CRISPR/Cas9
Gene-based medicines - (Genetic engineering)
CRISPR / Cas9 - specific, efficient and versatile gene editing technology that we can use to modify, delete or correct precise areas of our DNA.
CRISPR/Cas9 edits genes by precisely cutting DNA and then letting natural DNA repair processes to take over. The system consists of two parts: the Cas9 enzyme and a guide RNA.
Telomeres
Telomeres, the specific DNA–protein structures found at both ends of each chromosome, protect genome from nucleolytic degradation, unnecessary recombination, repair, and interchromosomal fusion. Telomeres therefore play a vital role in preserving the information in our genome. As a normal cellular process, a small portion of telomeric DNA is lost with each cell division. When telomere length reaches a critical limit, the cell undergoes senescence and/or apoptosis. Telomere length may therefore serve as a biological clock to determine the lifespan of a cell and an organism. Certain agents associated with specific lifestyles may expedite telomere shortening by inducing damage to DNA in general or more specifically at telomeres and may therefore affect health and lifespan of an individual. In this review we highlight the lifestyle factors that may adversely affect health and lifespan of an individual by accelerating telomere shortening and also those that can potentially protect telomeres and health of an individual.
Telomere length can be prevented from shortening by an enzyme Telomerase. Telomerase has a protein subunit (hTERT) and an RNA subunit (hTR). This enzyme is active in germline and stem cells and maintains their telomere length by adding ‘TTAGGG’ repeats to the ends of chromosomes. Therefore, telomeres do not shorten in these types of cells. Telomerase is inactive in normal somatic cells. These cells, therefore, lose telomeres over time and when telomere length reaches below a critical limit, cells either senesce or die. In the absence of appropriate signals for senescence or apoptotic death, continued cell division leads to severe telomere shortening and genomic instability.
Gene TERT - Telomerase
Location: 5p15.33
Homo sapiens
Telomerase is a ribonucleoprotein polymerase that maintains telomere ends by addition of the telomere repeat TTAGGG. The enzyme consists of a protein component with reverse transcriptase activity, encoded by this gene, and an RNA component which serves as a template for the telomere repeat. Telomerase expression plays a role in cellular senescence, as it is normally repressed in postnatal somatic cells resulting in progressive shortening of telomeres.
Telomerase also participates in chromosomal repair, since de novo synthesis of telomere repeats may occur at double-stranded breaks.
TP2; TRT; CMM9; EST2; TCS1; hTRT; DKCA2; DKCB4; hEST2; PFBMFT1
Gene Sirt6 - Repair DNALocation: 19p13.3Homo sapiens
This gene encodes a member of the sirtuin family of NAD-dependent enzymes that are implicated in cellular stress resistance, genomic stability, aging and energy homeostasis. The encoded protein is localized to the nucleus, exhibits ADP-ribosyl transferase and histone deacetylase activities, and plays a role in DNA repair, maintenance of telomeric chromatin, inflammation, lipid and glucose metabolism.
sirtuin 6, SIR2L6
Telomeres
Telomere length shortens with age. Progressive shortening of telomeres leads to senescence, apoptosis, or oncogenic transformation of somatic cells, affecting the health and lifespan of an individual. Shorter telomeres have been associated with increased incidence of diseases and poor survival. The rate of telomere shortening can be either increased or decreased by specific lifestyle factors. Better choice of diet and activities has great potential to reduce the rate of telomere shortening or at least prevent excessive telomere attrition, leading to delayed onset of age-associated diseases and increased lifespan.
TTAGGG, TAGGG, TTTGGG, TTAAGG
CRISPR/Cas9 edits genes by precisely cutting DNA and then letting natural DNA repair processes to take over. The system consists of two parts: the Cas9 enzyme and a guide RNA.
Cas9: a CRISPR-associated (Cas) endonuclease is a 160 kilodalton protein, or enzyme, that acts as “molecular scissors” to cut DNA at a location specified by a guide RNA.
Deoxyribonucleic acid (DNA): the molecule that most organisms use to store genetic information, which contains the “instructions for life”.
Ribonucleic acid (RNA): a molecule related to DNA that living things use for a number of purposes, including transporting and reading the DNA “instructions”.
Guide RNA (gRNA): a type of RNA molecule that binds to Cas9 and specifies, based on the sequence of the gRNA, the location at which Cas9 will cut DNA.
