B24 protein stored in lampbrush spheres is involved in early cleavage in urodele amphibians

Albani, Francesca; Perrin, Karine; Bucci, Stefania; Ragghianti, Matilde; Mancino, Giorgio; Lacroix, J. C.

doi:10.1002/(sici)1097-010x(19980201)280:2<142::aid-jez5>3.0.co;2-o

Cited by 5 publications

(2 citation statements)

References 33 publications

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“…18,21 Recent studies, however, suggest that MCM2-7 is transported into nuclei in Xenopus egg extracts. [27][28][29] It has also been established that the MCM complex that contains maternal MCM3 is accumulated into germinal vesicles (meiotic nuclei) 19 and that MCM2 orthologs have active NLS. 20,30 Perhaps maternal MCM2-7 can be transported into the nuclei, but presumably at a much slower rate than zygotic MCM2-7 can be transported, depending on the NLS of MCM2.…”

Section: Discussionmentioning

confidence: 99%

“…So far, we have found only one fragment of newt MCM3 cDNA that encodes protein with significant similarity to the C-terminal regions of Xenopus MCM3m by searching the public sequence databases. 19 These results show that the maternal-specific genes of MCM3 and MCM6 have been retained in only a small fraction of species.…”

Section: Identification Of Maternal and Zygotic Mcm3 And Mcm6 In Xenomentioning

confidence: 99%

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Evolutionary diversification ofMCM3genes inXenopus laevisandDanio rerio

et al. 2014

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Embryonic cell cycles of amphibians are rapid and lack zygotic transcription and checkpoint control. At the midblastula transition, zygotic transcription is initiated and cell divisions become asynchronous. Several cell cycle-related amphibian genes retain 2 distinct forms, maternal and zygotic, but little is known about the functional differences between these 2 forms of proteins. The minichromosome maintenance (MCM) 2-7 complex, consisting of 6 MCM proteins, plays a central role in the regulation of eukaryotic DNA replication. Almost all eukaryotes retain just a single MCM gene for each subunit. Here we report that Xenopus and zebrafish have 2 copies of MCM3 genes, one of which shows a maternal and the other a zygotic expression pattern. Phylogenetic analysis shows that the Xenopus and zebrafish zygotic MCM3 genes are more similar to their mammalian MCM3 ortholog, suggesting that maternal MCM3 was lost during evolution in most vertebrate lineages. Maternal MCM3 proteins in these 2 species are functionally different from zygotic MCM3 proteins because zygotic, but not maternal, MCM3 possesses an active nuclear localization signal in its C-terminal region, such as mammalian MCM3 orthologs do. mRNA injection experiments in zebrafish embryos show that overexpression of maternal MCM3 impairs proliferation and causes developmental defects, whereas zygotic MCM3 has a much weaker effect. This difference is brought about by the difference in their C-terminal regions, which contain putative nuclear localization signals; swapping the C-terminal region between maternal and zygotic genes diminishes the developmental defects. This study suggests that evolutionary diversification has occurred in MCM3 genes, leading to distinct functions, possibly as an adaption to the rapid DNA replication required for early development of Xenopus and zebrafish.

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