Lei Xiong, Hao-Han Guo, Jin-Xiu Pan, Xiao Ren, Daehoon Lee, Li Chen, Lin Mei, Wen-Cheng Xiong
{"title":"ATP6AP2 是 LRP6/β-catenin 蛋白运输的调节因子,它以细胞类型依赖的方式促进 Wnt/β-catenin 信号传导和骨形成","authors":"Lei Xiong, Hao-Han Guo, Jin-Xiu Pan, Xiao Ren, Daehoon Lee, Li Chen, Lin Mei, Wen-Cheng Xiong","doi":"10.1038/s41413-024-00335-7","DOIUrl":null,"url":null,"abstract":"<p>Wnt/β-catenin signaling is critical for various cellular processes in multiple cell types, including osteoblast (OB) differentiation and function. Exactly how Wnt/β-catenin signaling is regulated in OBs remain elusive. ATP6AP2, an accessory subunit of V-ATPase, plays important roles in multiple cell types/organs and multiple signaling pathways. However, little is known whether and how ATP6AP2 in OBs regulates Wnt/β-catenin signaling and bone formation. Here we provide evidence for ATP6AP2 in the OB-lineage cells to promote OB-mediated bone formation and bone homeostasis selectively in the trabecular bone regions. Conditionally knocking out (CKO) ATP6AP2 in the OB-lineage cells (<i>Atp6ap2</i><sup><i>Ocn-Cre</i></sup>) reduced trabecular, but not cortical, bone formation and bone mass. Proteomic and cellular biochemical studies revealed that LRP6 and N-cadherin were reduced in <i>ATP6AP2-KO</i> BMSCs and OBs, but not osteocytes. Additional in vitro and in vivo studies revealed impaired β-catenin signaling in <i>ATP6AP2-KO</i> BMSCs and OBs, but not osteocytes, under both basal and Wnt stimulated conditions, although LRP5 was decreased in <i>ATP6AP2-KO</i> osteocytes, but not BMSCs. Further cell biological studies uncovered that osteoblastic ATP6AP2 is not required for Wnt3a suppression of β-catenin phosphorylation, but necessary for LRP6/β-catenin and N-cadherin/β-catenin protein complex distribution at the cell membrane, thus preventing their degradation. Expression of active β-catenin diminished the OB differentiation deficit in <i>ATP6AP2-KO</i> BMSCs. Taken together, these results support the view for ATP6AP2 as a critical regulator of both LRP6 and N-cadherin protein trafficking and stability, and thus regulating β-catenin levels, demonstrating an un-recognized function of osteoblastic ATP6AP2 in promoting Wnt/LRP6/β-catenin signaling and trabecular bone formation.</p>","PeriodicalId":9134,"journal":{"name":"Bone Research","volume":null,"pages":null},"PeriodicalIF":14.3000,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"ATP6AP2, a regulator of LRP6/β-catenin protein trafficking, promotes Wnt/β-catenin signaling and bone formation in a cell type dependent manner\",\"authors\":\"Lei Xiong, Hao-Han Guo, Jin-Xiu Pan, Xiao Ren, Daehoon Lee, Li Chen, Lin Mei, Wen-Cheng Xiong\",\"doi\":\"10.1038/s41413-024-00335-7\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Wnt/β-catenin signaling is critical for various cellular processes in multiple cell types, including osteoblast (OB) differentiation and function. Exactly how Wnt/β-catenin signaling is regulated in OBs remain elusive. ATP6AP2, an accessory subunit of V-ATPase, plays important roles in multiple cell types/organs and multiple signaling pathways. However, little is known whether and how ATP6AP2 in OBs regulates Wnt/β-catenin signaling and bone formation. Here we provide evidence for ATP6AP2 in the OB-lineage cells to promote OB-mediated bone formation and bone homeostasis selectively in the trabecular bone regions. Conditionally knocking out (CKO) ATP6AP2 in the OB-lineage cells (<i>Atp6ap2</i><sup><i>Ocn-Cre</i></sup>) reduced trabecular, but not cortical, bone formation and bone mass. Proteomic and cellular biochemical studies revealed that LRP6 and N-cadherin were reduced in <i>ATP6AP2-KO</i> BMSCs and OBs, but not osteocytes. Additional in vitro and in vivo studies revealed impaired β-catenin signaling in <i>ATP6AP2-KO</i> BMSCs and OBs, but not osteocytes, under both basal and Wnt stimulated conditions, although LRP5 was decreased in <i>ATP6AP2-KO</i> osteocytes, but not BMSCs. Further cell biological studies uncovered that osteoblastic ATP6AP2 is not required for Wnt3a suppression of β-catenin phosphorylation, but necessary for LRP6/β-catenin and N-cadherin/β-catenin protein complex distribution at the cell membrane, thus preventing their degradation. Expression of active β-catenin diminished the OB differentiation deficit in <i>ATP6AP2-KO</i> BMSCs. Taken together, these results support the view for ATP6AP2 as a critical regulator of both LRP6 and N-cadherin protein trafficking and stability, and thus regulating β-catenin levels, demonstrating an un-recognized function of osteoblastic ATP6AP2 in promoting Wnt/LRP6/β-catenin signaling and trabecular bone formation.</p>\",\"PeriodicalId\":9134,\"journal\":{\"name\":\"Bone Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":14.3000,\"publicationDate\":\"2024-05-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Bone Research\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.1038/s41413-024-00335-7\",\"RegionNum\":1,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CELL & TISSUE ENGINEERING\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bone Research","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1038/s41413-024-00335-7","RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CELL & TISSUE ENGINEERING","Score":null,"Total":0}
ATP6AP2, a regulator of LRP6/β-catenin protein trafficking, promotes Wnt/β-catenin signaling and bone formation in a cell type dependent manner
Wnt/β-catenin signaling is critical for various cellular processes in multiple cell types, including osteoblast (OB) differentiation and function. Exactly how Wnt/β-catenin signaling is regulated in OBs remain elusive. ATP6AP2, an accessory subunit of V-ATPase, plays important roles in multiple cell types/organs and multiple signaling pathways. However, little is known whether and how ATP6AP2 in OBs regulates Wnt/β-catenin signaling and bone formation. Here we provide evidence for ATP6AP2 in the OB-lineage cells to promote OB-mediated bone formation and bone homeostasis selectively in the trabecular bone regions. Conditionally knocking out (CKO) ATP6AP2 in the OB-lineage cells (Atp6ap2Ocn-Cre) reduced trabecular, but not cortical, bone formation and bone mass. Proteomic and cellular biochemical studies revealed that LRP6 and N-cadherin were reduced in ATP6AP2-KO BMSCs and OBs, but not osteocytes. Additional in vitro and in vivo studies revealed impaired β-catenin signaling in ATP6AP2-KO BMSCs and OBs, but not osteocytes, under both basal and Wnt stimulated conditions, although LRP5 was decreased in ATP6AP2-KO osteocytes, but not BMSCs. Further cell biological studies uncovered that osteoblastic ATP6AP2 is not required for Wnt3a suppression of β-catenin phosphorylation, but necessary for LRP6/β-catenin and N-cadherin/β-catenin protein complex distribution at the cell membrane, thus preventing their degradation. Expression of active β-catenin diminished the OB differentiation deficit in ATP6AP2-KO BMSCs. Taken together, these results support the view for ATP6AP2 as a critical regulator of both LRP6 and N-cadherin protein trafficking and stability, and thus regulating β-catenin levels, demonstrating an un-recognized function of osteoblastic ATP6AP2 in promoting Wnt/LRP6/β-catenin signaling and trabecular bone formation.
期刊介绍:
Established in 2013, Bone Research is a newly-founded English-language periodical that centers on the basic and clinical facets of bone biology, pathophysiology, and regeneration. It is dedicated to championing key findings emerging from both basic investigations and clinical research concerning bone-related topics. The journal's objective is to globally disseminate research in bone-related physiology, pathology, diseases, and treatment, contributing to the advancement of knowledge in this field.