Calpain specificity and expression in chicken tissues.

We have compared ubiquitous calpains in chicken (Gallus gallus), turkey (Meleagris gallopavo) and mammals. In chicken, we studied their distribution in different tissues. The calpain activity was determined by casein zymography, a technique avoiding any prior sample purification, thus limiting any autolysis and denaturation reactions.

Linkage between the proteasome pathway and neurodegenerative diseases and aging.

During aging, the production of free radicals increases. This can result in damage to protein, the accumulation of which is characteristic of the aging process. This questions the efficacy of proteolytic systems.

Increased muscle proteasome activities in rats fed a polyunsaturated fatty acid supplemented diet.

Changes in the proteasome system, a dominant actor in protein degradation in eukaryotic cells, have been documented in a large number of physiological and pathological conditions. We investigated the influence of monounsaturated or polyunsaturated fatty acids (PUFAs) supplemented diets on the proteasome system, in rat skeletal muscles. Thirty rats were randomly assigned to three groups.

Differential expression of ubiquitin and proteasome-dependent pathway components in rat tissues.

The ATP-ubiquitin-dependent pathway in eukaryotes is a complex system, which plays an essential role in selective protein degradation. The functional diversity of this system must be matched to the specific protein metabolism related to the physiology of each cell types. The aim of our work was to study the expression of different components of the proteasome-dependent pathway in various rat tissues.

Peptidase activities of the 20/26S proteasome and a novel protease in human brain.

Many neurodegenerative diseases are characterized by ubiquitin-positive protein aggregates or inclusion bodies. Ubiquitin-conjugated proteins are degraded by the 20/26S proteasome, and reduced proteasome peptidase activities in brain homogenates have been reported in pathologic lesions of Parkinson's and Alzheimer's diseases. However, it is unknown whether crude extracts of human brain contain other proteases having peptidase activities.

Brain proteasomal function in sporadic Parkinson's disease and related disorders.

Because genetic defects relating to the ubiquitin-proteasome system were reported in familial parkinsonism, we evaluated proteasomal function in autopsied brains with sporadic Parkinson's disease. We found that proteasome peptidase activities in a fraction specific to the proteasome were preserved in five brain areas (including the striatum) of Parkinson's disease where neuronal loss is not observed. Striatal protein levels of two proteasome subunits were normal in Parkinson's disease but reduced mildly in disease controls (multiple system atrophy).

Changes in proteasome activity during postmortem aging of bovine muscle.

Changes in the chymotrypsin-like, trypsin-like, peptidylglutamylpeptide hydrolyzing and caseinolytic activities of proteasomes in bovine rectus abdominis muscle were measured during the first seven days of postmortem storage. Enzyme assays were performed in crude extracts under near-physiological conditions, since the activities are likely to be altered by purification. The different proteasome activities at cellular pH were stable at different times postmortem, and were 40, 76, 50 and 61% of their at-death value after 7 days of storage at 4 °C.