PKC Theta Ablation Improves Healing in a Mouse Model of Muscular Dystrophy

Abstract

Inflammation is a key pathological characteristic of dystrophic muscle lesion formation, limiting muscle regeneration and resulting in fibrotic and fatty tissue replacement of muscle, which exacerbates the wasting process in dystrophic muscles. Limiting immune response is thus one of the therapeutic options to improve healing, as well as to improve the efficacy of gene- or cell-mediated strategies to restore dystrophin expression. Protein kinase C θ (PKCθ) is a member of the PKCs family highly expressed in both immune cells and skeletal muscle; given its crucial role in adaptive, but also innate, immunity, it is being proposed as a valuable pharmacological target for immune disorders. In our study we asked whether targeting PKCθ could represent a valuable approach to efficiently prevent inflammatory response and disease progression in a mouse model of muscular dystrophy. We generated the bi-genetic mouse model mdx/θ−/−, where PKCθ expression is lacking in mdx mice, the mouse model of Duchenne muscular dystrophy. We found that muscle wasting in mdx/θ−/− mice was greatly prevented, while muscle regeneration, maintenance and performance was significantly improved, as compared to mdx mice. This phenotype was associated to reduction in inflammatory infiltrate, pro-inflammatory gene expression and pro-fibrotic markers activity, as compared to mdx mice. Moreover, BM transplantation experiments demonstrated that the phenotype observed was primarily dependent on lack of PKCθ expression in hematopoietic cells.These results demonstrate a hitherto unrecognized role of immune-cell intrinsic PKCθ activity in the development of DMD. Although the immune cell population(s) involved remain unidentified, our findings reveal that PKCθ can be proposed as a new pharmacological target to counteract the disease, as well as to improve the efficacy of gene- or cell- therapy approaches.

Inositol 1,4,5-trisphosphate (IP3)-dependent Ca2+ signaling mediates delayed myogenesis in Duchenne muscular dystrophy fetal muscle

“…Taken together with the work of Oh and collaborators, demonstrating that slow fiber expression during embryogenesis and early postnatal growth is under the control of a developmental program in a calcineurin-independent manner (Oh et al, 2005), we investigated the expression level of another calcium-dependent protein, PKCα. In accordance with previously published data that demonstrated that PKCα exerted a primary role in pathogenesis of DMD (Wang et al, 2009;Madaro et al, 2012), we showed its early overactivation in DMD fetal muscle tissues. PKCα is involved in signal transduction cascades regulating the proliferation of myoblasts (Goel and Dey, 2002).…”

“…(2009), Madaro et al (2012) and the work of Kawasaki, demonstrating the role of PKC in the phosphorylation of Orai1 (Kawasaki et al, 2010), we decided to investigate the expression of PKCα in murine fetal muscle tissues. In skeletal muscle, PKCα Development (2016Development ( ) 143, 658-669 doi:10.1242 protein is regulated by Ca 2+ concentration and plays a fundamental role in muscle development and plasticity (Gundersen, 2011).…”

Targeting early PKCθ‐dependent T‐cell infiltration of dystrophic muscle reduces disease severity in a mouse model of muscular dystrophy

“…In this study, we examined the acute inflammatory cell infiltrate in 2-, 4-, and 12-week-old mdx muscle, and determined the kinetics of T-cell infiltration, thus identifying the relevant period for T-cell-based interventions. To target T cells, we used the compound C20, a potent and selective protein kinase C theta (PKCθ) inhibitor [25][26][27][28][29][30][31][32]. PKCθ is a key regulator of effector T-cell activation [26,[33][34][35] and previous studies have shown that lack of PKCθ ameliorates T-cell-mediated inflammatory diseases [34,[36][37][38].…”

PKC Proteins and Muscular Dystrophy

“…Madaro et al in 2012 [36] showed that in double null mice pkcθ/mdx the muscle wasting was significantly reduced, while muscle regeneration was increased with respect to mdx dystrophic mice. This response was mainly associated with the lack of PKCθ in inflammatory cells, suggesting that PKCθ could represent a pharmacological target to improve the efficacy of therapy approach [37].…”