Coordinated regulation of the ribosome and proteasome by PRMT1 in the maintenance of neural stemness in cancer cells and neural stem cells

• Published in: The Journal of biological chemistry Vol. 297; no. 5; p. 101275
• Main Authors: Chen, Lu, Zhang, Min, Fang, Lei, Yang, Xiaoli, Cao, Ning, Xu, Liyang, Shi, Lihua, Cao, Ying
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2021; American Society for Biochemistry and Molecular Biology
• Subjects: A549 Cells; Animals; cancer cell; cell differentiation; deubiquitination; Hep G2 Cells; Humans; Mice; Mice, Knockout; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Neoplastic Stem Cells - metabolism; Neoplastic Stem Cells - pathology; neural stem cell (NSC); Neural Stem Cells - metabolism; Neural Stem Cells - pathology; neural stemness; PRMT1; proteasome; Proteasome Endopeptidase Complex - genetics; Proteasome Endopeptidase Complex - metabolism; Protein-Arginine N-Methyltransferases - genetics; Protein-Arginine N-Methyltransferases - metabolism; Repressor Proteins - genetics; Repressor Proteins - metabolism; ribosome; Ribosomes - genetics; Ribosomes - metabolism; tumorigenicity; USP7; NPC; proteasome; WCL; cell differentiation; USP7; primNSC; PRMT1; rRNA; ChIP; PRMT; neural stem cell (NSC); RA; cancer cell; tumorigenicity; PEI; ribosome; deubiquitination; mESC; IF; RT-qPCR; MDN1; neural stemness; NSC
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/j.jbc.2021.101275

Previous studies suggested that cancer cells resemble neural stem/progenitor cells in regulatory network, tumorigenicity, and differentiation potential, and that neural stemness might represent the ground or basal state of differentiation and tumorigenicity. The neural ground state is reflected in the upregulation and enrichment of basic cell machineries and developmental programs, such as cell cycle, ribosomes, proteasomes, and epigenetic factors, in cancers and in embryonic neural or neural stem cells. However, how these machineries are concertedly regulated is unclear. Here, we show that loss of neural stemness in cancer or neural stem cells via muscle-like differentiation or neuronal differentiation, respectively, caused downregulation of ribosome and proteasome components and major epigenetic factors, including PRMT1, EZH2, and LSD1. Furthermore, inhibition of PRMT1, an oncoprotein that is enriched in neural cells during embryogenesis, caused neuronal-like differentiation, downregulation of a similar set of proteins downregulated by differentiation, and alteration of subcellular distribution of ribosome and proteasome components. By contrast, PRMT1 overexpression led to an upregulation of these proteins. PRMT1 interacted with these components and protected them from degradation via recruitment of the deubiquitinase USP7, also known to promote cancer and enriched in embryonic neural cells, thereby maintaining a high level of epigenetic factors that maintain neural stemness, such as EZH2 and LSD1. Taken together, our data indicate that PRMT1 inhibition resulted in repression of cell tumorigenicity. We conclude that PRMT1 coordinates ribosome and proteasome activity to match the needs for high production and homeostasis of proteins that maintain stemness in cancer and neural stem cells.