PP09.11 – 2460: Colocalization of HIF1 alpha and abnormal mitochondrial accumulations in muscle fibers in different neuromuscular diseases

Abstract

Objective We perform the comparative study of immunohistochemical distribution of mitochondrial and hypoxia markers in abnormal mitochondrial clusters in striated muscle fibers of patients with myopathies. Such clusters, accordingly to recent data obtained by means of electron microscopy, play compensatory role in muscle tissue in different neuromuscular diseases. However, the regulatory impact's nature and the interaction with hypoxia are still unclear. Methods Fluorescence immunohistochemistry was performed. Primary mouse mitochondria monoclonal antibody, biotin conjugate (clone MTCO2) and Alexa Fluor 488 goat anti-mouse IgG as secondary antibody were used for mitochondria visualization. Visual image of HIF1 alpha was achieved by using primary rabbit polyclonal antibodies to HIF1 alpha and Alexa Fluor 555 goat anti-rabbit IgG secondary antibody. Paraffin embedded muscle tissue section slides obtained from 25 patients with mitochondrial myopathies, muscular dystrophies (DMD, merosinopathy, calpainopathy) and congenital myopathies (multicore, nemaline) were stained. Evaluation of the products is carried out by using The EVOS® FL Imaging System. Results Mitochondria and abnormal mitochondrial accumulations were visualized in subsarcolemmal zones of some muscle fibers using fluorescent immunohistochemistry. In the same muscle fibers we also observed increased expression HIF1 alpha; its localization matched with location of detected mitochondrial clusters, resulted in fluorescent lights overlapping and color change of subsarcolemmal zones luminescence. In the cases of muscular dystrophies it was observed that severity of pathological changes in muscles positively correlated with expression intensity of HIF1 alpha in the absence of mitochondrial marker expression. Conclusion The obtained results suggest that there is a colocalization of increased intracellular marker of hypoxia HIF1 alpha concentration and abnormal mitochondrial accumulations in different neuromuscular diseases. It can be explained by such clusters emerging in the areas of intracellular hypoxia. So hypoxia can be an important factor that stimulates mitochondrial proliferation, which may be important for tissue adaptation to different pathological conditions.