Gene Expression Regulation

Publication Title: 
Nature

The nematode Caenorhabditis elegans is an important model for studying the genetics of ageing, with over 50 life-extension mutations known so far. However, little is known about the pathobiology of ageing in this species, limiting attempts to connect genotype with senescent phenotype. Using ultrastructural analysis and visualization of specific cell types with green fluorescent protein, we examined cell integrity in different tissues as the animal ages.

Author(s): 
Herndon, Laura A.
Schmeissner, Peter J.
Dudaronek, Justyna M.
Brown, Paula A.
Listner, Kristin M.
Sakano, Yuko
Paupard, Marie C.
Hall, David H.
Driscoll, Monica
Publication Title: 
Oncogene

A wide range of human diseases, including cancer, has a striking age-dependent onset. However, the molecular mechanisms that connect aging and cancer are just beginning to be unraveled. FOXO transcription factors are promising candidates to serve as molecular links between longevity and tumor suppression. These factors are major substrates of the protein kinase Akt. In the presence of insulin and growth factors, FOXO proteins are relocalized from the nucleus to the cytoplasm and degraded via the ubiquitin-proteasome pathway.

Author(s): 
Greer, Eric L.
Brunet, Anne
Publication Title: 
Journal of Cell Science

In mammalian cells, products of the INK4a-ARF locus play major roles in senescence and tumour suppression in different contexts, whereas the adjacent INK4b gene is more generally associated with transforming growth factor beta (TGF-beta)-mediated growth arrest. As the chicken genome does not encode an equivalent of INK4a, we asked whether INK4b and/or ARF contribute to replicative senescence in chicken cells.

Author(s): 
Kim, Soo-Hyun
Rowe, Janice
Fujii, Hideta
Jones, Rebecca
Schmierer, Bernhard
Kong, Byung-Whi
Kuchler, Karl
Foster, Douglas
Ish-Horowicz, David
Peters, Gordon
Publication Title: 
Nature

XPF-ERCC1 endonuclease is required for repair of helix-distorting DNA lesions and cytotoxic DNA interstrand crosslinks. Mild mutations in XPF cause the cancer-prone syndrome xeroderma pigmentosum. A patient presented with a severe XPF mutation leading to profound crosslink sensitivity and dramatic progeroid symptoms. It is not known how unrepaired DNA damage accelerates ageing or its relevance to natural ageing. Here we show a highly significant correlation between the liver transcriptome of old mice and a mouse model of this progeroid syndrome.

Author(s): 
Niedernhofer, Laura J.
Garinis, George A.
Raams, Anja
Lalai, Astrid S.
Robinson, Andria Rasile
Appeldoorn, Esther
Odijk, Hanny
Oostendorp, Roos
Ahmad, Anwaar
van Leeuwen, Wibeke
Theil, Arjan F.
Vermeulen, Wim
van der Horst, Gijsbertus T. J.
Meinecke, Peter
Kleijer, Wim J.
Vijg, Jan
Jaspers, Nicolaas G. J.
Hoeijmakers, Jan H. J.
Publication Title: 
Journal of Biochemistry

FOXO (Forkhead box O) transcription factors constitute an evolutionally conserved subgroup within the large Forkhead family of transcription regulators. FOXO factors are important regulators of the cell cycle, apoptosis, DNA repair, metabolism, oxidative stress resistance and longevity. Genetic studies of Caenorhabditis elegans demonstrated that FOXO factors are major targets of the insulin-like signalling implicated during the regulation of glucose metabolism and lifespan extension.

Author(s): 
Daitoku, Hiroaki
Fukamizu, Akiyoshi
Publication Title: 
International Journal of Hematology

FKHRL1 is one of the human homologues of DAF-16, which is concerned with longevity in Caenorhabditis elegans. Previously, we demonstrated that FKHRL1 functions downstream of Akt in erythropoietin (EPO) signaling and that it is directly phosphorylated by activated Akt. Because phosphorylated FKHRL1 loses its transcriptional activity and translocates into the cytoplasm, FKHRL1 appears to be nonfunctional in the presence of EPO.

Author(s): 
Uchida, Mie
Kirito, Keita
Endo, Hitoshi
Ozawa, Keiya
Komatsu, Norio
Publication Title: 
Cell Death and Differentiation

Ageing in divergent animal phyla is influenced by several evolutionarily conserved signalling pathways, mitochondrial activity and various environmental factors such as nutrient availability and temperature. Although ageing is a multifactorial process with many mechanisms contributing to the decline, the intracellular accumulation of damaged proteins and mitochondria is a feature common to all aged cells.

Author(s): 
Vellai, T.
Publication Title: 
PloS One

In previous investigations an impact of cellular copper homeostasis on ageing of the ascomycete Podospora anserina has been demonstrated. Here we provide new data indicating that mitochondria play a major role in this process. Determination of copper in the cytosolic fraction using total reflection X-ray fluorescence spectroscopy analysis and eGfp reporter gene studies indicate an age-related increase of cytosolic copper levels. We show that components of the mitochondrial matrix (i.e. eGFP targeted to mitochondria) become released from the organelle during ageing.

Author(s): 
Scheckhuber, Christian Q.
Grief, J¸rgen
Boilan, Emmanuelle
Luce, Karin
Debacq-Chainiaux, Florence
Rittmeyer, Claudia
Gredilla, Ricardo
Kolbesen, Bernd O.
Toussaint, Olivier
Osiewacz, Heinz D.
Publication Title: 
The EMBO journal

Senescence is an irreversible cell-cycle arrest that is elicited by a wide range of factors, including replicative exhaustion. Emerging evidences suggest that cellular senescence contributes to ageing and acts as a tumour suppressor mechanism. To identify novel genes regulating senescence, we performed a loss-of-function screen on normal human diploid fibroblasts. We show that downregulation of the AMPK-related protein kinase 5 (ARK5 or NUAK1) results in extension of the cellular replicative lifespan.

Author(s): 
Humbert, Nicolas
Navaratnam, Naveenan
Augert, Arnaud
Da Costa, Marco
Martien, SÈbastien
Wang, Jing
Martinez, Dolores
Abbadie, Corinne
Carling, David
de Launoit, Yvan
Gil, Jesus
Bernard, David
Publication Title: 
Ageing Research Reviews

This article proposes that behavioural advancement during mammalian evolution had been in part mediated through extension of total developmental time. Such time extensions would have resulted in increased numbers of neuronal precursor cells, hence larger brains and a disproportionate increase in the neocortex. Larger neocortical areas enabled new connections to be formed during development and hence expansion of existing behavioural circuits.

Author(s): 
Neill, David

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