Medication of the studied population.

<p><i>Values are expressed in % as result of Chi-squared test. NSAID = non-steroidal anti-inflammatory drugs; ACE = angiotensin converting enzyme.</i></p

Clinical characteristics of the studied population.

<p><i>Values are expressed as mean ± SD as a result of Mann-Whitney U-Test for age and BMI or in % as a result of Chi-squared for the others.</i></p

PTH1R Mutants Found in Patients with Primary Failure of Tooth Eruption Disrupt G-Protein Signaling

<div><p>Aim</p><p>Primary failure of tooth eruption (PFE) is causally linked to heterozygous mutations of the parathyroid hormone receptor (PTH1R) gene. The mutants described so far lead to exchange of amino acids or truncation of the protein that may result in structural changes of the expressed PTH1R. However, functional effects of these mutations have not been investigated yet.</p><p>Materials and Methods</p><p>In HEK293 cells, PTH1R wild type was co-transfected with selected PTH1R mutants identified in patients with PFE. The effects on activation of PTH-regulated intracellular signaling pathways were analyzed by ELISA and Western immunoblotting. Differential effects of wild type and mutated PTH1R on TRESK ion channel regulation were analyzed by electrophysiological recordings in <i>Xenopus laevis</i> oocytes.</p><p>Results</p><p>In HEK293 cells, activation of PTH1R wild type increases cAMP and in response activates cAMP-stimulated protein kinase as detected by phosphorylation of the vasodilator stimulated phosphoprotein (VASP). In contrast, the PTH1R mutants are functionally inactive and mutant PTH1R/Gly452Glu has a dominant negative effect on the signaling of PTH1R wild type. Confocal imaging revealed that wild type PTH1R is expressed on the cell surface, whereas PTH1R/Gly452Glu mutant is mostly retained inside the cell. Furthermore, in contrast to wild type PTH1R which substantially augmented K⁺ currents of TRESK channels, coupling of mutated PTH1R to TRESK channels was completely abolished.</p><p>Conclusions</p><p>PTH1R mutations affect intracellular PTH-regulated signaling <i>in vitro</i>. In patients with primary failure of tooth eruption defective signaling of PTH1R mutations is suggested to occur in dento-alveolar cells and thus may lead to impaired tooth movement.</p></div

Membrane localization of PTH1R wild type and mutants.

<p>Membrane fractions of <i>Xenopus laevis</i> oocytes injected with cRNA of myc-tagged wild type (WT) and mutated PTH1R or H₂O were analyzed by Western immunoblotting. As revealed by myc-tag antibody specific signals (as indicated on the right) were detected in preparations of PTH1R wild type and PTH1R/Gly452Gly whereas these protein bands were absent in samples of PTH1R/Trp339stop and H₂O (negative control). Loading of equal amounts of protein is monitored by unspecific double bands (asterisk) in all samples. Quality and amount of cRNA injected into oocytes for heterologous expression of receptors is documented by RNA gel (lower panel).</p