Fußhöller, David Maximilian: The voltage-gated H+ channel Hv1 and the plasma-membrane Ca2+ ATPase PMCA4 in human sperm. - Bonn, 2015. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5n-40402
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5n-40402,
author = {{David Maximilian Fußhöller}},
title = {The voltage-gated H+ channel Hv1 and the plasma-membrane Ca2+ ATPase PMCA4 in human sperm},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2015,
month = aug,

note = {The intracellular Ca2+concentration ([Ca2+]i) coordinates several sperm functions required for fertilization. In particular, Ca2+ controls the beat of the flagellum and, thereby, the swimming behavior. In humans, the sperm-specific Ca2+ channel CatSper (cation channel of sperm) represents the principal pathway for Ca2+ entry into the flagellum. In general, CatSper is activated at depolarized membrane potentials (Vm) and at alkaline intracellular pH (pHi). Moreover, hormones in the oviduct such as progesterone and prostaglandins directly activate CatSper and,
thereby, control sperm motility. The mechanism(s) that oppose Ca2+ influx via CatSper and restore Ca2+ levels during recovery from stimulation are unknown. Furthermore, the voltage-gated H+ channel HV1 is functionally expressed in human sperm, and Hv1 has been proposed to control pHi and, thereby, CatSper. There is however no experimental evidence supporting the hypothesis that Hv1 is key for human sperm function.
Here, the role of Na/Ca2+ exchange and plasma membrane Ca2+ ATPases (PMCA) for Ca2+ extrusion in human sperm was investigated. I demonstrate that PMCA4 rather than Na+/Ca2+ exchange represents the predominant route of Ca2+ extrusion in human sperm. The localization of PMCA4 in the mid piece of the flagellum suggests that PMCA4 acts as a “gatekeeper” for Ca2+ diffusion from the flagellum into the head. Moreover, the expression and role of Hv1 in human sperm was studied. The experiments reveal that the pHi of human sperm is not controlled by Hv1. Remarkably, a sperm-specific truncated Hv1 isoform was identified (termed HvSper) that acivates faster and at more negative voltages than Hv1; in sperm, Hv1 and HvSper might assemble into heterodimers that share properties of both isoforms. However, the role of Hv1 and HvSper as well as the mechanism(s) regulating piHi in human sperm remain elusive.},

url = {http://hdl.handle.net/20.500.11811/6485}

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