phloretin inhibition
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Glifloziny patří mezi velmi perspektivní antidiabetika a kardiovaskulární léky. Jejich mechanismus účinku spočívá v inhibici transportního systému, který zajišťuje kotransport sodíku a glukózy (SGLT) a je exprimován v tenkém střevě (SGLT1), proximálním tubulu (SGLT2), ale i v jiných tkáních. Selektivita účinku vůči SGLT1 a SGLT2 je nejvýznamnějším faktorem ovlivňujícím farmakodynamické účinky gliflozinů. Článek je prvním v řadě textů, které dále popíší metabolismus a transport gliflozinů, míru a cesty jejich glukuronizace a lékové interakce.
Gliflozins are among the most promising antidiabetics and cardiovascular drugs. Their mechanism of action is the inhibition of sodium-glucose co-transporter (SGLT), which is expressed in the small intestine (SGLT1), the proximal tubule (SGLT2), and other tissues. The selectivity of action against SGLT1 and SGLT2 is the most important factor influencing the pharmacodynamic effects of gliflozins. The article is the first in a series of articles that further describe the metabolism and transport of gliflozins, the extent and pathways of their glucuronidation, and the drug interactions of gliflozins.
The human Na+ /H+ antiporter NHA2 (SLC9B2) transports Na+ or Li+ across the plasma membrane in exchange for protons, and is implicated in various pathologies. It is a 537 amino acids protein with an 82 residues long hydrophilic cytoplasmic N-terminus followed by a transmembrane part comprising 14 transmembrane helices. We optimized the functional expression of HsNHA2 in the plasma membrane of a salt-sensitive Saccharomyces cerevisiae strain and characterized in vivo a set of mutated or truncated versions of HsNHA2 in terms of their substrate specificity, transport activity, localization, and protein stability. We identified a highly conserved proline 246, located in the core of the protein, as being crucial for ion selectivity. The replacement of P246 with serine or threonine resulted in antiporters with altered substrate specificity that were not only highly active at acidic pH 4.0 (like the native antiporter), but also at neutral pH. P246T/S versions also exhibited increased resistance to the HsNHA2-specific inhibitor phloretin. We experimentally proved that a putative salt bridge between E215 and R432 is important for antiporter function, but also structural integrity. Truncations of the first 50-70 residues of the N-terminus doubled the transport activity of HsNHA2, while changes in the charge at positions E47, E56, K57, or K58 decreased the antiporter's transport activity. Thus, the hydrophilic N-terminal part of the protein appears to allosterically auto-inhibit cation transport of HsNHA2. Our data also show this in vivo approach to be useful for a rapid screening of SNP's effect on HsNHA2 activity.
- MeSH
- lidé MeSH
- Na(+)-H(+) antiport * chemie genetika MeSH
- protony * MeSH
- Saccharomyces cerevisiae genetika metabolismus MeSH
- sekvence aminokyselin MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
