| Description |
Air pollution is a growing global health issue with considerable local relevance. In particular, exposure to wood smoke particulate matter (WSPM) is associated with the development and exacerbation of chronic inflammatory conditions and irreversible damage of the airways and alveoli. However, exact mechanisms that underly the toxic effects of WSPM are poorly defined. Transient receptor potential (TRP) channels are a family of sensory ion channels that have been studied extensively for their functions in mediating various irritant responses. Recently TRPs are being evaluated as drivers of air pollution toxicity. Our laboratory has previously shown that transient receptor potential ankyrin-1 (TRPA1) and vanilloid-3 (TRPV3) are molecular targets of WSPM in the lung epithelium. The hypothesis of this project was that the activation of these channels by WSPM would alter endoplasmic reticulum (ER) calcium homeostasis, ultimately triggering endoplasmic reticulum stress (ERS), and cytotoxicity in lung epithelial cells. In this study, TRPA1 was found to functionally reside both within/in the ER and plasma membranes, whereas TRPV3 primarily localized to the ER of these cells. Further, the induction of ERS and ultimate cytotoxicity caused by pine WSPM and chemical mimics was attenuated by TRPA1 inhibition, but exacerbated by TRPV3 inhibition. Interestingly, cells treated with cytotoxic doses of pine WSPM suppressed the transcription of TRPA1, but induced TRPV3 in a time-dependent manner. The overexpression of TRPV3 in lung epithelial cells was found to confer general resistance to ERS by a variety of known ERS inducers, including pine WSPM, as well as more global cellular events associated with ERS, such as cell cycle arrest at G2. In a similar trend, the knockdown of TRPV3 expression by shRNA sensitized cells towards ERS following treatment with pine WSPM. Lastly, using a calcium flux assay and antagonists of each channel, we demonstrated functional interactions between TRPA1 and TRPV3 activity, wherein activation and/or inhibition of each channel influenced the activity of the other. Collectively, this study describes a role for TRPA1 in lung epithelial cells, as a proapoptotic molecular target of WSPM through promoting the induction of ERS, and a novel role for TRPV3 in dampening proapoptotic signaling through fettering ERS responses. |
