Expression patterns of sterol transporters NPC1 and NPC2 in the cnidarian–dinoflagellate symbiosis |
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Authors: | Vincent Dani Fabrice Priouzeau Marjolijn Mertz Magali Mondin Sophie Pagnotta Sandra Lacas‐Gervais Simon K. Davy Cécile Sabourault |
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Affiliation: | 1. Institut de Biologie Valrose (iBV), Université C?te d'Azur, Nice, France;2. UMR7138, Equipe Symbiose Marine, Université C?te d'Azur, Nice, France;3. Centre Commun de Microscopie Appliquée, Université C?te d'Azur, Nice, France;4. School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand |
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Abstract: | The symbiotic interaction between cnidarians (e.g., corals and sea anemones) and photosynthetic dinoflagellates of the genus Symbiodinium is triggered by both host–symbiont recognition processes and metabolic exchange between the 2 partners. The molecular communication is crucial for homeostatic regulation of the symbiosis, both under normal conditions and during stresses that further lead to symbiosis collapse. It is therefore important to identify and fully characterise the key players of this intimate interaction at the symbiotic interface. In this study, we determined the cellular and subcellular localization and expression of the sterol‐trafficking Niemann–Pick type C proteins (NPC1 and NPC2) in the symbiotic sea anemones Anemonia viridis and Aiptasia sp. We first established that NPC1 is localised within vesicles in host tissues and to the symbiosome membranes in several anthozoan species. We demonstrated that the canonical NPC2‐a protein is mainly expressed in the epidermis, whereas the NPC2‐d protein is closely associated with symbiosome membranes. Furthermore, we showed that the expression of the NPC2‐d protein is correlated with symbiont presence in healthy symbiotic specimens. As npc2‐d is a cnidarian‐specific duplicated gene, we hypothesised that it probably arose from a subfunctionalisation process that might result in a gain of function and symbiosis adaptation in anthozoans. Niemann–Pick type C proteins may be key players in a functional symbiosis and be useful tools to study host–symbiont interactions in the anthozoan–dinoflagellate association. |
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Keywords: | Symbiodinium symbiosome NPC1 NPC2 perisymbiont membrane |
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