Further definition of the protein kinase C activation domain of the parathyroid hormone

Abstract

The protein kinase C (PKC) activation domain of the parathyroid hormone (PTH) was believed to be the 28-34 region of the molecule. We have now shown that PTH-(29-32) is the smallest PTH fragment that can stimulate significantly membrane-associated PKC activity in ROS 17/2 rat osteosarcoma cells. As was previously shown for full-length PTH-(1-84) and the fully bioactive PTH-(1-34) fragment, there were two peaks in the PKC response to PTH-(29-32): one peak was obtained with low picomolar concentrations and the other with much higher nanomolar concentrations of the fragment. The PKC-activating ability was unaffected by the loss of Asn33 and Phe34, but it was abolished by removing His32. Thus, the PTH-(28-31) and PTH-(29-31) fragments did not stimulate membrane-associated PKC activity. The much larger PTH-(1-31) fragment also did not stimulate membrane-associated PKC activity, although it stimulated adenylyl cyclase as strongly as PTH-(1-34). This functional sensitivity to the loss of the polar His32 was not caused by a specific need for His or another polar amino acid in this position because replacing it with the apolar Leu did not abolish adenylyl cyclase or PKC activation. It is concluded that the minimum, fully functional PKC activation domain of the PTH molecule is Gln29-Asp30-Val31-His32.

Regulation of osterix (Osx, Sp7) and the Osx promoter by parathyroid hormone in osteoblasts

“…PTH (1-31), which induces cAMP as strongly as PTH (1-34) ( Jouishomme et al 1994), also inhibited Osx expression (Fig. 4A).…”

“…PTH (1-31), a PTH fragment that specifically stimulates cAMP (Jouishomme et al 1994), caGsa, Fsk, and 8-Br-cAMP all inhibited Osx mRNA levels. PTH (3-34), previously shown not to stimulate cAMP (Erclik & Mitchell 2002), had no effect on Osx mRNA levels.…”

Agonist-regulated Cleavage of the Extracellular Domain of Parathyroid Hormone Receptor Type 1

“…Forms of the Receptor-Although PTH(1-34) and PTH(1-14) have been described to fully activate the PTHR with almost equal potency compared with full-length PTH, PTH(1-31) has been reported to stimulate adenylyl cyclase activity but not to activate protein kinase C (20,21). PTH(7-34) is a competitive antagonist to PTH(1-34) and is believed to have no intrinsic activity (22).…”

International Union of Basic and Clinical Pharmacology. XCIII. The Parathyroid Hormone Receptors—Family B G Protein–Coupled Receptors

“…One such analog is Gly1,Arg19-PTH(1-28) reported by Takasu et al (1999a). The PTH(1-28) scaffold was chosen for this analog because the goal was to generate a purely cAMP-based agonist ligand, and the (29-32) region of PTH had been reported to contain determinants of PKC activation (Jouishomme et al, 1994). However, Gly1-PTH(1-34)-based analogs were also found to be selectively PLC defective (Takasu et al, 1999a), whereas PTH(1-31) and PTH(1-30), each containing Ser1 but missing at least some of the (29-32) segment, showed equal effects on signaling via the cAMP and PLC pathways (Takasu and Bringhurst, 1998).…”