TY - JOUR
T1 - Cbl-PI3K interaction regulates Cathepsin K secretion in osteoclasts
AU - Yu, Jungeun
AU - Adapala, Naga Suresh
AU - Doherty, Laura
AU - Sanjay, Archana
N1 - Funding Information:
YF osteoclasts are defective in secreting Cathepsin K, but secretion of Cathepsin D is normal. These data suggest that in YF osteoclasts, the cargo present in the secretory lysosomes is not secreted properly, while other secretory mechanisms are not perturbed. The Protein kinase C-δ deficiency in osteoclasts does not affect v-ATPase localization, but attenuates Cathepsin K secretion [ 42 ]. Differential secretion and targeting of vesicles is supported by other studies. Disruption of the Mannose-6-phosphate pathway in osteoclasts augmented Cathepsin K secretion without affecting Cathepsin D targeting and secretion [ 30 ]. Our results and other findings suggest the existence of distinct/different pools of secretory lysosomes in osteoclasts, each relying on specific signaling cues essential for their exocytosis. This flexibility will allow cells to secrete cargo based on need.
Funding Information:
The authors thank D. Fremont for M-CSF cDNA and M. Glogauer for Tnfsf11 cDNA, B. Lee for the anti vATPase (E subunit) antibody. National Institute of Health Grant (AR0550601) to A.S supported part of the work. Study was supported by United States National Institute of Health grant AR055601 (AS).
Publisher Copyright:
© 2019 Elsevier Inc.
PY - 2019/10
Y1 - 2019/10
N2 - Effective bone resorption by osteoclasts is critical for balanced bone remodeling. We have previously reported that mice harboring a substitution mutation of tyrosine 737 to phenylalanine in the adapter protein Cbl (CblY737F, YF) have increased bone volume partly due to decreased osteoclast-mediated bone resorption. The CblY737F mutation abrogates interaction between Cbl and the p85 subunit of PI3K. Here, we studied the mechanism for defective resorptive function of YF mutant osteoclasts. The YF osteoclasts had intact actin cytoskeletons and sealing zones. Expression and localization of proteins needed for acidification of the resorptive lacunae were also comparable between the WT and YF osteoclasts. In contrast, secretion of Cathepsin K, a major protease needed to degrade collagen, was diminished in the conditioned media derived from YF osteoclasts. The targeting of Cathepsin K into LAMP2-positive vesicles was also compromised due to decreased number of LAMP2-positive vesicles in YF osteoclasts. Further, we found that in contrast to WT, conditioned media derived from YF osteoclasts promoted increased numbers of alkaline phosphatase positive colonies, and increased expression of osteogenic markers in WT calvarial cultures. Cumulatively, our results suggest that the Cbl-PI3K interaction regulates Cathepsin K secretion required for proper bone resorption, and secretion of factors which promote osteogenesis.
AB - Effective bone resorption by osteoclasts is critical for balanced bone remodeling. We have previously reported that mice harboring a substitution mutation of tyrosine 737 to phenylalanine in the adapter protein Cbl (CblY737F, YF) have increased bone volume partly due to decreased osteoclast-mediated bone resorption. The CblY737F mutation abrogates interaction between Cbl and the p85 subunit of PI3K. Here, we studied the mechanism for defective resorptive function of YF mutant osteoclasts. The YF osteoclasts had intact actin cytoskeletons and sealing zones. Expression and localization of proteins needed for acidification of the resorptive lacunae were also comparable between the WT and YF osteoclasts. In contrast, secretion of Cathepsin K, a major protease needed to degrade collagen, was diminished in the conditioned media derived from YF osteoclasts. The targeting of Cathepsin K into LAMP2-positive vesicles was also compromised due to decreased number of LAMP2-positive vesicles in YF osteoclasts. Further, we found that in contrast to WT, conditioned media derived from YF osteoclasts promoted increased numbers of alkaline phosphatase positive colonies, and increased expression of osteogenic markers in WT calvarial cultures. Cumulatively, our results suggest that the Cbl-PI3K interaction regulates Cathepsin K secretion required for proper bone resorption, and secretion of factors which promote osteogenesis.
KW - Cathepsin K
KW - LAMP2
KW - Osteoclast
KW - PI3K and Cbl
KW - Vesicular trafficking
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U2 - 10.1016/j.bone.2019.07.009
DO - 10.1016/j.bone.2019.07.009
M3 - Article
C2 - 31299383
AN - SCOPUS:85068873137
SN - 8756-3282
VL - 127
SP - 376
EP - 385
JO - Bone
JF - Bone
ER -