title: Development of a highly sensitive, high-throughput, mass spectrometry-based assay for rat procollagen type-I N-terminal propeptide (PINP) to measure bone formation activity.
abstract: Type-I procollagen aminoterminal propeptide (PINP) is a useful biomarker for bone formation activity that is used to monitor treatment of bone disorders including osteoporosis. Studies with human patients under long-term therapy for osteoporosis by daily injection of parathyroid hormone (PTH) demonstrated that the circulating level of PINP at 3 months of treatment, measured by radioimmunoassay, was a good predictor for bone mineral density (BMD) at 18 months. It is important to have PINP assays for other species to elucidate processes of bone formation and for the development of new therapeutic options that can enhance bone formation activity. Currently, only a human PINP radioimmunoassay is commercially available for clinical use, which may not be cross reactive with PINP from other species. For example, rat PINP has little amino acid sequence homology to human PINP. Therefore, we developed a new, highly sensitive, high-throughput mass spectrometry-based assay for PINP from rat plasma or serum that does not rely on antibody reagents. Circulating levels of PINP showed age-dependent changes in rats. Prednisolone treatment, which is known to retard bone formation activity, led to a significant decrease in PINP, whereas PTH treatment dose-dependently increased PINP. The throughput of the assay parallels that of most antibody-based assays so that it can handle a large number of samples that are generated from preclinical animal studies. PINP in rats may serve as a biomarker for bone formation activity, and this assay could be instrumental in studying bone physiology in rat experimental models.
authors.affiliation: Integrative Biology, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA. bomiehan@lilly.com
authors.forename: Bomie
authors.initials: B
authors.lastname: Han
authors.forename: Marci
authors.initials: M
authors.lastname: Copeland
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Geiser
authors.forename: Laura V
authors.initials: LV
authors.lastname: Hale
authors.forename: Anita
authors.initials: A
authors.lastname: Harvey
authors.forename: Yanfei L
authors.initials: YL
authors.lastname: Ma
authors.forename: Connie S
authors.initials: CS
authors.lastname: Powers
authors.forename: Masahiko
authors.initials: M
authors.lastname: Sato
authors.forename: Jinsam
authors.initials: J
authors.lastname: You
authors.forename: John E
authors.initials: JE
authors.lastname: Hale
mesh_terms: D000818:Animals; D015415:Biomarkers; D001846:Bone Development; D001842:Bone and Bones / Q000378:metabolism*; D002417:Cattle; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006041:Goats; D006168:Guinea Pigs; D006736:Horses; D013058:Mass Spectrometry / Q000379:methods*; D010281:Parathyroid Hormone / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry*; D011239:Prednisolone / Q000494:pharmacology; D011347:Procollagen / Q000737:chemistry*; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity; D012756:Sheep; D013552:Swine
chemical_list: D015415:Biomarkers; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D011347:Procollagen; C047202:procollagen Type I N-terminal peptide; D011239:Prednisolone