[Transcriptomic analysis of suspended Vero cells and reduction of cellular autophagy by epidermal growth factor].

Abstract

The culture of suspended Vero cells is facing difficulties such as low cell viability and long doubling time. To investigate the main reasons for the slow growth and low viability of suspended Vero cells, this study conducted transcriptomic analysis of suspended Vero cells (Vero-XF) and adherent Vero cells (Vero-AD) to screen the differentially expressed genes (DEGs) affecting the growth of suspended cells. In addition, epidermal growth factor (EGF) was supplemented to the culture system to improve the growth of Vero-XF. The results showed that compared with the Vero-AD group, the Vero-XF group had 7 376 significant DEGs. Kyoto encyclopedia of genes and genomes enrichment analysis revealed that the DEGs were mainly enriched in the autophagy and mitophagy pathways. Eleven DEGs were selected and verified by quantitative real-time PCR, which showed up-regulated expression of ATG9B, WIPI2, LAMP2, OPTN, Rab7a, and DEPTOR and down-regulated expression of ATG4D, being consistent with the results of transcriptomic analysis. In addition, the Vero-XF group showed significantly up-regulated expression of ATG101, ATG2A, and STX17 and insignificant change in the expression of NBR1, compared with the Vero-AD group. The protein levels of LC3 and P62 in Vero-XF and Vero-AD were determined by Western blotting, which showed up-regulated expression of LC3Ⅱ/Ⅰ and down-regulated expression of P62 in Vero-XF, indicating a higher level of autophagy. Finally, the exogenous supplementation of EGF at 10, 20, and 30 μg/L in the culture system reduced the autophagy level of Vero-XF by 22.35%, 48.15%, and 71.29%, increased the specific growth rate by 15.48%, 33.33%, and 57.14%, and decreased the apoptosis rate by 2.84%, 15.46%, and 16.23%, respectively. The results of this study preliminarily reveal that the activation of autophagy is one of the reasons for the slow growth of Vero-XF, which provides reference for the subsequent culture of suspended Vero cells.