Muscular dystrophy alters the processing of light acetylcholinesterase but not butyrylcholinesterase forms in liver of Lama2dy mice

Abstract

In order to know whether the histopathological changes of liver, which accompany muscular dystrophy, affect the synthesis of cholinesterases, the distribution and glycosylation of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) forms in normal (NL) and dystrophic Lama2dy mouse liver (DL) were investigated. About half of liver AChE, and 25% of BuChE were released with a saline buffer (fraction S1), and the rest with a saline-Brij 96 buffer (S2). Abundant light (G2A and G1A) AChE (87%) and BuChE (93%) forms, and a few G4H and G4A ChE species were identified in liver. The dystrophic syndrome had no effect on solubilization or composition of ChE forms. Most of the light AChE and BuChE species (>95%) were bound by octyl-Sepharose, while most light AChE forms (80%), but not BuChE isoforms (15%), were retained in phenyl-agarose. About half of the AChE dimers lost their amphiphilic anchor with phosphatidylinositol-specific phospholipase C (PIPLC), and the fraction of PIPLC-resistant species increased in DL. AChE T and R transcripts were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) of liver RNA. ChE components of liver, erythrocyte, and plasma were distinguished by their amphiphilic properties and interaction with lectins. The dystrophic syndrome increased the liver content of the light AChE forms with Lens culinaris agglutinin (LCA) reactivity. The abundance of ChE tetramers in plasma and their small amount in liver suggest that after their assembly in liver they are rapidly secreted, while the light species remain associated to hepatic membranes. J. Neurosci. Res. 62:134–145, 2000. © 2000 Wiley-Liss, Inc.