Tropomyosin 1 deficiency facilitates cell state transitions and enhances hemogenic endothelial cell specification during hematopoiesis

Abstract

Tropomyosins coat actin filaments and impact actin-related signaling and cell morphogenesis. Genome-wide association studies have linked Tropomyosin 1 (TPM1) with human blood trait variation. Prior work suggested that TPM1 regulated blood cell formation in vitro, but it was unclear how or when TPM1 affected hematopoiesis. Using gene-edited induced pluripotent stem cell (iPSC) model systems, TPM1 knockout was found to augment developmental cell state transitions, as well as TNF and GTPase signaling pathways, to promote hemogenic endothelial (HE) cell specification and hematopoietic progenitor cell (HPC) production. Single-cell analyses showed decreased TPM1 expression during human HE specification, suggesting that TPM1 regulated in vivo hematopoiesis via similar mechanisms. Indeed, analyses of a TPM1 gene trap mouse model showed that TPM1 deficiency enhanced the formation of HE during embryogenesis. These findings illuminate novel effects of TPM1 on developmental hematopoiesis.