title: Epigenetic and Posttranslational Modifications in Light Signal Transduction and the Circadian Clock in Neurospora crassa.
abstract: Blue light, a key abiotic signal, regulates a wide variety of physiological processes in many organisms. One of these phenomena is the circadian rhythm presents in organisms sensitive to the phase-setting effects of blue light and under control of the daily alternation of light and dark. Circadian clocks consist of autoregulatory alternating negative and positive feedback loops intimately connected with the cellular metabolism and biochemical processes. Neurospora crassa provides an excellent model for studying the molecular mechanisms involved in these phenomena. The White Collar Complex (WCC), a blue-light receptor and transcription factor of the circadian oscillator, and Frequency (FRQ), the circadian clock pacemaker, are at the core of the Neurospora circadian system. The eukaryotic circadian clock relies on transcriptional/translational feedback loops: some proteins rhythmically repress their own synthesis by inhibiting the activity of their transcriptional factors, generating self-sustained oscillations over a period of about 24 h. One of the basic mechanisms that perpetuate self-sustained oscillations is post translation modification (PTM). The acronym PTM generically indicates the addition of acetyl, methyl, sumoyl, or phosphoric groups to various types of proteins. The protein can be regulatory or enzymatic or a component of the chromatin. PTMs influence protein stability, interaction, localization, activity, and chromatin packaging. Chromatin modification and PTMs have been implicated in regulating circadian clock function in Neurospora. Research into the epigenetic control of transcription factors such as WCC has yielded new insights into the temporal modulation of light-dependent gene transcription. Here we report on epigenetic and protein PTMs in the regulation of the Neurospora crassa circadian clock. We also present a model that illustrates the molecular mechanisms at the basis of the blue light control of the circadian clock.
authors.affiliation: Department of Biology and Biotechnologies "Charles Darwin", Sapienza-University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy. marco.proietto@uniroma1.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Proietto
authors.affiliation: Department of Biology and Biotechnologies "Charles Darwin", Sapienza-University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy. michele.bianchi@uniroma1.it.
authors.forename: Michele Maria
authors.initials: MM
authors.lastname: Bianchi
authors.affiliation: Department of Biology and Biotechnologies "Charles Darwin", Sapienza-University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy. paola.ballario@uniroma1.it.|Pasteur Institute, Cenci Bolognetti Foundation and Department of Biology and Biotechnology "Charles Darwin", Sapienza-University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy. paola.ballario@uniroma1.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Ballario
authors.affiliation: Department of Biology and Biotechnologies "Charles Darwin", Sapienza-University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy. andrea.brenna@unifr.ch.|Pasteur Institute, Cenci Bolognetti Foundation and Department of Biology and Biotechnology "Charles Darwin", Sapienza-University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy. andrea.brenna@unifr.ch.|Department of Biology, Division of Biochemistry, University of Fribourg, Chemin du Musée 5, Fribourg 1700, Switzerland. andrea.brenna@unifr.ch.
authors.forename: Andrea
authors.initials: A
authors.lastname: Brenna
mesh_terms: D002843:Chromatin / Q000378:metabolism; D057906:Circadian Clocks / Q000235:genetics* / Q000528:radiation effects; D044127:Epigenesis, Genetic / Q000528:radiation effects; D055537:Light Signal Transduction / Q000235:genetics* / Q000528:radiation effects; D009492:Neurospora crassa / Q000235:genetics* / Q000528:radiation effects; D011499:Protein Processing, Post-Translational / Q000235:genetics* / Q000528:radiation effects
chemical_list: D002843:Chromatin
keywords: Neurospora crassa; acetylation; chromatin remodeling; circadian rhythms; light signal transduction; methylation; phosphorylation