<i>Nanos2</i> marks precursors of somatic lineages and is required for germline formation in the sea anemone <i>Nematostella vectensis</i>.

Abstract

In animals, stem cell populations of varying potency facilitate regeneration and tissue homeostasis. Notably, germline stem cells in both vertebrates and invertebrates express highly conserved RNA binding proteins, such as <i>nanos</i>, <i>vasa</i>, and <i>piwi</i>. In highly regenerative animals, these genes are also expressed in somatic stem cells, which led to the proposal that they had an ancestral role in all stem cells. In cnidarians, multi- and pluripotent interstitial stem cells have only been identified in hydrozoans. Therefore, it is currently unclear if cnidarian stem cell systems share a common evolutionary origin. We, therefore, aimed to characterize conserved stem cell marker genes in the sea anemone <i>Nematostella vectensis</i>. Through transgenic reporter genes and single-cell transcriptomics, we identify cell populations expressing the germline-associated markers <i>piwi1</i> and <i>nanos2</i> in the soma and germline, and gene knockout shows that Nanos2 is indispensable for germline formation. This suggests that <i>nanos</i> and <i>piwi</i> genes have a conserved role in somatic and germline stem cells in cnidarians.