Gamete fusion triggers bipartite transcription factor assembly to block re-fertilization
| Autor: | Pedro Junior Nkosi, Aleksandar Vjestica, Laura Merlini, Sophie G. Martin |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Cytoplasm Transcription Genetic Biology Haploidy Karyogamy Cell Fusion Polyploidy 03 medical and health sciences 0302 clinical medicine Meiosis Gene Expression Regulation Fungal Schizosaccharomyces medicine Transcription factor Cell Nucleus Multidisciplinary Zygote Reproduction biology.organism_classification Aneuploidy Diploidy Cell biology Sexual reproduction 030104 developmental biology medicine.anatomical_structure Schizosaccharomyces pombe Gamete Schizosaccharomyces pombe Proteins Ploidy 030217 neurology & neurosurgery Signal Transduction Transcription Factors |
| Zdroj: | Nature |
| ISSN: | 0028-0836 |
| DOI: | 10.1038/s41586-018-0407-5 |
| Popis: | The ploidy cycle, which is integral to sexual reproduction, requires meiosis to halve chromosome numbers as well as mechanisms that ensure zygotes are formed by exactly two partners1-4. During sexual reproduction of the fungal model organism Schizosaccharomyces pombe, haploid P and M cells fuse to form a diploid zygote that immediately enters meiosis5. Here we reveal that rapid post-fusion reconstitution of a bipartite transcription factor blocks re-fertilization. We first identify mutants that undergo transient cell fusion involving cytosol exchange but not karyogamy, and show that this drives distinct cell fates in the two gametes. The P partner undergoes lethal haploid meiosis, whereas the M cell persists in mating. The zygotic transcription that drives meiosis is rapidly initiated first from the P parental genome, even in wild-type cells. This asymmetric gene expression depends on a bipartite complex formed post-fusion between the cytosolic M-cell-specific peptide Mi and the nuclear P-cell-specific homeobox protein Pi6,7, which captures Mi in the P nucleus. Zygotic transcription is thus poised to initiate in the P nucleus as fast as Mi reaches it after fusion, a design that we reconstruct using two synthetic interactors localized to the nucleus and the cytosol of two respective partner cells. Notably, delaying zygotic transcription-by postponing Mi expression or deleting its transcriptional target in the P genome-leads to zygotes fusing with additional gametes, thus forming polyploids and eventually aneuploid progeny. The signalling cascade to block re-fertilization shares components with, but bifurcates from, meiotic induction8-10. Thus, a cytoplasmic connection upon gamete fusion leads to asymmetric reconstitution of a bipartite transcription factor to rapidly block re-fertilization and induce meiosis, ensuring genome maintenance during sexual reproduction. |
| Databáze: | OpenAIRE |
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