The Runt family of transcription factors is evolutionarily conserved. Although its role in vertebrate endoskeleton formation is established, its function in invertebrate exoskeleton biomineralization remains unclear. Here, we show that PmRunt , the sole Runt homolog in pearl oyster Pinctada fucata martensii , is a master regulator of both biomineralization and immunity. Knockdown of PmRunt severely inhibited calcification and growth by disrupting ion homeostasis, reducing CA and inverting the expression balance of crystallization regulators. Transcriptomic exhibited that the interruption of PmRunt expression in mantle induced disorder of ion transportation and absorption of Ca 2 + and HCO 3- , protein/phosphonate synthesis as well as cell proliferation and differentiation. And CUT&Tag analyses revealed that PmRunt may directly bind RUNX2/3-type motifs (GAAACC) to regulate key genes (including matrix protein, cell cycle proteins and mineralization-related genes), while also associating with immune-related genes likely reflecting an ancestral RUNX1-like function in resident hemocytes. Our findings elucidate a conserved genetic pathway for biomineralization and provide novel insights into the evolutionary deep homology of skeletal systems.
Liu et al. (Fri,) studied this question.