Knockdown of tmem183a in Zebrafish Causes Thrombocytopenia and Reduces Coagulation Factors, Disrupting Hemostasis

Transmembrane proteins are a class of membrane-embedded proteins with largely unexplored functions. Previous RNAseq analysis identified transmembrane protein 183a (tmem183a) expression in zebrafish thrombocytes, and its knockdown led to increased gill bleeding. This study aimed to investigate the mechanism behind tmem183a knockdown-induced gill bleeding and its role in thrombocyte function and hemostasis.

Using piggyback gene knockdown and flow cytometry analysis, we found that tmem183a knockdown in zebrafish reduced thrombocyte counts. qRT-PCR analysis revealed decreased mRNA levels of thpo, fli1, and mpl1 that are involved in thrombocyte differentiation and development, suggesting that their reduced expression contributed to thrombocytopenia. Further investigation into the coagulation pathways showed reduced fibrin generation as indicated by kPTT and kPT measurements and prolonged in vivo clot formation by laser-induced thrombosis assay. Additionally, whole blood aggregation in tmem183a knockdown zebrafish was decreased when stimulated by a collagen agonist. qRT-PCR measurements of coagulation factors f5, f7, f8, f9a, f9b, f9l, f10, and vwf following tmem183a knockdown showed decreased mRNA levels for all factors except for an increase in f10 and no significant change in vwf compared to controls.

The above findings suggested that tmem183a knockdown causes increased bleeding due to reduced thrombocyte counts and lower expression of key coagulation factors, underscoring its role in regulating hemostasis.