Research Article

Cellular and Molecular Life Sciences

, Volume 71, Issue 17, pp 3339-3361

Open Access This content is freely available online to anyone, anywhere at any time.

Altered proteostasis in aging and heat shock response in C. elegans revealed by analysis of the global and de novo synthesized proteome

  • Vanessa LiangAffiliated withBrain and Mind Research Institute, University of Sydney
  • , Milena UllrichAffiliated withBrain and Mind Research Institute, University of SydneyInstitute for Integrative Neuroanatomy, Charité, Universitätsmedizin Berlin
  • , Hong LamAffiliated withSchool of Molecular Bioscience, University of Sydney
  • , Yee Lian ChewAffiliated withSchool of Molecular Bioscience, University of Sydney
  • , Samuel BanisterAffiliated withDrug Discovery Research Laboratory, Brain and Mind Research Institute, University of Sydney
  • , Xiaomin SongAffiliated withAustralian Proteome Analysis Facility, Macquarie University
  • , Thiri ZawAffiliated withAustralian Proteome Analysis Facility, Macquarie University
  • , Michael KassiouAffiliated withDrug Discovery Research Laboratory, Brain and Mind Research Institute, University of Sydney
  • , Jürgen GötzAffiliated withBrain and Mind Research Institute, University of SydneyClem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland Email author 

Abstract

Protein misfolding and aggregation as a consequence of impaired protein homeostasis (proteostasis) not only characterizes numerous age-related diseases but also the aging process itself. Functionally related to the aging process are, among others, ribosomal proteins, suggesting an intimate link between proteostasis and aging. We determined by iTRAQ quantitative proteomic analysis in C. elegans how the proteome changes with age and in response to heat shock. Levels of ribosomal proteins and mitochondrial chaperones were decreased in aged animals, supporting the notion that proteostasis is altered during aging. Mitochondrial enzymes of the tricarboxylic acid cycle and the electron transport chain were also reduced, consistent with an age-associated energy impairment. Moreover, we observed an age-associated decline in the heat shock response. In order to determine how protein synthesis is altered in aging and in response to heat shock, we complemented our global analysis by determining the de novo proteome. For that, we established a novel method that enables both the visualization and identification of de novo synthesized proteins, by incorporating the non-canonical methionine analogue, azidohomoalanine (AHA), into the nascent polypeptides, followed by reacting the azide group of AHA by ‘click chemistry’ with an alkyne-labeled tag. Our analysis of AHA-tagged peptides demonstrated that the decreased abundance of, for example, ribosomal proteins in aged animals is not solely due to degradation but also reflects a relative decrease in their synthesis. Interestingly, although the net rate of protein synthesis is reduced in aged animals, our analyses indicate that the synthesis of certain proteins such as the vitellogenins increases with age.

Keywords

Click chemistry Heat shock proteins iTRAQ quantitative mass spectrometry Ribosomal proteins Aging C. elegans