title: TRP channels: a missing bond in the entrainment mechanism of peripheral clocks throughout evolution.
abstract: Circadian rhythm may be understood as a temporal organization that works to orchestrate physiological processes and behavior in a period of approximately 24 h. Because such temporal organization has evolved in the presence of predictable environmental clues, such as day length, tides, seasons, and temperature, the organism has confronted the natural selection in highly precise intervals of opportunities and risks, generating temporal programs and resetting mechanisms, which are well conserved among different taxa of animals. The present review brings some evidence of how these programs may have co-evolved in systems able to deal with 2 or more environmental clues, and how they similarly function in different group of animals, stressing how important temperature and light were to establish the temporal organizations. For example, melanopsin and rhodopsin, photopigments present respectively in circadian and visual photoreceptors, are required for temperature discrimination in Drosophila melanogaster. These pigments may signal light and temperature via activation of cationic membrane channel, named transient-receptor potential channel (TRP). In fact, TRPs have been suggested to function as thermal sensor for various groups of animals. Another example is the clock machinery at the molecular level. A set of very-well conserved proteins, known as clock proteins, function as transcription factors in positive and negative auto-regulatory loops generating circadian changes of their expression, and of clock-controlled genes. Similar molecular machinery is present in organisms as diverse as cyanobacteria (Synechococcus), fungi (Neurospora), insects (Drosophila), and vertebrates including humans.
authors.affiliation: Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais ; Belo Horizonte, Brazil.
authors.forename: Maristela O
authors.initials: MO
authors.lastname: Poletini
authors.affiliation: Department of Physiology; Institute of Biosciences; University of Sao Paulo ; São Paulo, Brazil.
authors.forename: Maria Nathália
authors.initials: MN
authors.lastname: Moraes
authors.affiliation: Department of Physiology; Institute of Biosciences; University of Sao Paulo ; São Paulo, Brazil.
authors.forename: Bruno César
authors.initials: BC
authors.lastname: Ramos
authors.affiliation: Department of Physiology; Institute of Biosciences; University of Sao Paulo ; São Paulo, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Jerônimo
authors.affiliation: Department of Physiology; Institute of Biosciences; University of Sao Paulo ; São Paulo, Brazil.
authors.forename: Ana Maria de Lauro
authors.initials: AM
authors.lastname: Castrucci
keywords: TRP channels; clock genes; opsins; photo-transduction; thermo-transduction