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Expression of CD59, a regulator of the membrane attack complex of complement, on human skeletal muscle fibers
J M Navenot1, M Villanova, B Lucas-Héron
1Etablissement de Transfusion Sanguine Loire-Atlantique-Vendée, Nantes,France.
Insights
CD59, a complement regulator, is present on human skeletal muscle fibers, while CD55 is not. This finding suggests CD59
Area of Science:
- Immunology
- Cell Biology
- Muscle Physiology
Background:
- Complement regulatory proteins control complement deposition on cells.
- CD55 and CD59 are key regulators of the complement cascade.
- Their expression on skeletal muscle is not well understood.
Purpose of the Study:
- To investigate the expression of CD55 and CD59 on human skeletal muscle fibers.
- To determine the role of these proteins in muscle physiology and pathology.
Main Methods:
- Immunoblotting with murine monoclonal antibodies to detect CD55 and CD59.
- Immunocytochemistry using anti-CD59 monoclonal antibody for localization.
- Analysis of protein expression in human skeletal muscle samples.
Main Results:
- CD59 was detected in human skeletal muscle fibers.
- CD55 was not found in skeletal muscle fibers.
- CD59 showed dense granular staining at the sarcolemma.
Conclusions:
- CD59, but not CD55, is expressed on normal human skeletal muscle fibers.
- CD59 likely prevents membrane attack complex deposition and complement-mediated damage.
- CD59 may be crucial in preventing myopathies involving complement activation.
Abstract:
Control of complement deposition on autologous cells is mediated by a group of complement regulatory membrane proteins acting at different levels of the complement cascade. Decay accelerating factor (CD55) prevents the assembly of C3 convertases and CD59 membrane inhibitor of reactive lysis (MIRL) restricts homologous complement lysis by the membrane attack complex of complement (MAC) by inhibition of C5b-8 catalyzed insertion of C9. The aim of this work was to study the eventual expression of CD55 and CD59 on human skeletal muscle fibers. Highly sensitive immunoblotting using murine monoclonal antibodies showed that CD59, but not CD55, was present in skeletal muscle fibers. Immunocytochemistry with a monoclonal antibody against CD59 demonstrated a dense granular immunostaining mainly localized at the level of the sarcolemma. Thus, CD59, but not CD55, is expressed on normal skeletal muscle fibers. CD59 may play a prominent role in preventing MAC deposition and subsequent complement-mediated damage in myopathies where the complement system activation is involved.