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Derepression
In genetics and cell biology, repression is a mechanism often used to decrease or inhibit the expression of a gene. Removal of repression is called derepression. This mechanism may occur at different stages in the expression of a gene, with the result of increasing the overall RNA or protein products. Dysregulation of derepression mechanisms can result in altered gene expression patterns, which may lead to negative phenotypic consequences such as disease. Derepression of transcription Transcription can be repressed in a variety of ways, and therefore can be derepressed in different ways as well. A common mechanism is allosteric regulation. This is when a substrate binds a repressor protein and causes it to undergo a conformational change. If the repressor is bound upstream of a gene, such as in an operator sequence, then it would be repressing the gene's expression. This conformational change would take away the repressor’s ability to bind DNA, thus removing its repressive effec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (biology)
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auxin
Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essential for plant body development. The Dutch biologist Frits Warmolt Went first described auxins and their role in plant growth in the 1920s. Kenneth V. Thimann became the first to isolate one of these phytohormones and to determine its chemical structure as indole-3-acetic acid (IAA). Went and Thimann co-authored a book on plant hormones, ''Phytohormones'', in 1937. Overview Auxins were the first of the major plant hormones to be discovered. They derive their name from the Greek word αυξειν (''auxein'' – "to grow/increase"). Auxin is present in all parts of a plant, although in very different concentrations. The concentration in each position is crucial developmental information, so it is subject to tight regulation through both meta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beckwith–Wiedemann Syndrome
Beckwith–Wiedemann syndrome (; abbreviated BWS) is an overgrowth disorder usually present at birth, characterized by an increased risk of childhood cancer and certain congenital features. A minority (97th centile) * Macroglossia * Hemihyperplasia (asymmetric overgrowth of one or more regions of the body) * Omphalocele (also called exomphalos) or umbilical hernia * Embryonal tumor (e.g., Wilms tumor, hepatoblastoma, neuroblastoma, rhabdomyosarcoma) in childhood * Visceromegaly involving one or more intra-abdominal organs including liver, spleen, kidneys, adrenal glands, and/or pancreas * Cytomegaly of the fetal adrenal cortex (pathognomonic) * Renal abnormalities including structural abnormalities, nephromegaly, nephrocalcinosis, and/or later development of medullary sponge kidney * Anterior linear ear lobe creases and/or posterior helical ear pits * Placental mesenchymal dysplasia * Cleft palate (rare in BWS) * Cardiomyopathy (rare in BWS) * Positive family history (≥1 family m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuron
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. Non-animals like plants and fungi do not have nerve cells. Neurons are typically classified into three types based on their function. Sensory neurons respond to stimuli such as touch, sound, or light that affect the cells of the sensory organs, and they send signals to the spinal cord or brain. Motor neurons receive signals from the brain and spinal cord to control everything from muscle contractions to glandular output. Interneurons connect neurons to other neurons within the same region of the brain or spinal cord. When multiple neurons are connected together, they form what is called a neural circuit. A typical neuron consists of a cell body (soma), dendrites, and a single axon. The soma is a compact structure, and the axon and dend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MECP2
''MECP2'' (methyl CpG binding protein 2) is a gene that encodes the protein MECP2. MECP2 appears to be essential for the normal function of nerve cells. The protein seems to be particularly important for mature nerve cells, where it is present in high levels. The MECP2 protein is likely to be involved in turning off ("repressing" or " silencing") several other genes. This prevents the genes from making proteins when they are not needed. Recent work has shown that MECP2 can also activate other genes. The MECP2 gene is located on the long (q) arm of the X chromosome in band 28 ("Xq28"), from base pair 152,808,110 to base pair 152,878,611. MECP2 is an important reader of DNA methylation. Its methyl-CpG-binding (MBD) domain recognizes and binds 5-mC regions. MECP2 is X-linked and subject to X inactivation. MECP2 gene mutations are the cause of most cases of Rett syndrome, a progressive neurologic developmental disorder and one of the most common causes of cognitive disability in fem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autism
The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulties in social interaction, verbal and nonverbal communication, and the presence of repetitive behavior and restricted interests. Other common signs include unusual responses to sensory stimuli. Autism is generally understood as a ''spectrum disorder'', which means that it can manifest differently in each person: any given autistic individual is likely to show some, but not all, of the characteristics associated with it, and the person may exhibit them to varying degrees. Some autistic people remain nonspeaking over the course of their lifespan, while others have relatively unimpaired spoken language. There is large variation in the level of support people require, and the same person may present differently at varying times. Historically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurodevelopmental Disorder
Neurodevelopmental disorders are a group of disorders that affect the development of the nervous system, leading to abnormal brain function which may affect emotion, learning ability, self-control, and memory. The effects of neurodevelopmental disorders tend to last for a person's lifetime. Types Neurodevelopmental disorders are impairments of the growth and development of the brain and/or central nervous system. A narrower use of the term refers to a disorder of brain function that affects emotion, learning ability, self-control and memory which unfolds as an individual develops and grows. According to the DSM-5, the neurodevelopmental disorders include the following: # Attention deficit hyperactivity disorder (ADHD) # DLD - Developmental language disorder (formerly known as SLI- Specific Language Impairment) # Communication, speech, or language disorders, expressive language disorder, fluency disorder, social (pragmatic) communication disorder, and speech sound disorder. # ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rett Syndrome
Rett syndrome (RTT) is a genetic disorder that typically becomes apparent after 6–18 months of age and almost exclusively in females. Symptoms include impairments in language and coordination, and repetitive movements. Those affected often have slower growth, difficulty walking, and a smaller head size. Complications of Rett syndrome can include seizures, scoliosis, and sleeping problems. The severity of the condition is variable. Rett syndrome is due to a genetic mutation in the MECP2 gene, on the X chromosome. It almost always occurs as a new mutation, with less than one percent of cases being inherited from a person's parents. It occurs almost exclusively in girls; boys who have a similar mutation typically die shortly after birth. Diagnosis is based on the symptoms and can be confirmed with genetic testing. There is no known cure for Rett syndrome. Treatment is directed at improving symptoms. Anticonvulsants may be used to help with seizures. Special education, ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CREB-binding Protein
Cyclic adenosine monophosphate Response Element Binding protein Binding Protein (CREB-binding protein), also known as CREBBP or CBP or KAT3A, is a coactivator encoded by the ''CREBBP'' gene in humans, located on chromosome 16p13.3. CBP has intrinsic acetyltransferase functions; it is able to add acetyl groups to both transcription factors as well as histone lysines, the latter of which has been shown to alter chromatin structure making genes more accessible for transcription. This relatively unique acetyltransferase activity is also seen in another transcription enzyme, EP300 (p300). Together, they are known as the p300-CBP coactivator family and are known to associate with more than 16,000 genes in humans; however, while these proteins share many structural features, emerging evidence suggests that these two co-activators may promote transcription of genes with different biological functions. For example, CBP alone has been implicated in a wide variety of pathophysiologies inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoplasm
In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are cytosol (a gel-like substance), the organelles (the cell's internal sub-structures), and various cytoplasmic inclusions. The cytoplasm is about 80% water and is usually colorless. The submicroscopic ground cell substance or cytoplasmic matrix which remains after exclusion of the cell organelles and particles is groundplasm. It is the hyaloplasm of light microscopy, a highly complex, polyphasic system in which all resolvable cytoplasmic elements are suspended, including the larger organelles such as the ribosomes, mitochondria, the plant plastids, lipid droplets, and vacuoles. Most cellular activities take place within the cytoplasm, such as many metabolic pathways including glycolysis, and proces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PSEN1
Presenilin-1 (PS-1) is a presenilin protein that in humans is encoded by the ''PSEN1'' gene. Presenilin-1 is one of the four core proteins in the gamma secretase complex, which is considered to play an important role in generation of amyloid beta (Aβ) from amyloid-beta precursor protein (APP). Accumulation of amyloid beta is associated with the onset of Alzheimer's disease. Structure Presenilin possesses a 9 transmembrane domain topology, with an extracellular C-terminus and a cytosolic N-terminus. Presenilin undergoes endo-proteolytic processing to produce ~27-28 kDa N-terminal and ~16-17 kDa C-terminal fragments in humans. Furthermore, presenilin exists in the cell mainly as a heterodimer of the C-terminal and N-terminus fragments. When presenilin 1 is overexpressed, the full length protein accumulates in an inactive form. Based on evidence that a gamma-secretase inhibitor binds to the fragments, the cleaved presenilin complex is considered to be the active form. Function ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurodegenerative Disease
A neurodegenerative disease is caused by the progressive loss of structure or function of neurons, in the process known as neurodegeneration. Such neuronal damage may ultimately involve cell death. Neurodegenerative diseases include amyotrophic lateral sclerosis, multiple sclerosis, Parkinson's disease, Alzheimer's disease, Huntington's disease, multiple system atrophy, and prion diseases. Neurodegeneration can be found in the brain at many different levels of neuronal circuitry, ranging from molecular to systemic. Because there is no known way to reverse the progressive degeneration of neurons, these diseases are considered to be incurable; however research has shown that the two major contributing factors to neurodegeneration are oxidative stress and inflammation. Biomedical research has revealed many similarities between these diseases at the subcellular level, including atypical protein assemblies (like proteinopathy) and induced cell death. These similarities suggest that t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
