Release of proteins: Insights into oxidative response of Taxus cuspidata cells induced by shear stress

The sensitivity of plant cells to shear stress has been regarded as one obstacle to the scale-up of plant cell suspension cultures. For better understanding on molecular levels of oxidative responses caused by laminar shear stress, extracellular proteins of the suspension cultured Taxus cuspidata cells were investigated by two-dimensional-liquid chromatography–tandem mass spectrometry (2D LC–MS/MS). Totally 35, 73, and 70 proteins in media were identified in shake flask (3 h) and a Couette-type shear device after laminar shear treatment (3 h and 6 h), respectively. These proteins were, respectively, categorized into different kinds of bioprocesses including stress responses, detoxification, transporter, cell wall catabolic and glycolysis and various metabolisms including carbohydrate, energy, and sulfur. Some cytoplasm proteins were released into the media after shear treatment. The glutathione S-transferase, aldo/keto reductase, peroxidase 3 precursor, oxidoreductase associated with oxidative stress and heat shock proteins, transport-associated proteins were only monitored in shear-treated cells. Particularly, shear treatment-induced accumulation of geranylgeranyl diphosphate synthase and isopentenyl diphosphate delta isomerase, which closely associated with Taxol biosynthesis. These findings provide new insights into better understanding of the molecular and signal basis of plant cell cultures in response of oxidative stress induced by shear stress.