Characterization of a novel species-specific 51-amino acid peptide, PEP51, as a caspase-3/7 activator in ovarian follicles of the ascidian, Ciona intestinalis Type A
Invertebrates lack hypothalamic-pituitary-gonadal axis, and have acquired species-specific regulatory systems for ovarian follicle development. Ascidians are marine invertebrates that are the phylogenetically closest living relatives to vertebrates, and we have thus far substantiated the molecular m...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2023-09-01
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| Series: | Frontiers in Endocrinology |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fendo.2023.1260600/full |
| _version_ | 1797667922054742016 |
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| author | Tsubasa Sakai Tatsuya Yamamoto Takehiro Watanabe Akiko Hozumi Akira Shiraishi Tomohiro Osugi Shin Matsubara Tsuyoshi Kawada Yasunori Sasakura Toshio Takahashi Honoo Satake |
| author_facet | Tsubasa Sakai Tatsuya Yamamoto Takehiro Watanabe Akiko Hozumi Akira Shiraishi Tomohiro Osugi Shin Matsubara Tsuyoshi Kawada Yasunori Sasakura Toshio Takahashi Honoo Satake |
| author_sort | Tsubasa Sakai |
| collection | DOAJ |
| description | Invertebrates lack hypothalamic-pituitary-gonadal axis, and have acquired species-specific regulatory systems for ovarian follicle development. Ascidians are marine invertebrates that are the phylogenetically closest living relatives to vertebrates, and we have thus far substantiated the molecular mechanisms underlying neuropeptidergic follicle development of the cosmopolitan species, Ciona intestinalis Type A. However, no ovarian factor has so far been identified in Ciona. In the present study, we identified a novel Ciona-specific peptide, termed PEP51, in the ovary. Immunohistochemical analysis demonstrated the specific expression of PEP51 in oocyte-associated accessory cells, test cells, of post-vitellogenic (stage III) follicles. Immunoelectron microscopy revealed that PEP51 was localized in the cytosol of test cells in early stage III follicles, which lack secretory granules. These results indicate that PEP51 acts as an intracellular factor within test cells rather than as a secretory peptide. Confocal laser microscopy verified that activation of caspase-3/7, the canonical apoptosis marker, was detected in most PEP51-positive test cells of early stage III. This colocalization of PEP51 and the apoptosis marker was consistent with immunoelectron microscopy observations demonstrating that a few normal (PEP51-negative) test cells reside in the aggregates of PEP51-positive apoptotic test cells of early stage III follicles. Furthermore, transfection of the PEP51 gene into COS-7 cells and HEK293MSR cells resulted in activation of caspase-3/7, providing evidence that PEP51 induces apoptotic signaling. Collectively, these results showed the existence of species-specific ovarian peptide-driven cell metabolism in Ciona follicle development. Consistent with the phylogenetic position of Ciona as the closest sister group of vertebrates, the present study sheds new light on the molecular and functional diversity of the regulatory systems of follicle development in the Chordata. |
| first_indexed | 2024-03-11T20:20:38Z |
| format | Article |
| id | doaj.art-a3fb9f5c148840b6b418c82b31488cf7 |
| institution | Directory Open Access Journal |
| issn | 1664-2392 |
| language | English |
| last_indexed | 2024-03-11T20:20:38Z |
| publishDate | 2023-09-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Endocrinology |
| spelling | doaj.art-a3fb9f5c148840b6b418c82b31488cf72023-10-03T05:01:19ZengFrontiers Media S.A.Frontiers in Endocrinology1664-23922023-09-011410.3389/fendo.2023.12606001260600Characterization of a novel species-specific 51-amino acid peptide, PEP51, as a caspase-3/7 activator in ovarian follicles of the ascidian, Ciona intestinalis Type ATsubasa Sakai0Tatsuya Yamamoto1Takehiro Watanabe2Akiko Hozumi3Akira Shiraishi4Tomohiro Osugi5Shin Matsubara6Tsuyoshi Kawada7Yasunori Sasakura8Toshio Takahashi9Honoo Satake10Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, JapanBioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, JapanBioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, JapanShimoda Marine Research Center, University of Tsukuba, Shizuoka, JapanBioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, JapanBioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, JapanBioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, JapanBioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, JapanShimoda Marine Research Center, University of Tsukuba, Shizuoka, JapanBioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, JapanBioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, JapanInvertebrates lack hypothalamic-pituitary-gonadal axis, and have acquired species-specific regulatory systems for ovarian follicle development. Ascidians are marine invertebrates that are the phylogenetically closest living relatives to vertebrates, and we have thus far substantiated the molecular mechanisms underlying neuropeptidergic follicle development of the cosmopolitan species, Ciona intestinalis Type A. However, no ovarian factor has so far been identified in Ciona. In the present study, we identified a novel Ciona-specific peptide, termed PEP51, in the ovary. Immunohistochemical analysis demonstrated the specific expression of PEP51 in oocyte-associated accessory cells, test cells, of post-vitellogenic (stage III) follicles. Immunoelectron microscopy revealed that PEP51 was localized in the cytosol of test cells in early stage III follicles, which lack secretory granules. These results indicate that PEP51 acts as an intracellular factor within test cells rather than as a secretory peptide. Confocal laser microscopy verified that activation of caspase-3/7, the canonical apoptosis marker, was detected in most PEP51-positive test cells of early stage III. This colocalization of PEP51 and the apoptosis marker was consistent with immunoelectron microscopy observations demonstrating that a few normal (PEP51-negative) test cells reside in the aggregates of PEP51-positive apoptotic test cells of early stage III follicles. Furthermore, transfection of the PEP51 gene into COS-7 cells and HEK293MSR cells resulted in activation of caspase-3/7, providing evidence that PEP51 induces apoptotic signaling. Collectively, these results showed the existence of species-specific ovarian peptide-driven cell metabolism in Ciona follicle development. Consistent with the phylogenetic position of Ciona as the closest sister group of vertebrates, the present study sheds new light on the molecular and functional diversity of the regulatory systems of follicle development in the Chordata.https://www.frontiersin.org/articles/10.3389/fendo.2023.1260600/fulltest cellsovarian peptidesapoptosisascidianfollicle |
| spellingShingle | Tsubasa Sakai Tatsuya Yamamoto Takehiro Watanabe Akiko Hozumi Akira Shiraishi Tomohiro Osugi Shin Matsubara Tsuyoshi Kawada Yasunori Sasakura Toshio Takahashi Honoo Satake Characterization of a novel species-specific 51-amino acid peptide, PEP51, as a caspase-3/7 activator in ovarian follicles of the ascidian, Ciona intestinalis Type A Frontiers in Endocrinology test cells ovarian peptides apoptosis ascidian follicle |
| title | Characterization of a novel species-specific 51-amino acid peptide, PEP51, as a caspase-3/7 activator in ovarian follicles of the ascidian, Ciona intestinalis Type A |
| title_full | Characterization of a novel species-specific 51-amino acid peptide, PEP51, as a caspase-3/7 activator in ovarian follicles of the ascidian, Ciona intestinalis Type A |
| title_fullStr | Characterization of a novel species-specific 51-amino acid peptide, PEP51, as a caspase-3/7 activator in ovarian follicles of the ascidian, Ciona intestinalis Type A |
| title_full_unstemmed | Characterization of a novel species-specific 51-amino acid peptide, PEP51, as a caspase-3/7 activator in ovarian follicles of the ascidian, Ciona intestinalis Type A |
| title_short | Characterization of a novel species-specific 51-amino acid peptide, PEP51, as a caspase-3/7 activator in ovarian follicles of the ascidian, Ciona intestinalis Type A |
| title_sort | characterization of a novel species specific 51 amino acid peptide pep51 as a caspase 3 7 activator in ovarian follicles of the ascidian ciona intestinalis type a |
| topic | test cells ovarian peptides apoptosis ascidian follicle |
| url | https://www.frontiersin.org/articles/10.3389/fendo.2023.1260600/full |
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