A Limited and Diverse Set of Suppressor Mutations Restore Function to INX-8 Mutant Hemichannels in the <i>Caenorhabditis elegans</i> Somatic Gonad
In <i>Caenorhabditis elegans</i>, gap junctions couple cells of the somatic gonad with the germline to support germ cell proliferation and gametogenesis. A strong loss-of-function mutation (T239I) affects the second extracellular loop (EL2) of the somatic INX-8 hemichannel subunit. These...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-12-01
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| Series: | Biomolecules |
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| Online Access: | https://www.mdpi.com/2218-273X/10/12/1655 |
| _version_ | 1797545117289021440 |
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| author | Todd Starich David Greenstein |
| author_facet | Todd Starich David Greenstein |
| author_sort | Todd Starich |
| collection | DOAJ |
| description | In <i>Caenorhabditis elegans</i>, gap junctions couple cells of the somatic gonad with the germline to support germ cell proliferation and gametogenesis. A strong loss-of-function mutation (T239I) affects the second extracellular loop (EL2) of the somatic INX-8 hemichannel subunit. These mutant hemichannels form non-functional gap junctions with germline-expressed innexins. We conducted a genetic screen for suppressor mutations that restore germ cell proliferation in the T239I mutant background and isolated seven intragenic mutations, located in diverse domains of INX-8 but not the EL domains. These second-site mutations compensate for the original channel defect to varying degrees, from nearly complete wild-type rescue, to partial rescue of germline proliferation. One suppressor mutation (E350K) supports the innexin cryo-EM structural model that the channel pore opening is surrounded by a cytoplasmic dome. Two suppressor mutations (S9L and I36N) may form leaky channels that support germline proliferation but cause the demise of somatic sheath cells. Phenotypic analyses of three of the suppressors reveal an equivalency in the rescue of germline proliferation and comparable delays in gametogenesis but a graded rescue of fertility. The mutations described here may be useful for elucidating the biochemical pathways that produce the active biomolecules transiting through soma–germline gap junctions. |
| first_indexed | 2024-03-10T14:10:54Z |
| format | Article |
| id | doaj.art-978cd57cbd45474f8e03474af30e5ac4 |
| institution | Directory Open Access Journal |
| issn | 2218-273X |
| language | English |
| last_indexed | 2024-03-10T14:10:54Z |
| publishDate | 2020-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Biomolecules |
| spelling | doaj.art-978cd57cbd45474f8e03474af30e5ac42023-11-21T00:11:14ZengMDPI AGBiomolecules2218-273X2020-12-011012165510.3390/biom10121655A Limited and Diverse Set of Suppressor Mutations Restore Function to INX-8 Mutant Hemichannels in the <i>Caenorhabditis elegans</i> Somatic GonadTodd Starich0David Greenstein1Department Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USADepartment Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USAIn <i>Caenorhabditis elegans</i>, gap junctions couple cells of the somatic gonad with the germline to support germ cell proliferation and gametogenesis. A strong loss-of-function mutation (T239I) affects the second extracellular loop (EL2) of the somatic INX-8 hemichannel subunit. These mutant hemichannels form non-functional gap junctions with germline-expressed innexins. We conducted a genetic screen for suppressor mutations that restore germ cell proliferation in the T239I mutant background and isolated seven intragenic mutations, located in diverse domains of INX-8 but not the EL domains. These second-site mutations compensate for the original channel defect to varying degrees, from nearly complete wild-type rescue, to partial rescue of germline proliferation. One suppressor mutation (E350K) supports the innexin cryo-EM structural model that the channel pore opening is surrounded by a cytoplasmic dome. Two suppressor mutations (S9L and I36N) may form leaky channels that support germline proliferation but cause the demise of somatic sheath cells. Phenotypic analyses of three of the suppressors reveal an equivalency in the rescue of germline proliferation and comparable delays in gametogenesis but a graded rescue of fertility. The mutations described here may be useful for elucidating the biochemical pathways that produce the active biomolecules transiting through soma–germline gap junctions.https://www.mdpi.com/2218-273X/10/12/1655gap junctionsinnexinssoma–germline interactions |
| spellingShingle | Todd Starich David Greenstein A Limited and Diverse Set of Suppressor Mutations Restore Function to INX-8 Mutant Hemichannels in the <i>Caenorhabditis elegans</i> Somatic Gonad Biomolecules gap junctions innexins soma–germline interactions |
| title | A Limited and Diverse Set of Suppressor Mutations Restore Function to INX-8 Mutant Hemichannels in the <i>Caenorhabditis elegans</i> Somatic Gonad |
| title_full | A Limited and Diverse Set of Suppressor Mutations Restore Function to INX-8 Mutant Hemichannels in the <i>Caenorhabditis elegans</i> Somatic Gonad |
| title_fullStr | A Limited and Diverse Set of Suppressor Mutations Restore Function to INX-8 Mutant Hemichannels in the <i>Caenorhabditis elegans</i> Somatic Gonad |
| title_full_unstemmed | A Limited and Diverse Set of Suppressor Mutations Restore Function to INX-8 Mutant Hemichannels in the <i>Caenorhabditis elegans</i> Somatic Gonad |
| title_short | A Limited and Diverse Set of Suppressor Mutations Restore Function to INX-8 Mutant Hemichannels in the <i>Caenorhabditis elegans</i> Somatic Gonad |
| title_sort | limited and diverse set of suppressor mutations restore function to inx 8 mutant hemichannels in the i caenorhabditis elegans i somatic gonad |
| topic | gap junctions innexins soma–germline interactions |
| url | https://www.mdpi.com/2218-273X/10/12/1655 |
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