pS14-RPN6) mediates the activation of 26S proteasomes by PKA. Genetic mimicry of pS14-RPN6 has been shown to be benign at baseline and capable of protecting against cardiac proteinopathy in mice. Here we report the results from a comprehensive baseline characterization of the Rpn6 mice (S14A), the first animal model of genetic blockade of the activation of 26S proteasomes by PKA.
Wild type and homozygous S14A littermate mice were subjected to serial M-mode echocardiography at 1 through 7 months of age, to left ventricular (LV) catheterization via the carotid artery for assessment of LV mechanical performance, and to cardiac gravimetric analyses at 26 weeks of age. Mouse mortality and morbidity were monitored daily for up to one year. Males and females were studied in parallel.
Mice homozygous for S14A were viable and fertile and did not show discernible developmental abnormalities or increased mortality or morbidity compared with their Rpn6 wild type littermates by at least one year of age, the longest cohort observed thus far. Neither serial echocardiography nor hemodynamic assessments detected a remarkable difference in cardiac morphometry and function between S14A and wild type littermate mice. No cardiac gravimetric difference was observed.
The findings of the present study indicate that genetic blockade of the activation of 26S proteasomes by PKA is well tolerated by mice at baseline. Therefore, the S14A mouse provides a desirable genetic tool for further investigating the in vivo pathophysiological and pharmacological significance of pS14-RPN6.
长期以来一直有人提出环磷酸腺苷依赖性蛋白激酶（PKA）可激活蛋白酶体，最近使用细胞培养和基因工程小鼠的研究证实，RPN6/PSMD11在丝氨酸14位点（pS14-RPN6）的直接磷酸化介导了PKA对26S蛋白酶体的激活。已证明pS14-RPN6的基因模拟在基线时是良性的，并且能够预防小鼠的心脏蛋白病。在此，我们报告了Rpn6小鼠（S14A）全面基线特征的研究结果，这是首个通过基因阻断PKA激活26S蛋白酶体的动物模型。
对野生型和纯合S14A同窝小鼠在1至7月龄时进行系列M型超声心动图检查，通过颈动脉进行左心室（LV）插管以评估LV机械性能，并在26周龄时进行心脏重量分析。每天监测小鼠的死亡率和发病率，最长观察一年。同时对雄性和雌性小鼠进行研究。
S14A纯合小鼠存活且可育，与Rpn6野生型同窝小鼠相比，至少在一岁时（迄今为止观察到的最长队列）未显示出明显的发育异常、死亡率或发病率增加。系列超声心动图和血流动力学评估均未发现S14A和野生型同窝小鼠在心脏形态和功能上有显著差异。未观察到心脏重量差异。
本研究结果表明，PKA激活26S蛋白酶体的基因阻断在基线时小鼠耐受性良好。因此，S14A小鼠为进一步研究pS14-RPN6的体内病理生理和药理意义提供了理想的遗传工具。
