Distribution of dystrophin- and utrophin-associated protein complexes during activation of human neutrophils

Objective: Dystrophins, utrophins, and their associated proteins are involved in structural and signaling roles in nonmuscle tissues; however, description of these proteins in neutrophils remained unexplored. Therefore we characterize the pattern expression, and the cellular distribution of dystrophin and utrophin gene products and dystrophin-associated proteins (i.e., β-dystroglycan, α-syntrophin, and α-dystrobrevins) in relation to actin filaments in resting and activated with formyl-methionyl-leucyl-phenylalanine human neutrophils. Materials and Methods: Resting and fMLP-activated human neutrophils were analyzed by immunoblot and by confocal microscopy analysis. Immunoprecipitation assays were performed to corroborate the presence of protein complexes. Results: Immunoprecipitation assays and confocal analysis demonstrated the presence of two dystrophin-associated protein complexes in resting and activated neutrophils: the former formed by Dp71d/Dp71Δ₁₁₀ ^m and dystrophin-associated proteins (β-dystroglycan, α-syntrophin, α-dystrobrevin-1, and -2), while the latter contains Up400, instead of Dp71d/Dp71Δ₁₁₀ ^m, as a central component of the dystrophin-associated protein complexes (DAPC). Confocal analysis also showed the subcellular redistribution of Dp71d/Dp71Δ₁₁₀ ^m∼DAPC and Up400∼DAPC in F-actin-based structures displayed during activation process with fMLP. Conclusions: Our study showed the existence of two protein complexes formed by Dp71d/Dp71Δ₁₁₀ ^m or Up400 associated with DAPs in resting and fMLP-treated human polymorphonuclears. The interaction of these complexes with the actin cytoskeleton is indicative of their dynamic participation in the chemotaxis process.