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Putar D, Čizmar A, Chao X, Šimić M, Šoštar M, Ćutić T, Mijanović L, Smolko A, Tu H, Cosson P, Weber I, Cai H, Filić V. IqgC is a potent regulator of macropinocytosis in the presence of NF1 and its loading to macropinosomes is dependent on RasG. Open Biol 2024; 14:230372. [PMID: 38263885 PMCID: PMC10806400 DOI: 10.1098/rsob.230372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 11/26/2023] [Indexed: 01/25/2024] Open
Abstract
RasG is a major regulator of macropinocytosis in Dictyostelium discoideum. Its activity is under the control of an IQGAP-related protein, IqgC, which acts as a RasG-specific GAP (GTPase activating protein). IqgC colocalizes with the active Ras at the macropinosome membrane during its formation and for some time after the cup closure. However, the loss of IqgC induces only a minor enhancement of fluid uptake in axenic cells that already lack another RasGAP, NF1. Here, we show that IqgC plays an important role in the regulation of macropinocytosis in the presence of NF1 by restricting the size of macropinosomes. We further provide evidence that interaction with RasG is indispensable for the recruitment of IqgC to forming macropinocytic cups. We also demonstrate that IqgC interacts with another small GTPase from the Ras superfamily, Rab5A, but is not a GAP for Rab5A. Since mammalian Rab5 plays a key role in early endosome maturation, we hypothesized that IqgC could be involved in macropinosome maturation via its interaction with Rab5A. Although an excessive amount of Rab5A reduces the RasGAP activity of IqgC in vitro and correlates with IqgC dissociation from endosomes in vivo, the physiological significance of the Rab5A-IqgC interaction remains elusive.
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Affiliation(s)
- Darija Putar
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Anja Čizmar
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Xiaoting Chao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101 Beijing, People's Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049 Beijing, People's Republic of China
| | - Marija Šimić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Marko Šoštar
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Tamara Ćutić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Lucija Mijanović
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Ana Smolko
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Hui Tu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101 Beijing, People's Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049 Beijing, People's Republic of China
| | - Pierre Cosson
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101 Beijing, People's Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049 Beijing, People's Republic of China
| | - Vedrana Filić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
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Mijanović L, Weber I. Adhesion of Dictyostelium Amoebae to Surfaces: A Brief History of Attachments. Front Cell Dev Biol 2022; 10:910736. [PMID: 35721508 PMCID: PMC9197732 DOI: 10.3389/fcell.2022.910736] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/13/2022] [Indexed: 12/23/2022] Open
Abstract
Dictyostelium amoebae adhere to extracellular material using similar mechanisms to metazoan cells. Notably, the cellular anchorage loci in Amoebozoa and Metazoa are both arranged in the form of discrete spots and incorporate a similar repertoire of intracellular proteins assembled into multicomponent complexes located on the inner side of the plasma membrane. Surprisingly, however, Dictyostelium lacks integrins, the canonical transmembrane heterodimeric receptors that dominantly mediate adhesion of cells to the extracellular matrix in multicellular animals. In this review article, we summarize the current knowledge about the cell-substratum adhesion in Dictyostelium, present an inventory of the involved proteins, and draw parallels with the situation in animal cells. The emerging picture indicates that, while retaining the basic molecular architecture common to their animal relatives, the adhesion complexes in free-living amoeboid cells have evolved to enable less specific interactions with diverse materials encountered in their natural habitat in the deciduous forest soil. Dissection of molecular mechanisms that underlay short lifetime of the cell-substratum attachments and high turnover rate of the adhesion complexes in Dictyostelium should provide insight into a similarly modified adhesion phenotype that accompanies the mesenchymal-amoeboid transition in tumor metastasis.
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Affiliation(s)
- Lucija Mijanović
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
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Filić V, Mijanović L, Putar D, Talajić A, Ćetković H, Weber I. Regulation of the Actin Cytoskeleton via Rho GTPase Signalling in Dictyostelium and Mammalian Cells: A Parallel Slalom. Cells 2021; 10:1592. [PMID: 34202767 PMCID: PMC8305917 DOI: 10.3390/cells10071592] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/16/2021] [Accepted: 06/16/2021] [Indexed: 01/15/2023] Open
Abstract
Both Dictyostelium amoebae and mammalian cells are endowed with an elaborate actin cytoskeleton that enables them to perform a multitude of tasks essential for survival. Although these organisms diverged more than a billion years ago, their cells share the capability of chemotactic migration, large-scale endocytosis, binary division effected by actomyosin contraction, and various types of adhesions to other cells and to the extracellular environment. The composition and dynamics of the transient actin-based structures that are engaged in these processes are also astonishingly similar in these evolutionary distant organisms. The question arises whether this remarkable resemblance in the cellular motility hardware is accompanied by a similar correspondence in matching software, the signalling networks that govern the assembly of the actin cytoskeleton. Small GTPases from the Rho family play pivotal roles in the control of the actin cytoskeleton dynamics. Indicatively, Dictyostelium matches mammals in the number of these proteins. We give an overview of the Rho signalling pathways that regulate the actin dynamics in Dictyostelium and compare them with similar signalling networks in mammals. We also provide a phylogeny of Rho GTPases in Amoebozoa, which shows a variability of the Rho inventories across different clades found also in Metazoa.
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Affiliation(s)
- Vedrana Filić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
| | | | | | | | | | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
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