PMID- 26212375
OWN - NLM
STAT- MEDLINE
DCOM- 20161031
LR  - 20211203
IS  - 1097-4644 (Electronic)
IS  - 0730-2312 (Linking)
VI  - 117
IP  - 2
DP  - 2016 Feb
TI  - Lysosomal pH Plays a Key Role in Regulation of mTOR Activity in Osteoclasts.
PG  - 413-25
LID - 10.1002/jcb.25287 [doi]
AB  - Mammalian target of rapamycin (mTOR) is a serine/threonine kinase involved in the 
      regulation of cell growth. It has been shown to play an important role in 
      osteoclast differentiation, particularly at the earlier stages of 
      osteoclastogenesis. mTOR activation and function, as part of mTORC1 complex, is 
      dependent on lysosomal localization and the vacuolar H(+) -ATPase (V-ATPase) 
      activity; however, the precise mechanism is still not well understood. Using 
      primary mouse osteoclasts that are known to have higher lysosomal pH due to R740S 
      mutation in the V-ATPase a3 subunit, we investigated the role of lysosomal pH in 
      mTORC1 signaling. Our results demonstrated that +/R740S cells had increased basal 
      mTOR protein levels and mTORC1 activity compared to +/+ osteoclasts, while mTOR 
      gene expression was decreased. Treatment with lysosomal inhibitors chloroquine 
      and ammonium chloride, compounds known to raise lysosomal pH, significantly 
      increased mTOR protein levels in +/+ cells, confirming the importance of 
      lysosomal pH in mTOR signaling. These results also suggested that mTOR could be 
      degraded in the lysosome. To test this hypothesis, we cultured osteoclasts with 
      chloroquine or proteasomal inhibitor MG132. Both chloroquine and MG132 increased 
      mTOR and p-mTOR protein levels in +/+ osteoclasts, suggesting that mTOR undergoes 
      both lysosomal and proteasomal degradation. Treatment with cycloheximide, an 
      inhibitor of new protein synthesis, confirmed that mTOR is constitutively 
      expressed and degraded. These results show that, in osteoclasts, the lysosome 
      plays a key role not only in mTOR activation but also in its deactivation through 
      protein degradation, representing a novel molecular mechanism of mTOR regulation.
CI  - (c) 2015 Wiley Periodicals, Inc.
FAU - Hu, Yingwei
AU  - Hu Y
AD  - Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
AD  - Institute of Dental Medicine, Qilu Hospital, Shandong University, Jinan, China.
FAU - Carraro-Lacroix, Luciene R
AU  - Carraro-Lacroix LR
AD  - Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
FAU - Wang, Andrew
AU  - Wang A
AD  - Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
FAU - Owen, Celeste
AU  - Owen C
AD  - Centre for Modeling Human Disease, Samuel Lunenfeld Research Institute, Mount 
      Sinai Hospital, Toronto, ON, Canada.
FAU - Bajenova, Elena
AU  - Bajenova E
AD  - Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
FAU - Corey, Paul N
AU  - Corey PN
AD  - Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
FAU - Brumell, John H
AU  - Brumell JH
AD  - Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada.
AD  - Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
AD  - Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
FAU - Voronov, Irina
AU  - Voronov I
AD  - Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Cell Biochem
JT  - Journal of cellular biochemistry
JID - 8205768
RN  - 0 (Multiprotein Complexes)
RN  - EC 2.7.1.1 (mTOR protein, mouse)
RN  - EC 2.7.11.1 (Mechanistic Target of Rapamycin Complex 1)
RN  - EC 2.7.11.1 (TOR Serine-Threonine Kinases)
RN  - EC 3.4.25.1 (Proteasome Endopeptidase Complex)
SB  - IM
MH  - Animals
MH  - Autophagy
MH  - Cells, Cultured
MH  - Enzyme Activation
MH  - Gene Expression
MH  - Hydrogen-Ion Concentration
MH  - Lysosomes/*metabolism
MH  - Male
MH  - Mechanistic Target of Rapamycin Complex 1
MH  - Mice, Inbred C3H
MH  - Mice, Transgenic
MH  - Multiprotein Complexes/metabolism
MH  - Osteoclasts/*enzymology
MH  - Proteasome Endopeptidase Complex/metabolism
MH  - Protein Transport
MH  - Proteolysis
MH  - TOR Serine-Threonine Kinases/genetics/*metabolism
OTO - NOTNLM
OT  - AUTOPHAGY
OT  - LYSOSOME
OT  - OSTEOCLAST
OT  - V-ATPase
OT  - mTOR
OT  - pH
EDAT- 2015/07/28 06:00
MHDA- 2016/11/01 06:00
CRDT- 2015/07/28 06:00
PHST- 2015/05/05 00:00 [received]
PHST- 2015/07/21 00:00 [accepted]
PHST- 2015/07/28 06:00 [entrez]
PHST- 2015/07/28 06:00 [pubmed]
PHST- 2016/11/01 06:00 [medline]
AID - 10.1002/jcb.25287 [doi]
PST - ppublish
SO  - J Cell Biochem. 2016 Feb;117(2):413-25. doi: 10.1002/jcb.25287.