title: New actions of parathyroid hormone through its degradation.
abstract: Parathyroid hormone degradation is intimately connected with its action. By the action of the unique renal neutral cytosolic PTH ase, PTH is split into 1-34 and 35-84 fragments, and further into 35-70 and 71-84 fragments. Amino-terminal 1-34 peptide was found to participate in the autoregulation of PTH secretion, suppressing the intact PTH secretion both in vivo in humans and in vitro in the dispersed bovine parathyroid cells. C-terminal fragment 35-84 and N-terminal fragment 1-34 both suppress the alkaline phosphatase production by ROS 17/2.8 cells to a lesser extent than the intact PTH 1-84, and the sum of the effects of the two fragments approximately equaled that of the intact hormone. Fragments 35-70 and 71-84 were devoid of such activity. Intracellular free calcium of human vascular endothelial cells was raised by intact 1-84, lowered on the contrary by C-terminal 35-84 fragment, but fragments 1-34, 35-70 and 71-84 had no effect. Fragments generated by the actions, supporting the physiological significance of PTH degradation by its target cells.
authors.affiliation: National Sanatorium Hyogo Chuo Hospital, Kobe, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Fujita
authors.forename: M
authors.initials: M
authors.lastname: Fukase
authors.forename: H
authors.initials: H
authors.lastname: Baba
authors.forename: T
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: S
authors.initials: S
authors.lastname: Takata
authors.forename: T
authors.initials: T
authors.lastname: Fujimi
authors.forename: M
authors.initials: M
authors.lastname: Nishikawa
authors.forename: C
authors.initials: C
authors.lastname: Nakamoto
mesh_terms: D000818:Animals; D006801:Humans; D010281:Parathyroid Hormone / Q000378:metabolism* / Q000502:physiology*; D010446:Peptide Fragments / Q000378:metabolism
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments