telomere capping
Definition
Target type: biologicalprocess
A process in which telomeres are protected from degradation and fusion, thereby ensuring chromosome stability by protecting the ends from both degradation and from being recognized as damaged DNA. May be mediated by specific single- or double-stranded telomeric DNA binding proteins. [GOC:mah, GOC:rn, PMID:11349150, PMID:11352055]
Telomere capping is a crucial biological process that protects the ends of chromosomes from degradation and fusion, preventing genomic instability and cell death. Telomeres are specialized DNA-protein structures located at the ends of eukaryotic chromosomes. They consist of repetitive DNA sequences, typically TTAGGG in humans, and associated proteins.
During DNA replication, the lagging strand cannot be completely copied, resulting in a shortening of the chromosome ends with each round of replication. Telomeres act as buffers, sacrificing themselves to prevent the loss of essential genetic information. However, if telomeres become too short, they can trigger cellular senescence or apoptosis.
Telomere capping involves a multi-step process that ensures the proper protection and function of telomeres:
1. **Shelterin Complex Formation:** The shelterin complex, a group of six proteins, binds to the telomeric DNA and forms a protective cap. These proteins include TRF1, TRF2, POT1, TPP1, TIN2, and RAP1.
2. **T-loop Formation:** TRF1 and TRF2 proteins bind to the double-stranded telomeric DNA, while POT1 binds to the single-stranded overhang. The interaction between these proteins facilitates the formation of a t-loop, where the single-stranded overhang invades the double-stranded telomeric DNA, forming a loop structure.
3. **Protection from Nucleases and Exonucleases:** The shelterin complex prevents the recognition of telomeres by DNA repair machinery, which could otherwise trigger degradation or fusion of the chromosome ends.
4. **Regulation of Telomere Length:** The shelterin complex also plays a role in regulating telomere length. TRF1 acts as a negative regulator, preventing excessive telomere elongation, while other proteins contribute to telomere maintenance.
5. **Telomerase Activity:** Telomerase, a specialized reverse transcriptase, adds telomeric repeats to the chromosome ends, counteracting the shortening that occurs during DNA replication. This enzyme is active in germ cells and some stem cells but is typically inactive in somatic cells.
6. **Signaling Pathways:** Telomere length and capping status can influence signaling pathways involved in cell cycle regulation, apoptosis, and aging. When telomeres become critically short, they can trigger cellular senescence or apoptosis, preventing the accumulation of cells with damaged DNA.
Telomere capping is essential for maintaining genomic stability and ensuring the proper functioning of chromosomes. Dysregulation of telomere capping can contribute to various diseases, including cancer, premature aging, and developmental disorders. Understanding the complex mechanisms of telomere capping provides insights into the intricate processes of DNA replication, repair, and cell aging.'
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Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Protection of telomeres protein 1 | A protection of telomeres protein 1 that is encoded in the genome of human. [PRO:CNx, Reactome:R-HSA-174890] | Homo sapiens (human) |
| DNA-dependent protein kinase catalytic subunit | A DNA-dependent protein kinase catalytic subunit that is encoded in the genome of human. [PRO:DNx, UniProtKB:P78527] | Homo sapiens (human) |
Compounds (47)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| vanillin | Vanilla: A plant genus of the family ORCHIDACEAE that is the source of the familiar flavoring used in foods and medicines (FLAVORING AGENTS). | benzaldehydes; monomethoxybenzene; phenols | anti-inflammatory agent; anticonvulsant; antioxidant; flavouring agent; plant metabolite |
| caffeine | purine alkaloid; trimethylxanthine | adenosine A2A receptor antagonist; adenosine receptor antagonist; adjuvant; central nervous system stimulant; diuretic; EC 2.7.11.1 (non-specific serine/threonine protein kinase) inhibitor; EC 3.1.4.* (phosphoric diester hydrolase) inhibitor; environmental contaminant; food additive; fungal metabolite; geroprotector; human blood serum metabolite; mouse metabolite; mutagen; plant metabolite; psychotropic drug; ryanodine receptor agonist; xenobiotic | |
| cgs 15943 | 9-chloro-2-(2-furyl)-(1,2,4)triazolo(1,5-c)quinazolin-5-imine: non-xanthine triazoloquinazoline adenosine antagonist CGS 15943 : A member of the class of triazoloquinazolines that is [1,2,4]triazolo[1,5-c]quinazoline substited at positions 2, 5 and 9 by furan-2-yl, amino and chloro groups respectively. A potent antagonist at adenosine A1 and adenosine A2A receptors. | aromatic amine; biaryl; furans; organochlorine compound; primary amino compound; quinazolines; triazoloquinazoline | adenosine A1 receptor antagonist; adenosine A2A receptor antagonist; antineoplastic agent; central nervous system stimulant |
| 2-(4-morpholinyl)-8-phenyl-4h-1-benzopyran-4-one | 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one: specific inhibitor of phosphatidylinositol 3-kinase; structure in first source | chromones; morpholines; organochlorine compound | autophagy inhibitor; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor; geroprotector |
| suramin | suramin : A member of the class of phenylureas that is urea in which each of the amino groups has been substituted by a 3-({2-methyl-5-[(4,6,8-trisulfo-1-naphthyl)carbamoyl]phenyl}carbamoyl)phenyl group. An activator of both the rabbit skeletal muscle RyR1 and sheep cardiac RyR2 isoform ryanodine receptor channels, it has been used for the treatment of human African trypanosomiasis for over 100 years. Suramin: A polyanionic compound with an unknown mechanism of action. It is used parenterally in the treatment of African trypanosomiasis and it has been used clinically with diethylcarbamazine to kill the adult Onchocerca. (From AMA Drug Evaluations Annual, 1992, p1643) It has also been shown to have potent antineoplastic properties. | naphthalenesulfonic acid; phenylureas; secondary carboxamide | angiogenesis inhibitor; antinematodal drug; antineoplastic agent; apoptosis inhibitor; EC 2.7.11.13 (protein kinase C) inhibitor; GABA antagonist; GABA-gated chloride channel antagonist; purinergic receptor P2 antagonist; ryanodine receptor agonist; trypanocidal drug |
| trifluoperazine | N-alkylpiperazine; N-methylpiperazine; organofluorine compound; phenothiazines | antiemetic; calmodulin antagonist; dopaminergic antagonist; EC 1.8.1.12 (trypanothione-disulfide reductase) inhibitor; EC 5.3.3.5 (cholestenol Delta-isomerase) inhibitor; phenothiazine antipsychotic drug | |
| flavone | flavone : The simplest member of the class of flavones that consists of 4H-chromen-4-one bearing a phenyl substituent at position 2. flavone: RN given refers to unlabeled cpd; structure given in first source | flavones | metabolite; nematicide |
| alpha-naphthoflavone | alpha-naphthoflavone : An extended flavonoid resulting from the formal fusion of a benzene ring with the h side of flavone. A synthetic compound, it is an inhibitor of aromatase (EC 1.14.14.14). alpha-naphthoflavone: inhibits P4501A1 and P4501A2; stimulates some activities of P4503A4 | extended flavonoid; naphtho-gamma-pyrone; organic heterotricyclic compound | aryl hydrocarbon receptor agonist; aryl hydrocarbon receptor antagonist; EC 1.14.14.14 (aromatase) inhibitor |
| 4,5-dimethoxy-2-nitrobenzaldehyde | aromatic ether; C-nitro compound | ||
| schizandrin b | schizandrin B: a phytogenic antineoplastic agent with anti-inflammatory activity; isolated from Schisandra plant | ||
| gefitinib | aromatic ether; monochlorobenzenes; monofluorobenzenes; morpholines; quinazolines; secondary amino compound; tertiary amino compound | antineoplastic agent; epidermal growth factor receptor antagonist | |
| 2-(4-morpholinyl)-4h-1-benzopyran-4-one | 2-(4-morpholinyl)-4H-1-benzopyran-4-one: an aminochromone; exhibits both antiproliferative and antichemotactic activity in vitro | ||
| sorafenib | (trifluoromethyl)benzenes; aromatic ether; monochlorobenzenes; phenylureas; pyridinecarboxamide | angiogenesis inhibitor; anticoronaviral agent; antineoplastic agent; EC 2.7.11.1 (non-specific serine/threonine protein kinase) inhibitor; ferroptosis inducer; tyrosine kinase inhibitor | |
| wortmannin | acetate ester; cyclic ketone; delta-lactone; organic heteropentacyclic compound | anticoronaviral agent; antineoplastic agent; autophagy inhibitor; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor; geroprotector; Penicillium metabolite; radiosensitizing agent | |
| dasatinib | dasatinib (anhydrous) : An aminopyrimidine that is 2-methylpyrimidine which is substituted at position 4 by the primary amino group of 2-amino-1,3-thiazole-5-carboxylic acid and at position 6 by a 4-(2-hydroxyethyl)piperazin-1-yl group, and in which the carboxylic acid group has been formally condensed with 2-chloro-6-methylaniline to afford the corresponding amide. A multi-targeted kinase inhibitor, it is used, particularly as the monohydrate, for the treatment of chronic, accelerated, or myeloid or lymphoid blast phase chronic myeloid leukemia. Note that the name 'dasatinib' is used to refer to the monohydrate (USAN) as well as to anhydrous dasatinib (INN). N-(2-chloro-6-methylphenyl)-2-((6-(4-(2-hydroxyethyl)piperazin-1-yl)-2-methylpyrimidin-4-yl)amino)-1,3-thiazole-5-carboxamide: a dasatinib prodrug; structure in first source | 1,3-thiazoles; aminopyrimidine; monocarboxylic acid amide; N-(2-hydroxyethyl)piperazine; N-arylpiperazine; organochlorine compound; secondary amino compound; tertiary amino compound | anticoronaviral agent; antineoplastic agent; tyrosine kinase inhibitor |
| uccf-029 | organic heterotricyclic compound; organooxygen compound | ||
| ku 55933 | 2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one: specific inhibitor of the ataxia-telangiectasia mutated kinase ATM; structure in first source | ||
| su 11248 | monocarboxylic acid amide; pyrroles | angiogenesis inhibitor; antineoplastic agent; EC 2.7.10.1 (receptor protein-tyrosine kinase) inhibitor; immunomodulator; neuroprotective agent; vascular endothelial growth factor receptor antagonist | |
| tanespimycin | CP 127374: analog of herbimycin A | 1,4-benzoquinones; ansamycin; carbamate ester; organic heterobicyclic compound; secondary amino compound | antineoplastic agent; apoptosis inducer; Hsp90 inhibitor |
| braco-19 | BRACO-19: structure in first source | acridines; N-alkylpyrrolidine | |
| ic 86621 | 1-(2-hydroxy-4-morpholin-4-ylphenyl)ethanone: a DNA-dependent protein kinase inhibitor | aromatic ketone | |
| nu 7026 | 2-(morpholin-4-yl)benzo(h)chromen-4-one: a radiosensitizing agent that inhibits DNA-dependent protein kinase; structure in first source | organic heterotricyclic compound; organooxygen compound | |
| pi103 | PI103: pyridofuropyrimidine antineoplastic; a potent inhibitor of class I phosphatidylinositide 3-kinases (PI3K); structure in first soruce | aromatic amine; morpholines; organic heterotricyclic compound; phenols; tertiary amino compound | antineoplastic agent; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor; mTOR inhibitor |
| nu 7441 | 8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one: structure in first source | dibenzothiophenes | |
| idelalisib | idelalisib : A member of the class of quinazolines that is 5-fluoro-3-phenylquinazolin-4-one in which the hydrogen at position 2 is replaced by a (1S)-1-(3H-purin-6-ylamino)propyl group. used for for the treatment of refractory indolent non-Hodgkin's lymphoma and relapsed chronic lymphocytic leukemia. idelalisib: an antineoplastic agent and p110delta inhibitor; structure in first source | aromatic amine; organofluorine compound; purines; quinazolines; secondary amino compound | antineoplastic agent; apoptosis inducer; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor |
| ku-0060648 | dibenzothiophenes | ||
| ku 60019 | |||
| buparlisib | NVP-BKM120: a pan class I PI3 kinase inhibitor with antineoplastic activity; structure in first source | aminopyridine; aminopyrimidine; morpholines; organofluorine compound | antineoplastic agent; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor |
| ku 0063794 | Ku 0063794: an mTOR inhibitor; structure in first source | benzyl alcohols; monomethoxybenzene; morpholines; pyridopyrimidine; tertiary amino compound | antineoplastic agent; mTOR inhibitor |
| gdc 0941 | pictrelisib : A sulfonamide composed of indazole, morpholine, and methylsulfonyl-substituted piperazine rings bound to a thienopyrimidine ring. | indazoles; morpholines; piperazines; sulfonamide; thienopyrimidine | EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor |
| PP121 | aromatic amine; cyclopentanes; pyrazolopyrimidine; pyrrolopyridine | antineoplastic agent; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor; tyrosine kinase inhibitor | |
| gdc 0980 | |||
| pki 587 | gedatolisib: inhibits both phosphatidylinositol 3-kinase and mTOR; structure in first source | ||
| cp 466722 | quinazolines | ||
| (3R)-4-[2-(1H-indol-4-yl)-6-(1-methylsulfonylcyclopropyl)-4-pyrimidinyl]-3-methylmorpholine | indoles | ||
| torin 1 | torin 1 : A member of the class of pyridoquinolines that is 9-(quinolin-3-yl)benzo[h][1,6]naphthyridin-2-one bearing an additional 4-(4-propionylpiperazin-1-yl)-3-(trifluoromethyl)phenyl substituent at position 1. It is a potent inhibitor of mTOR and exhibits anti-cancer properties. | N-acylpiperazine; N-arylpiperazine; organofluorine compound; pyridoquinoline; quinolines | antineoplastic agent; mTOR inhibitor |
| ve 821 | 3-amino-6-(4-(methylsulfonyl)phenyl)-N-phenylpyrazine-2-carboxamide: an antineoplastic agent; structure in first source | aromatic amide | |
| gdc-0032 | |||
| torin 2 | torin 2 : A member of the class of pyridoquinolines that is benzo[h][1,6]naphthyridin-2-one carrying additional 3-(trifluoromethyl)phenyl and 6-aminopyridin-3-yl substituents at positions 1 and 9 respectively. It is a potent inhibitor of mTOR and exhibits anti-cancer properties. | aminopyridine; organofluorine compound; primary amino compound; pyridoquinoline | antineoplastic agent; mTOR inhibitor |
| cudc-907 | |||
| sar245408 | |||
| byl719 | proline derivative | ||
| cc-115 | 1-ethyl-7-(2-methyl-6-(1H-1,2,4-triazol-3-yl)pyridin-3-yl)-3,4-dihydropyrazino(2,3-b)pyrazin-2(1H)-one: an mTOR kinase inhibitor; structure in first source | ||
| vx-970 | berzosertib: an ATR kinase inhibitor | sulfonamide | |
| etp-46464 | ETP-46464: inhibits ATM and Rad3-related kinase; structure in first source | ||
| isogranulatimide | isogranulatimide: G2 checkpoint inhibitor; structure in first source | ||
| pp242 | torkinib : A member of the class of pyrazolopyrimidines that is 1H-pyrazolo[3,4-d]pyrimidine substituted by isopropyl, 5-hydroxyindol-2-yl and amino groups at positions 1, 3 and 4 respectively. It is a potent inhibitor of mTOR and exhibits anti-cancer properties. | aromatic amine; biaryl; hydroxyindoles; phenols; primary amino compound; pyrazolopyrimidine | antineoplastic agent; mTOR inhibitor |