Disruption of Endoplasmic Reticulum Proteostasis in Age-Related Nervous System Disorders

Functions and distribution of calpain-calpastatin system components in brain during mammal ontogeny

Calpain and calpastatin are the key components of the calcium-dependent proteolytic system. Calpains are regulatory, calcium-dependent, cytoplasmic proteinases, and calpastatin is the endogenous inhibitor of calpains. Due to the correlation between changes in the activity of the calpain-calpastatin system in the brain and central nervous system (CNS) pathology states, this proteolytic system is a prime focus of research on CNS pathological processes, generally characterized by calpain activity upregulation. The present review aims to generalize existing data on cerebral calpain distribution and function through mammalian ontogenesis. Special attention is given to the most recent studies on the topic as more information on calpain-calpastatin system involvement in normal CNS development and functioning has become available. We also discuss data on calpain and calpastatin activity and production in different brain regions during ontogenesis as comparative analysis of these results in association with ontogeny processes can reveal brain regions and developmental stages with pronounced function of the calpain system.

Neuronal IRE-1 coordinates an organism-wide cold stress response by regulating fat metabolism

Cold affects many aspects of biology, medicine, agriculture, and industry. Here, we identify a conserved endoplasmic reticulum (ER) stress response, distinct from the canonical unfolded protein response, that maintains lipid homeostasis during extreme cold. We establish that the ER stress sensor IRE-1 is critical for resistance to extreme cold and activated by cold temperature. Specifically, neuronal IRE-1 signals through JNK-1 and neuropeptide signaling to regulate lipid composition within the animal. This cold-response pathway can be bypassed by dietary supplementation with unsaturated fatty acids. Altogether, our findings define an ER-centric conserved organism-wide cold stress response, consisting of molecular neuronal sensors, effectors, and signaling moieties, which control adaptation to cold conditions in the organism. Better understanding of the molecular basis of this stress response is crucial for the optimal use of cold conditions on live organisms and manipulation of lipid saturation homeostasis, which is perturbed in human pathologies.