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SIM1
Single-minded homolog 1, also known as class E basic helix-loop-helix protein 14 (bHLHe14), is a protein that in humans is encoded by the ''SIM1'' gene. Function SIM1 and SIM2 genes are homologs of ''Drosophila melanogaster'' single-minded (sim), so named because cells in the midline of the sim mutant embryo fail to properly develop and eventually die, and thus the paired longitudinal axon bundles that span the anterior-posterior axis of the embryo (analogous to the embryo's spinal cord) are collapsed into a "single" rudimentary axon bundle at the midline. SIM is a basic helix-loop-helix-PAS domain transcription factor that regulates gene expression in the midline cells. Because the sim gene plays an important role in Drosophila development and has peak levels of expression during the period of neurogenesis, it was proposed that the human SIM2 gene, which resides in a critical region of chromosome 21, is a candidate for involvement in certain dysmorphic features (particularly fac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SIM2
Single-minded homolog 2 is a protein that in humans is encoded by the ''SIM2'' gene. It plays a major role in the development of the central nervous system midline as well as the construction of the face and head. Function SIM1 and SIM2 genes are ''Drosophila'' single-minded (sim) gene homologs. The Drosophila sim gene encodes a transcription factor that is a master regulator of neurogenesis of midline cells in the central nervous system. SIM2 maps within the so-called Down syndrome chromosomal region, specifically on the q arm of chromosome 21, band 22.2. Based on the mapping position, its potential function as transcriptional repressor and similarity to Drosophila sim, it is proposed that SIM2 may contribute to some specific Down syndrome phenotypes Interactions SIM2 has been shown to interact with Aryl hydrocarbon receptor nuclear translocator. When the SIM2 gene is tranfected into PC12 cells, it affects the normal cycle of cell maturation. SIM2 inhibits the expression ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aryl Hydrocarbon Receptor Nuclear Translocator
The ARNT gene encodes the aryl hydrocarbon receptor nuclear translocator protein that forms a complex with ligand-bound aryl hydrocarbon receptor (AhR), and is required for receptor function. The encoded protein has also been identified as the beta subunit of a heterodimeric transcription factor, hypoxia-inducible factor 1 (HIF1). A t(1;12)(q21;p13) translocation, which results in a TEL-ARNT fusion protein, is associated with leukemia, acute myeloblastic leukemia. Three alternatively spliced variants encoding different isoforms have been described for this gene. The aryl hydrocarbon receptor (AhR) is involved in the induction of several enzymes that participate in xenobiotic metabolism. The ligand-free, cytosolic form of the aryl hydrocarbon receptor is complexed to Hsp90, heat shock protein 90. Binding of ligand, which includes dioxins and dioxin-like compounds, dioxin and polycyclic aromatic hydrocarbons, results in translocation of the ligand-binding subunit only into the nucle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PAS Domain
A Per-Arnt-Sim (PAS) domain is a protein domain found in all kingdoms of life. Generally, the PAS domain acts as a molecular sensor, whereby small molecules and other proteins associate via binding of the PAS domain. Due to this sensing capability, the PAS domain has been shown as the key structural motif involved in protein-protein interactions of the circadian clock, and it is also a common motif found in signaling proteins, where it functions as a signaling sensor. Discovery PAS domains are found in a large number of organisms from bacteria to mammals. The PAS domain was named after the three proteins in which it was first discovered: * Per – period circadian protein * Arnt – aryl hydrocarbon receptor nuclear translocator protein * Sim – single-minded protein Since the initial discovery of the PAS domain, a large quantity of PAS domain binding sites have been discovered in bacteria and eukaryotes. A subset called PAS LOV proteins are responsive to oxygen, light a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haploinsufficiency
Haploinsufficiency in genetics describes a model of dominant gene action in diploid organisms, in which a single copy of the wild-type allele at a locus in heterozygous combination with a variant allele is insufficient to produce the wild-type phenotype. Haploinsufficiency may arise from a ''de novo'' or inherited loss-of-function mutation in the variant allele, such that it yields little or no gene product (often a protein). Although the other, standard allele still produces the standard amount of product, the total product is insufficient to produce the standard phenotype. This heterozygous genotype may result in a non- or sub-standard, deleterious, and (or) disease phenotype. Haploinsufficiency is the standard explanation for dominant deleterious alleles. In the alternative case of haplosufficiency, the loss-of-function allele behaves as above, but the single standard allele in the heterozygous genotype produces sufficient gene product to produce the same, standard phenotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxytocin
Oxytocin (Oxt or OT) is a peptide hormone and neuropeptide normally produced in the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, reproduction, childbirth, and the period after childbirth. Oxytocin is released into the bloodstream as a hormone in response to sexual activity and during labour. It is also available in pharmaceutical form. In either form, oxytocin stimulates uterine contractions to speed up the process of childbirth. In its natural form, it also plays a role in bonding with the baby and milk production. Production and secretion of oxytocin is controlled by a positive feedback mechanism, where its initial release stimulates production and release of further oxytocin. For example, when oxytocin is released during a contraction of the uterus at the start of childbirth, this stimulates production and release of more oxytocin and an increase in the intensity and frequency of contractions. This process compounds in intensity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraventricular Nucleus
The paraventricular nucleus (PVN, PVA, or PVH) is a nucleus in the hypothalamus. Anatomically, it is adjacent to the third ventricle and many of its neurons project to the posterior pituitary. These projecting neurons secrete oxytocin and a smaller amount of vasopressin, otherwise the nucleus also secretes corticotropin-releasing hormone (CRH) and thyrotropin-releasing hormone (TRH). CRH and TRH are secreted into the hypophyseal portal system and act on different targets neurons in the anterior pituitary. PVN is thought to mediate many diverse functions through these different hormones, including osmoregulation, appetite, and the response of the body to stress. Location The paraventricular nucleus lies adjacent to the third ventricle. It lies within the periventricular zone and is not to be confused with the periventricular nucleus, which occupies a more medial position, beneath the third ventricle. The PVN is highly vascularised and is protected by the blood–brain barrier, althou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanocortin
The melanocortins are a family of neuropeptide hormones which are the ligands of the melanocortin receptorsEricson, M.D., et al., ''Bench-top to clinical therapies: A review of melanocortin ligands from 1954 to 2016.'' Biochim Biophys Acta Mol Basis Dis, 2017. 1863(10 Pt A): p. 2414-2435. The melanocortin system consists of melanocortin receptors, ligands, and accessory proteins. The genes of the melanocortin system are found in chordates. Melanocortins were originally named so because their earliest known function was in melanogenesis. It is now known that the melanocortin system regulates diverse functions throughout the body, including inflammatory response, fibrosis, melanogenesis, steroidogenesis, energy homeostasis, sexual function, and exocrine gland function. There are four endogenous melanocortin agonists which are derived from post-transcriptional processing of the precursor molecule proopiomelanocortin (POMC) (Figure 1). They are Adrenocorticotropic hormone (ACTH), a-mel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperphagia
Polyphagia or hyperphagia is an abnormally strong, incessant sensation of hunger or desire to eat often leading to overeating. In contrast to an increase in appetite following exercise, polyphagia does not subside after eating and often leads to rapid intake of excessive quantities of food. Polyphagia is not a disorder by itself; rather, it is a symptom indicating an underlying medical condition. It is frequently a result of abnormal blood glucose levels (both hyperglycemia and hypoglycemia), and, along with polydipsia and polyuria, it is one of the "3 Ps" commonly associated with uncontrolled diabetes mellitus. Etymology and pronunciation The word ''polyphagia'' () uses combining forms of '' poly-'' + '' -phagia'', from the Greek words πολύς (polys), "very much" or "many", and φαγῶ (phago), "eating" or "devouring". Underlying conditions and possible causes Polyphagia is one of the most common symptoms of diabetes mellitus. It is associated with hyperthyroidism an ... [...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] |
Down Syndrome
Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual disability, and characteristic facial features. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an eight- or nine-year-old child, but this can vary widely. The parents of the affected individual are usually genetically normal. The probability increases from less than 0.1% in 20-year-old mothers to 3% in those of age 45. The extra chromosome is believed to occur by chance, with no known behavioral activity or environmental factor that changes the probability. Down syndrome can be identified during pregnancy by prenatal screening followed by diagnostic testing or after birth by direct observation and genetic testing. Since the introduction of screening, Down syndrome pregnancies are often abor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
