Loss of ANT1 Increases Fibrosis and Epithelial Cell Senescence in Idiopathic Pulmonary Fibrosis
Idiopathic Pulmonary Fibrosis (IPF) is an interstitial lung disease characterized by progressive lung scarring and remodeling. Although treatments exist that slow disease progression, IPF is irreversible and there is no cure. Cellular senescence, a major hallmark of aging, has been implicated in IPF pathogenesis, and mitochondrial dysfunction is increasingly recognized as a driver of senescence. Adenine nucleotide translocases (ANTs) are abundant mitochondrial ATP-ADP transporters critical for regulating cell fate and maintaining mitochondrial function. We sought to determine how alterations in ANTs influence cellular senescence in pulmonary fibrosis. We found SLC25A4 (ANT1) and SLC25A5 (ANT2) expression is reduced in the lungs of IPF patients and particularly within alveolar type II cells by single cell RNA sequencing. Loss of ANT1 by siRNA in lung epithelial cell lines resulted in increased senescence markers such as beta-galactosidase staining and p21 by Western Blot and RT-qPCR. Bleomycin treated ANT1 knockdown cells also had increased senescence markers when compared to bleomycin treated control cells. Global loss of ANT1 resulted in worse lung fibrosis and increased senescence in the bleomycin and asbestos-induced mouse models of pulmonary fibrosis. This data supports the concept that loss of ANT1 drives IPF pathogenesis through mitochondrial dysfunction associated cellular senescence (MiDaS). In summary, loss of ANT1 induces cellular senescence, leading to abnormal tissue remodeling and enhanced lung fibrosis in IPF. Modulation of ANTs presents a new therapeutic avenue that may alter cellular senescence pathways and limit pulmonary fibrosis.