Cheng-Teng Nga, Lin-Yue Lanry Yungb, Hannah Lee-Foon Swac, Rebecca Wan-Yan Pohd, Jayantha Gunaratnec,*, Boon-Huat Baya,*
a Department of Anatomy, Yong Loo Lin School of Medicine
b Department of Chemical and Biomolecular Engineering, National University of Singapore
c Quantitative Proteomics Group, Institute of Molecular and Cell Biology, Agency for Science Technology and Research Singapore
d Carl Zeiss Pte Ltd, Microscopy Business Group, Singapore
Published in Biomaterials 39 (2015) 31-38
Despite the availability of toxicity studies on cellular exposure to gold nanoparticles (AuNPs), there is scarcity of information with regard to the bystander effects induced by AuNPs on neighboring cells not exposed to the NPs. In this study, we showed that exposure of small airway epithelial cells (SAECs) to AuNPs induced changes in protein expression associated with functional effects in neighboring MRC5 lung fibroblasts in a co-culture system. Uptake of 20 nm size AuNPs by SAECs was first verified by focused ion beam scanning electron microscopy. Subsequently, pretreated SAECs were co-cultured with unexposed MRC5 lung fibroblasts, which then underwent proteome profiling using a quantitative proteomic approach. Stable-isotope labeling by amino acids in cell culture-based quantitative mass spectrometry (SILAC-qMS) identified 109 proteins (which included 47 up-regulated and 62 down-regulated proteins) that were differentially expressed in the lung fibroblasts co-cultured with AuNP pretreated SAECs. There was altered expression of proteins such as Paxillin, breast cancer anti-estrogen resistance 1 and Caveolin-1, which are known to be involved in the cell adhesion process. Morphological studies revealed that there was a concomitant increase in cell adhesion and altered F-actin stress fiber arrangement involving vinculin in the lung fibroblasts. It is likely that phenotypic changes observed in the underlying lung fibroblasts were mediated by AuNP-induced downstream signals in the pretreated SAECs and cell-cell cross talk.
Figure Legend: SILAC-qMS revealed that AuNP-treatment induces cell adhesion and cell cytoskeleton remodelling in SAECs
(A) Scatter plot showing the up-regulated (red), down-regulated (blue), and unchanged (black) protein clusters annotated with validated proteins-of-interest. (B) Gene ontology analysis of proteins differentially-expressed by MRC5 lung fibroblasts in response to treatment of SAECs with AuNPs, as compared with the untreated control. (C) MRC5 lung fibroblasts co-cultured with SAECs treated with or without AuNPs were stained for F-actin (green) and DAPI (blue). Lung fibroblasts co-cultured with AuNP-treated SAECs exhibited an increase in stress fibers with enrichment at the cell membrane and adhesion sites. Bar ¼ 20 mm. (D) Alteration of adhesion dynamics in lung fibroblasts co-cultured with AuNP-treated SAECs, showing an increase in vinculin adhesion sites in anchoring F-actin to cell membrane. Vinculin staining shown as green fluorescence while focal adhesions and actin stress fibers staining are shown as red fluorescence. Bar ¼ 20 µm.
For more information about QPG, please click here.