title: Monthly administration of a novel PTH-collagen binding domain fusion protein is anabolic in mice.
abstract: We synthesized fusion proteins of parathyroid hormone (PTH) (1-33) and the collagen binding domain of ColH (CBD) and tested them for anabolic bone activity in mice. Two fusion proteins were synthesized, linking the carboxy terminus of PTH(1-33) either directly to the amino terminal of the CBD or to the CBD through an adjacent ColH domain (PTH-PKD-CBD). Both PTH-CBD and PTH-PKD-CBD increased cAMP accumulation in cells stably transfected with the PTH/PTHrP receptor, and both peptides bound to type 1 collagen in flow-through assays. Distribution studies indicated that the PTH-CBD was concentrated in the bone and skin, tissues with abundant collagen and blood flow. Administration of 320 μg/kg PTH-CBD either weekly (for 8 weeks) or monthly (for 6 months) to 7-week-old C57BL/6J mice resulted in a sustained increase in bone mineral density (BMD) (15% for weekly studies, 13% for monthly studies; P < 0.05). PTH-PKD-CBD showed only 5% increases in BMD after weekly administration, and, as expected, neither weekly nor monthly PTH(1-34) affected BMD. PTH-CBD increased serum alkaline phosphatase levels. Importantly, there were no significant increases in serum calcium observed. Collectively, the data suggest that PTH-CBD has a sustained anabolic effect in bone with either weekly or monthly administration. This approach of targeted delivery of PTH to bone may show promise for the treatment of disorders of low bone mass, such as postmenopausal osteoporosis.
authors.affiliation: Pediatric Endocrinology, Children's Hospital at Montefiore, Bronx, NY, USA. tponnapa@montefiore.org
authors.forename: Tulasi
authors.initials: T
authors.lastname: Ponnapakkam
authors.forename: R
authors.initials: R
authors.lastname: Katikaneni
authors.forename: E
authors.initials: E
authors.lastname: Miller
authors.forename: A
authors.initials: A
authors.lastname: Ponnapakkam
authors.forename: S
authors.initials: S
authors.lastname: Hirofumi
authors.forename: S
authors.initials: S
authors.lastname: Miyata
authors.forename: L J
authors.initials: LJ
authors.lastname: Suva
authors.forename: J
authors.initials: J
authors.lastname: Sakon
authors.forename: O
authors.initials: O
authors.lastname: Matsushita
authors.forename: R C
authors.initials: RC
authors.lastname: Gensure
mesh_terms: D000595:Amino Acid Sequence; D045930:Anabolic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology; D000818:Animals; D001426:Bacterial Proteins / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001842:Bone and Bones / Q000187:drug effects* / Q000378:metabolism; D003094:Collagen / Q000378:metabolism*; D017364:Collagenases / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D004334:Drug Administration Schedule; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010281:Parathyroid Hormone / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology; D054730:Protein Interaction Domains and Motifs; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage* / Q000009:adverse effects / Q000494:pharmacology; D013997:Time Factors
chemical_list: D045930:Anabolic Agents; D001426:Bacterial Proteins; D010281:Parathyroid Hormone; D011993:Recombinant Fusion Proteins; D003094:Collagen; C118796:ColH protein, Clostridium histolyticum; D017364:Collagenases