ETV2 regulates PARP-1 binding protein to induce ER stress-mediated death in tuberin-deficient cells.

Shikshya Shrestha,Joel Moss,Xiaoli Liu,Jewel Imani,Kosmas Kosmas,Weiliang Qiu,Helen Christou,Rieko Onishi,Kimberly Glass,Anne Hentschel,Julie Ng,Pierce H Louis ,Elizabeth P Henske ,Mark A Perrella ,Wendy K Steagall ,Kelan G Tantisira ,Abhijeet R Sonawane ,Anthony M Lamattina ,Gustavo Pacheco‐Rodriguez ,Souheil El–Chemaly

doi:10.26508/lsa.202201369

Abstract

Lymphangioleiomyomatosis (LAM) is a rare progressive disease, characterized by mutations in the tuberous sclerosis complex genes (TSC1 or TSC2) and hyperactivation of mechanistic target of rapamycin complex 1 (mTORC1). Here, we report that E26 transformation-specific (ETS) variant transcription factor 2 (ETV2) is a critical regulator of Tsc2-deficient cell survival. ETV2 nuclear localization in Tsc2-deficient cells is mTORC1-independent and is enhanced by spleen tyrosine kinase (Syk) inhibition. In the nucleus, ETV2 transcriptionally regulates poly(ADP-ribose) polymerase 1 binding protein (PARPBP) mRNA and protein expression, partially reversing the observed down-regulation of PARPBP expression induced by mTORC1 blockade during treatment with both Syk and mTORC1 inhibitors. In addition, silencing Etv2 or Parpbp in Tsc2-deficient cells induced ER stress and increased cell death in vitro and in vivo. We also found ETV2 expression in human cells with loss of heterozygosity for TSC2, lending support to the translational relevance of our findings. In conclusion, we report a novel ETV2 signaling axis unique to Syk inhibition that promotes a cytocidal response in Tsc2-deficient cells and therefore maybe a potential alternative therapeutic target in LAM.

Highlights

Lymphangioleiomyomatosis (LAM) is a rare, multisystem disease associated with smooth muscle–like “LAM cells” over-proliferating in lungs, kidneys, and lymphatics
We have previously shown that similar to mammalian target of rapamycin complex 1 (mTORC1) inhibition, spleen tyrosine kinase (Syk) inhibition leads to decreased proliferation of tuberin-deficient cells in vitro and in vivo (Cui et al, 2017)
We used gene profiling and network-based approaches with Passing Attributes between Networks for Data Assimilation (PANDA) analyses and identified Ets variant 2 (ETV2) as a regulatory transcription factor uniquely altered under Syk inhibition and not under mTORC1 inhibitory conditions

Summary

Introduction

Lymphangioleiomyomatosis (LAM) is a rare, multisystem disease associated with smooth muscle–like “LAM cells” over-proliferating in lungs, kidneys, and lymphatics. We have previously shown that there is increased expression and activation of spleen tyrosine kinase (Syk) in both Tsc2-deficient cells and LAM lung nodules (Cui et al, 2017). R406, a Syk inhibitor (SykI) had antiproliferative effects in Tsc2-deficient cells in vitro and in vivo (Cui et al, 2017). We demonstrated that mTORC1 inhibition altered Syk expression and activity, suggesting a feedback loop between the two pathways in Tsc2-deficient cells (Cui et al, 2017). We sought to investigate regulatory pathways of Syk inhibition that are independent of its cross-talk with mTORC1 signaling in Tsc2-deficient cells and potentially identify target(s) of SykI that can have cytotoxic effects on Tsc2-deficient cells

Methods

Results

Conclusion