Cell-penetrating peptides, targeting the regulation of store-operated channels, slow decay of the progesterone-induced [Ca2+]i signal in human sperm.
Mol Hum Reprod
; 21(7): 563-70, 2015 Jul.
Article
in En
| MEDLINE
| ID: mdl-25882543
ABSTRACT
Previous work has provided evidence for involvement of store-operated channels (SOCs) in [Ca(2+)]i signalling of human sperm, including a contribution to the transient [Ca(2+)]i elevation that occurs upon activation of CatSper, a sperm-specific cation channel localized to the flagellum, by progesterone. To further investigate the potential involvement of SOCs in the generation of [Ca(2+)]i signals in human sperm, we have used cell-penetrating peptides containing the important basic sequence KIKKK, part of the STIM-Orai activating region/CRAC activating domain (SOAR/CAD) of the regulatory protein stromal interaction molecule 1. SOAR/CAD plays a key role in controlling the opening of SOCs, which occurs upon mobilization of stored Ca(2+). Resting [Ca(2+)]i temporarily decreased upon application of KIKKK peptide (3-4 min), but scrambled KIKKK peptide had a similar effect, indicating that this action was not sequence-specific. However, in cells pretreated with KIKKK, the transient [Ca(2+)]i elevation induced by stimulation with progesterone decayed significantly more slowly than in parallel controls and in cells pretreated with scrambled KIKKK peptide. Examination of single-cell responses showed that this effect was due, at least in part, to an increase in the proportion of cells in which the initial transient was maintained for an extended period, lasting up to 10 min in a subpopulation of cells. We hypothesize that SOCs contribute to the progesterone-induced [Ca(2+)]i transient, and that interference with the regulatory mechanisms of SOC delays their closure, causing a prolongation of the [Ca(2+)]i transient.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Progesterone
/
Spermatozoa
/
Calcium Channels
/
Calcium
/
Calcium Signaling
/
Cell-Penetrating Peptides
Limits:
Humans
/
Male
Language:
En
Journal:
Mol Hum Reprod
Journal subject:
BIOLOGIA MOLECULAR
/
MEDICINA REPRODUTIVA
Year:
2015
Document type:
Article
Affiliation country:
United kingdom