Chronic Alcohol Exposure Affects the Cell Components Involved in Membrane Traffic in Neuronal Dendrites

Abstract

The specific traffic of the membrane components in neurons is a major requirement to establish and maintain neuronal domains-the axonal and the somatodendritic domains-and their polarized morphology. Unlike axons, dendrites contain membranous organelles, which are involved in the secretory pathway, including the endoplasmic reticulum, the Golgi apparatus and post-Golgi apparatus carriers, the cytoskeleton, and plasma membrane. A variety of molecules and factors are also involved in this process. Previous studies have shown that chronic alcohol exposure negatively affects several of these cell components, such as the Golgi apparatus or cytoskeleton in neurons. Yet very little information is available on the possible effects of this exposure on the remaining cell elements involved in intracellular trafficking in neurons, particularly in dendrites. By qualitative and quantitative electron microscopy, immunofluorescence and immunoblotting, we herein show that chronic exposure to moderate levels (30 mM) of ethanol in cultured neurons reduces the volume and surface density of the rough endoplasmic reticulum, and increases the levels of GRP78, a chaperone involved in endoplasmic reticulum stress. Ethanol also significantly diminishes the proportion of neurons that show an extension of Golgi into dendrites and dendritic Golgi outposts, a structure present exclusively in longer, thicker apical dendrites. Both Golgi apparatus types were also fragmented into a large number of cells. We also investigated the effect of alcohol on the levels of microtubule-based motor proteins KIF5, KIF17, KIFC2, dynein, and myosin IIb, responsible for transporting different cargoes in dendrites. Of these, alcohol differently affects several of them by lowering dynein and raising KIF5, KIFC2, and myosin IIb. These results, together with other previously published ones, suggest that practically all the protein trafficking steps in dendrites are altered to a greater or lesser extent by chronic alcohol exposure in neuronal cells, which may have negative repercussions for the development and maintenance of their polarized morphology and function.

A Systems Approach Implicates a Brain Mitochondrial Oxidative Homeostasis Co-expression Network in Genetic Vulnerability to Alcohol Withdrawal

“…Dissociation of HSPA5 during ER stress allows ATF6 to be transported to the Golgi (Shen et al, 2002). Chronic exposure to moderate levels of ethanol in neurons ( in vitro ) increases the levels of HSPA5 (Romero et al, 2015). Hspa5 expression is also altered by chronic ethanol consumption in rats (Bell et al, 2009).…”

The Role of Golgi Morphology in Post-Alcohol Recovery of Hepatocytes: Observations in Cellular and Animal Models

“…In response to stress, including exposure of cytotoxic agents, the compact Golgi structure can undergo remodeling characterized by varying degrees of scattering and unstacking [5][6][7][8][9][10]. Multiple studies have demonstrated that in hepatocytes, ethanol (EtOH) administration and it's subsequent metabolism have the ability to alter the structure of the Golgi [11][12][13].…”

Chronic Alcohol Exposure Decreases 53BP1 Protein Levels Leading to a Defective DNA Repair in Cultured Primary Cortical Neurons

“…Cultured primary cortical neurons were prepared from cerebral hemispheres of 16-day-old fetal Sprague-Dawley rats. Hemispheres were dissected, mechanically dissociated and plated in polylysine coated dishes (Price and Brewer 2001;Romero et al 2013Romero et al , 2015. Cells were cultured in the Neurobasal medium supplemented with B27 and Glutamax (Price and Brewer 2001).…”

“…These ethanol concentrations are equivalent to blood levels reported in pregnant chronic drinkers and are considered to correspond to moderate alcohol consumption (Eckardt et al 1998). The concentration of ethanol in the medium was determined using a kit from Sigma-Aldrich (nicotinamide adenine dinucleotide-alcohol dehydrogenase Reagent Multiple Test Vial N7160) and ethanol evaporation was minimized as previously described (Romero et al 2015). Cell viability was determined by the trypan blue exclusion test.…”