Variation in prostaglandin metabolism during growth of the diatom Thalassiosira rotula

Valeria Di Dato,Anna Perna,Federica Di Costanzo,Francesco Esposito,Adele Cutignano,Carolina Fontanarosa,Adrianna Ianora,Giovanna Romano,Alberto Amato,Angela Amoresano,Roberta Barbarinaldi

doi:10.1038/s41598-020-61967-3

Abstract

Prostaglandins (PGs) are hormone-like mediators in many physiological and pathological processes that are present in all vertebrates, in some terrestrial and aquatic invertebrates, and have also been identified in some macroalgae. They have recently been reported also in marine microalgae but their role as chemical mediators is largely unknown. Here we studied the expression pattern of the PG biosynthetic pathway during different growth phases of the centric diatom Thalassiosira rotula and assessed the release of PGs in the surrounding environment for the first time. We show that enzymes responsible for PGs formation such as cyclooxygenase, prostaglandin E synthase 2-like and prostaglandin F synthase are mainly expressed at the end of the exponential phase and that PGs are released especially during the stationary and senescent phases, suggesting a possible signaling function for these compounds. Phylogenetic analysis of the limiting enzyme, COX, indicate the presence in diatoms of more than one enzyme related to the oxidative metabolism of fatty acids belonging to the peroxidase-cyclooxygenase superfamily. These findings suggest a more complex evolution and diversity of metabolic pathways leading to the synthesis of lipid mediators in diatoms.

Highlights

Prostaglandins (PGs) are hormone-like mediators in many physiological and pathological processes that are present in all vertebrates, in some terrestrial and aquatic invertebrates, and have been identified in some macroalgae
Arachidonic acid (ARA), eicosapentaenoic acid (EPA), eicosatrienoic acid (ETrA) and docosahexaenoic acid (DHA) are polyunsaturated fatty acids that are physiologically important for animals at all taxonomic levels, including humans
Included in the eicosanoids are prostaglandins (PGs) synthesized principally from arachidonic acid (ARA) in animals, and from EPA and ETrA, through the enzymatic route initiated by cyclooxygenase (COXs) enzymes[5]

Summary

Introduction

Prostaglandins (PGs) are hormone-like mediators in many physiological and pathological processes that are present in all vertebrates, in some terrestrial and aquatic invertebrates, and have been identified in some macroalgae. Phylogenetic analysis of the limiting enzyme, COX, indicate the presence in diatoms of more than one enzyme related to the oxidative metabolism of fatty acids belonging to the peroxidase-cyclooxygenase superfamily These findings suggest a more complex evolution and diversity of metabolic pathways leading to the synthesis of lipid mediators in diatoms. Included in the eicosanoids are prostaglandins (PGs) synthesized principally from arachidonic acid (ARA) in animals, and from EPA and ETrA, through the enzymatic route initiated by cyclooxygenase (COXs) enzymes[5]. PGs synthesis, in mammals, is initiated by phospholipases (PLAs), a family of enzymes that hydrolyze membrane phospholipids liberating the precursors, ARA, EPA, and ETrA These are rapidly converted, through cyclization and inclusion of molecular oxygen, into the unstable metabolite PGG2 by the action of COXs enzymes that subsequently reduce it into PGH2. The presence of PGs has been reported in some plant species, such as onions and poplar trees[11]

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Conclusion