Short carboxyl terminal parathyroid hormone peptides modulate human parathyroid hormone signaling in mouse osteoblasts

Kittrawee Kritmetapak; Ravinder J Singh; Theodore A Craig; Jolaine M Hines; Rajiv Kumar

doi:10.1016/j.bbrc.2021.07.085

Short carboxyl terminal parathyroid hormone peptides modulate human parathyroid hormone signaling in mouse osteoblasts

Biochem Biophys Res Commun. 2021 Oct 1:572:15-19. doi: 10.1016/j.bbrc.2021.07.085. Epub 2021 Jul 28.

Authors

Kittrawee Kritmetapak¹, Ravinder J Singh², Theodore A Craig³, Jolaine M Hines⁴, Rajiv Kumar⁵

Affiliations

¹ Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic Rochester, 200 First Street Southwest, Rochester, MN, 55905, USA; Division of Nephrology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
² Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester, 200 First Street Southwest, Rochester, MN, 55905, USA.
³ Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic Rochester, 200 First Street Southwest, Rochester, MN, 55905, USA.
⁴ Immunochemical Core Laboratory, Mayo Clinic Rochester, 200 First Street Southwest, Rochester, MN, 55905, USA.
⁵ Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic Rochester, 200 First Street Southwest, Rochester, MN, 55905, USA; Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, 200 First Street Southwest, Rochester, MN, 55905, USA. Electronic address: rkumar@mayo.edu.

Abstract

Background: Novel human parathyroid hormone (hPTH) peptides of unknown biological activity have recently been identified in the serum of subjects with normal renal function, chronic renal failure, and end-stage renal disease through the application of liquid chromatography-high resolution mass spectrometry.

Purpose: of experiments: To determine the bioactivity of these peptides, we synthesized hPTH28-84, hPTH38-84, and hPTH45-84 peptides by solid phase peptide synthesis and tested their bioactivity in MC3T3-E1 mouse osteoblasts, either individually or together with the native hormone, hPTH1-84, by assessing the accumulation of 3´,5´-cyclic adenosine monophosphate (cAMP) and the induction of alkaline phosphatase activity.

Results: Increasing doses of hPTH1-84 (1-100 nM) increased the accumulation of cAMP and alkaline phosphatase activity in osteoblasts. hPTH28-84, hPTH38-84, and hPTH45-84 in concentrations of 1-100 nM were biologically inert. Surprisingly, 100 nM hPTH38-84 and hPTH45-84 increased the accumulation of cAMP in osteoblasts treated with increasing amounts of hPTH1-84. Human PTH28-84 had no effects on cAMP activity alone or in combination with hPTH1-84. Conversely, 100 nM hPTH38-84, hPTH45-84, and hPTH28-84 blocked the activation of alkaline phosphatase activity by hPTH1-84.

Conclusions: The data show that the short carboxyl-terminal hPTH peptides, hPTH38-84 and hPTH45-84, increase the amount of cellular cAMP generated in cultured osteoblasts in response to treatment with full-length hPTH1-84 when compared to full-length hPTH1-84 alone. Human PTH28-84 had no effect on cAMP activity alone or in combination with hPTH1-84. Human PTH28-84, hPTH38-84 and hPTH45-84 reduced the effects of hPTH1-84 in osteoblasts with respect to the induction of alkaline phosphatase activity compared to hPTH1-84 alone. Short carboxyl peptides of human PTH are biologically inert but when administered together with full-length hPTH1-84 modulate the bioactivity of hPTH1-84 in osteoblasts.

Keywords: Alkaline phosphatase; Carboxyl-terminal hPTH peptides; Mouse osteoblasts; cAMP; hPTH1-84; hPTH28-84; hPTH38-84; hPTH45-84.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

3T3 Cells
Animals
Cells, Cultured
Mice
Osteoblasts / metabolism*
Parathyroid Hormone / chemical synthesis
Parathyroid Hormone / chemistry
Parathyroid Hormone / metabolism*
Signal Transduction

Substances

PTH protein, human
Parathyroid Hormone

Abstract

Publication types

MeSH terms

Substances

Grants and funding