The identification of phosphorylated forms of myelin basic protein associated with mitochondria

Abstract

Current data demonstrate that neurodegenerative processes are associated with mitochondrial dysfunction. One of the causes of mitochondrial dysfunction is increased permeability of the inner membrane and the formation of the so-called non-selective mitochondrial permeability transition pore (mPTP), which is recognized as an early stage of programmed cell death. One of the factors of neurodegeneration is disruption of the interaction between glial cells and axons. We recently demonstrated that the myelin protein 2′,3′-cyclic-nucleotide 3′-phosphodiesterase (CNPase), which is localized in mitochondria, is involved in the regulation of the mPTP. Here, we show that two phosphoproteins with molecular weights of 21.5 and 17 kDa increase their phosphorylation state after pore opening. Using two-dimensional electrophoresis followed by mass spectrometry, we identified these proteins as phosphorylated isoforms of the myelin basic protein (MBP). We found that association of the 21.5 and 17 kDa isoforms of MBP increased under conditions of an opened pore. Thus, one more myelin protein is probably involved in the regulation of the mPTP.