Mitochondria and chloroplasts, energy-converting organelles in eukaryotic cells, are relicts of ancient bacterial endosymbionts. In addition to these particular organelles, there are many other endosymbiotic events which have integrated new functions into eukaryotic host cells. In order to maintain a permanent endosymbiotic relationship, a host cell and an endosymbiotic cell coordinate their proliferation. The major goal of our study is to understand how organelle (or other endosymbiotic cell) division is controlled by host cells and how host cells proliferate depending on chemical energy that are supplied by organelles (or other endosymbiotic cells).
Reminiscent of their cyanobacterial (A) ancestor, chloroplasts replicate by binary division (B, unicellular alga; C, land plant cells). Chloroplast division is performed by the division ring (D) which involves cyanobacterial FtsZ and eukaryotic dynamin (E).
Hirooka S, Itabashi T, Ichinose TM, Onuma R, Fujiwara T, Yamashita S, Jong LW, Tomita R, Iwane AH, Miyagishima SY. Life cycle and functional genomics of the unicellular red alga Galdieria for elucidating algal and plant evolution and industrial use. Proc Natl Acad Sci U S A. 2022 Oct 11;119(41):e2210665119.
Onuma R, Hirooka S, Kanesaki Y, Fujiwara T, Yoshikawa H, Miyagishima SY. Changes in the transcriptome, ploidy, and optimal light intensity of a cryptomonad upon integration into a kleptoplastic dinoflagellate. ISME J. 2020 Oct;14(10):2407-2423.
Uzuka A, Kobayashi Y, Onuma R, Hirooka S, Kanesaki Y, Yoshikawa H, Fujiwara T, Miyagishima SY. Responses of unicellular predators to cope with the phototoxicity of photosynthetic prey. Nat Commun. 2019 Dec 6;10(1):5606.
Miyagishima SY, Era A, Hasunuma T, Matsuda M, Hirooka S, Sumiya N, Kondo A, Fujiwara T. Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga Cyanidioschyzon merolae. mBio. 2019 Jul 2;10(4). pii: e00833-19.