CRISPR screen uncovers SLC26A2 as a modulator of tungsten toxicity in endochondral ossification.

Tungsten is an emerging environmental contaminant, highlighting the urgent need to elucidate its toxicological characteristics and assess long-term health risks. Our previous investigations show that tungsten deposition in the bone is associated with stalled pre-B lymphocyte differentiation, inhibition of osteogenesis, and increased intervertebral disc degeneration and fibrosis. To delineate the underlying molecular mechanisms, we employed CRISPR-based genomics on NALM-6 cells and identified Solute Carrier Family 26 Member 2 (SLC26A2), a sulfate/chloride antiporter, as a pivotal mediator of tungsten-induced toxicity. SLC26A2 deletion reduced tungsten-induced growth inhibition and intercellular tungsten levels. Functional impairment of SLC26A2 is associated with chondrodysplasias, thus, we hypothesized that tungsten would impair the development of cartilage and bone tissues. Indeed, tungstate exposure impaired chondrogenesis and osteogenesis in murine limb cultures, which was reversible by sulfate supplementation. Our study demonstrates that tungsten exploits SLC26A2 for cellular entry and correlates with bone development disruption through proteoglycan and collagen depletion.