Identification of molecular mechanisms of carbon nanoparticle-induced senescence and aging ex vivo and in vivo: Role of reactive oxygen species

• Applicants: Professorin Dr. Judith Haendeler; Privatdozent Dr. Klaus Unfried
• Subject Area: Biogerontology and Geriatric Medicine ; Public Health, Healthcare Research, Social and Occupational Medicine
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 270971646

The common principle of all combustion-derived carbon nanoparticles (CDNP) is the carbonaceous core with a primary diameter below 100 nm. Multiple studies have demonstrated that the effects of pure carbon nanoparticles can explain several adverse health outcomes to the lung and the cardiovascular system induced by inhaled CDNP. Epidemiologic data indicate that chronic exposure to CDNP leads to features of premature lung aging and age-related cardiovascular diseases. During the process of aging a functional decline of organs occurs resulting to multiple organ failure and death. One hallmark of aging is the occurrence of cellular senescence. Several studies demonstrated that senescent cells are present in vivo and are less functional than non-senescent cells. The Haendeler and Unfried groups together demonstrated for the first time that pure carbon nanoparticles induce features of cellular senescence in endothelial cells and lung epithelial cells. This exposure also increased reactive oxygen species (ROS), believed to be involved in aging and age-associated diseases. Therefore, the aims of this research proposal are to identify the so far unknown underlying molecular mechanisms leading to carbon nanoparticle-induced senescence in primary human lung epithelial cells and vessel endothelial cells ex vivo and to determine whether these mechanisms are also relevant in vivo. First, we will investigate whether ROS are causally involved in senescence induction by concurrent treatment with different antioxidants and subsequent measurement of senescence parameters. Furthermore, we will determine whether carbon nanoparticles change the expression and/or activity of oxidative and/or antioxidative systems. If so, the respective proteins will be permanently re-expressed or downregulated by a lentiviral approach. As mitochondria play an important role in aging processes and senescence, the functionality of these organelles will be measured after carbon nanoparticle treatment. One relevant protein for mitochondrial functions, aging and senescence is mitochondrial Telomerase Reverse Transcriptase (TERT), which is reduced by carbon nanoparticles. Thus, we will determine whether re-expression of mitochondrially localized TERT rescues lung epithelial cells and vessel endothelial cells from carbon nanoparticle-induced senescence. Another important feature of declined lung and vessel functions is impaired intercellular communication. Thus, we will determine the effect of carbon nanoparticles on intercellular communication with a specific focus on Connexin 43. To get further insights in so far unknown pathways, we will perform transcriptome and proteome analyses. Finally, we will investigate whether carbon nanoparticles in non-inflammatory doses also induce senescence in vivo. To test specific pathways we will use two mouse models, one overexpressing NADPH oxidase 4 specifically in the endothelium and one containing TERT exclusively in the mitochondria of all tissues.

• DFG Programme: Research Grants