Ring finger protein 138 inhibits transcription factor C/EBPα protein turnover leading to differentiation arrest in acute myeloid leukemia

Anil Kumar Singh; Vishal Upadhyay; Arppita Sethi; Sangita Chowdhury; Shivkant Mishra; Shailendra Prasad Verma; Madan Lal Brahma Bhatt; Arun Kumar Trivedi

doi:10.1042/BCJ20240027

Ring finger protein 138 inhibits transcription factor C/EBPα protein turnover leading to differentiation arrest in acute myeloid leukemia

Biochem J. 2024 May 22;481(10):653-666. doi: 10.1042/BCJ20240027.

Authors

Anil Kumar Singh^{1

2}, Vishal Upadhyay^{1

2}, Arppita Sethi^{1

2}, Sangita Chowdhury¹, Shivkant Mishra¹, Shailendra Prasad Verma^{1

3}, Madan Lal Brahma Bhatt³, Arun Kumar Trivedi^{1

2}

Affiliations

¹ Division of Cancer Biology, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Sitapur Road, Lucknow 226031, UP, India.
² Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
³ King George's Medical University, Lucknow 226003, UP, India.

PMID: 38666590
DOI: 10.1042/BCJ20240027

Abstract

E3 ubiquitin ligase, ring finger protein 138 (RNF138) is involved in several biological processes; however, its role in myeloid differentiation or tumorigenesis remains unclear. RNAseq data from TNMplot showed that RNF138 mRNA levels are highly elevated in acute myeloid leukemia (AML) bone marrow samples as compared with bone marrow of normal volunteers. Here, we show that RNF138 serves as an E3 ligase for the tumor suppressor CCAAT/enhancer binding protein (C/EBPα) and promotes its degradation leading to myeloid differentiation arrest in AML. Wild-type RNF138 physically interacts with C/EBPα and promotes its ubiquitin-dependent proteasome degradation while a mutant RNF-138 deficient in ligase activity though interacts with C/EBPα, fails to down-regulate it. We show that RNF138 depletion enhances endogenous C/EBPα levels in peripheral blood mononuclear cells (PBMCs) isolated from healthy volunteers. Our data further shows that RNF138-mediated degradation of C/EBPα negatively affects its transactivation potential on its target genes. Furthermore, RNF138 overexpression inhibits all-trans-retinoic acid-induced differentiation of HL-60 cells whereas RNF138 RNAi enhances. In line with RNF138 inhibiting C/EBPα protein turnover, we also observed that RNF138 overexpression inhibited β-estradiol (E2)-induced C/EBPα driven granulocytic differentiation in C/EBPα inducible K562-p42C/EBPα-estrogen receptor cells. Furthermore, we also recapitulated these findings in PBMCs isolated from AML patients where depletion of RNF138 increased the expression of myeloid differentiation marker CD11b. These results suggest that RNF138 inhibits myeloid differentiation by targeting C/EBPα for proteasomal degradation and may provide a plausible mechanism for loss of C/EBPα expression often observed in myeloid leukemia. Also, targeting RNF138 may resolve differentiation arrest by restoring C/EBPα expression in AML.

Keywords: C/EBPα; RNF138; acute myeloid leukaemia; differentiation; ubiquitin ligases; ubiquitination.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

CCAAT-Enhancer-Binding Protein-alpha* / genetics
CCAAT-Enhancer-Binding Protein-alpha* / metabolism
CCAAT-Enhancer-Binding Proteins
Cell Differentiation*
HEK293 Cells
HL-60 Cells
Humans
Leukemia, Myeloid, Acute* / genetics
Leukemia, Myeloid, Acute* / metabolism
Leukemia, Myeloid, Acute* / pathology
Proteolysis
Ubiquitin-Protein Ligases* / genetics
Ubiquitin-Protein Ligases* / metabolism

Substances

Ubiquitin-Protein Ligases
CCAAT-Enhancer-Binding Protein-alpha
CEBPA protein, human
CCAAT-Enhancer-Binding Proteins