FIG. 6.

APA-1 overexpression induces transcription of extracellular matrix-remodeling genes. (A) Early-passage HFFs were infected with concentrated retrovirus expressing empty vector (LXSN) or APA-1 and selected as before. APA-1 protein was analyzed by Western blot and compared to uninfected early-passage (early) and senescent HFFs. Arrowheads indicate the two forms of APA-1. (B) APA-1 induces transcription of senescence-associated matrix-remodeling genes. Total RNA was harvested from the cells described in A and analyzed by Northern blotting for MMP1, PAI2, MMP12, MMP2, and 36B4 (loading control). Specific bands are represented by arrowheads, and the asterisk (*) represents residual signal on the PAI2 blot from a previous probe. Signals were quantified by phosphorimaging, and relative signal (with respect to the 36B4 loading control) is indicated beneath each blot. (C) hTert-immortalized fibroblasts have increased levels of MMP1 and PAI2 mRNAs, similar to senescent controls. RNA was harvested from the cells described in Fig. 2D as well as Cl39T cells. Then 30 μg of total RNA was analyzed by Northern blotting for MMP1, PAI2, and 36B4. Relative signals as determined by phophorimaging are indicated beneath each blot.