Changes in osteoblast, chondrocyte, and adipocyte lineages mediate the bone anabolic actions of PTH and small molecule GSK-3 inhibitor.
Parathyroid hormone (PTH) and glycogen synthase kinase-3 (GSK-3) inhibitor 603281-31-8, administered once daily increased bone formation in vivo. We investigated the molecular mechanisms of the anabolic responses of PTH and 603281-31-8 in rat osteopenia model. Female 6-month-old rats were ovariectomized (Ovx) and permitted to lose bone for 1 month, followed by treatment with PTH (1-38) at 10 microg/kg/day s.c. or 603281-31-8 at 3 mg/kg/day p.o. for 60 days. Twenty-four hours after the last treatment, RNA from distal femur metaphysis was subjected to gene expression analysis. Differentially expressed genes (P<0.05) were subjected to pathway analysis to delineate relevant bio-processes involved in skeletal biology. Genes involved in morphogenesis, cell growth/differentiation, and apoptosis were significantly altered by Ovx and the treatments. Analysis of morphogenesis genes showed an overrepresentation of genes involved in osteogenesis, chondrogenesis, and adipogenesis. A striking finding was that Ovx decreased several markers of osteogenesis/chondrogenesis and increased markers of adipogenesis/lipid metabolism. Treatment with either PTH or the GSK-3 inhibitor reversed these effects, albeit at different levels. Histological analysis confirmed that osteopenia in Ovx animals was associated with three-fold increase in marrow adiposity. PTH and GSK-3 inhibitor restored bone volume, and reversed or normalized marrow adiposity. Ex vivo studies showed that PTH and GSK-3 inhibitor increased the ratio of colony forming marrow stromal progenitors (CFU-fs) that were alkaline phosphatase positive (putative osteoblasts). Our results suggest that the bone anabolic actions of PTH and GSK-3 inhibitor in vivo involve concerted effects on mesenchymal lineages; osteoblasts, chondrocytes, and adipocytes.
Kulkarni
Nalini H
NH
Lilly Research Laboratories, Eli Lilly & Company, Lilly Corporate Center, Indianapolis, Indiana 46285, USA.
Wei
Tao
T
Kumar
Amar
A
Dow
Ernst R
ER
Stewart
Trent R
TR
Shou
Jianyong
J
N'cho
Mathias
M
Sterchi
Diane L
DL
Gitter
Bruce D
BD
Higgs
Richard E
RE
Halladay
David L
DL
Engler
Thomas A
TA
Martin
T John
TJ
Bryant
Henry U
HU
Ma
Yanfei L
YL
Onyia
Jude E
JE
D017667:Adipocytes / Q000166:cytology / Q000187:drug effects*; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001854:Bone Marrow Cells / Q000166:cytology; D019070:Cell Lineage / Q000187:drug effects*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects*; D004195:Disease Models, Animal; D004334:Drug Administration Schedule; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000008:administration & dosage / Q000037:antagonists & inhibitors*; D006801:Humans; D007279:Injections, Subcutaneous; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects*; D010052:Ovariectomy; D010281:Parathyroid Hormone / Q000008:administration & dosage / Q000378:metabolism*; D010446:Peptide Fragments / Q000008:administration & dosage / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000187:drug effects; D017154:Stromal Cells / Q000166:cytology / Q000187:drug effects; D013977:Tibia / Q000166:cytology; D013997:Time Factors
D015415:Biomarkers; D004791:Enzyme Inhibitors; D010281:Parathyroid Hormone; D010446:Peptide Fragments; C035747:parathyroid hormone (1-38); D038362:Glycogen Synthase Kinase 3; D000469:Alkaline Phosphatase