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The eukaryotic translation initiation factor 5A (eIF5A) is an essential protein for the viability of the cells whose proposed function is to prevent the stalling of the ribosomes during translation elongation. eIF5A activity requires a unique and functionally essential post-translational modification, the change of a lysine to hypusine. eIF5A is recognized as a promoter of cell proliferation, but it has also been suggested to induce apoptosis. To date, the precise molecular mechanism through which eIF5A affects these processes remains elusive. In the present study, we explored whether eIF5A is involved in controlling the stress-induced expression of the key cellular regulator p53. Our results show that treatment of HCT-116 colon cancer cells with the deoxyhypusine (DHS) inhibitor N1-guanyl-1,7-diamineheptane (GC7) caused both inhibition of eIF5A hypusination and a significant reduction of p53 expression in UV-treated cells, and that eIF5A controls p53 expression at the level of protein synthesis. Furthermore, we show that treatment with GC7 followed by UV-induced stress counteracts the pro-apoptotic process triggered by p53 up-regulation. More in general, the importance of eIF5A in the cellular stress response is illustrated by the finding that exposure to UV light promotes the binding of eIF5A to the ribosomes, whereas UV treatment complemented by the presence of GC7 inhibits such binding, allowing a decrease of de novo synthesis of p53 protein.

Light influences a wide range of physiological processes from prokaryotes to mammals. Neurospora crassa represents an important model system used for studying this signal pathway. At molecular levels, the WHITE COLLAR Complex (WCC), a heterodimer formed by WC-1 (the blue light photo-sensor) and WC-2 (the transcriptional activator), is the critical positive regulator of light-dependent gene expression. GATN (N indicates any other nucleotide) repeats are consensus sequences within the promoters of light-dependent genes recognized by the WCC. The distal GATN is also known as C-box since it is involved in the circadian clock. However, we know very little about the role of the proximal GATN, and the molecular mechanism that controls the transcription of light-induced genes during the dark/light transition it is still unclear. Here we showed a first indication that mutagenesis of the proximal GATA sequence within the target promoter of the albino-3 gene or deletion of the WC-1 zinc finger domain led to a rise in expression of light-dependent genes already in the dark, effectively decoupling light stimuli and transcriptional activation. This is the first observation of cis -/ trans -acting repressive machinery, which is not consistent with the light-dependent regulatory mechanism observed in the eukaryotic world so far.

DNA is an entity shielded by mechanisms that maintain genomic stability and are essential for living cells; however, DNA is constantly subject to assaults from the environment throughout the cellular life span, making the genome susceptible to mutation and irreparable damage. Cells are prepared to mend such events through cell death as an extrema ratio to solve those threats from a multicellular perspective. However, in cells under various stress conditions, checkpoint mechanisms are activated to allow cells to have enough time to repair the damaged DNA. In yeast, entry into the cell cycle when damage is not completely repaired represents an adaptive mechanism to cope with stressful conditions. In multicellular organisms, entry into cell cycle with damaged DNA is strictly forbidden. However, in cancer development, individual cells undergo checkpoint adaptation, in which most cells die, but some survive acquiring advantageous mutations and selfishly evolve a conflictual behavior. In this review, we focus on how, in cancer development, cells rely on checkpoint adaptation to escape DNA stress and ultimately to cell death.

The term orthodisease defines human disorders in which the pathogenic gene has orthologs in model organism genomes. Yeasts have been instrumental for gaining insights into the molecular basis of many human disorders, particularly those resulting from impaired cellular metabolism. We and others have used yeasts as a model system to study the molecular basis of Hailey-Hailey disease (HHD), a human blistering skin disorder caused by haploinsufficiency of the gene ATP2C1 the orthologous of the yeast gene PMR1 . We observed that K. lactis cells defective for PMR1 gene share several biological similarities with HHD derived keratinocytes. Based on the conservation of ATP2C1/PMR1 function from yeast to human, here we used a yeast-based assay to screen for molecules able to influence the pleiotropy associated with PMR1 deletion. We identified six compounds, Kaempferol, Indirubin, Lappaconite, Cyclocytidine, Azomycin and Nalidixic Acid that induced different major shape phenotypes in K. lactis . These include mitochondrial and the cell-wall morphology-related phenotypes. Interestingly, a secondary assay in mammalian cells confirmed activity for Kaempferol. Indeed, this compound was also active on human keratinocytes depleted of ATP2C1 function by siRNA-treatment used as an in-vitro model of HHD. We found that Kaempferol was a potent NRF2 regulator, strongly inducing its expression and its downstream target NQO1 . In addition, Kaempferol could decrease oxidative stress of ATP2C1 defective keratinocytes, characterized by reduced NRF2-expression. Our results indicated that the activation of these pathways might provide protection to the HHD-skin cells. As oxidative stress plays pivotal roles in promoting the skin lesions of Hailey-Hailey, the NRF2 pathway could be a viable therapeutic target for HHD.

Glioblastoma (GBM) is the most aggressive human brain tumor. The high growth potential and decreased susceptibility to apoptosis of the glioma cells is mainly dependent on genetic amplifications or mutations of oncogenic or pro-apoptotic genes, respectively. We have previously shown that the activation of the M2 acetylcholine muscarinic receptors inhibited cell proliferation and induced apoptosis in two GBM cell lines and cancer stem cells. The aim of this study was to delve into the molecular mechanisms underlying the M2-mediated cell proliferation arrest. Exploiting U87MG and U251MG cell lines as model systems, we evaluated the ability of M2 receptors to interfere with Notch-1 and EGFR pathways, whose activation promotes GBM proliferation. We demonstrated that the activation of M2 receptors, by agonist treatment, counteracted Notch and EGFR signaling, through different regulatory cascades depending, at least in part, on p53 status. Only in U87MG cells, which mimic p53-wild type GBMs, did M2 activation trigger a molecular circuitry involving p53, Notch-1, and the tumor suppressor mir-34a-5p. This regulatory module negatively controls Notch-1, which affects cell proliferation mainly through the Notch-1/EGFR axis. Our data highlighted, for the first time, a molecular circuitry that is deregulated in the p53 wild type GBM, based on the cross-talk between M2 receptor and the Notch-1/EGFR pathways, mediated by mir-34a-5p.