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Nucleolar Architecture Is Modulated by a Small Molecule, the Inositol Pyrophosphate 5-InsP(7)
Inositol pyrophosphates (PP-InsPs); are a functionally diverse family of eukaryotic molecules that deploy a highly-specialized array of phosphate groups as a combinatorial cell-signaling code. One reductive strategy to derive a molecular-level understanding of the many actions of PP-InsPs is to indi...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2023
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9855682/ https://www.ncbi.nlm.nih.gov/pubmed/36671538 http://dx.doi.org/10.3390/biom13010153 |
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author | Sahu, Soumyadip Gordon, Jacob Gu, Chunfang Sobhany, Mack Fiedler, Dorothea Stanley, Robin E. Shears, Stephen B. |
author_facet | Sahu, Soumyadip Gordon, Jacob Gu, Chunfang Sobhany, Mack Fiedler, Dorothea Stanley, Robin E. Shears, Stephen B. |
author_sort | Sahu, Soumyadip |
collection | PubMed |
description | Inositol pyrophosphates (PP-InsPs); are a functionally diverse family of eukaryotic molecules that deploy a highly-specialized array of phosphate groups as a combinatorial cell-signaling code. One reductive strategy to derive a molecular-level understanding of the many actions of PP-InsPs is to individually characterize the proteins that bind them. Here, we describe an alternate approach that seeks a single, collective rationalization for PP-InsP binding to an entire group of proteins, i.e., the multiple nucleolar proteins previously reported to bind 5-InsP(7) (5-diphospho-inositol-1,2,3,4,6-pentakisphosphate). Quantitative confocal imaging of the outer nucleolar granular region revealed its expansion when cellular 5-InsP(7) levels were elevated by either (a) reducing the 5-InsP(7) metabolism by a CRISPR-based knockout (KO) of either NUDT3 or PPIP5Ks; or (b), the heterologous expression of wild-type inositol hexakisphosphate kinase, i.e., IP6K2; separate expression of a kinase-dead IP6K2 mutant did not affect granular volume. Conversely, the nucleolar granular region in PPIP5K KO cells shrank back to the wild-type volume upon attenuating 5-InsP(7) synthesis using either a pan-IP6K inhibitor or the siRNA-induced knockdown of IP6K1+IP6K2. Significantly, the inner fibrillar volume of the nucleolus was unaffected by 5-InsP(7). We posit that 5-InsP(7) acts as an ‘electrostatic glue’ that binds together positively charged surfaces on separate proteins, overcoming mutual protein–protein electrostatic repulsion the latter phenomenon is a known requirement for the assembly of a non-membranous biomolecular condensate. |
format | Online Article Text |
id | pubmed-9855682 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-98556822023-01-21 Nucleolar Architecture Is Modulated by a Small Molecule, the Inositol Pyrophosphate 5-InsP(7) Sahu, Soumyadip Gordon, Jacob Gu, Chunfang Sobhany, Mack Fiedler, Dorothea Stanley, Robin E. Shears, Stephen B. Biomolecules Article Inositol pyrophosphates (PP-InsPs); are a functionally diverse family of eukaryotic molecules that deploy a highly-specialized array of phosphate groups as a combinatorial cell-signaling code. One reductive strategy to derive a molecular-level understanding of the many actions of PP-InsPs is to individually characterize the proteins that bind them. Here, we describe an alternate approach that seeks a single, collective rationalization for PP-InsP binding to an entire group of proteins, i.e., the multiple nucleolar proteins previously reported to bind 5-InsP(7) (5-diphospho-inositol-1,2,3,4,6-pentakisphosphate). Quantitative confocal imaging of the outer nucleolar granular region revealed its expansion when cellular 5-InsP(7) levels were elevated by either (a) reducing the 5-InsP(7) metabolism by a CRISPR-based knockout (KO) of either NUDT3 or PPIP5Ks; or (b), the heterologous expression of wild-type inositol hexakisphosphate kinase, i.e., IP6K2; separate expression of a kinase-dead IP6K2 mutant did not affect granular volume. Conversely, the nucleolar granular region in PPIP5K KO cells shrank back to the wild-type volume upon attenuating 5-InsP(7) synthesis using either a pan-IP6K inhibitor or the siRNA-induced knockdown of IP6K1+IP6K2. Significantly, the inner fibrillar volume of the nucleolus was unaffected by 5-InsP(7). We posit that 5-InsP(7) acts as an ‘electrostatic glue’ that binds together positively charged surfaces on separate proteins, overcoming mutual protein–protein electrostatic repulsion the latter phenomenon is a known requirement for the assembly of a non-membranous biomolecular condensate. MDPI 2023-01-12 /pmc/articles/PMC9855682/ /pubmed/36671538 http://dx.doi.org/10.3390/biom13010153 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Sahu, Soumyadip Gordon, Jacob Gu, Chunfang Sobhany, Mack Fiedler, Dorothea Stanley, Robin E. Shears, Stephen B. Nucleolar Architecture Is Modulated by a Small Molecule, the Inositol Pyrophosphate 5-InsP(7) |
title | Nucleolar Architecture Is Modulated by a Small Molecule, the Inositol Pyrophosphate 5-InsP(7) |
title_full | Nucleolar Architecture Is Modulated by a Small Molecule, the Inositol Pyrophosphate 5-InsP(7) |
title_fullStr | Nucleolar Architecture Is Modulated by a Small Molecule, the Inositol Pyrophosphate 5-InsP(7) |
title_full_unstemmed | Nucleolar Architecture Is Modulated by a Small Molecule, the Inositol Pyrophosphate 5-InsP(7) |
title_short | Nucleolar Architecture Is Modulated by a Small Molecule, the Inositol Pyrophosphate 5-InsP(7) |
title_sort | nucleolar architecture is modulated by a small molecule, the inositol pyrophosphate 5-insp(7) |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9855682/ https://www.ncbi.nlm.nih.gov/pubmed/36671538 http://dx.doi.org/10.3390/biom13010153 |
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