title: Prolonged Pharmacokinetic and Pharmacodynamic Actions of a Pegylated Parathyroid Hormone (1-34) Peptide Fragment.
abstract: Polyethylene glycol (PEG) addition can prolong the pharmacokinetic and pharmacodynamic actions of a bioactive peptide in vivo, in part by impeding rates of glomerular filtration. For parathyroid hormone (PTH) peptides, pegylation could help in exploring the actions of the hormone in the kidney; e.g., in dissecting the relative roles that filtered versus blood-borne PTH play in regulating phosphate transport. It could also lead to potential alternate forms of treatment for hypoparathyroidism. We thus synthesized the fluorescent pegylated PTH derivative [Lys13(tetramethylrhodamine {TMR}), Cys35(PEG-20,000 Da)]PTH(1-35) (PEG-PTHTMR) and its non-pegylated counterpart [Lys13(TMR), Cys35]PTH(1-35) (PTHTMR) and assessed their properties in cells and in mice. In PTHR1-expressing HEK-293 cells, PEG-PTHTMRand PTHTMRexhibited similar potencies for inducing cAMP signaling, whereas when injected into mice, the pegylated analog persisted much longer in the circulation (>24 hours versus ∼ 1 hour) and induced markedly more prolonged calcemic and phosphaturic responses than did the non-pegylated control. Fluorescence microscopy analysis of kidney sections obtained from the injected mice revealed much less PEG-PTHTMRthan PTHTMRon the luminal brush-border surfaces of renal proximal tubule cells (PTCs), on which PTH regulates phosphate transporter function, whereas immunostained phosphorylated PKA substrate, a marker of cAMP signaling, was increased to similar extents for the two ligands and for each, was localized to the basolateral portion of the PTCs. Pegylation of a bioactive PTH peptide thus led to prolonged pharmacokinetic/pharmacodynamic properties in vivo, as well as to new in vivo data that support a prominent role for PTH action at basolateral surfaces of renal proximal tubule cells. © 2016 American Society for Bone and Mineral Research.
authors.affiliation: Endocrine Unit, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Guo
authors.affiliation: Endocrine Unit, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA.
authors.forename: Ashok
authors.initials: A
authors.lastname: Khatri
authors.affiliation: Endocrine Unit, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA.
authors.forename: Akira
authors.initials: A
authors.lastname: Maeda
authors.affiliation: Endocrine Unit, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Potts
authors.affiliation: Endocrine Unit, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA.
authors.forename: Harald
authors.initials: H
authors.lastname: Jüppner
authors.affiliation: Endocrine Unit, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Gardella
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000097:blood; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D005453:Fluorescence; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000201:enzymology / Q000473:pathology; D008024:Ligands; D008297:Male; D008810:Mice, Inbred C57BL; D010281:Parathyroid Hormone / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology* / Q000652:urine; D011092:Polyethylene Glycols / Q000737:chemistry*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000378:metabolism; D012235:Rhodamines / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D008024:Ligands; D010281:Parathyroid Hormone; D012333:RNA, Messenger; D044168:Receptor, Parathyroid Hormone, Type 1; D012235:Rhodamines; D011092:Polyethylene Glycols; C005358:tetramethylrhodamine; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D002117:Calcitriol