Atp6v1h Deficiency Blocks Bone Loss in Simulated Microgravity Mice through the Fos-Jun-Src-Integrin Pathway.

The microgravity conditions in outer space are widely acknowledged to induce significant bone loss. Recent studies have implicated the close relationship between Atp6v1h gene and bone loss. Despite this, the role of Atp6v1h in bone remodeling and its molecular mechanisms in microgravity have not been fully elucidated. To address this, we used a mouse tail suspension model to simulate microgravity. We categorized both wild-type and Atp6v1h knockout (Atp6v1h+/-) mice into two groups: regular feeding and tail-suspension feeding, ensuring uniform feeding conditions across all cohorts. Analysis via micro-CT scanning, hematoxylin-eosin staining, and tartrate-resistant acid phosphatase assays indicated that wild-type mice underwent bone loss under simulated microgravity. Atp6v1h+/- mice exhibited bone loss due to Atp6v1h deficiency but did not present aggravated bone loss under the same simulated microgravity. Transcriptomic sequencing revealed the upregulation of genes, such as Fos, Src, Jun, and various integrin subunits in the context of simulated microgravity and Atp6v1h knockout. Real-time quantitative polymerase chain reaction (RT-qPCR) further validated the modulation of downstream osteoclast-related genes in response to interactions with ATP6V1H overexpression cell lines. Co-immunoprecipitation indicated potential interactions between ATP6V1H and integrin beta 1, beta 3, beta 5, alpha 2b, and alpha 5. Our results indicate that Atp6v1h level influences bone loss in simulated microgravity by modulating the Fos-Jun-Src-Integrin pathway, which, in turn, affects osteoclast activity and bone resorption, with implications for osteoporosis. Therefore, modulating Atp6v1h expression could mitigate bone loss in microgravity conditions. This study elucidates the molecular mechanism of Atp6v1h's role in osteoporosis and positions it as a potential therapeutic target against environmental bone loss. These findings open new possibilities for the treatment of multifactorial osteoporosis.

Long Noncoding RNA lnc-TCEA1-3 Affects Osteoclastic Function by Regulating ATP6V1H.

H subunit of V-ATPase (ATP6V1H) is specifically expressed in osteoclasts and its deficiency lead to osteoporosis. Our group previously found four intronic SNPs of ATP6V1H related to reduced bone mineral density, but the mechanisms was not clear. In this study, we found that the above four SNPs were located at lncRNA lnc-TCEA1-3 by using bioinformatics analysis. We further detected the function of lnc-TCEA1-3 on regulating ATP6V1H and osteoclast function using Atp6v1h knockout mice, lentivirus transfection and qPCR analysis. Over expression of lnc-TCEA1-3 up regulated the expression of ATP6V1H in HEK293 cells, HOS cells and primarily cultured osteoclasts, and increased the number of primarily cultured osteoclasts. In addition, over expression of lnc-TCEA1-3 exerted distinct effect on two transcripts of ATP6V1H in HEK293, HOS and osteoclasts. This study will facilitate the in-depth analysis of the effects of ATP6V1H on bone diseases, and discover new therapeutic strategies.

ATP6V1H deficiency impairs glucose tolerance by augmenting endoplasmic reticulum stress in high fat diet fed mice.

Vacuolar H+-ATPase (V-ATPase) is a ubiquitous proton pump that mediates the proton transmembrane transportation in various cells. Previously, H subunit of V-ATPase (ATP6V1H) was found to be related with insulin secretion and diabetes. However, the mechanism by which ATP6V1H regulates insulin secretion and glucose metabolism remains unclear. Herein, we established a high-fat-diet (HFD) fed model with Atp6v1h+/- mice and detected the expression and secretion of insulin and some biochemical indices of glucose metabolism, in order to explore the related mechanisms in ß-cells. Transcriptome sequencing, qPCR and western blot analysis showed that ATP6V1H deficiency worsened fatty acid-induced glucose tolerance impairment by augmenting endoplasmic reticulum stress in ß-cells, and alternative splicing of ATP6V1H might be involved in this process. These results indicated that ATP6V1H deficiency increased the susceptibility to T2DM.