Figure 2

SSPN increases abundance of laminin-binding complexes at the sarcolemma. Several lines of SSPN-transgenic mice with 0.5-, 1.5-, and 3-fold levels of SSPN overexpression were generated to investigate the dose-dependent effects of SSPN expression. SSPN transgenic mice on C57/Bl6 background (WT, WT^0.5, WT^1.5, WT^3.0) as well as 0.5-, 1.5-, and 3-fold SSPN transgenic on mdx background (mdx, mdx^0.5, mdx^1.5, mdx^3.0) were analyzed [19, 70]. (A) Transverse cryosections of quadriceps muscle from six-week old SSPN-transgenic mice were stained with antibodies to dystrophin (Dys) and hSSPN to reveal exogenous SSPN expression (hSSPN Tg). (B) Muscle sections from SSPN-transgenic mdx mice were also stained with utrophin (Utr) and hSSPN. Sections overlayed with Wisteria floribunda agglutinin (WFA) lectin reveal increased cell surface glycosylation with elevations in SSPN overexpression [19]. WFA lectin binds terminal GalNAc residues and serves as a marker for the CT antigen modification of α-DG that normally occurs at the NMJ [19]. Note that SSPN increases cell surface expression of dystrophin, utrophin, and glycosylation in a manner dependent on SSPN abundance. Bar, 50 μm. CT, cytotoxic T cell; NMJ, neuromuscular junction.