The effect of mild traumatic brain injury on peripheral nervous system pathology in wild-type mice and the G93A mutant mouse model of motor neuron disease

Traumatic brain injury (TBI) is associated with a risk of neurodegenerative disease. Some suggest a link between TBI and motor neuron disease (MND), including amyotrophic lateral sclerosis (ALS). To investigate the potential mechanisms linking TBI to MND, we measured motor function and neuropathology following mild-TBI in wild-type and a transgenic model of ALS, G93A mutant mice. Mild-TBI did not alter the lifespan of G93A mice or age of onset; however, rotarod performance was impaired in G93A verses wild-type mice. Grip strength was reduced only in G93A mice after mild-TBI. Increased electromyography (EMG) abnormalities and markers of denervation (AchR, Runx1) indicate that mild-TBI may result in peripheral effects that are exaggerated in G93A mice. Markers of inflammation (cell edema, astrogliosis and microgliosis) were detected at 24 and 72h in the brain and spinal cord in wild-type and G93A mice. Levels of F2-isoprostanes, a marker of oxidative stress, were increased in the spinal cord 24h post mild-TBI in wild-type mice but were not affected by TBI in G93A mice. In summary, our data demonstrate that mild-TBI induces inflammation and oxidative stress and negatively impacts muscle denervation and motor performance, suggesting mild-TBI can potentiate motor neuron pathology and influence the development of MND in mice.

Novel mechanisms of protein synthesis in diabetic nephropathy--role of mRNA translation

Ambient protein levels are affected by both synthesis and degradation. Synthesis of a protein is regulated by transcription and messenger RNA (mRNA) translation. Translation has emerged as an important site of regulation of protein expression during development and disease. It is under the control of distinct factors that regulate initiation, elongation and termination phases. Regulation of translation occurs via signaling reactions, guanosine diphosphate-guanosine triphosphate binding and by participation of non-coding RNA species such as microRNA. Recent work has revealed an important role for translation in hypertrophy, matrix protein synthesis, elaboration of growth factors in in vivo and in vitro models of diabetic nephropathy. Studies of translation dysregulation in diabetic nephropathy have enabled identification of novel therapeutic targets. Translation of mRNA is a fertile field for exploration in investigation of kidney disease.