Publikationsdatenbank

Investigation of the NH4+ conductance of the human analogue of TRPV3 (2018)

Art

Vortrag

Autoren

Liebe, H (WE 2)

Liebe, F (WE 2)

Vitzthum, C (WE 2)

Sponder, G (WE 2)

Stumpff, F (WE 2)

Kongress

23. Tagung der DVG-Fachgruppe Physiologie und Biochemie der Deutschen Veterinärmedizinischen Gesellschaft

Wien, 21. – 23.02.2018

Quelle

23. Tagung der Fachgruppe Physiologie und Biochemie der Deutschen Veterinärmedizinischen Gesellschaft : PROGRAMM & ABSTRACTS — Veterinärmedizinische Universität Wien (Hrsg.)

Wien, 2018 — S. 35

ISBN: 978-3-86345-307-7

Sprache

Englisch

Verweise

URL (Volltext): https://www.vetmeduni.ac.at/fileadmin/v/DVG-Tagung-2018/160218_Abstract_Program_Guide_sortiert_final.pdf

Kontakt

Institut für Veterinär-Physiologie

Oertzenweg 19 b
14163 Berlin
+49 30 838 62600
physiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Introduction: The Olmsted syndrome is a rare hereditary skin disease observed in patients with a gain of function mutation of the hTRPV3 channel, leading to severe hyperkeratosis. However, the details of the pathogenesis of this disease and others linked to mutations of hTRPV3 remain obscure. In particular, it is unclear if hTRPV3 plays a role in conducting NH4 + as a major product of protein metabolism.

Methods: Xenopus oocytes were injected either with a linearized strep-tagged hTRPV3-cRNA transcript or with RNase-free water as control. The expression was verified using western blotting. In Xenopus oocytes, membrane potential and pHi was measured using double-barreled pH-sensitive microelectrodes. Additionally, membrane patches were investigated to determine the single channel conductance for NH4+.

Results: In NaCl solution, the pHi of hTRPV3 overexpressing oocytes (7.57 ± 0.03) was similar (p = 0.16) to controls (7.62 ± 0.03). All oocytes showed a significant depolarization (p ≤ 0.001) and acidification (p ≤ 0.001) when treated with NH4Cl solution for ten minutes,
after which oocytes expressing hTRPV3 had a significantly (p = 0.013) lower pHi (6.00 ± 0.11, n/N = 16/3) than controls (6.36 ± 0.09, n/N = 17/3). Furthermore, the hTRPV3 oocytes had a significantly (p = 0.010) higher relative permeability of Na+ versus NMDG+ (1.94 ± 0.17) than the controls (1.39 ± 0.12). Single channel conductances of patches from oocytes were significantly higher after expression of hTRPV3 (p = 0.036 for Na+ and p = 0.016 for NH4 +). In 13 hTRPV3 patches, large conductances of 91 ± 8 pS for Na+ and 190 ± 15 pS for NH4 + were observed. Eleven patches showed conductances lower than 100 pS (25 ± 4 pS for Na+ and 38 ± 6 pS for NH4 +)
indicating endogenous channel activity. Five of these patches also showed large channel events. Eleven patches showed no single channel activity. Conversely, 12 out of 21 control patches showed endogenous channels; no patch had a conductance over 95 pS.

Conclusion: Channel-mediated uptake of NH4 + has be considered as a major pathway for the exchange of ammonia in cellular systems, with the conductance of hTRPV3 for NH4 + of 190 ± 15 pS. Given that TRPV3 is highly expressed by the keratinocytes of the human skin, implications may follow for the pathophysiology of certain skin diseases.