Changes in brain proteasome dynamics associated with aging

In the nervous system, proteasomes are important for proteolysis and cellular homeostasis of neurons and glial cells and for brain health. Proteasome function declines with age in many tissues, including the nervous system, and this decline affects many of the nervous system processes important to brain health and may be related to age-related cognitive decline. Therefore, we analyzed the factors that contribute to this decline in function using the brain of mice from different months of life. Peptidase activity of proteasomes in crude extracts decreased with aging, while ubiquitinated proteins increased with aging. Additionally, there was a tendency for the number of subunits that form proteasomes to decrease slightly with age. On the other hand, ump1, which is required for proteasome formation, accumulated with age. Therefore, analysis of proteasome dynamics in each month revealed that proteasome formation decreased with aging. This study suggests that with aging, not only 20S proteasome function but also 26 proteasome function decreases, the decline in proteasome function is due to the lack of proteasome formation, the PA28-20S-PA700 complex, which is involved in immunity, increases in the brain, and one factor in this lack of proteasome formation is that the proteins called UMP1.