Advances in Genome Editing
Yashwant Pathak in Gene Delivery, 2022
The TALEN (Transcription Activator-Like Effector Nucleases) tool was introduced in 2011 to improve the efficiency, reliability, and accessibility of genome editing. The transcription activator-like effectors (TALES) generated by the phytopathogenic bacteria Xanthomonas genus gave rise to the TALEN system (Moore et al., 2014). The activator proteins are members of the DNA binding protein family and, like transcription factors in eukaryotic genomes, can be utilized to promote the expression of their target genes. The TALE proteins’ DNA binding domain is constituted of monomers of 34 amino acid residues, each of which binds one nucleotide in the target nucleotide sequence (Christian et al., 2012). Apart from two hypervariable amino acids (the repeat variable di-residues) at positions 12 and 13, the amino acid sequence of each repeat is fundamentally similar and in charge of identifying a specific nucleotide. (Mak et al., 2013). To produce TALEN-induced targeted genomic alteration, the functional endonuclease FokI is artificially coupled to DNA binding domains to form site-specific DSBs and encourage DNA recombination. The FokI cleavage domain must be dimerized in order to cleave the two strands of the targeted DNA. As a result, TALEN modules are built in pairs to engage opposing DNA target loci, with sufficient separation (12–20 bp) between the two binding sites (Li et al., 2011).
Spontaneous (Unexplained) Thrombosis: The Inherited Basis for the Thrombohemorrhagic Balance
E. Nigel Harris, Thomas Exner, Graham R. V. Hughes, Ronald A. Asherson in Phospholipid-Binding Antibodies, 2020
Although SK has been used for thrombolysis for a long period, it took more than 40 years with painstaking research from Astrup’s original observation to the final isolation and characterization of the natural activator, t-PA.36-38 By now, it is well appreciated that t-PA is localized in the vascular endothelium, and released in response to thrombin and a series of vasoactive constituents. Astonishingly, it was subsequently shown that it is released in close connection with inhibitors, of which there are more than one form.38 Presently, the physiological relation between the activator and the inhibitors remains unclear. Synthesis and release are modulated in several ways, e.g., by thrombin, endotoxin, growth factors, interleukin 1, etc.39 A hitherto important distinction from G AGs and thrombomodulin is that t-PA/PAI may be brought out of their site in the vessel endothelium, making them available for analysis in the blood. To bring this about stasis and/or a derivative of vasopressin, DDAVP, are used.
Antiplatelet Therapy
Hau C. Kwaan, Meyer M. Samama in Clinical Thrombosis, 2019
Activator antagonists are also under study. There are presently available antagonists to the following platelet activators: Thromboxane: several compounds, some of which are structural analogs to the eicosanoids, exist. One, called BM 13177,18 has reached its clinical phase.Serotonin, such as ketanserin;19,20 PAF-acether: two inhibitors are derived from Chinese medicinal plants — BN 52021 from Ginko biloba21 and kadsurenone;22 triazolobenzodiazepines such as alprazolam23 and a synthetic tetrahydrofuranoid called L-652,73124 are also under study.Collagen: the octapeptide Lys-Pro-Gly-Glu-Pro-Gly-Pro-Lys selectively inhibits platelet activation induced by collagen but has little effect on adhesion.25
Zinc pyrithione is a potent inhibitor of PLPro and cathepsin L enzymes with ex vivo inhibition of SARS-CoV-2 entry and replication
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Jerneja Kladnik, Ana Dolinar, Jakob Kljun, David Perea, Judith Grau-Expósito, Meritxell Genescà, Marko Novinec, Maria J. Buzon, Iztok Turel
The introduction of a methyl group at positions 3 (1b), 4 (1c), 5 (1d), and 6 (1e) resulted in somehow stronger inhibition of cathepsin L, compared with the unsubstituted complex 1a (IC50=1.88 ± 0.49 µM), with an IC50 of 0.35 ± 0.12 µM for 1b, 0.41 ± 0.08 µM for 1c, 0.44 ± 0.12 µM for 1d, and 0.24 ± 0.05 µM for 1e. Similar values were obtained for the complex with isoquinoline ligand (1f, IC50=0.14 ± 0.05 µM) and the complex with methoxy-substituted ligand (1h, IC50=0.74 ± 0.13 µM). Interestingly, the zinc complex with quinoline-derived pyrithione 1g showed complex behaviour with cathepsin L that prevented IC50 calculation. In Supplementary Figure 21, it can be observed that complex 1g has a dual mode of action. At concentrations below 0.1 µM and above 1 µM it acts as inhibitor, whereas in the intermediate concentration range it acts as activator. In addition, it is important to note that the ligands themselves are much weaker cathepsin L inhibitors compared to their zinc complexes (Supplementary Table 3).
Unmasking allosteric-binding sites: novel targets for GPCR drug discovery
Published in Expert Opinion on Drug Discovery, 2022
Verònica Casadó-Anguera, Vicent Casadó
- An allosteric modulator is a ligand that can modify the action of the endogenous activator, an orthosteric agonist or of an antagonist when is bound to the allosteric site on the receptor. Allosteric modulators can be positive (PAM), negative (NAM) or silent (SAM). A PAM increases the affinity and/or efficacy of an orthosteric agonist, activator, or antagonist. In contrast, a NAM decreases the affinity and/or efficacy of an orthosteric agonist, activator, or antagonist. Instead, an orthosteric agonist is ‘a ligand that binds to the orthosteric site of a receptor and modifies the receptor state, generating a biologic response. Conventional orthosteric agonists increase receptor activity, whereas orthosteric inverse agonists reduce it.’ A SAM is a ligand that binds to the allosteric site of a receptor but does not alter the affinity and/or efficacy of an orthosteric agonist, activator, or antagonist. Thus, a SAM (or ‘neutral allosteric ligand,’ NAL), via a steric interaction, can ‘prevent the binding of other allosteric ligands to the same allosteric site,’ and can act as a PAM or NAM of other ligands, including allosteric ligands binding to a different allosteric site on the receptor or different orthosteric ligands [5].
Effect of ultraviolet radiation on the Nrf2 signaling pathway in skin cells
Published in International Journal of Radiation Biology, 2021
Alena Ryšavá, Jitka Vostálová, Alena Rajnochová Svobodová
Pharmacological activation of the Nrf2 transcription factor seems to be an efficient strategy for suppressing OS associated with massive ROS generation in various tissues and organs, including the skin. Currently, more than 200 compounds have been reported to activate the Nrf2 protein in diverse cell types and stimulate its target genes expression (Victor et al. 2020). The activators include synthetic compounds as well as natural molecules commonly occurring in plants or food. To date, the most potent known Nrf2 activators are the semi-synthetic cyanoenone triterpenoids, designed from the natural product oleanolic acid (Dayalan Naidu and Dinkova-Kostova 2020). The best described natural Nrf2 activator is sulforaphane (Briones-Herrera et al. 2018; Cuadrado et al. 2019). Nrf2 activator dimethyl fumarate is marketed as a treatment for melanoma, the skin disorder psoriasis and some chronic inflammatory diseases, with the others under pre- or clinical trials for the treatment of the same (Cuadrado et al. 2019).
Related Knowledge Centers
- Protein Domain
- Rna Polymerase
- Transcription Factor
- Transcription
- DNA-Binding Protein
- Enhancer
- Promoter
- Rna Polymerase
- General Transcription Factor
- DNA-Binding Domain
- Transactivation Domain