Ciliary neurotrophic factor inhibits bone formation and plays a sex-specific role in bone growth and remodeling.
Ciliary neurotrophic factor (CNTF) receptor (CNTFR) expression has been described in osteoblast-like cells, suggesting a role for CNTF in bone metabolism. When bound to CNTF, neuropoietin (NP), or cardiotrophin-like-cytokine (CLC), CNTFR forms a signaling complex with gp130 and the leukemia inhibitory factor receptor, which both play critical roles in bone cell biology. This study aimed to determine the role of CNTFR-signaling cytokines in bone. Immunohistochemistry detected CNTF in osteoblasts, osteocytes, osteoclasts, and proliferating chondrocytes. CNTFR mRNA was detected in primary calvarial osteoblasts and was upregulated during osteoblast differentiation. Treatment of osteoblasts with CNTF or CLC, but not NP, significantly inhibited mineralization and osterix mRNA levels. Twelve-week-old male CNTF ( -/- ) mice demonstrated reduced femoral length, cortical thickness, and periosteal circumference; but femoral trabecular bone mineral density (Tb.BMD) and tibial trabecular bone volume (BV/TV) were not significantly different from wild-type, indicating a unique role for CNTF in bone growth in male mice. In contrast, female CNTF ( -/- ) femora were of normal width, but femoral Tb.BMD, tibial BV/TV, trabecular number, and trabecular thickness were all increased. Female CNTF ( -/- ) tibiae also demonstrated high osteoblast number and mineral apposition rate compared to wild-type littermates, and this was intrinsic to the osteoblast lineage. CNTF is expressed locally in bone and plays a unique role in female mice as an inhibitor of trabecular bone formation and in male mice as a stimulus of cortical growth.
St. Vincent's Institute, 9 Princes Street, Fitzroy, VIC 3065, Australia.
Narelle E
NE
McGregor
Ingrid J
IJ
Poulton
Emma C
EC
Walker
Sueli
S
Pompolo
Julian M W
JM
Quinn
T John
TJ
Martin
Natalie A
NA
Sims
D000818:Animals; D001861:Bone Regeneration / Q000187:drug effects / Q000502:physiology; D016723:Bone Remodeling / Q000187:drug effects* / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D019070:Cell Lineage / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D020934:Ciliary Neurotrophic Factor / Q000378:metabolism* / Q000494:pharmacology; D016207:Cytokines / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D020801:Receptor, Ciliary Neurotrophic Factor / Q000235:genetics*; D012727:Sex Characteristics; D012737:Sex Factors; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D020934:Ciliary Neurotrophic Factor; D016207:Cytokines; D012333:RNA, Messenger; D020801:Receptor, Ciliary Neurotrophic Factor