Critical role for the TGF-β1/mTORC1 signaling axis in defining the transcriptional identity of CTHRC1+ pathologic fibroblasts
TL;DR
It is concluded that mTORC1 plays a key role in shaping the transcriptional identity of these fibroblasts, with implications for therapeutic inhibition of mTORC1 in fibrosis and cancer.
Abstract
Fibrosis, marked by excess extracellular matrix (ECM) deposition, is the end stage of many diseases. Single-cell studies have highlighted the emergence of disease-specific fibroblast populations, including a high collagen–synthesizing CTHRC1+ subpopulation. The profibrotic cytokine TGF-β1 promotes fibrogenesis via cooperation between Smad and mTORC1/4E-BP1 signaling axes. Using CRISPR-Cas9 gene editing, we report that more than one-third of TGF-β1–regulated matrisome genes are under mTORC1 control. Mapping the transcriptome of TGF-β1–stimulated fibroblasts revealed similarity to CTHRC1+ fibroblasts identified in idiopathic pulmonary fibrosis (IPF). This overlap is lost when mTORC1 is disabled. Using the selective mTORC1 inhibitor RMC-5552, we confirm a causal role for mTORC1 in promoting the acquisition of the collagen-high, CTHRC1+ phenotype in response to TGF-β1 stimulation in fibroblasts derived from patients with either IPF or lung adenocarcinoma. We conclude that mTORC1 plays a key role in shaping the transcriptional identity of these fibroblasts, with implications for therapeutic inhibition of mTORC1 in fibrosis and cancer.
