TY - GEN A1 - Fernando, Raquel A1 - Drescher, Cathleen A1 - Deubel, Stefanie A1 - Grune, Tilman A1 - Castro, Jose Pedro T1 - Distinct proteasomal activity for fast and slow twitch skeletal muscle during aging T2 - Free radical biology and medicine : the official journal of the Oxygen Society, a constituent member of the International Society for Free Radical Research N2 - Skeletal muscle alterations during aging lead to dysfunctional metabolism, correlating with frailty and early mortality. The loss of proteostasis is a hallmark of aging. Whether proteostasis loss plays a role in muscle aging remains elusive. To address this question we collected muscles, Soleus (SOL, type I) and Extensor digitorum longus (EDL, type II), from young (4 months) and old (25 months) C57BL/6 mice and evaluated the proteasomal system. Initial work showed decreased 26 S activity in old SOL. EDL displayed lower proteasomal activity in both ages compared to any of the SOL ages. Moreover, in order to understand if during aging there is the so-called “fiber switch from fast-to-slow”, we performed western blots against sMHC and fMHC (slow and fast myosin heavy chain, respectively). Preliminary results suggest that young SOL is composed by slow twitch fibers but also contains fast twitch fibers, while young EDL seems to be mostly composed by fast twitch fibers that level down during aging, suggesting the switch. As a conclusion, EDL seems to have less proteasomal activity, however, if this is a contributor or a consequence to the muscle fiber switch during aging still needs further investigation. Y1 - 2018 U6 - https://doi.org/10.1016/j.freeradbiomed.2018.04.393 SN - 0891-5849 SN - 1873-4596 VL - 120 SP - S119 EP - S119 PB - Elsevier CY - New York ER - TY - JOUR A1 - Castro, Jose Pedro A1 - Fernando, Raquel A1 - Reeg, Sandra A1 - Meinl, Walter A1 - Almeida, Henrique A1 - Grune, Tilman T1 - Non-enzymatic cleavage of Hsp90 by oxidative stress leads to actin aggregate formation BT - A novel gain-of-function mechanism JF - Redox Biology N2 - Aging is accompanied by the accumulation of oxidized proteins. To remove them, cells employ the proteasomal and autophagy-lysosomal systems; however, if the clearance rate is inferior to its formation, protein aggregates form as a hallmark of proteostasis loss. In cells, during stress conditions, actin aggregates accumulate leading to impaired proliferation and reduced proteasomal activity, as observed in cellular senescence. The heat shock protein 90 (Hsp90) is a molecular chaperone that binds and protects the proteasome from oxidative inactivation. We hypothesized that in oxidative stress conditions a malfunction of Hsp90 occurs resulting in the aforementioned protein aggregates. Here, we demonstrate that upon oxidative stress Hsp90 loses its function in a highly specific non-enzymatic iron-catalyzed oxidation event and its breakdown product, a cleaved form of Hsp90 (Hsp90cl), acquires a new function in mediating the accumulation of actin aggregates. Moreover, the prevention of Hsp90 cleavage reduces oxidized actin accumulation, whereas transfection of the cleaved form of Hsp90 leads to an enhanced accumulation of oxidized actin. This indicates a clear role of the Hsp90cl in the aggregation of oxidized proteins. KW - Oxidative stress KW - Protein oxidation KW - Heat shock protein 90 KW - Proteasome KW - Protein aggregates Y1 - 2019 U6 - https://doi.org/10.1016/j.redox.2019.101108 SN - 2213-2317 VL - 21 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Fernando, Raquel A1 - Drescher, Cathleen A1 - Nowotny, Kerstin A1 - Grune, Tilman A1 - Castro, Jose Pedro T1 - Impaired proteostasis during skeletal muscle aging JF - Free radical biology and medicine : the official journal of the Oxygen Society, a constituent member of the International Society for Free Radical Research N2 - Aging is a complex phenomenon that has detrimental effects on tissue homeostasis. The skeletal muscle is one of the earliest tissues to be affected and to manifest age-related changes such as functional impairment and the loss of mass. Common to these alterations and to most of tissues during aging is the disruption of the proteostasis network by detrimental changes in the ubiquitin-proteasomal system (UPS) and the autophagy-lysosomal system (ALS). In fact, during aging the accumulation of protein aggregates, a process mainly driven by increased levels of oxidative stress, has been observed, clearly demonstrating UPS and ALS dysregulation. Since the UPS and ALS are the two most important pathways for the removal of misfolded and aggregated proteins and also of damaged organelles, we provide here an overview on the current knowledge regarding the connection between the loss of proteostasis and skeletal muscle functional impairment and also how redox regulation can play a role during aging. Therefore, this review serves for a better understanding of skeletal muscle aging in regard to the loss of proteostasis and how redox regulation can impact its function and maintenance. KW - Skeletal muscle KW - Proteostasis KW - Proteasome and lysosome KW - Oxidative stress KW - Redox regulation KW - Aging Y1 - 2018 U6 - https://doi.org/10.1016/j.freeradbiomed.2018.08.037 SN - 0891-5849 SN - 1873-4596 VL - 132 SP - 58 EP - 66 PB - Elsevier CY - New York ER - TY - JOUR A1 - Fernando, Raquel A1 - Drescher, Cathleen A1 - Deubel, Stefanie A1 - Jung, Tobias A1 - Ost, Mario A1 - Klaus, Susanne A1 - Grune, Tilman A1 - Castro, Jose Pedro T1 - Low proteasomal activity in fast skeletal muscle fibers is not associated with increased age-related oxidative damage JF - Experimental gerontology N2 - The skeletal muscle is a crucial tissue for maintaining whole body homeostasis. Aging seems to have a disruptive effect on skeletal muscle homeostasis including proteostasis. However, how aging specifically impacts slow and fast twitch fiber types remains elusive. Muscle proteostasis is largely maintained by the proteasomal system. Here we characterized the proteasomal system in two different fiber types, using a non-sarcopenic aging model. By analyzing the proteasomal activity and amount, as well as the polyubiquitinated proteins and the level of protein oxidation in Musculus soleus (Sol) and Musculus extensor digitorum longus (EDL), we found that the slow twitch Sol muscle shows an overall higher respiratory and proteasomal activity in young and old animals. However, especially during aging the fast twitch EDL muscle reduces protein oxidation by an increase of antioxidant capacity. Thus, under adaptive non-sarcopenic conditions, the two fibers types seem to have different strategies to avoid age-related changes. KW - Proteasomal system KW - Skeletal muscle KW - Fast and slow fibers KW - Polyubiquitination KW - Oxidized proteins KW - Antioxidants KW - Aging KW - Mitochondrial respiration Y1 - 2018 U6 - https://doi.org/10.1016/j.exger.2018.10.018 SN - 0531-5565 SN - 1873-6815 VL - 117 SP - 45 EP - 52 PB - Elsevier CY - Oxford ER -