Erythropoietic Defect Associated with Reduced Cell Proliferation in Mice Lacking the 26S Proteasome Shuttling Factor Rad23b

Abstract

k Rad23a and Rad23b proteins are linked to nucleotide excision DNA repair (NER) via association with the DNA damage recognition protein xeroderma pigmentosum group C (XPC) are and known to be implicated in protein turnover by the 26S proteasome. Rad23b-null mice are NER proficient, likely due to the redundant function of the Rad23b paralogue, Rad23a. However, Rad23b-null midgestation embryos are anemic, and most embryos die before birth. Using an unbiased proteomics approach, we found that the majority of Rad23b-interacting partners are associated with the ubiquitin-proteasome system (UPS). We tested the requirement for Rad23b-dependent UPS activity in cellular proliferation and more specifically in the process of erythropoiesis. In cultured fibroblasts derived from embryos lacking Rad23b, proliferation rates were reduced. In fetal livers of Rad23b-null embryos, we observed reduced proliferation, accumulation of early erythroid progenitors, and a block during erythroid maturation. In primary wild-type (WT) erythroid cells, knockdown of Rad23b or chemical inhibition of the proteasome reduced survival and differentiation capability. Finally, the defects linked to Rad23b loss specifically affected fetal definitive erythropoiesis and stress erythropoiesis in adult mice. Together, these data indicate a previously unappreciated requirement for Rad23b and the UPS in regulation of proliferation in different cell types.

Functional and mechanistic studies of XPC DNA-repair complex as transcriptional coactivator in embryonic stem cells

“…A transcriptional role for RAD23B has also been suggested in yeast, again through its interaction with the proteasome regulatory subunit (47). Further studies are needed to test the contribution of RAD23B alone to transcriptional regulation, which might partially explain the developmental abnormalities observed in Rad23b −/− mice (48,49).…”

Regulation of GATA1 levels in erythropoiesis

“…The role of the proteasome in erythropoiesis has been highlighted through the years, and it is well known that proteasome‐inhibitor drugs used as anti‐tumoral agents, especially in multiple myeloma, may cause anemia as an adverse event . However, perhaps counterintuitively, chemical inhibition of the proteasome in murine erythroid progenitors, or loss of the proteasome shuttle protein Rad23b, results in reduced levels of GATA1 leading to early apoptosis in vitro and to anemia in vivo, respectively . A better understanding of the action of the proteasome in erythropoiesis and how it may regulate directly or indirectly GATA1 levels, is currently the research focus of several groups …”

“…[112][113][114] However, perhaps counterintuitively, chemical inhibition of the proteasome in murine erythroid progenitors, or loss of the proteasome shuttle protein Rad23b, results in reduced levels of GATA1 leading to early apoptosis in vitro and to anemia in vivo, respectively. 115 A better understanding of the action of the proteasome in erythropoiesis and how it may regulate directly or indirectly GATA1 levels, is currently the research focus of several groups. 113,114,116,117 9 | THE EFFECTS OF ARTIFICIALLY ALTERING GATA1 PROTEIN LEVELS As outlined above, GATA1 translation and protein levels are exquisitely regulated in hematopoiesis and it is now well established that tinkering with GATA1 protein levels has important functional implications and may also result in hematological disease.…”

Damage-Net: A program for DNA repair meta-analysis identifies a network of novel repair genes that facilitate cancer evolution

“…Damage-Net was written in the Python coding language with the database backend written in SQL and was compiled to function as an independent program on Windows, Linux and Mac OS. It currently contains the results of 39 publications that investigated various aspects of DNA repair on a large-scale (Supplementary Table 1) [ [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] ], as well as the gene expression and mutation data for 33 cancer sub-types from the TCGA database. The proteomic datasets were all selected from peer-reviewed publications that investigated aspects of the DNA damage-response.…”