Cell cycle-coupled [Ca(2+)](i) oscillations in mouse zygotes and function of the inositol 1,4,5-trisphosphate receptor-1.
Sperm entry in mammalian eggs initiates oscillations in the concentration of free calcium ([Ca(2+)](i)). In mouse eggs, oscillations start at metaphase II (MII) and conclude as the zygotes progress into interphase and commence pronuclear (PN) formation. The inositol 1,4,5-trisphosphate receptor (IP(3)R-1), which underlies the oscillations, undergoes degradation during this transition, suggesting that one or more of the eggs' Ca(2+)-releasing machinery components may be regulated in a cell cycle-dependent manner, thereby coordinating [Ca(2+)](i) responses with the cell cycle. To ascertain the site(s) of interaction, we initiated oscillations at different stages of the cell cycle in zygotes with different IP(3)R-1 mass. In addition to sperm, we used two other agonists: porcine sperm factor (pSF), which stimulates production of IP(3), and adenophostin A, a non-hydrolyzable analogue of IP(3). None of the agonists tested induced oscillations at interphase, suggesting that neither decreased IP(3)R-1 mass nor lack of production or excessive IP(3) degradation can account for the insensitivity to IP(3) at this stage. Moreover, the releasable Ca(2+) content of the stores did not change by interphase, but it did decrease by first mitosis. More importantly, experiments revealed that IP(3)R-1 sensitivity and possibly IP(3) binding were altered at interphase, and our data demonstrate stage-specific IP(3)R-1 phosphorylation by M-phase kinases. Accordingly, increasing the activity of M-phase kinases restored the oscillatory-permissive state in zygotes. We therefore propose that the restriction of oscillations in mouse zygotes to the metaphase stage may be coordinated at the level of IP(3)R-1 and that this involves cell cycle stage-specific receptor phosphorylation.
Jellerette
Teru
T
Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA.
Kurokawa
Manabu
M
Lee
Bora
B
Malcuit
Chris
C
Yoon
Sook-Young
SY
Smyth
Jeremy
J
Vermassen
Elke
E
De Smedt
Humbert
H
Parys
Jan B
JB
Fissore
Rafael A
RA
D000241:Adenosine / Q000031:analogs & derivatives* / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002453:Cell Cycle / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D005453:Fluorescence; D006657:Histones / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008297:Male; D051379:Mice; D008845:Microinjections; D004676:Myelin Basic Protein / Q000378:metabolism; D010766:Phosphorylation; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D013094:Spermatozoa / Q000502:physiology; D013997:Time Factors; D015053:Zygote / Q000378:metabolism* / Q000502:physiology
D015220:Calcium Channels; D006657:Histones; D053496:Inositol 1,4,5-Trisphosphate Receptors; D004676:Myelin Basic Protein; D018160:Receptors, Cytoplasmic and Nuclear; C085029:adenophostin A; D000241:Adenosine