{"title":"Sex-specific protective effects of angiotensin II type 1 receptor knockdown on disuse muscle atrophy in the rat soleus muscle.","authors":"Toshinori Yoshihara, Mizuki Takaragawa, Shohei Dobashi, Hisashi Naito","doi":"10.1152/japplphysiol.00731.2025","DOIUrl":null,"url":null,"abstract":"<p><p>Skeletal muscle disuse leads to atrophy. Accumulating evidence suggests that angiotensin II type 1 receptor (AT1R) contributes to sex-dependent catabolic signaling. However, the direct role of AT1R in skeletal muscle is unclear. This study investigated whether selective suppression of AT1R expression in the rat soleus muscle via adeno-associated virus serotype 9 (AAV9)-mediated short hairpin RNA (shRNA) delivery could mitigate hindlimb unloading (HU)-induced muscle atrophy, and whether this effect differed between male and female rats. Male and female rats received intramuscular injections of AAV9 vectors encoding AT1R-targeted shRNA into the soleus muscle. After 7 d of HU, <i>AT1R</i> gene copy number (digital PCR), receptor abundance (ligand binding assay), muscle fiber cross-sectional area (CSA), and downstream molecular markers (including phosphorylated Smad2/3 and Smad1/5/8, HDAC4 expression, and the atrogenes, <i>Fbxo32</i> and <i>Trim63</i>) were assessed. Female rats exhibited substantially higher <i>AT1R</i> gene copy numbers, which were selectively reduced by AAV9-shRNA. Ligand binding confirmed reduced receptor abundance in both sexes. CSA loss attenuation was observed exclusively in females, particularly in type I fibers. In female animals, AT1R knockdown substantially increased Smad1/5/8 phosphorylation and decreased HDAC4 expression. The AT1R copy number was positively correlated with <i>Fbxo32</i> and <i>Trim63</i> expression, independent of AAV dose. AT1R plays a sex-specific role in disuse-induced muscle atrophy, as muscle-specific AT1R knockdown conferred selective protection in female rats. The effect appears to be mediated via Smad1/5/8-HDAC4 signaling rather than oxidative stress or autophagy. This study provides mechanistic support for sex-informed therapeutic strategies targeting the muscle-localized renin-angiotensin system.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3000,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of applied physiology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1152/japplphysiol.00731.2025","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"PHYSIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Skeletal muscle disuse leads to atrophy. Accumulating evidence suggests that angiotensin II type 1 receptor (AT1R) contributes to sex-dependent catabolic signaling. However, the direct role of AT1R in skeletal muscle is unclear. This study investigated whether selective suppression of AT1R expression in the rat soleus muscle via adeno-associated virus serotype 9 (AAV9)-mediated short hairpin RNA (shRNA) delivery could mitigate hindlimb unloading (HU)-induced muscle atrophy, and whether this effect differed between male and female rats. Male and female rats received intramuscular injections of AAV9 vectors encoding AT1R-targeted shRNA into the soleus muscle. After 7 d of HU, AT1R gene copy number (digital PCR), receptor abundance (ligand binding assay), muscle fiber cross-sectional area (CSA), and downstream molecular markers (including phosphorylated Smad2/3 and Smad1/5/8, HDAC4 expression, and the atrogenes, Fbxo32 and Trim63) were assessed. Female rats exhibited substantially higher AT1R gene copy numbers, which were selectively reduced by AAV9-shRNA. Ligand binding confirmed reduced receptor abundance in both sexes. CSA loss attenuation was observed exclusively in females, particularly in type I fibers. In female animals, AT1R knockdown substantially increased Smad1/5/8 phosphorylation and decreased HDAC4 expression. The AT1R copy number was positively correlated with Fbxo32 and Trim63 expression, independent of AAV dose. AT1R plays a sex-specific role in disuse-induced muscle atrophy, as muscle-specific AT1R knockdown conferred selective protection in female rats. The effect appears to be mediated via Smad1/5/8-HDAC4 signaling rather than oxidative stress or autophagy. This study provides mechanistic support for sex-informed therapeutic strategies targeting the muscle-localized renin-angiotensin system.
期刊介绍:
The Journal of Applied Physiology publishes the highest quality original research and reviews that examine novel adaptive and integrative physiological mechanisms in humans and animals that advance the field. The journal encourages the submission of manuscripts that examine the acute and adaptive responses of various organs, tissues, cells and/or molecular pathways to environmental, physiological and/or pathophysiological stressors. As an applied physiology journal, topics of interest are not limited to a particular organ system. The journal, therefore, considers a wide array of integrative and translational research topics examining the mechanisms involved in disease processes and mitigation strategies, as well as the promotion of health and well-being throughout the lifespan. Priority is given to manuscripts that provide mechanistic insight deemed to exert an impact on the field.