mTORC1 Signaling Promotes Limb Bud Cell Growth and Chondrogenesis.
mTORC1 signaling has been shown to promote limb skeletal growth through stimulation of protein synthesis in chondrocytes. However, potential roles of mTORC1 in prechondrogenic mesenchyme have not been explored. In this study, we first deleted Raptor, a unique and essential component of mTORC1, in prechondrogenic limb mesenchymal cells. Deletion of Raptor reduced the size of limb bud cells, resulting in overall diminution of the limb bud without affecting skeletal patterning. We then examined the potential role of mTORC1 in chondrogenic differentiation in vitro. Both pharmacological and genetic disruption of mTORC1 significantly suppressed the number and size of cartilage nodules in micromass cultures of limb bud mesenchymal cells. Similarly, inhibition of mTORC1 signaling in chondrogenic ATDC5 cells greatly impaired cartilage nodule formation, and decreased the expression of the master transcriptional factor Sox9, along with the cartilage matrix genes Acan and Col2a1. Thus, we have identified an important role for mTORC1 signaling in promoting limb mesenchymal cell growth and chondrogenesis during embryonic development. J. Cell. Biochem. 118: 748-753, 2017. © 2016 Wiley Periodicals, Inc.
Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China.
Ming
M
Jiang
Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China.
Xuejie
X
Fu
Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China.
Huilin
H
Yang
Department of Orthopaedic Surgery, Washington University in St Louis, St Louis, Missouri.|Department of Medicine, Washington University in St Louis, St Louis, Missouri.|Department of Developmental Biology, Washington University in St Louis, St Louis, Missouri.
Fanxin
F
Long
Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China.
Jianquan
J
Chen
D048868:Adaptor Proteins, Signal Transducing / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D020219:Chondrogenesis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D053595:Embryonic Stem Cells / Q000166:cytology / Q000502:physiology; D005260:Female; D018878:Limb Buds / Q000166:cytology / Q000196:embryology* / Q000502:physiology; D000076222:Mechanistic Target of Rapamycin Complex 1; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D046912:Multiprotein Complexes / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D011247:Pregnancy; D000076223:Regulatory-Associated Protein of mTOR; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D046912:Multiprotein Complexes; D000076223:Regulatory-Associated Protein of mTOR; C540162:Rptor protein, mouse; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus
CELL SIZE; CHONDROGENESIS; RAPTOR; mTORC1