An Essential Signaling Function of Cytoplasmic NELFB is Independent of RNA Polymerase II Pausing

Haihui Pan; Xiaolong Cheng; Pedro Felipe Gardeazábal Rodríguez; Xiaowen Zhang; Inhee Chung; Victor X Jin; Wei Li; Yanfen Hu; Rong Li

doi:10.1016/j.jbc.2023.105259

An Essential Signaling Function of Cytoplasmic NELFB is Independent of RNA Polymerase II Pausing

J Biol Chem. 2023 Sep 15;105259. doi: 10.1016/j.jbc.2023.105259. Online ahead of print.

Authors

Haihui Pan¹, Xiaolong Cheng², Pedro Felipe Gardeazábal Rodríguez³, Xiaowen Zhang⁴, Inhee Chung³, Victor X Jin⁵, Wei Li², Yanfen Hu³, Rong Li⁶

Affiliations

¹ Department of Biochemistry & Molecular Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC 20037, USA. Electronic address: haihui.pan@outlook.com.
² Department of Genomics & Precision Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC 20037, USA; Center for Genetic Medicine Research, Children's National Hospital, Washington, DC 20010, USA.
³ Department of Anatomy & Cell Biology, School of Medicine & Health Sciences, The George Washington University, Washington, DC 20037, USA.
⁴ Department of Biochemistry & Molecular Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC 20037, USA.
⁵ Institute of Health Equity and Cancer Center, The Medical College of Wisconsin, Milwaukee, WI 53226, USA.
⁶ Department of Biochemistry & Molecular Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC 20037, USA. Electronic address: rli69@gwu.edu.

PMID: 37717699
DOI: 10.1016/j.jbc.2023.105259

Abstract

The four-subunit negative elongation factor (NELF) complex mediates RNA polymerase II (Pol II) pausing at promoter-proximal regions. Ablation of individual NELF subunits destabilizes the NELF complex and causes cell lethality, leading to the prevailing concept that NELF-mediated Pol II pausing is essential for cell proliferation. Using separation-of-function mutations, we show here that NELFB function in cell proliferation can be uncoupled from that in Pol II pausing. NELFB mutants sequestered in the cytoplasm and deprived of NELF nuclear function still support cell proliferation and part of the NELFB-dependent transcriptome. Mechanistically, cytoplasmic NELFB physically and functionally interacts with pro-survival signaling kinases, most notably PI3K/AKT. Ectopic expression of membrane-tethered PI3K/AKT partially bypasses the role of NELFB in cell proliferation, but not Pol II occupancy. Together, these data expand the current understanding of the physiological impact of Pol II pausing and underscore the multiplicity of the biological functions of individual NELF subunits.