Engineering Yeast Cells to Facilitate Information Exchange

Although continuous advances in theoretical modelling of Molecular Communications (MC) are observed, there is still an insuperable gap between theory and experimental testbeds, especially at the microscale. In this paper, the development of the first testbed incorporating engineered yeast cells is reported. Different from the existing literature, eukaryotic yeast cells are considered for both the sender and the receiver, with {\alpha}-factor molecules facilitating the information transfer. The use of such cells is motivated mainly by the well understood biological mechanism of yeast mating, together with their genetic amenability. In addition, recent advances in yeast biosensing establish yeast as a suitable detector and a neat interface to in-body sensor networks. The system under consideration is presented first, and the mathematical models of the underlying biological processes leading to an end-to-end (E2E) system are given. The experimental setup is then described and used to obtain experimental results which validate the developed mathematical models. Beyond that, the ability of the system to effectively generate output pulses in response to repeated stimuli is demonstrated, reporting one event per two hours. However, fast RNA fluctuations indicate cell responses in less than three minutes, demonstrating the potential for much higher rates in the future.Comment: 18 pages, 9 figures (2 of which are not colored) all .png, recently accepted for publication at TMBM

Histone acetyltransferase NAA40 modulates acetyl-CoA levels and lipid synthesis

Work in the A.K. laboratory was co-funded by the European Regional Development Fund and the Republic of Cyprus through the Research & Innovation Foundation (Projects: EXCELLENCE/0918/0081, EXCELLENCE/0918/0105 and EXCELLENCE/1216/0215) and was also supported by a Marie Skłodowska-Curie individual fellowship grant (no. 890750) to E.C. JLG’s laboratory is supported by the Wellcome Trust (Equipment grant 093,148/Z/10/Z)), the Medical Research Council (G0801841 & UD99999906), and UK Dementia Research Institute. The K.S. laboratory is co-funded by the European Regional Development Fund and the Republic of Cyprus through the Research & Innovation Foundation (Projects: OPPORTUNITY/0916/ERC-StG/003,INFRASTRUCTURES/1216/0034POST-DOC/0916/0111, INTERNATIONAL/OTHER/0118/0018).Peer reviewe

Histone acetyltransferase NAA40 modulates acetyl-CoA levels and lipid synthesis.

BACKGROUND: Epigenetic regulation relies on the activity of enzymes that use sentinel metabolites as cofactors to modify DNA or histone proteins. Thus, fluctuations in cellular metabolite levels have been reported to affect chromatin modifications. However, whether epigenetic modifiers also affect the levels of these metabolites and thereby impinge on downstream metabolic pathways remains largely unknown. Here, we tested this notion by investigating the function of N-alpha-acetyltransferase 40 (NAA40), the enzyme responsible for N-terminal acetylation of histones H2A and H4, which has been previously implicated with metabolic-associated conditions such as age-dependent hepatic steatosis and calorie-restriction-mediated longevity. RESULTS: Using metabolomic and lipidomic approaches, we found that depletion of NAA40 in murine hepatocytes leads to significant increase in intracellular acetyl-CoA levels, which associates with enhanced lipid synthesis demonstrated by upregulation in de novo lipogenesis genes as well as increased levels of diglycerides and triglycerides. Consistently, the increase in these lipid species coincide with the accumulation of cytoplasmic lipid droplets and impaired insulin signalling indicated by decreased glucose uptake. However, the effect of NAA40 on lipid droplet formation is independent of insulin. In addition, the induction in lipid synthesis is replicated in vivo in the Drosophila melanogaster larval fat body. Finally, supporting our results, we find a strong association of NAA40 expression with insulin sensitivity in obese patients. CONCLUSIONS: Overall, our findings demonstrate that NAA40 affects the levels of cellular acetyl-CoA, thereby impacting lipid synthesis and insulin signalling. This study reveals a novel path through which histone-modifying enzymes influence cellular metabolism with potential implications in metabolic disorders

Histone Modifications as an Intersection Between Diet and Longevity

Histone modifications are key epigenetic regulators that control chromatin structure and gene transcription, thereby impacting on various important cellular phenotypes. Over the past decade, a growing number of studies have indicated that changes in various histone modifications have a significant influence on the aging process. Furthermore, it has been revealed that the abundance and localization of histone modifications are responsive to various environmental stimuli, such as diet, which can also affect gene expression and lifespan. This supports the notion that histone modifications can serve as a main cellular platform for signal integration. Hence, in this review we focus on the role of histone modifications during aging, report the data indicating that diet affects histone modification levels and explore the idea that histone modifications may function as an intersection through which diet regulates lifespan. A greater understanding of the epigenetic mechanisms that link environmental signals to longevity may provide new strategies for therapeutic intervention in age-related diseases and for promoting healthy aging

Calorie restriction breaks an epigenetic barrier to longevity

International audienceIt is becoming increasingly evident that aging is controlled by both genetic and epigenetic factors. Histone modifying enzymes and their modifications comprise one of the main components of epigenetic mechanisms which have been directly linked to lifespan regulation in many organisms. Studies in diverse species have highlighted changes in the distribution or abundance of certain histone marks during the lifespan of a cell or an organism, leading to alterations in gene expression. In some cases, this aging-dependent patterning of histone modifications affects the expression of key longevity genes while, in other cases, they drive large-scale transcriptome changes that eventually contribute to functional decline and other hallmarks of aging. Since epigenetic factors, including histone modifications, are malleable to environmental signals, it was reasonably hypothesized that the epigenome could act as a platform through which external signals control lifespan via gene regulation. However, evidence connecting an environmental stimulus to a specific histone modification and the subsequent alteration of a particular gene expression program influencing lifespan was lacking. Using the genetically tractable eukaryote Saccharomyces cerevisiae we have recently reported that histone H4 N-terminal acetylation (N-acH4), a modification catalyzed by the N-terminal acetyltransferase Nat4, responds to calorie restriction (CR) in order to enable the expression of genes which directly delay agin

Histone Modifications as an Intersection Between Diet and Longevity

International audienceHistone modifications are key epigenetic regulators that control chromatin structure and gene transcription, thereby impacting on various important cellular phenotypes. Over the past decade, a growing number of studies have indicated that changes in various histone modifications have a significant influence on the aging process. Furthermore, it has been revealed that the abundance and localization of histone modifications are responsive to various environmental stimuli, such as diet, which can also affect gene expression and lifespan. This supports the notion that histone modifications can serve as a main cellular platform for signal integration. Hence, in this review we focus on the role of histone modifications during aging, report the data indicating that diet affects histone modification levels and explore the idea that histone modifications may function as an intersection through which diet regulates lifespan. A greater understanding of the epigenetic mechanisms that link environmental signals to longevity may provide new strategies for therapeutic intervention in age-related diseases and for promoting healthy aging