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A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by viruses such as HIV and hepatitis B to replicate their genomes, by retrotransposon mobile genetic elements to proliferate within the host genome, and by eukaryotic cells to extend the telomeres at the ends of their linear chromosomes. Contrary to a widely held belief, the process does not violate the flows of genetic information as described by the classical central dogma, as transfers of information from RNA to DNA are explicitly held possible.
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.
Telomerase, also called terminal transferase, is a ribonucleoprotein that adds a species-dependent telomere repeat sequence to the 3' end of telomeres. A telomere is a region of repetitive sequences at each end of the chromosomes of most eukaryotes. Telomeres protect the end of the chromosome from DNA damage or from fusion with neighbouring chromosomes. The fruit fly Drosophila melanogaster lacks telomerase, but instead uses retrotransposons to maintain telomeres.
Elizabeth Helen Blackburn, is an Australian-American Nobel laureate who is the former president of the Salk Institute for Biological Studies. Previously she was a biological researcher at the University of California, San Francisco, who studied the telomere, a structure at the end of chromosomes that protects the chromosome. In 1984, Blackburn co-discovered telomerase, the enzyme that replenishes the telomere, with Carol W. Greider. For this work, she was awarded the 2009 Nobel Prize in Physiology or Medicine, sharing it with Greider and Jack W. Szostak, becoming the first Australian woman Nobel laureate. She also worked in medical ethics, and was controversially dismissed from the Bush administration's President's Council on Bioethics.
Thomas Robert Cech is an American chemist who shared the 1989 Nobel Prize in Chemistry with Sidney Altman, for their discovery of the catalytic properties of RNA. Cech discovered that RNA could itself cut strands of RNA, suggesting that life might have started as RNA. He also studied telomeres, and his lab discovered an enzyme, TERT, which is part of the process of restoring telomeres after they are shortened during cell division. As president of Howard Hughes Medical Institute, he promoted science education, and he teaches an undergraduate chemistry course at the University of Colorado.
The Hayflick limit, or Hayflick phenomenon, is the number of times a normal somatic, differentiated human cell population will divide before cell division stops. However, this limit does not apply to stem cells.
Dyskeratosis congenita (DKC), also known as Zinsser-Engman-Cole syndrome, is a rare progressive congenital disorder with a highly variable phenotype. The entity was classically defined by the triad of abnormal skin pigmentation, nail dystrophy, and leukoplakia of the oral mucosa, but these components do not always occur. DKC is characterized by short telomeres. Some of the manifestations resemble premature ageing. The disease initially mainly affects the skin, but a major consequence is progressive bone marrow failure which occurs in over 80%, causing early mortality.
Eternal youth is the concept of human physical immortality free of ageing. The youth referred to is usually meant to be in contrast to the depredations of aging, rather than a specific age of the human lifespan. Eternal youth is common in mythology, and is a popular theme in fiction.
Carolyn Widney Greider is an American molecular biologist and Nobel laureate. She joined the University of California, Santa Cruz as a Distinguished Professor in the department of molecular, cell, and developmental biology in October 2020.
Telomerase reverse transcriptase is a catalytic subunit of the enzyme telomerase, which, together with the telomerase RNA component (TERC), comprises the most important unit of the telomerase complex.
Telomerase RNA component, also known as TR, TER or TERC, is an ncRNA found in eukaryotes that is a component of telomerase, the enzyme used to extend telomeres. TERC serves as a template for telomere replication by telomerase. Telomerase RNAs differ greatly in sequence and structure between vertebrates, ciliates and yeasts, but they share a 5' pseudoknot structure close to the template sequence. The vertebrate telomerase RNAs have a 3' H/ACA snoRNA-like domain.
Sierra Sciences, LLC is a biotechnology company founded by William H. Andrews, former director of molecular biology at Geron Corporation. Andrews founded Sierra Sciences in 1999 in Reno, Nevada with the goal of preventing and/or reversing cellular senescence, and ultimately curing diseases associated with human aging, including the aging process itself.
Telomere-binding proteins function to bind telomeric DNA in various species. In particular, telomere-binding protein refers to TTAGGG repeat binding factor-1 (TERF1) and TTAGGG repeat binding factor-2 (TERF2). Telomere sequences in humans are composed of TTAGGG sequences which provide protection and replication of chromosome ends to prevent degradation. Telomere-binding proteins can generate a T-loop to protect chromosome ends. TRFs are double-stranded proteins which are known to induce bending, looping, and pairing of DNA which aids in the formation of T-loops. They directly bind to TTAGGG repeat sequence in the DNA. There are also subtelomeric regions present for regulation. However, in humans, there are six subunits forming a complex known as shelterin.
Chromosomal instability (CIN) is a type of genomic instability in which chromosomes are unstable, such that either whole chromosomes or parts of chromosomes are duplicated or deleted. More specifically, CIN refers to the increase in rate of addition or loss of entire chromosomes or sections of them. The unequal distribution of DNA to daughter cells upon mitosis results in a failure to maintain euploidy leading to aneuploidy. In other words, the daughter cells do not have the same number of chromosomes as the cell they originated from. Chromosomal instability is the most common form of genetic instability and cause of aneuploidy.
Titia de Lange is the Director of the Anderson Center for Cancer Research, the Leon Hess professor and the head of Laboratory Cell Biology and Genetics at Rockefeller University.
Telomeric repeat–containing RNA (TERRA) is a long non-coding RNA transcribed from telomeres - repetitive nucleotide regions found on the ends of chromosomes that function to protect DNA from deterioration or fusion with neighboring chromosomes. TERRA has been shown to be ubiquitously expressed in almost all cell types containing linear chromosomes - including humans, mice, and yeasts. While the exact function of TERRA is still an active area of research, it is generally believed to play a role in regulating telomerase activity as well as maintaining the heterochromatic state at the ends of chromosomes. TERRA interaction with other associated telomeric proteins has also been shown to help regulate telomere integrity in a length-dependent manner.
Bryant Villeponteau is an American scientist, entrepreneur, and longevity expert who has worked in both academia and industry.
Victoria Lundblad is an American geneticist whose work focuses on the genetic control of chromosome behavior in yeast. Many of her discoveries have concerned telomerase, the RNA-containing enzyme that completes the ends of chromosomes. She works at the Salk Institute in La Jolla, California.
Telomeres, the caps on the ends of eukaryotic chromosomes, play critical roles in cellular aging and cancer. An important facet to how telomeres function in these roles is their involvement in cell cycle regulation.
Joachim Lingner is a Swiss molecular biologist. He holds the professorship for life sciences and leads the Lingner Lab at the École Polytechnique Fédérale de Lausanne (EPFL).
References
- ↑ "Whitehead Institute - News - 2004 - Developmental science". wi.mit.edu. Retrieved August 15, 2020.
- ↑ "2016-2017 Fellows | Research UC Berkeley". vcresearch.berkeley.edu. Retrieved October 2, 2020.
- 1 2 "Long-sought structure of telomerase paves way for drugs for aging, cancer | Research UC Berkeley". vcresearch.berkeley.edu. Retrieved August 14, 2020.
- 1 2 3 4 5 "Trading in the Scalpel for a Sharper Blade | Research UC Berkeley". vcresearch.berkeley.edu. Retrieved August 14, 2020.
- ↑ Sanders, Robert (April 25, 2018). "Long-sought structure of telomerase paves way for drugs for aging, cancer". Berkeley News. Retrieved August 15, 2020.
- ↑ McMillan, Fiona. "Researchers Have Discovered What The 'Immortality' Enzyme Looks Like". Forbes. Retrieved August 15, 2020.
- ↑ "The 3D Structure of Telomerase: Uncovering Its Role in Human Disease". Drug Discovery from Technology Networks. Retrieved August 15, 2020.
- ↑ Sanders, Robert (April 23, 2020). "Nine faculty elected to American Academy of Arts and Sciences". Berkeley News. Retrieved August 15, 2020.
