Fig. 2
Expression of MMP-3 in the healthy adult mouse retina. a Immunostaining with ab3 revealed a punctate expression pattern in all retinal layers, with the most prominent expression in the inner retina. b Double labeling for MMP-3 (ab3) and glutamine synthetase (GS) indicated a close association of these MMP-3-positive structures with the radial processes of Müller glia. c Immunostaining with ab4 revealed MMP-3 expression in neurons in the GCL and INL. No staining at all was seen on negative control sections (insert). c’ The magnification images show a double staining with Brn3a, indicating that MMP-3 is expressed by Brn3a+ RGCs (arrow a) as well as Brn3a− displaced amacrine cells (arrow b). Scale bars, 20 μm. d Western blotting on naive retina tissue lysates (R) revealed that both antibodies recognized pro-MMP-3 (55 kDa) and active MMP-3 (47 kDa). In addition, ab4 also abundantly labeled free TIMP-1 (28 kDa) and MMP-3-TIMP-1 complexes (75 kDa), and a band around 110 kDa. Recombinant human MMP-3 (rh) was loaded as a positive control. e Immunostaining with antibody sc-5538-R showed high TIMP-1 expression in the GCL and more faint expression in the INL and the ECM of both plexiform layers. Scale bar, 20 μm. f Western blotting for TIMP-1 on naive retina tissue lysates (R) revealed 28 kDa unbound TIMP-1, as well as a 75 kDa complex of TIMP-1 and MMP-3.