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Transrepression
In the field of molecular biology, transrepression is a process whereby one protein represses (i.e., inhibits) the activity of a second protein through a protein-protein interaction. Since this repression occurs between two different protein molecules (intermolecular), it is referred to as a trans-acting process. The protein that is repressed is usually a transcription factor whose function is to up-regulate (i.e., increase) the rate of gene transcription. Hence the net result of transrepression is down regulation of gene transcription. An example of transrepression is the ability of the glucocorticoid receptor to inhibit the transcriptional promoting activity of the AP-1 and NF-κB transcription factors. In addition to transactivation, transrepression is an important pathway for the anti-inflammatory effects of glucocorticoids. Other nuclear receptors such as LXR and PPAR have been demonstrated to also have the ability to transrepress the activity of other proteins. See also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selective Glucocorticoid Receptor Agonist
Selective glucocorticoid receptor modulators (SEGRMs) and selective glucocorticoid receptor agonists (SEGRAs) formerly known as dissociated glucocorticoid receptor agonists (DIGRAs) are a class of experimental drugs designed to share many of the desirable anti-inflammatory, immunosuppressive, or anticancer properties of classical glucocorticoid drugs but with fewer side effects such as skin atrophy. Although preclinical evidence on SEGRAMs’ anti-inflammatory effects are culminating, currently, the efficacy of these SEGRAMs on cancer are largely unknown. Selective glucocorticoid receptor agonists (SEGRAs) are historically and typically steroidal in structure while selective glucocorticoid receptor modulators (SEGRMs) are typically nonsteroidal. The combined abbreviation of selective glucocorticoid receptor agonist and modulator is SEGRAM. A number of such ligands have been developed and are being evaluated in preclinical and clinical testing. SEGRAMs achieve their selectivit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucocorticoid
Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebrate animal cell. The name "glucocorticoid" is a portmanteau (glucose + cortex + steroid) and is composed from its role in regulation of glucose metabolism, synthesis in the adrenal cortex, and its steroidal structure (see structure below). Glucocorticoids are part of the feedback mechanism in the immune system, which reduces certain aspects of immune function, such as inflammation. They are therefore used in medicine to treat diseases caused by an overactive immune system, such as allergies, asthma, autoimmune diseases, and sepsis. Glucocorticoids have many diverse (pleiotropic) effects, including potentially harmful side effects. They also interfere with some of the abnormal mechanisms in cancer cells, so they are used in high doses to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucocorticoid Receptor
The glucocorticoid receptor (GR, or GCR) also known as NR3C1 (nuclear receptor subfamily 3, group C, member 1) is the receptor to which cortisol and other glucocorticoids bind. The GR is expressed in almost every cell in the body and regulates genes controlling the development, metabolism, and immune response. Because the receptor gene is expressed in several forms, it has many different (pleiotropic) effects in different parts of the body. When glucocorticoids bind to GR, its primary mechanism of action is the regulation of gene transcription. ree full text/ref> The unbound receptor resides in the cytosol of the cell. After the receptor is bound to glucocorticoid, the receptor-glucocorticoid complex can take either of two paths. The activated GR complex up-regulates the expression of anti-inflammatory proteins in the nucleus or represses the expression of pro-inflammatory proteins in the cytosol (by preventing the translocation of other transcription factors from the cytosol ... [...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] |
NF-κB
Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a protein complex that controls transcription of DNA, cytokine production and cell survival. NF-κB is found in almost all animal cell types and is involved in cellular responses to stimuli such as stress, cytokines, free radicals, heavy metals, ultraviolet irradiation, oxidized LDL, and bacterial or viral antigens. NF-κB plays a key role in regulating the immune response to infection. Incorrect regulation of NF-κB has been linked to cancer, inflammatory and autoimmune diseases, septic shock, viral infection, and improper immune development. NF-κB has also been implicated in processes of synaptic plasticity and memory. Discovery NF-κB was discovered by Ranjan Sen in the lab of Nobel laureate David Baltimore via its interaction with an 11-base pair sequence in the immunoglobulin light-chain enhancer in B cells. Later work by Alexander Poltorak and Bruno Lemaitre in mice and ''Drosophila'' frui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peroxisome Proliferator-activated Receptor
In the field of molecular biology, the peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptor proteins that function as transcription factors regulating the expression of genes. PPARs play essential roles in the regulation of cellular differentiation, development, and metabolism (carbohydrate, lipid, protein), and tumorigenesis of higher organisms. Nomenclature and tissue distribution Three types of PPARs have been identified: alpha, gamma, and delta (beta): * α (alpha) - expressed in liver, kidney, heart, muscle, adipose tissue, and others * β/δ (beta/delta) - expressed in many tissues, especially in brain, adipose tissue, and skin * γ (gamma) - although transcribed by the same gene, this PPAR, by way of alternative splicing, is expressed in three forms: ** γ1 - expressed in virtually all tissues, including heart, muscle, colon, kidney, pancreas, and spleen ** γ2 - expressed mainly in adipose tissue; it is 30 amino acids longer than γ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liver X Receptor
The liver X receptor (LXR) is a member of the nuclear receptor family of transcription factors and is closely related to nuclear receptors such as the PPARs, FXR and RXR. Liver X receptors (LXRs) are important regulators of cholesterol, fatty acid, and glucose homeostasis. LXRs were earlier classified as orphan nuclear receptors, however, upon discovery of endogenous oxysterols as ligands they were subsequently deorphanized. Two isoforms of LXR have been identified and are referred to as LXRα and LXRβ. The liver X receptors are classified into subfamily 1 (thyroid hormone receptor-like) of the nuclear receptor superfamily, and are given the nuclear receptor nomenclature symbols NR1H3 (LXRα) and NR1H2 (LXRβ) respectively. LXRα and LXRβ were discovered separately between 1994-1995. LXRα isoform was independently identified by two groups and initially named RLD-1 and LXR, whereas four groups identified the LXRβ isoform and called it UR, NER, OR-1, and RIP-15. The h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-inflammatory
Anti-inflammatory is the property of a substance or treatment that reduces inflammation or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs remedy pain by reducing inflammation as opposed to opioids, which affect the central nervous system to block pain signaling to the brain. Nonsteroidal anti-inflammatory drugs Nonsteroidal anti-inflammatory drugs (NSAIDs) alleviate pain by counteracting the cyclooxygenase (COX) enzyme. On its own, COX enzyme synthesizes prostaglandins, creating inflammation. In whole, the NSAIDs prevent the prostaglandins from ever being synthesized, reducing or eliminating the inflammation and resulting pain. Some common examples of NSAIDs are aspirin, ibuprofen, and naproxen. The newer specific COX-inhibitors are not classified together with the traditional NSAIDs, even though they presumably share the same mode of action. On the other hand, there are analgesics that are commonly associat ... [...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] |
Molecular Biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physical structure of biological macromolecules is known as molecular biology. Molecular biology was first described as an approach focused on the underpinnings of biological phenomena - uncovering the structures of biological molecules as well as their interactions, and how these interactions explain observations of classical biology. In 1945 the term molecular biology was used by physicist William Astbury. In 1953 Francis Crick, James Watson, Rosalind Franklin, and colleagues, working at Medical Research Council unit, Cavendish laboratory, Cambridge (now the MRC Laboratory of Molecular Biology), made a double helix model of DNA which changed the entire research scenario. They proposed the DNA structure based on previous research done by Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (genetics)
Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules called non-coding RNAs (ncRNAs). mRNA comprises only 1–3% of total RNA samples. Less than 2% of the human genome can be transcribed into mRNA ( Human genome#Coding vs. noncoding DNA), while at least 80% of mammalian genomic DNA can be actively transcribed (in one or more types of cells), with the majority of this 80% considered to be ncRNA. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. Transcription proceeds in the following general steps: # RNA polymerase, together with one or more general transcription factors, binds to promoter DNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
