Evolutionary Origin of the Mammalian Hematopoietic System Found in a Colonial Chordate

Rosental, B.; Kowarsky, M. A.; Seita, J.; Corey, D. M.; Ishizuka, K. J.; Palmeri, K. J.; Chen, S.-Y.; Sinha, R.; Okamoto, J.; Mantalas, G.; Manni, L.; Raveh, T.; Clarke, D. N.; Newman, A. M.; Neff, N. F.; Nolan, G. P.; Quake, S. R.; Weissman, I. L.; Voskoboynik, A.

doi:10.1101/206318

bioRxiv · 10.1101/206318

Evolutionary Origin of the Mammalian Hematopoietic System Found in a Colonial Chordate

Rosental, B.·Kowarsky, M. A.·Seita, J.·Corey, D. M.·Ishizuka, K. J.·Palmeri, K. J.·Chen, S.-Y.·Sinha, R.·Okamoto, J.·Mantalas, G.·Manni, L.·Raveh, T.·Clarke, D. N.·Newman, A. M.·Neff, N. F.·Nolan, G. P.·Quake, S. R.·Weissman, I. L.·Voskoboynik, A.

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Abstract

Hematopoiesis is an essential process that evolved in multicellular animals. At the heart of this process are hematopoietic stem cells (HSCs), which are multipotent, self-renewing and generate the entire repertoire of blood and immune cells throughout life. Here we studied the hematopoietic system of Botryllus schlosseri, a colonial tunicate that has vasculature, circulating blood cells, and interesting characteristics of stem cell biology and immunity. Self-recognition between genetically compatible B. schlosseri colonies leads to the formation of natural parabionts with shared circulation, whereas incompatible colonies reject each other. Using flow-cytometry, whole-transcriptome sequencing of defined cell populations, and diverse functional assays, we identified HSCs, progenitors, immune-effector cells, the HSC niche, and demonstrated that self-recognition inhibits cytotoxic reaction. Our study implies that the HSC and myeloid lineages emerged in a common ancestor of tunicates and vertebrates and suggests that hematopoietic bone marrow and the B. schlosseri endostyle niche evolved from the same origin.

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Rosental, B., Kowarsky, M. A., Seita, J., Corey, D. M., Ishizuka, K. J., Palmeri, K. J., Chen, S.-Y., Sinha, R., Okamoto, J., Mantalas, G., Manni, L., Raveh, T., Clarke, D. N., Newman, A. M., Neff, N. F., Nolan, G. P., Quake, S. R., Weissman, I. L., Voskoboynik, A.. 2017-12-26. Evolutionary Origin of the Mammalian Hematopoietic System Found in a Colonial Chordate. https://doi.org/10.1101/206318

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