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Kay RR, Lutton J, Coker H, Paschke P, King JS, Bretschneider T. The Amoebal Model for Macropinocytosis. Subcell Biochem 2022; 98:41-59. [PMID: 35378702 DOI: 10.1007/978-3-030-94004-1_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Macropinocytosis is a relatively unexplored form of large-scale endocytosis driven by the actin cytoskeleton. Dictyostelium amoebae form macropinosomes from cups extended from the plasma membrane, then digest their contents and absorb the nutrients in the endo-lysosomal system. They use macropinocytosis for feeding, maintaining a high rate of fluid uptake that makes assay and experimentation easy. Mutants collected over the years identify cytoskeletal and signalling proteins required for macropinocytosis. Cups are organized around plasma membrane domains of intense PIP3, Ras and Rac signalling, proper formation of which also depends on the RasGAPs NF1 and RGBARG, PTEN, the PIP3-regulated protein kinases Akt and SGK and their activators PDK1 and TORC2, Rho proteins, plus other components yet to be identified. This PIP3 domain directs dendritic actin polymerization to the extending lip of macropinocytic cups by recruiting a ring of the SCAR/WAVE complex around itself and thus activating the Arp2/3 complex. The dynamics of PIP3 domains are proposed to shape macropinocytic cups from start to finish. The role of the Ras-PI3-kinase module in organizing feeding structures in unicellular organisms most likely predates its adoption into growth factor signalling, suggesting an evolutionary origin for growth factor signalling.
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Affiliation(s)
- Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, UK.
| | - Josiah Lutton
- Department of Computer Science, University of Warwick, Coventry, UK
| | - Helena Coker
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Peggy Paschke
- MRC Laboratory of Molecular Biology, Cambridge, UK.,Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, UK
| | - Jason S King
- School of Biomedical Sciences, University of Sheffield, Sheffield, UK
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Oku N, Hasada A, Kimura K, Honoki H, Katsuta R, Yajima A, Nukada T, Ishigami K, Igarashi Y. Sulfoquinovosylglyceryl ether, a new group of ether lipids from lake ball-forming green alga Aegagropilopsis moravica (family Pithophoraceae). Chem Asian J 2021; 16:1493-1498. [PMID: 33871157 DOI: 10.1002/asia.202100278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/16/2021] [Indexed: 12/23/2022]
Abstract
Ether lipids are a minor group of glycerolipids but widespread in nature, playing a vital function as membrane lipids, signalling molecules, or buoyant material. We have discovered sulfoquinovosylchimyl alcohol (1), a sulfonate-substituted glyceroglycolipid, from a lake ball-forming green alga Aegagropilopsis moravica (family Pithophoraceae), with the guidance of antimicrobial activity. The structure of 1, including absolute configurations of all sterogenic centers, was established by extensive NMR analysis, chemical degradation studies, and finally by total synthesis. Lipid 1 is an ether variant of a lyso-form of sulfoquinovosyldiacylglycerol, a chloroplast-specific membrane lipid, and thus represents a new lipid class, sulfoquinovosylglyceryl ether. A high occurrence of mobile life form in the family Pithophoraceae and a unique behaviour of chloroplasts reported in closely related Aegagropila linnaei, the famous lake-ball alga, implies a possible role of lipid 1 or its acyl derivatives in ecological adaptation to dysphotic niches.
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Affiliation(s)
- Naoya Oku
- Research Center for Biotechnology and Pharmaceutical Engineering and Department of Biotechnology, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan
| | - Atsumi Hasada
- Research Center for Biotechnology and Pharmaceutical Engineering and Department of Biotechnology, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan
| | - Kenji Kimura
- Graduate School of Agriculture, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Hideharu Honoki
- Toyama Science Museum, 1-8-31 Nishinakano, Toyama, 939-8034, Japan
| | - Ryo Katsuta
- Department of Chemistry for Life Sciences and Agriculture, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Arata Yajima
- Department of Chemistry for Life Sciences and Agriculture, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Tomoo Nukada
- Department of Chemistry for Life Sciences and Agriculture, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Ken Ishigami
- Department of Chemistry for Life Sciences and Agriculture, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Yasuhiro Igarashi
- Research Center for Biotechnology and Pharmaceutical Engineering and Department of Biotechnology, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan
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