LARG GEF and ARHGAP18 orchestrate RhoA activity to control mesenchymal stem cell lineage
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| Title: | LARG GEF and ARHGAP18 orchestrate RhoA activity to control mesenchymal stem cell lineage |
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| Authors: | Sherwin S. Yen, Maya Styner, Keith Burridge, Gunes Uzer, William R. Thompson, Zhihui Xie, Buer Sen, Janet Rubin |
| Contributors: | Physical Therapy, School of Health and Rehabilitation Sciences |
| Source: | Bone. 107:172-180 |
| Publisher Information: | Elsevier BV, 2018. |
| Publication Year: | 2018 |
| Subject Terms: | Male, rho GTP-Binding Proteins, 0301 basic medicine, LARG, Bone Marrow Cells, ARHGAP18, adipogenesis, osteogenesis, Mice, 03 medical and health sciences, Osteogenesis, Animals, Cell Lineage, Biomedical Engineering and Bioengineering, mesenchymal stem cells, 0303 health sciences, Adipogenesis, Mechanical Engineering, GTPase-Activating Proteins, RhoA, Cell Differentiation, Mesenchymal Stem Cells, Adaptation, Physiological, BRC, Mice, Inbred C57BL, Stress, Mechanical, rhoA GTP-Binding Protein, Rho Guanine Nucleotide Exchange Factors |
| Description: | The quantity and quality of bone depends on osteoblastic differentiation of mesenchymal stem cells (MSCs), where adipogenic commitment depletes the available pool for osteogenesis. Cell architecture influences lineage decisions, where interfering with cytoskeletal structure promotes adipogenesis. Mechanical strain suppresses MSC adipogenesis partially through RhoA driven enhancement of cytoskeletal structure. To understand the basis of force-driven RhoA activation, we considered critical GEFs (activators) and GAPs (inactivators) on bone marrow MSC lineage fate. Knockdown of LARG accelerated adipogenesis and repressed basal RhoA activity. Importantly, mechanical activation of RhoA was almost entirely inhibited following LARG depletion, and the ability of strain to inhibit adipogenesis was impaired. Knockdown of ARHGAP18 increased basal RhoA activity and actin stress fiber formation, but did not enhance mechanical strain activation of RhoA. ARHGAP18 null MSCs exhibited suppressed adipogenesis assessed by Oil-Red-O staining and Western blot of adipogenic markers. Furthermore, ARHGAP18 knockdown enhanced osteogenic commitment, confirmed by alkaline phosphatase staining and qPCR of Sp7, Alpl, and Bglap genes. This suggests that ARHGAP18 conveys tonic inhibition of MSC cytoskeletal assembly, returning RhoA to an "off state" and affecting cell lineage in the static state. In contrast, LARG is recruited during dynamic mechanical strain, and is necessary for mechanical suppression of adipogenesis. In summary, mechanical activation of RhoA in mesenchymal progenitors is dependent on LARG, while ARHGAP18 limits RhoA delineated cytoskeletal structure in static cultures. Thus, on and off GTP exchangers work through RhoA to influence MSC fate and responses to static and dynamic physical factors in the microenvironment. |
| Document Type: | Article |
| File Description: | application/pdf |
| Language: | English |
| ISSN: | 8756-3282 |
| DOI: | 10.1016/j.bone.2017.12.001 |
| DOI: | 10.17615/sg2p-4h46 |
| Access URL: | https://europepmc.org/articles/pmc5743610?pdf=render https://pubmed.ncbi.nlm.nih.gov/29208526 https://www.sciencedirect.com/science/article/pii/S8756328217304416 http://www.ncbi.nlm.nih.gov/pubmed/29208526 https://core.ac.uk/display/146989135 https://scholarworks.boisestate.edu/mecheng_facpubs/87/ https://works.bepress.com/gunes-uzer/11/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5743610/ |
| Rights: | Elsevier TDM |
| Accession Number: | edsair.doi.dedup.....b185bbae9f422ce317cb8fd5cd5499a8 |
| Database: | OpenAIRE |
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Nájsť tento článok vo Web of Science | Abstract: | The quantity and quality of bone depends on osteoblastic differentiation of mesenchymal stem cells (MSCs), where adipogenic commitment depletes the available pool for osteogenesis. Cell architecture influences lineage decisions, where interfering with cytoskeletal structure promotes adipogenesis. Mechanical strain suppresses MSC adipogenesis partially through RhoA driven enhancement of cytoskeletal structure. To understand the basis of force-driven RhoA activation, we considered critical GEFs (activators) and GAPs (inactivators) on bone marrow MSC lineage fate. Knockdown of LARG accelerated adipogenesis and repressed basal RhoA activity. Importantly, mechanical activation of RhoA was almost entirely inhibited following LARG depletion, and the ability of strain to inhibit adipogenesis was impaired. Knockdown of ARHGAP18 increased basal RhoA activity and actin stress fiber formation, but did not enhance mechanical strain activation of RhoA. ARHGAP18 null MSCs exhibited suppressed adipogenesis assessed by Oil-Red-O staining and Western blot of adipogenic markers. Furthermore, ARHGAP18 knockdown enhanced osteogenic commitment, confirmed by alkaline phosphatase staining and qPCR of Sp7, Alpl, and Bglap genes. This suggests that ARHGAP18 conveys tonic inhibition of MSC cytoskeletal assembly, returning RhoA to an "off state" and affecting cell lineage in the static state. In contrast, LARG is recruited during dynamic mechanical strain, and is necessary for mechanical suppression of adipogenesis. In summary, mechanical activation of RhoA in mesenchymal progenitors is dependent on LARG, while ARHGAP18 limits RhoA delineated cytoskeletal structure in static cultures. Thus, on and off GTP exchangers work through RhoA to influence MSC fate and responses to static and dynamic physical factors in the microenvironment. |
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| ISSN: | 87563282 |
| DOI: | 10.1016/j.bone.2017.12.001 |