Changes in Activity and Kinetic Properties of the Proteasome in Different Rat Organs during Development and Maturation

Abstract

The proteasome is considered the most important proteolytic system for removal of damaged proteins with aging. Using fluorogenic peptide substrates, the chymotrypsin-like, the trypsin-like, and the peptidylglutamyl peptidase activities of the proteasome were measured in the soluble fractions of liver, brain, and lens rat homogenates. Specific activity was significantly decreased in liver and brain homogenates with maturation of the animal, that is, from newborn (7 days old) to fertile rats (2–4 months old). Rat lens homogenate exhibited an increase in activity with maturation and also with aging. Chymotrypsin-like activity was stimulated by calcium and this proteolytic activity was significantly decreased with maturation of the rat brain. The Michaelis-Menten constant (K m) increased with age in rat liver and lens, indicating a loss of affinity for its substrates by the proteasome in the animal with maturation and aging. The present data suggest that the loss of function of the proteasome with maturation may be due to structural changes of the proteasome or a decreased content of regulatory components.

Molecular alterations in proteasomes of rat liver during aging result in altered proteolytic activities

“…Magnification, ×40 different proteases (Puente and Lopez-Otin 2004), which could be differently affected by aging or protein extraction protocols and therefore mask the real age-dependent alteration of proteasome activities. Indeed, our analysis of 20S proteasomes purified to apparent homogeneity and measurement of their peptide hydrolysing activity using fluorogenic peptide substrates revealed a significantly decreased caspase-like activity in 20S proteasome population purified from livers of aged as compared to young rats, which is in agreement with results of other investigators (Shibatani et al 1996;Conconi et al 1996;Hayashi and Goto 1998;Petersen et al 2010;Rodriguez et al 2010). This phenomenon most likely not only reflects alterations in the specific activities of the 20S proteasome subpopulations but also in their concentrations, keeping in mind that each subpopulation has a specific pattern of activities.…”

“…Their stoichiometry is α 7 β 7 β 7 α 7 , and three of the β-subunits, β1, β2 and β5, contain the proteolytically active sites catalysing the caspase-, trypsin-, and chymotrypsin-like activities, respectively. In liver tissue of aging mice and rats, all or some of these activities when measured with fluorogenic peptide substrates have been found to decrease (Sahakian et al 1995;Shibatani et al 1996;Conconi et al 1996;Breusing et al 2009;Dasuri et al 2009;Hayashi and Goto 1998;Rodriguez et al 2010) or decrease temporarily before increasing again (Petersen et al 2010;Keller et al 2000). However, no change of activity was measured in liver of aged as compared to young mice in one investigation (Huber et al 2009), an observation corroborating the data published by Scrofano and colleagues, who determined liver proteasome activity in young and old mice by use of β-lactoglobulin and oxidized ribonuclease as substrates (Scrofano et al 1998).…”

Methamphetamine oxidatively damages parkin and decreases the activity of 26S proteasome in vivo

“…. The values for the V max and K m of synaptosomal chymotrypsin-like activity were similar to those reported previously(Andersson et al 1999;Farout et al 2000;Kisselev and Goldberg 2005;Tydlacka et al 2008;Wang et al 2008a;Petersen et al 2010).…”

The proteasome controls presynaptic differentiation through modulation of an on-site pool of polyubiquitinated conjugates

“…Developmental regulation of the UPS controls presynaptic formation. In the rat brain, activity of proteasome catalytic subunits is high at the first postnatal week with subsequent reduction ( Petersen et al, 2010 ). Also, UPS components are up-regulated at this developmental stage, and high concentrations of K48-tagged proteins are observed ( Chen et al, 2011 ).…”