Journal: FEBS letters
Article Title: Proteolytic cleavage of Trop2 at Arg87 is mediated by matriptase and regulated by Val194.
doi: 10.1002/1873-3468.13899
Figure Lengend Snippet: Fig. 2. Identification of Trop2 as a target for matriptase. (A) Sequence alignment of a part of human EpCAM and human Trop2 protein sequences. Scissors denote reported N-terminal cleavage site in human EpCAM between Arg80 and Arg81 [19]. It corresponds to Arg87 and Thr88 (boxed) in human Trop2 which were selected for generating alanine substitution mutants. (The conserved residues between the two proteins are indicated by asterisks below the sequence.) Amino acid numbering is including the signal peptide. (B) Expression of WT Trop2-HA and the indicated alanine substitution mutants. Total cell lysate from HEK293 cells transiently transfected with either WT Trop2- HA or R87A Trop2-HA or T88A Trop2-HA was immunoblotted before (left) and after PNGase treatment (right) using anti-HA antibody (upper panel) and anti-GAPDH antibody (lower panel) (C) Cell surface localization of Trop2 (green) in nonpermeabilized HEK293 cells transiently expressing the indicated Trop2-HA constructs visualized by indirect immunofluorescence using anti-Trop2 ECD antibody. DAPI (blue) was used as a nuclear stain. Bar = 10 µm. HEK293 cells transfected with an EV served as a negative control. (D) HEK293 cells were cotransfected with the indicated amount of WT Trop2-HA and either WT matriptase (Mat-HA) or inactive matriptase (Mat-M-HA) constructs. Cell lysates were prepared 48 h post-transfection followed by immunoblotting with anti-HA antibody to detect matriptase as well as Trop2 protein. GAPDH is the loading control (lower panel). Filled triangle and hollow triangle represents full-length Trop2 and DN-Trop2, respectively. (E) Immunoblot showing matriptase expression in the total cell lysates of the indicated cell lines using anti-matriptase antibody (upper panel). Expression of GAPDH in each cell line serves as the loading control (lower panel).
Article Snippet: Antibodies used in this study include a goat polyclonal anti-Trop2 antibody directed against ECD of Trop2 (1 : 3000, AF650; R & D Systems, Minneapolis, MN, USA), rabbit monoclonal antibody targeted against C-terminal region of Trop2 (1 : 2000, ab214 488; abcam, Cambridge, MA, USA), mouse monoclonal anti-HA (1 : 1000, ab18 181; abcam), anti-CD63 (1 : 500, ab59 479; abcam), sheep polyclonal anti-matriptase catalytic domain antibody (1 : 1000, AF3946; R & D Systems), mouse monoclonal antibody against GAPDH (1 : 10 000, MA5-15738; Thermo Fisher Scientific), and mouse monoclonal anti-Flag antibody (1 : 1000, F1804; Sigma-Aldrich, St. Louis, MO, USA).
Techniques: Sequencing, Expressing, Transfection, Construct, Staining, Negative Control, Western Blot, Control