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  • Cell surface metalloproteases coordinate signaling during


    Cell surface metalloproteases coordinate signaling during development, tissue homeostasis, and disease. A disintegrin and metalloprotease 17 (ADAM17) is a well-characterized member among ADAM family, which mediates the cleavage of various cell surface proteins (Black, 2002, Black et al., 1997, Dello Sbarba and Rovida, 2002, Wang et al., 2011). We have reported previously that ADAM17 can regulate pig CD163, TNFα and CD16 on the cell surface, playing an important role in modulating inflammation and infection of PRRSV (Gu et al., 2016, Gu et al., 2015, Guo et al., 2014, Li et al., 2016). However, whether and how this metalloprotease ADAM17 is involved in PEDV infection remains unknown. In this study, the role of ADAM17 on PEDV infection was examined in HEK293 and IPEC-J2 cells, and we found that modulation of APN expression as a consequence of ADAM17 sheddase activity regulates PEDV infection.
    Materials and Methods
    Results and Discussion
    Acknowledgments The research was supported by grants from the National Science Foundation of China (31572497 & 31500128) and Heilongjiang Science Foundation (QC2014C038).
    Introduction Lactic rgd peptide
    bacteria used in cheese manufacturing as starter cultures have a significant role in cheese ripening since their intracellular peptidases contribute to amino acid liberation from milk proteins, creating desirable organoleptic characteristics i.e. cheese flavor, taste, appearance and texture (Giannoglou, Karra et al., 2016). X-prolyl dipeptidyl aminopeptidase (PepX) is a proline-specific peptidase that is important for the hydrolysis of peptides bonds (Baankreis and Exterkate, 1991, Kok and De Vos, 1994). PepX hydrolyses the peptide bond at the carboxyl side of the proline residue, cleaving dipeptidyl residues when this amino acid is the penultimate N-terminal residue. S. thermophilus is one of the most widely used lactic acid bacteria in dairy industry. It is added as a component of the starter culture used in yoghurt fermentation and cheese manufacturing for milk acidification and release of intracellular peptidases in the product mass during the ripening stage. Gomez, Gaya, Nuñez, and Medina (1998) studied S. thermophilus capacity for debittering when added as adjunct culture for production of a semi-hard cows’ milk cheese and reported potential prevention of the bitter taste. High pressure processing (HPP) is a non-thermal technology that affects the activity of lactic acid intracellular peptidases, added during cheese manufacturing as starter cultures, resulting in acceleration of cheese ripening. In the literature, there is a significant number of papers describing the combined effect of HP and temperature on these peptidases. Miyakawa, Anjitsu, Ishibashi, and Shimamura (1994) studied the effect of pressure (400 MPa) at 30 °C for 10 min on the activity of Lactobacillus helveticus peptidases and reported increased activities of aminopeptidase (AP) and X-prolyl dipeptidyl aminopeptidase (X-PDAP), which are important for the acceleration of cheese ripening. Malone, Wick, Shellhammer, and Courtney (2003) studied the activity of aminopeptidases of Lactococcus lactis, used in Cheddar cheese manufacturing, after HPP at 25 °C for 5 min and reported activation, inactivation or no effect on proteolytic and glycolytic enzymes, depending on the pressure and enzymes. Katsaros, Giannoglou, and Taoukis (2009) investigated kinetically the effect of HPP on Lactobacillus bulgaricus ssp. delbrueckii aminopeptidases and reported increased activity of all HP-treated aminopeptidases with maximum activity after treatment at 200 MPa for 20 min at 20 °C. Knowledge about HPP-induced changes in conformation of peptidases is of great importance since it could contribute to elucidation of how structural changes are correlated with enzyme activity. This can be achieved by applying specific techniques, like Circular Dichroism (CD) spectroscopy but only with purified enzyme. Therefore, in order to investigate the effect of process parameters on the structure of enzymes, purification is essential. Several publications in the literature report isolation, purification and characterization of peptidases from different sources such as PepX from S. thermophilus ACA-DC 4 (Anastasiou, Papadelli, Georgalaki, Kalantzopoulos, & Tsakalidou, 2002), PepX from Streptococcus macedonicus ACA-DC 191 (Georgalaki, Papadeli, Anastasiou, Kalantzopoulos, & Tsakalidou, 2002), PepX fromLactobacillus curvatus DPC2024 (Magboul and McSweeney, 2000) or PepO from S. thermophilus A (Chavagnat, Meyer, & Casey, 2000).