A biphasic change in ribosomal conformation during transneuronal degeneration is altered by inhibition of mitochondrial, but not cytoplasmic protein synthesis

Abstract

Following loss of eighth nerve input, 20-40% of neurons in the neonatal chick cochlear nucleus, nucleus magnocellularis (NM), undergo cell death. Intracellular changes that precede the death of NM neurons include increased oxidative metabolism and mitochondrial volume, decreased cytoplasmic protein synthesis, and destruction of ribosomes. Six hours following afferent deprivation, dying NM neurons demonstrate complete loss of ribosomes and cessation of protein synthesis, suggesting that the rapid destruction of ribosomes leads to neuronal death. Increased NM neuron death occurs when mitochondrial upregulation is prevented by chloramphenicol, a mitochondrial protein synthesis inhibitor. This finding suggests that increased oxidative capacity is required for neuronal survival following loss of afferent input. To study changes in the ribosomes of afferent-deprived NM neurons, we obtained a monoclonal antibody to ribosomal RNA. This monoclonal antibody, Y10B, labels ribosomes of all NM neurons receiving normal synaptic activity. Following removal of afferent input, NM neurons demonstrate a biphasic change in their pattern of Y10B label. During the initial phase, there is a uniform decrease in the density of Y10B label. In the second phase, some NM neurons recover the capacity to bind the Y10B antibody while others remain unlabeled. During this second phase, NM neurons putatively destined to die, based on their failure to synthesize protein, are unlabeled by the Y10B antibody. New gene expression is not necessary to initiate the change in ribosomal immunoreactivity that leads deafferented NM neurons toward cell death. Blocking cytoplasmic protein synthesis with cycloheximide had no effect on the biphasic change in Y10B labeling of afferent-deprived NM neurons. Treating chicks with chloramphenicol, however, prevented the recovery of Y10B immunoreactivity in NM neurons during the second phase of the response to afferent deprivation.

Apoptosis in Auditory Brainstem Neurons after a Severe Noise Trauma of the Organ of Corti: Intracochlear GDNF Treatment Reduces the Number of Apoptotic Cells

“…It is presumed to be due to the degeneration of central cochlear nerve processes, dendrite shrinkage and glial responses, in addition to the reduction in the neuron soma size [26,27]. The degeneration of the CN we found could also be considered a withdrawal response after the loss of neurotropic effect exerted by the IHC-derived NT-3 and GDNF on the cochlear neurons [2,6].…”

Tcof1 /Treacle is required for neural crest cell formation and proliferation deficiencies that cause craniofacial abnormalities

“…Deparaffinized transverse sections (10-12 m) prepared from E8.5 embryos were processed for immunohistochemical staining with Y10B, a mouse monoclonal antibody to rRNA (19). To determine the extent of rRNA degradation, the slides were incubated with a 1:500 dilution of supernatant from the Y10B hybridoma and subsequently a 1:200 dilution of biotinylated horse anti-mouse antibody (Vector Laboratories, Burlingame, CA) as described previously (19).…”

“…The final stage of ribosome maturation occurs as ribosomal subunits such as 28S rRNA are processed from rRNA precursors and transferred to the cytoplasm. Hence, we analyzed wild-type and mutant embryos by immunohistochemistry with the monoclonal anti-rRNA antibody Y10B (18,19), which serves as a marker of mature ribosomal integrity by specifically labeling the 28S subunit of rRNA (18,20) (Fig. 5C).…”

Axonal ribosomes and mRNAs associate with fragile X granules in adult rodent and human brains

“…For detection of the ribosomal RNA 5S and 5.8S subunits, we used supernatant from hybridoma cells expressing the monoclonal antibody Y10b (gift from Dr. J. Twiss; 1:1000) (64,65). For detection of FXR2P, we used the ascites form of the monoclonal 1G2 (Developmental Studies Hybridoma Bank; 1:1000), the monoclonal A42 (Sigma; 1:500) or the monoclonal 55 (BD Biosciences; 1:500).…”