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RAR-related Orphan Receptor Alpha
RAR-related orphan receptor alpha (RORα), also known as NR1F1 (nuclear receptor subfamily 1, group F, member 1) is a nuclear receptor that in humans is encoded by the ''RORA'' gene. RORα participates in the transcriptional regulation of some genes involved in circadian rhythm. In mice, RORα is essential for development of cerebellum through direct regulation of genes expressed in Purkinje cells. It also plays an essential role in the development of type 2 innate lymphoid cells (ILC2) and mutant animals are ILC2 deficient. In addition, although present in normal numbers, the ILC3 and Th17 cells from RORα deficient mice are defective for cytokine production. Discovery The first three-human isoforms of RORα were initially cloned and characterized as nuclear receptors in 1994 by Giguère and colleagues, when their structure and function were first studied. In the early 2000s, various studies demonstrated that RORα displays rhythmic patterns of expression in a circadian cy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Receptor
In the field of molecular biology, nuclear receptors are a class of proteins responsible for sensing steroids, thyroid hormones, vitamins, and certain other molecules. These receptors work with other proteins to regulate the expression of specific genes thereby controlling the development, homeostasis, and metabolism of the organism. Nuclear receptors bind directly to DNA regulating the expression of adjacent genes; hence these receptors are classified as transcription factors. The regulation of gene expression by nuclear receptors often occurs in the presence of a ligand—a molecule that affects the receptor's behavior. Ligand binding to a nuclear receptor results in a conformational change activating the receptor. The result is up- or down-regulation of gene expression. A unique property of nuclear receptors that differentiates them from other classes of receptors is their direct control of genomic DNA. Nuclear receptors play key roles in both embryonic development a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc Finger
A zinc finger is a small protein structural motif that is characterized by the coordination of one or more zinc ions (Zn2+) in order to stabilize the fold. It was originally coined to describe the finger-like appearance of a hypothesized structure from the African clawed frog (''Xenopus laevis'') transcription factor IIIA. However, it has been found to encompass a wide variety of differing protein structures in eukaryotic cells. ''Xenopus laevis'' TFIIIA was originally demonstrated to contain zinc and require the metal for function in 1983, the first such reported zinc requirement for a gene regulatory protein followed soon thereafter by the Krüppel factor in ''Drosophila''. It often appears as a metal-binding domain in multi-domain proteins. Proteins that contain zinc fingers (zinc finger proteins) are classified into several different structural families. Unlike many other clearly defined supersecondary structures such as Greek keys or β hairpins, there are a number of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Dimer
In biochemistry, a protein dimer is a macromolecular complex formed by two protein monomers, or single proteins, which are usually non-covalently bound. Many macromolecules, such as proteins or nucleic acids, form dimers. The word ''dimer'' has roots meaning "two parts", '' di-'' + '' -mer''. A protein dimer is a type of protein quaternary structure. A protein homodimer is formed by two identical proteins. A protein heterodimer is formed by two different proteins. Most protein dimers in biochemistry are not connected by covalent bonds. An example of a non-covalent heterodimer is the enzyme reverse transcriptase, which is composed of two different amino acid chains. An exception is dimers that are linked by disulfide bridges such as the homodimeric protein NEMO. Some proteins contain specialized domains to ensure dimerization (dimerization domains) and specificity. The G protein-coupled cannabinoid receptors have the ability to form both homo- and heterodimers with several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rev-ErbA Alpha
Rev-Erb alpha (Rev-Erbɑ), also known as nuclear receptor subfamily 1 group D member 1 (NR1D1), is one of two Rev-Erb proteins in the nuclear receptor (NR) family of intracellular transcription factors. In humans, REV-ERBɑ is encoded by the ''NR1D1'' gene, which is highly conserved across animal species. Rev-Erbɑ plays an important role in regulation of the core circadian clock through repression of the positive clock element Bmal1. It also regulates several physiological processes under circadian control, including metabolic and immune pathways. Rev-Erbɑ mRNA demonstrates circadian oscillation in its expression, and it is highly expressed in mammals in the brain and metabolic tissues such as skeletal muscle, adipose tissue, and liver. Discovery Rev-Erbɑ was discovered in 1989 by Nobuyuki Miyajima and colleagues, who identified two ''erbA'' homologs on human chromosome 17 that were transcribed from opposite DNA strands in the same locus. One of the genes encoded a prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Response Element
Response elements are short sequences of DNA within a gene Promoter (genetics), promoter or Enhancer (genetics), enhancer region that are able to bind specific transcription factors and regulate Transcription (genetics), transcription of genes. Under conditions of stress, a transcription activator protein binds to the response element and stimulates transcription. If the same response element sequence is located in the control regions of different genes, then these genes will be activated by the same stimuli, thus producing a coordinated response. Hormone response element A hormone response element (HRE) is a short sequence of DNA within the Promoter (biology), promoter of a gene, that is able to bind to a specific hormone receptor complex and therefore regulate Transcription (genetics), transcription. The sequence is most commonly a pair of inverted repeats separated by three nucleotides, which also indicates that the receptor binds as a protein dimer, dimer. Specifically, HRE resp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transactivation
In the context of gene regulation: transactivation is the increased rate of gene expression triggered either by biological processes or by artificial means, through the expression of an intermediate transactivator protein. In the context of receptor signaling, transactivation occurs when one or more receptors activate yet another; receptor transactivation may result from the crosstalk of signaling cascades or the activation of G protein–coupled receptor hetero-oligomer subunits, among other mechanisms. Natural transactivation Transactivation can be triggered either by endogenous cellular or viral proteins, also called transactivators. These protein factors act in trans (''i.e.'', intermolecularly). HIV and HTLV are just two of the many viruses that encode transactivators to enhance viral gene expression. These transactivators can also be linked to cancer if they start interacting with, and increasing expression of, a cellular proto-oncogene. HTLV, for instance, has been ass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLOCK
A clock or a timepiece is a device used to measure and indicate time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month and the year. Devices operating on several physical processes have been used over the millennia. Some predecessors to the modern clock may be considered as "clocks" that are based on movement in nature: A sundial shows the time by displaying the position of a shadow on a flat surface. There is a range of duration timers, a well-known example being the hourglass. Water clocks, along with the sundials, are possibly the oldest time-measuring instruments. A major advance occurred with the invention of the verge escapement, which made possible the first mechanical clocks around 1300 in Europe, which kept time with oscillating timekeepers like balance wheels., pp. 103–104., p. 31. Traditionally, in horology, the term ''clock'' was used for a stri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARNTL
Aryl hydrocarbon receptor nuclear translocator-like protein 1 (ARNTL) or brain and muscle ARNT-Like 1 (BMAL1) is a protein that in humans is encoded by the gene on chromosome 11, region p15.3. It's also known as ''BMAL1'', ''MOP3'', and, less commonly, ''bHLHe5'', ''BMAL'', ''BMAL1C'', ''JAP3'', ''PASD3'', and ''TIC''. ''ARNTL'' encodes a transcription factor with a basic helix-loop-helix (bHLH) and two PAS domains. The human ''ARNTL'' gene has a predicted 24 exons, located on the p15 band of the 11th chromosome. The ARNTL protein is 626 amino acids long and plays a key role as one of the positive elements in the mammalian auto-regulatory transcription-translation negative feedback loop (TTFL), which is responsible for generating molecular circadian rhythms. Research has revealed that ''ARNTL'' is the only clock gene without which the circadian clock fails to function in humans. ''ARNTL'' has also been identified as a candidate gene for susceptibility to hypertension, diabetes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptochrome
Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fields in a number of species. The name ''cryptochrome'' was proposed as a ''portmanteau'' combining the '' chromatic'' nature of the photoreceptor, and the ''cryptogamic'' organisms on which many blue-light studies were carried out. The two genes ''Cry1'' and ''Cry2'' code the two cryptochrome proteins CRY1 and CRY2. In insects and plants, CRY1 regulates the circadian clock in a light-dependent fashion, whereas in mammals, CRY1 and CRY2 act as light-independent inhibitors of CLOCK-BMAL1 components of the circadian clock. In plants, blue-light photoreception can be used to cue developmental signals. Besides chlorophylls, cryptochromes are the only proteins known to form photoinduced radical-pairs ''in vivo''. These appear to enable some animal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PER1
The PER1 gene encodes the period circadian protein homolog 1 protein in humans. Function The PER1 protein is important to the maintenance of circadian rhythms in cells, and may also play a role in the development of cancer. This gene is a member of the period family of genes. It is expressed with a daily oscillating circadian rhythm, or an oscillation that cycles with a period of approximately 24 hours. PER1 is most notably expressed in the region of the brain called the suprachiasmatic nucleus (SCN), which is the primary circadian pacemaker in the mammalian brain. PER1 is also expressed throughout mammalian peripheral tissues. Genes in this family encode components of the circadian rhythms of locomotor activity, metabolism, and behavior. Circadian expression of PER1 in the suprachiasmatic nucleus will free-run in constant darkness, meaning that the 24-hour period of the cycle will persist without the aid of external light cues. Subsequently, a shift in the light/dark cycle evo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Negative Feedback
Negative feedback (or balancing feedback) occurs when some function (Mathematics), function of the output of a system, process, or mechanism is feedback, fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances. Whereas positive feedback tends to lead to instability via exponential growth, oscillation or chaos theory, chaotic behavior, negative feedback generally promotes stability. Negative feedback tends to promote a settling to List of types of equilibrium, equilibrium, and reduces the effects of perturbations. Negative feedback loops in which just the right amount of correction is applied with optimum timing can be very stable, accurate, and responsive. Negative feedback is widely used in mechanical and electronic engineering, and also within living organisms, and can be seen in many other fields from chemistry and economics to physical systems such as the climate. General negative feedback ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles (including birds) from which they diverged in the Carboniferous, over 300 million years ago. Around 6,400 extant species of mammals have been described divided into 29 orders. The largest orders, in terms of number of species, are the rodents, bats, and Eulipotyphla (hedgehogs, moles, shrews, and others). The next three are the Primates (including humans, apes, monkeys, and others), the Artiodactyla ( cetaceans and even-toed ungulates), and the Carnivora (cats, dogs, seals, and others). In terms of cladistics, which reflects evolutionary history, mammals are the only living members of the Synapsida (synapsids); this clade, together with Saur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
