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Shelterin
Shelterin (also called telosome) is a protein complex known to protect telomeres in many eukaryotes from DNA repair mechanisms, as well as to regulate telomerase activity. In mammals and other vertebrates, telomeric DNA consists of repeating double-stranded 5'-TTAGGG-3' (G-strand) sequences (2-15 kilobases in humans) along with the 3'-AATCCC-5' (C-strand) complement, ending with a 50-400 nucleotide 3' (G-strand) overhang. Much of the final double-stranded portion of the telomere forms a T-loop (Telomere-loop) that is invaded by the 3' (G-strand) overhang to form a small D-loop (Displacement-loop). The absence of shelterin causes telomere uncapping and thereby activates damage-signaling pathways that may lead to non-homologous end joining (NHEJ), homology directed repair (HDR), end-to-end fusions, genomic instability, senescence, or apoptosis. Subunits Shelterin has six subunits: TRF1, TRF2, POT1, RAP1, TIN2, and TPP1. They can operate in smaller subsets to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telomere
A telomere (; ) is a region of repetitive nucleotide sequences associated with specialized proteins at the ends of linear chromosomes. Although there are different architectures, telomeres, in a broad sense, are a widespread genetic feature most commonly found in eukaryotes. In most, if not all species possessing them, they protect the terminal regions of chromosomal DNA from progressive degradation and ensure the integrity of linear chromosomes by preventing DNA repair systems from mistaking the very ends of the DNA strand for a double-strand break. Discovery In the early 1970s, Soviet theorist Alexei Olovnikov first recognized that chromosomes could not completely replicate their ends; this is known as the "end replication problem". Building on this, and accommodating Leonard Hayflick's idea of limited somatic cell division, Olovnikov suggested that DNA sequences are lost every time a cell replicates until the loss reaches a critical level, at which point cell division e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D-loop
In molecular biology, a displacement loop or D-loop is a DNA structure where the two strands of a double-stranded DNA molecule are separated for a stretch and held apart by a third strand of DNA. An R-loop is similar to a D-loop, but in this case the third strand is RNA rather than DNA. The third strand has a base sequence which is complementary to one of the main strands and pairs with it, thus displacing the other complementary main strand in the region. Within that region the structure is thus a form of triple-stranded DNA. A diagram in the paper introducing the term illustrated the D-loop with a shape resembling a capital "D", where the displaced strand formed the loop of the "D". D-loops occur in a number of particular situations, including in DNA repair, in telomeres, and as a semi-stable structure in mitochondrial circular DNA molecules. In mitochondria Researchers at Caltech discovered in 1971 that the circular mitochondrial DNA from growing cells included a sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TERF1
Telomeric repeat-binding factor 1 is a protein that in humans is encoded by the ''TERF1'' gene. Gene The human TERF1 gene is located in the chromosome 8 at 73,921,097-73,960,357 bp. Two transcripts of this gene are alternatively spliced products. The TERF1 gene is also known as TRF, PIN2 (Proteinase Inhibitor 2), TRF1, t-TRF1 and h-TRF1-AS. Protein The protein structure contains a C-terminal Myb motif, a dimerization domain (TERF homology) near its N-terminus and an acidic N-terminus. Subcellular distribution The cellular distribution of this DNA binding protein features the nucleoplasm, chromosomes, a telomeric region, a nuclear telomere cap complex, the cytoplasm, the spindle, the nucleus and a nucleolus and a nuclear chromosome. Function TERF 1 gene encodes a telomere specific protein which is a component of the telomere's shelterin nucleoprotein complex. This protein is present at telomeres throughout the cell cycle and functions as an inhibitor of telomer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Cell Science
The ''Journal of Cell Science'' (formerly the ''Quarterly Journal of Microscopical Science'') is a peer-reviewed scientific journal in the field of cell biology. The journal is published by The Company of Biologists. The journal is partnered with Publons, is part of the Review Commons initiative and has two-way integration with bioRxiv. ''Journal of Cell Science'' is a hybrid journal and publishes 24 issues a year. Content over 6 months old is free to read. History Foundation and early years The journal was established in 1853 as the ''Quarterly Journal of Microscopical Science'' (''Q. J. Microsc. Sci.'', ). The founding editors were Edwin Lankester and George Busk.''Quarterly Journal of Microscopical Science'' 1(1), front matter (accessed 18 April ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life Expectancy
Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, current age, and other demographic factors like sex. The most commonly used measure is life expectancy at birth (LEB), which can be defined in two ways. ''Cohort'' LEB is the mean length of life of a birth cohort (all individuals born in a given year) and can be computed only for cohorts born so long ago that all their members have died. ''Period'' LEB is the mean length of life of a hypothetical cohort assumed to be exposed, from birth through death, to the mortality rates observed at a given year. National LEB figures reported by national agencies and international organizations for human populations are estimates of ''period'' LEB. In the Bronze Age and the Iron Age, human LEB was 26 years; in 2010, world LEB was 67.2 years. In recent years, LEB in Eswatini (formerly Swaziland) is 49, while LEB in Japan is 83. The combination of high infant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adeno-associated Virus
Adeno-associated viruses (AAV) are small viruses that infect humans and some other primate species. They belong to the genus '' Dependoparvovirus'', which in turn belongs to the family '' Parvoviridae''. They are small (approximately 26 nm in diameter) replication-defective, nonenveloped viruses and have linear single-stranded DNA (ssDNA) genome of approximately 4.8 kilobases (kb). AAV are not currently known to cause disease. The viruses cause a very mild immune response. Several additional features make AAV an attractive candidate for creating viral vectors for gene therapy, and for the creation of isogenic human disease models. Gene therapy vectors using AAV can infect both dividing and quiescent cells and persist in an extrachromosomal state without integrating into the genome of the host cell. In the native virus, however, integration of virally carried genes into the host genome does occur. Integration can be important for certain applications, but can also have unw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Therapy
Gene therapy is a medical field which focuses on the genetic modification of cells to produce a therapeutic effect or the treatment of disease by repairing or reconstructing defective genetic material. The first attempt at modifying human DNA was performed in 1980, by Martin Cline, but the first successful nuclear gene transfer in humans, approved by the National Institutes of Health, was performed in May 1989. The first therapeutic use of gene transfer as well as the first direct insertion of human DNA into the nuclear genome was performed by French Anderson in a trial starting in September 1990. It is thought to be able to cure many genetic disorders or treat them over time. Between 1989 and December 2018, over 2,900 clinical trials were conducted, with more than half of them in phase I.Gene Therapy Cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aging Cell
''Aging Cell'' is a peer-reviewed open access scientific journal and an official journal of the Anatomical Society. It is published on their behalf by John Wiley & Sons. It was established in 2002 and the editors-in-chief are Peter Adams (Sanford Burnham Prebys Medical Discovery Institute) and Adam Antebi (Max Planck Institute for Biology of Ageing). The journal covers research on all aspects of aging, publishing research articles, reviews, minireviews, and commentaries. Abstracting and indexing The journal is abstracted and indexed in: According to the ''Journal Citation Reports'', the journal has a 2021 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as ... of 11.005. References External links * Gerontology journals Molecular and cellular biology journals Wiley ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer Cell (journal)
''Cancer Cell'' is a peer-reviewed scientific journal scientific journal that publishes articles that provide major advances in cancer research and oncology. The journal considers manuscripts that answer important questions relevant to naturally occurring cancers. Areas covered include basic cancer biology, therapeutic development, translational research, cancer model development, multi-omics and computational biology. ''Cancer Cell'' is also interested in publishing clinical investigations, in particular those that lead to establishing new paradigms in the treatment, diagnosis, or prevention of cancers; those that provide important insights into cancer biology beyond what has been revealed by preclinical studies; and those that are mechanism-based proof-of-principle clinical studies. ''Cancer Cell'' is internationally regarded as one of the top cancer research and oncology journals. According to the Journal Citation Reports, the 2021 impact factor of the journal is 38.585. It is pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer Stem Cell
Cancer stem cells (CSCs) are cancer cells (found within tumors or hematological cancers) that possess characteristics associated with normal stem cells, specifically the ability to give rise to all cell types found in a particular cancer sample. CSCs are therefore tumorigenic (tumor-forming), perhaps in contrast to other non-tumorigenic cancer cells. CSCs may generate tumors through the stem cell processes of self-renewal and differentiation into multiple cell types. Such cells are hypothesized to persist in tumors as a distinct population and cause relapse and metastasis by giving rise to new tumors. Therefore, development of specific therapies targeted at CSCs holds hope for improvement of survival and quality of life of cancer patients, especially for patients with metastatic disease. Existing cancer treatments have mostly been developed based on animal models, where therapies able to promote tumor shrinkage were deemed effective. However, animals do not provide a complete mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glioblastoma
Glioblastoma, previously known as glioblastoma multiforme (GBM), is one of the most aggressive types of cancer that begin within the brain. Initially, signs and symptoms of glioblastoma are nonspecific. They may include headaches, personality changes, nausea, and symptoms similar to those of a stroke. Symptoms often worsen rapidly and may progress to unconsciousness. The cause of most cases of glioblastoma is not known. Uncommon risk factors include genetic disorders, such as neurofibromatosis and Li–Fraumeni syndrome, and previous radiation therapy. Glioblastomas represent 15% of all brain tumors. They can either start from normal brain cells or develop from an existing low-grade astrocytoma. The diagnosis typically is made by a combination of a CT scan, MRI scan, and tissue biopsy. There is no known method of preventing the cancer. Treatment usually involves surgery, after which chemotherapy and radiation therapy are used. The medication temozolomide is frequently use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Downregulation And Upregulation
In the biological context of organisms' production of gene products, downregulation is the process by which a cell decreases the quantity of a cellular component, such as RNA or protein, in response to an external stimulus. The complementary process that involves increases of such components is called upregulation. An example of downregulation is the cellular decrease in the expression of a specific receptor in response to its increased activation by a molecule, such as a hormone or neurotransmitter, which reduces the cell's sensitivity to the molecule. This is an example of a locally acting (negative feedback) mechanism. An example of upregulation is the response of liver cells exposed to such xenobiotic molecules as dioxin. In this situation, the cells increase their production of cytochrome P450 enzymes, which in turn increases degradation of these dioxin molecules. Downregulation or upregulation of an RNA or protein may also arise by an epigenetic alteration. Such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
