Age-Related Changes in the Autophagic Proteolysis of Rat Isolated Liver Cells: Effects of Antiaging Dietary Restrictions

Donati, Alessio; Cavallini, Gabriella; Paradiso, C.; Vittorini, Simona; Pollera, Maria; Gori, Zina; Bergamini, Ettore

doi:10.1093/gerona/56.9.b375

Cited by 128 publications

(72 citation statements)

References 34 publications

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“…Compromised autophagy with age was initially described in this organ (Bergamini & Kovacs, 1990; Donati et al., 2001) and working with liver allowed us to recover enough organelles for biochemical assays. We isolated APG (enriched in LC3‐II and p62; note that the low amounts of LAMP1 and cathepsin observed in this fraction could represent amphisomes [resulting from fusion of APG and late endosomes]) and AUT (also enriched in both markers but with higher abundance of lysosomal markers (LAMP1, CathB, and mucolipin; Figure 4a ).…”

Section: Resultsmentioning

confidence: 99%

“…Autophagic flux (combination of autophagosome biogenesis and their degradation by lysosomes) decreases in an age‐dependent manner in organs such as liver (Bergamini & Kovacs, 1990; Donati et al., 2001). Induction of autophagosome formation in response to liver‐specific stimuli such as glucagon decreases with age (Bergamini & Kovacs, 1990), but despite reduced biogenesis the overall number of autophagosomes is higher in old livers (Stupina, Terman, Kvitmitskaia‐Ryzhova, Mezhiborkaia & Zherebitskii, 1994) due to compromised maturation of autophagosomes into autolysosomes with age (Terman, 1995).…”

Section: Introductionmentioning

confidence: 99%

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Defective recruitment of motor proteins to autophagic compartments contributes to autophagic failure in aging

et al. 2018

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SummaryInability to preserve proteostasis with age contributes to the gradual loss of function that characterizes old organisms. Defective autophagy, a component of the proteostasis network for delivery and degradation of intracellular materials in lysosomes, has been described in multiple old organisms, while a robust autophagy response has been linked to longevity. The molecular mechanisms responsible for defective autophagic function with age remain, for the most part, poorly characterized. In this work, we have identified differences between young and old cells in the intracellular trafficking of the vesicular compartments that participate in autophagy. Failure to reposition autophagosomes and lysosomes toward the perinuclear region with age reduces the efficiency of their fusion and the subsequent degradation of the sequestered cargo. Hepatocytes from old mice display lower association of two microtubule‐based minus‐end‐directed motor proteins, the well‐characterized dynein, and the less‐studied KIFC3, with autophagosomes and lysosomes, respectively. Using genetic approaches to mimic the lower levels of KIFC3 observed in old cells, we confirmed that reduced content of this motor protein in fibroblasts leads to failed lysosomal repositioning and diminished autophagic flux. Our study connects defects in intracellular trafficking with insufficient autophagy in old organisms and identifies motor proteins as a novel target for future interventions aiming at correcting autophagic activity with anti‐aging purposes.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Defective recruitment of motor proteins to autophagic compartments contributes to autophagic failure in aging

et al. 2018

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“…Although macroautophagy, a nonselective form of autophagy, also decreases with age (Terman, 1995;Donati et al, 2001), the fact that the lysosomal population analyzed has been shown to be very active for CMA and that only a subset of oxidized proteins was detected in lysosomes encouraged us to analyze the role of CMA in the removal of oxidized proteins.…”

Section: Oxidized Proteins In Lysosomesmentioning

confidence: 99%

“…Similar assays to the ones described above confirmed that the oxidized proteins were of extralysosomal origin and could be degraded by the lysosomal proteases (our unpublished data). The last panel of Figure 1B shows the specificity of the antibody used in these studies against the carbonyl groups, which in nonderivatized samples only weakly cross-reacted with a single protein (compare signal in derivatized (lane 7) and nonderivatized samples (lane 8).Although macroautophagy, a nonselective form of autophagy, also decreases with age (Terman, 1995;Donati et al, 2001), the fact that the lysosomal population analyzed has been shown to be very active for CMA and that only a subset of oxidized proteins was detected in lysosomes encouraged us to analyze the role of CMA in the removal of oxidized proteins. …”

mentioning

confidence: 97%

“…In most of these oxidative events, damaged proteins are removed from the cell through degradation by proteases (Dunlop et al, 2002). The activity of different intracellular proteolytic systems decreases with age (Terman, 1995;Cuervo and Dice, 1998a;Friguet et al, 2000;Carrard et al, 2002;Donati et al, 2001;Merker et al, 2001;Friguet, 2002;Keller et al, 2002;Ward, 2002), and this impaired activity is considered responsible for the deficient removal of oxidized proteins in old organisms (Grune, 2000;Merker and Grune, 2000;Dunlop et al, 2002;Szweda et al, 2002).The susceptibility of oxidized proteins to proteases changes with the duration and degree of oxidative damage (Dunlop et al, 2002;Mehlhase and Grune, 2002). Thus, mild oxidation induces partial protein unfolding and facilitates proteolytic cleavage (Grune et al, 1995.…”

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Activation of Chaperone-mediated Autophagy during Oxidative Stress

Kiffin

Christian

Knecht

et al. 2004

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556

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Oxidatively damaged proteins accumulate with age in almost all cell types and tissues. The activity of chaperonemediated autophagy (CMA), a selective pathway for the degradation of cytosolic proteins in lysosomes, decreases with age. We have analyzed the possible participation of CMA in the removal of oxidized proteins in rat liver and cultured mouse fibroblasts. Added to the fact that CMA substrates, when oxidized, are more efficiently internalized into lysosomes, we have found a constitutive activation of CMA during oxidative stress. Oxidation-induced activation of CMA correlates with higher levels of several components of the lysosomal translocation complex, but in particular of the lumenal chaperone, required for substrate uptake, and of the lysosomal membrane protein (lamp) type 2a, previously identified as a receptor for this pathway. In contrast with the well characterized mechanism of CMA activation during nutritional stress, which does not require de novo synthesis of the receptor, oxidation-induced activation of CMA is attained through transcriptional up-regulation of lamp2a. We conclude that CMA is activated during oxidative stress and that the higher activity of this pathway under these conditions, along with the higher susceptibility of the oxidized proteins to be taken up by lysosomes, both contribute to the efficient removal of oxidized proteins. INTRODUCTIONAccumulation of oxidized protein is a common feature of aged cells (Dunlop et al., 2002;Grune et al., 2001Grune et al., , 2002bStadtman, 2001). Many physiological and pathological processes lead to the generation of free radicals and consequent damage of intracellular components, including proteins. In most of these oxidative events, damaged proteins are removed from the cell through degradation by proteases (Dunlop et al., 2002). The activity of different intracellular proteolytic systems decreases with age (Terman, 1995;Cuervo and Dice, 1998a;Friguet et al., 2000;Carrard et al., 2002;Donati et al., 2001;Merker et al., 2001;Friguet, 2002;Keller et al., 2002;Ward, 2002), and this impaired activity is considered responsible for the deficient removal of oxidized proteins in old organisms (Grune, 2000;Merker and Grune, 2000;Dunlop et al., 2002;Szweda et al., 2002).The susceptibility of oxidized proteins to proteases changes with the duration and degree of oxidative damage (Dunlop et al., 2002;Mehlhase and Grune, 2002). Thus, mild oxidation induces partial protein unfolding and facilitates proteolytic cleavage (Grune et al., 1995. However, persistent or extensive oxidative damage usually promotes protein aggregation, due to the exposure of patches of hydrophobic amino acids. Once a protein aggregates, it becomes less susceptible to proteolytic cleavage (Hoff et al., 1993;Davies, 2001;Demasi and Davies, 2003). Kinetics of degradation of oxidized proteins in vitro have been analyzed using different types of proteases (Merker and Grune, 2000;Dunlop et al., 2002;Szweda et al., 2002). One of the most extensively analyzed protease in this respect has be...

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