RNA polymerase III component Rpc9 regulates hematopoietic stem and progenitor cell maintenance in zebrafish

Abstract

Hematopoietic stem and progenitor cells (HSPCs) are capable of self-renewal and replenishing all lineages of blood cells throughout the lifetime and thus critical for tissue homeostasis. However, the mechanism regulating HSPC development is still incompletely understood. Here, we isolate a zebrafish mutant with defective T lymphopoiesis and positional cloning identifies that Rpc9, a component of DNA-directed RNA polymerase III (Pol III) complex, is responsible for the mutant phenotype. Further analysis shows that rpc9-deficiency leads to the impairment of HSPCs and their derivatives in zebrafish embryos. Excessive apoptosis is observed in the caudal hematopoietic tissue (CHT, the equivalent of fetal liver in mammals) of rpc9−/− embryos and the hematopoietic defects in rpc9−/− embryos can be fully rescued by suppression of p53. Thus, our work illustrate that Rpc9, a component of Pol III, plays an important tissue-specific role in HSPC maintenance during zebrafish embryogenesis and that it might be conserved across vertebrates including mammals.

Rac2 Regulates the Migration of T Lymphoid Progenitors to the Thymus during Zebrafish Embryogenesis

“…1D). Moreover, the expression of rac2 was absent in a T cell-deficient mutant line-rpc9 mutant, which is reported in our previous study (38) (Supplemental Fig. 1A), suggesting its role in T lymphoid progenitors.…”

“…Proteins were purified in radioimmunoprecipitation assay buffer. Western blotting analyses were conducted as described previously (38). Ab used for Western blotting included anti-b-actin (1:2000; Cell Signaling Technology), anti-Rac2 (1:200; Santa Cruz Biotechnology), anti-AKT (1:1000; Cell Signaling Technology), anti-pAKT (1:500; Cell Signaling Technology), anti-Pak1 (1:200; Cell Signaling Technology), and anti-pPak1 (1:500; Cell Signaling Technology).…”

COXIV and SIRT2‐mediated G6PD deacetylation modulate ROS homeostasis to extend pupal lifespan

“…The cell experiments described above showed that the PKA/TFAM pathway could enhance COXIV expression to reduce ROS levels. To verify the molecular pathway in vivo , day 2 DP were injected with the PKA agonist forskolin (FSK) to elevate p‐PKA levels [34], and the results showed that both TFAM and COXIV levels in brains were increased significantly (Figs 5A and S4A). In contrast, day 2 NP were injected with the PKA inhibitor H89, and the results showed that TFAM and COXIV levels decreased as did the p‐PKA level (Figs 5B and S4B).…”

Maf1 and Repression of RNA Polymerase III-Mediated Transcription Drive Adipocyte Differentiation

“…Expression of a splice mutant of the POLR3B subunit in zebrafish led to a disruption in the digestive organ and size reductions in other organs ( Yee et al, 2007 ). Furthermore, deficiency of rpc9 , another RNA pol III subunit, impaired hematopoietic stem and progenitor cell development in zebrafish ( Wei et al, 2016 ). How specific changes in RNA pol III-dependent transcription affect these processes remains undetermined.…”