TY - JOUR
T1 - Loss of Cbl-PI3K interaction in mice prevents significant bone loss following ovariectomy
AU - Adapala, N.S.
AU - Holland, D.
AU - Scanlon, V.
AU - Barbe, M.F.
AU - Langdon, Wallace
AU - Tsygankov, A.Y.
AU - Lorenzo, J.A.
AU - Sanjay, A.
PY - 2014
Y1 - 2014
N2 - Cbl and Cbl-b are E3 ubiquitin ligases and adaptor proteins, which perform regulatory roles in bone remodeling. Cbl. -/- mice have delayed bone development due to decreased osteoclast migration. Cbl-b. -/- mice are osteopenic due to increased bone resorbing activity of osteoclasts. Unique to Cbl, but not present in Cbl-b, is tyrosine 737 in the YEAM motif, which upon phosphorylation provides a binding site for the regulatory p85 subunit of PI3K. Substitution of tyrosine 737 with phenylalanine (Y737F, CblYF/YF mice) prevents Y737 phosphorylation and abrogates the Cbl-PI3K interaction. We have previously reported that CblYF/YF mice had increased bone volume due to defective bone resorption and increased bone formation. Here we show that the lumbar vertebra from CblYF/YF mice did not have significant bone loss following ovariectomy. Our data also suggests that abrogation of Cbl-PI3K interaction in mice results in the loss of coupling between bone resorption and formation, since ovariectomized CblYF/YF mice did not show significant changes in serum levels of c-terminal telopeptide (CTX), whereas the serum levels of pro-collagen type-1 amino-terminal pro-peptide (P1NP) were decreased. In contrast, following ovariectomy, Cbl. -/- and Cbl-b. -/- mice showed significant bone loss in the tibiae and L2 vertebrae, concomitant with increased serum CTX and P1NP levels. These data indicate that while lack of Cbl or Cbl-b distinctly affects bone remodeling, only the loss of Cbl-PI3K interaction protects mice from significant bone loss following ovariectomy. © 2014 Elsevier Inc.
AB - Cbl and Cbl-b are E3 ubiquitin ligases and adaptor proteins, which perform regulatory roles in bone remodeling. Cbl. -/- mice have delayed bone development due to decreased osteoclast migration. Cbl-b. -/- mice are osteopenic due to increased bone resorbing activity of osteoclasts. Unique to Cbl, but not present in Cbl-b, is tyrosine 737 in the YEAM motif, which upon phosphorylation provides a binding site for the regulatory p85 subunit of PI3K. Substitution of tyrosine 737 with phenylalanine (Y737F, CblYF/YF mice) prevents Y737 phosphorylation and abrogates the Cbl-PI3K interaction. We have previously reported that CblYF/YF mice had increased bone volume due to defective bone resorption and increased bone formation. Here we show that the lumbar vertebra from CblYF/YF mice did not have significant bone loss following ovariectomy. Our data also suggests that abrogation of Cbl-PI3K interaction in mice results in the loss of coupling between bone resorption and formation, since ovariectomized CblYF/YF mice did not show significant changes in serum levels of c-terminal telopeptide (CTX), whereas the serum levels of pro-collagen type-1 amino-terminal pro-peptide (P1NP) were decreased. In contrast, following ovariectomy, Cbl. -/- and Cbl-b. -/- mice showed significant bone loss in the tibiae and L2 vertebrae, concomitant with increased serum CTX and P1NP levels. These data indicate that while lack of Cbl or Cbl-b distinctly affects bone remodeling, only the loss of Cbl-PI3K interaction protects mice from significant bone loss following ovariectomy. © 2014 Elsevier Inc.
U2 - 10.1016/j.bone.2014.06.013
DO - 10.1016/j.bone.2014.06.013
M3 - Article
C2 - 24994594
SN - 8756-3282
VL - 67
SP - 1
EP - 9
JO - Bone
JF - Bone
ER -