Sea urchin egg activation at fertilization: Enzymatic basis

SummaryIt has recently been proposed that some of the processes induced by fertilisation in mammals may be mediated by integrins. By peforming immunofluorescence labelling and Western blots with antibodies directed against some of the α and β subunits of integrins, we show here the presence of some of these proteins in human and hamster oocytes. Among them, α2 and α5 were also present on in vitro preparations of sea urchin egg cortices. In addition, antibodies raised against these two proteins were the most effective at inhibiting attachment and fusion of human spermatozoa with hamster oocytes. We suggest that α2 and α5 integrin chains may be common mediators in adhesion-fusion mechanisms triggered by fertilisation. Using similar techniques, we show that eggs are rich three cytoskeletal proteins known to be linked to the β chain of integrins: talin, vinculin and α-actinin. Moreover, we found that talin and α-actinin were associated with proteins phosphorylated on tyrosine after fertilisation in sea urchin eggs. We suggest that integrins might be involved during fertilisation and trigger egg activation through cytoskeletal structures.

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2DE identification of proteins exhibiting turnover and phosphorylation dynamics during sea urchin egg activation

Developmental Biology ◽

10.1016/j.ydbio.2007.10.053 ◽

2008 ◽

Vol 313 (2) ◽

pp. 630-647 ◽

Cited By ~ 24

Author(s):

Michelle M. Roux ◽

Monte J. Radeke ◽

Manisha Goel ◽

Arcady Mushegian ◽

Kathy R. Foltz

Keyword(s):

Sea Urchin ◽

Egg Activation ◽

Sea Urchin Egg

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Assembly of unfertilized sea urchin egg tubulin at physiological temperatures.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)32654-1 ◽

1983 ◽

Vol 258 (7) ◽

pp. 4518-4525 ◽

Cited By ~ 2

Author(s):

K A Suprenant ◽

L I Rebhun

Keyword(s):

Sea Urchin ◽

Sea Urchin Egg

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A Ribonucleoprotein Which Catalyzes Thiol-Disulfide Exchange in the Sea Urchin Egg

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)96114-4 ◽

1967 ◽

Vol 242 (7) ◽

pp. 1458-1461

Author(s):

Hikoichi Sakai

Keyword(s):

Sea Urchin ◽

Disulfide Exchange ◽

Sea Urchin Egg

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Different Ca2+-releasing abilities of sperm extracts compared with tissue extracts and phospholipase C isoforms in sea urchin egg homogenate and mouse eggs

Biochemical Journal ◽

10.1042/bj3460743 ◽

2000 ◽

Vol 346 (3) ◽

pp. 743-749 ◽

Cited By ~ 32

Author(s):

Keith T. JONES ◽

Miho MATSUDA ◽

John PARRINGTON ◽

Matilda KATAN ◽

Karl SWANN

Keyword(s):

Phospholipase C ◽

Sea Urchin ◽

Tissue Extracts ◽

Sea Urchin Egg ◽

Boar Sperm ◽

Specific Activities ◽

Mammalian Eggs ◽

Mouse Eggs

A soluble phospholipase C (PLC) from boar sperm generates InsP3 and hence causes Ca2+ release when added to sea urchin egg homogenate. This PLC activity is associated with the ability of sperm extracts to cause Ca2+ oscillations in mammalian eggs following fractionation. A sperm PLC may, therefore, be responsible for causing the observed Ca2+ oscillations at fertilization. In the present study we have further characterized this boar sperm PLC activity using sea urchin egg homogenate. Consistent with a sperm PLC acting on egg PtdIns(4,5)P2, the ability of sperm extracts to release Ca2+ was blocked by preincubation with the PLC inhibitor U73122 or by the addition of neomycin to the homogenate. The Ca2+-releasing activity was also detectable in sperm from other species and in whole testis extracts. However, activity was not observed in extracts from other tissues. Moreover recombinant PLCβ1, -γ1, -γ2, -∆1, all of which had higher specific activities than boar sperm extracts, were not able to release Ca2+ in the sea urchin egg homogenate. In addition these PLCs were not able to cause Ca2+ oscillations following microinjection into mouse eggs. These results imply that the sperm PLC possesses distinct properties that allow it to hydrolyse PtdIns(4,5)P2 in eggs.

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