Pyrin Modulates the Intracellular Distribution of PSTPIP1
Figure 9
Pyrin recruits PSTPIP1 to ASC specks.
All images are from transfected COS cells. Representative images are shown. (A) The apoptotic speck protein, ASC (red), is normally diffusely distributed throughout the cell in cytoplasm and nucleus. (B) ASC (in this case, green) can coalesce into a small perinuclear aggregate, the speck. (C–D) Pyrin (red) is recruited to ASC specks via its PyD as previously shown [32]. (E–G) PSTPIP1 is not detected in ASC specks in the absence of co-transfected pyrin. (H–J) In 70% of cells transfected with untagged ASC, PSTPIP1-FLAG and pyrin-myc, PSTPIP1 is recruited to the speck (arrow, H). (K–P) In 30% of cases, transfection of the three proteins results in localization of pyrin in both PSTPIP1 filaments and in the speck (K–M), or exclusively in the speck (N–P). (Q–S) FLAG-tagged W232A PSTPIP1 does not interact with pyrin, and is not recruited to specks. (T–Y) Recruitment of PAPA mutants by myc-pyrin to the ASC speck. (T–V) A230T-FLAG. (W–Y) E250Q-FLAG. Pyrin recruits these mutant forms to ASC specks in 95% of transfected cells.