Specific proteolysis of the c-mos proto-oncogene product by calpain on fertilization of Xenopus eggs

Watanabe, Nobumoto; Woude, George F. Vande; Ikawa, Yoji; Sagata, Noriyuki

doi:10.1038/342505a0

Cited by 274 publications

(159 citation statements)

References 43 publications

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“…1 to monitor cyclin degradation. need to inhibit OA-sensitive phosphatases (27). The above results raise the question whether OA inactivates c-mos kinase in metaphase extracts.…”

mentioning

confidence: 88%

“…It has been suggested that cyclin is made protease resistant by c-mos kinase-catalyzed phosphorylation (27). This hypothesis is unlikely because phosphopeptide analysis of cyclin B phosphorylated with c-mos kinase reveals a pattern indistinguishable from that observed with cdc2 kinase (23).…”

mentioning

confidence: 88%

“…In vertebrates, c-mos protein kinase acts as a cytostatic factor which prevents proteolytic degradation of cyclin and arrests unfertilized eggs at the second meiotic metaphase (24). On fertilization or parthenogenetic activation, a calcium-dependent process inactivates c-mos kinase, resulting in cyclin degradation (27). The dramatic effects of inactivation of either the cdc2 or c-mos protein kinase on cyclin degradation suggest the involvement of unidentified protein phosphatases in the control of cyclin proteolysis.…”

mentioning

confidence: 99%

“…These results show that OA did not inactivate c-mos kinase irreversibly and suggest rather that it overcomes c-mos kinase inhibition of cyclin degradation. The alternative possibility that an OA-sensitive phosphatase directly and positively controls c-mos kinase activity and that OA cancels its cytostatic activity is unlikely, because c-mos kinase has been shown to be hyperphosphorylated in metaphase cells (27). Moreover, inhibition of type 2A phos- phatase by OA also induces cyclin proteolysis in interphase extracts prepared from fertilized eggs after c-mos kinase proteolysis (7).…”

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confidence: 99%

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An okadaic acid-sensitive phosphatase negatively controls the cyclin degradation pathway in amphibian eggs.

et al. 1991

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Inhibition of okadaic acid-sensitive phosphatases released the cyclin degradation pathway from its inhibited state in extracts prepared from unfertilized Xenopus eggs arrested at the second meiotic metaphase. It also switched on cyclin protease activity in a permanent fashion in interphase extracts prepared from activated eggs. Even after cdc2 kinase inactivation, microinjection of okadaic acid-treated interphase extracts pushed G2-arrested recipient oocytes into the M phase, suggesting that the phosphatase inhibitor stabilizes the activity of an unidentified factor which shares in common with cdc2 kinase the maturation-promoting factor activity.Exit from the M phase of the cell cycle requires inactivation of maturation-promoting factor (MPF), a universal inducer of mitosis recently identified as a stoichiometric complex between a cdc2+-encoded protein kinase and cyclin B, a protein whose concentration oscillates during the cell cycle (12, 16). MPF inactivation requires cyclin proteolysis (21), which begins at the end of metaphase and is completed within a very short window of the cell cycle (25, 28). At least two protein kinases have been shown to be involved in the control of cyclin degradation. One is cdc2 kinase itself, which promotes the abrupt degradation of cyclin about 15 min after its addition to interphase extracts made from fertilized or activated Xenopus eggs (8). At the end of the M phase, after cyclin has been destroyed, cdc2 kinase is inactivated and so is the proteolysis machinery. The second one is c-mos protein kinase, a proto-oncogene-encoded protein kinase. In vertebrates, c-mos protein kinase acts as a cytostatic factor which prevents proteolytic degradation of cyclin and arrests unfertilized eggs at the second meiotic metaphase (24). On fertilization or parthenogenetic activation, a calcium-dependent process inactivates c-mos kinase, resulting in cyclin degradation (27). The dramatic effects of inactivation of either the cdc2 or c-mos protein kinase on cyclin degradation suggest the involvement of unidentified protein phosphatases in the control of cyclin proteolysis.Therefore, the cyclin degradation pathway may be viewed as a complex network of protein kinases and protein phosphatases controlling ultimately the activity of a cyclin protease. Here we show that okadaic acid (OA), a potent inhibitor of type 1 and type 2A phosphatases (1, 3), overcomes a c-mos kinase inhibition of the cyclin degradation pathway in calcium-free extracts prepared from metaphasearrested eggs, while it deregulates and switches on cyclin protease activity in a permanent fashion in interphase extracts prepared from activated eggs. This leads us to propose that an OA-inhibited phosphatase, most likely type 2A phosphatase, exerts a negative control on the cyclin degradation pathway. Moreover, microinjection of OA-treated extracts pushes G2-arrested recipient oocytes into the M * Corresponding author.phase, even after cdc2 kinase inactivation. This suggests that the phosphatase inhibitor stabilizes the activity of an u...

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“…1 to monitor cyclin degradation. need to inhibit OA-sensitive phosphatases (27). The above results raise the question whether OA inactivates c-mos kinase in metaphase extracts.…”

mentioning

confidence: 88%

mentioning

confidence: 88%

mentioning

confidence: 99%

mentioning

confidence: 99%

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An okadaic acid-sensitive phosphatase negatively controls the cyclin degradation pathway in amphibian eggs.

et al. 1991

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“…Receptor internalisation, compartmentation and degradation is controlled by its tyrosine kinase activity (Honegger et al, 1987;Lai et al, 1989;Watanabe et al, 1989;Felder et al, 1990Felder et al, , 1992Lund et al, 1990;Sunada et al, 1990;Wiley et al, 1991). Internalised activated kinase appears to promote membrane fusion through phosphorylation of annexin I during invagination of multivesicular bodies (Futter et al, 1993).…”

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confidence: 99%

The calpain cleavage sites in the epidermal growth factor receptor kinase domain

Gregoriou

Willis

Pearson

et al. 1994

European Journal of Biochemistry

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The proteolysis of the human epidermal growth factor receptor cytoplasmic domain by calpain has been studied in vitro using purified recombinant cytoplasmic domain expressed in insect cells. Limited proteolysis produced kinase that was truncated at either N‐ or C‐termini, as well as in the hinge region. We identified seven sites of calpain proteolysis by N‐terminal sequencing of purified fragments. Calpain cleaved between the catalytic and autophosphorylation domains at two sites in the sequence Gln996–Asp1059, in the hinge region. Three new sites were also found in the autophosphorylation domain, preceding each of the major autophosphorylation sites. A fourth new site was located in the juxtamembrane domain, C‐terminal to the regulatory Thr654. We purified an active 42‐kDa fragment generated by calpain proteolysis between Leu659–Gln660 in the juxtamembrane domain, and in the hinge region. A fifth new site of calpain cleavage was found between the nucleotide binding motif Gly‐Xaa‐Gly‐Xaa‐Xaa‐Gly and the essential Lys721 in the catalytic core of the kinase. Since both of these features are required for catalysis, calpain cleavage at this site may potentially provide a mechanism for down‐regulation of kinase activity in vivo, under conditions of calpain activation. Thus the distribution of calpain cleavage sites along the kinase domain is consistent with a role for calpain both as a processing and as a degradative protease in epidermal growth factor receptor signalling.

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The ins and outs of meiosis

1999

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During oogenesis the oocyte is arrested in meiosis twice. First at prophase I, then a second time at metaphase I in many invertebrates and in metaphase II in the vast majority of vertebrates. Meiosis resumption is triggered by the sperm. This article examines mechanisms that cause oocytes' arrest in meiosis and how spermatozoa help the oocyte to get out of this cellular predicament. J. Exp. Zool. (Mol. Dev. Evol.) 285:226–236, 1999. © 1999 Wiley‐Liss, Inc.

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Specific proteolysis of the c-mos proto-oncogene product by calpain on fertilization of Xenopus eggs

Cited by 274 publications

References 43 publications

An okadaic acid-sensitive phosphatase negatively controls the cyclin degradation pathway in amphibian eggs.

An okadaic acid-sensitive phosphatase negatively controls the cyclin degradation pathway in amphibian eggs.

The calpain cleavage sites in the epidermal growth factor receptor kinase domain

The ins and outs of meiosis

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