Tyrosine Phosphorylation Regulates Plasma Membrane Expression and Stability of the Human Bile Acid Transporter ASBT (SLC10A2)

2019 ◽  
Vol 16 (8) ◽  
pp. 3569-3576 ◽  
Author(s):  
Paresh P. Chothe ◽  
Lindsay C. Czuba ◽  
Ebehiremen N. Ayewoh ◽  
Peter W. Swaan
Keyword(s):  
Plasma Membrane ◽  
Bile Acid ◽  
Tyrosine Phosphorylation ◽  
Membrane Expression ◽  
Human Bile ◽  
Plasma Membrane Expression ◽  
Bile Acid Transporter ◽  
Acid Transporter

scholarly journals Green tea catechin EGCG inhibits ileal apical sodium bile acid transporter ASBT

2010 ◽  
Vol 298 (3) ◽  
pp. G467-G473 ◽  
Author(s):  
Fadi Annaba ◽  
Pradeep Kumar ◽  
Amish K. Dudeja ◽  
Seema Saksena ◽  
Ravinder K. Gill ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Bile Acid ◽  
Green Tea ◽  
Insoluble Fraction ◽  
Membrane Expression ◽  
Tea Catechins ◽  
Hek 293 ◽  
Green Tea Catechins ◽  
Bile Acid Transporter ◽  
Acid Transporter

Green tea catechins exhibit hypocholesterolemic effects probably via their inhibitory effects on intestinal bile acid absorption. Ileal apical sodium-dependent bile acid transporter (ASBT) is responsible for reabsorption of bile acids. The present studies were, therefore, designed to investigate the modulation of ASBT function and membrane expression by green tea catechins in human embryonic kidney HEK-293 cells stably transfected with ASBT-V5 fusion protein and intestinal Caco-2 monolayers. Our data showed that ASBT activity was significantly decreased by (−)-epigallocatechin-3-gallate (EGCG) but not other green tea catechins. Inhibition of PKC, phosphatidylinositol 3-kinase, and MAPK-dependent pathways failed to block the reduction in ASBT activity by EGCG. Kinetics studies showed a significant decrease in the Vmax of the transporter, whereas total ASBT content on the plasma membrane was unaltered by EGCG. Concomitant with the decrease in ASBT function, EGCG significantly reduced ASBT pool in the detergent-insoluble fraction, while increasing its presence in the detergent-soluble fraction of plasma membrane. Furthermore, EGCG decreased the association of ASBT with floating lipid raft fractions of cellular membrane on Optiprep density gradient. In conclusion, our data demonstrate a novel role of lipid rafts in the modulation of ASBT function by the dietary component EGCG, which may underlie the hypocholesterolemic effects of green tea.

Electrostatic and potential cation-π forces may guide the interaction of extracellular loop III with Na+ and bile acids for human apical Na+-dependent bile acid transporter

2008 ◽  
Vol 410 (2) ◽  
pp. 391-400 ◽  
Author(s):  
Antara Banerjee ◽  
Naissan Hussainzada ◽  
Akash Khandelwal ◽  
Peter W. Swaan
Keyword(s):  
Amino Acids ◽  
Bile Acid ◽  
Bile Acids ◽  
Conformational Changes ◽  
Electrostatic Interactions ◽  
Extracellular Loop ◽  
Membrane Expression ◽  
Ligand Interaction ◽  
Bile Acid Transporter ◽  
Acid Transporter

The hASBT (human apical Na+-dependent bile acid transporter) constitutes a key target of anti-hypercholesterolaemic therapies and pro-drug approaches; physiologically, hASBT actively reclaims bile acids along the terminal ileum via Na+ co-transport. Previously, TM (transmembrane segment) 7 was identified as part of the putative substrate permeation pathway using SCAM (substitute cysteine accessibility mutagenesis). In the present study, SCAM was extended through EL3 (extracellular loop 3; residues Arg254–Val286) that leads into TM7 from the exofacial matrix. Activity of most EL3 mutants was significantly hampered upon cysteine substitution, whereas ten (out of 31) were functionally inactive (<10% activity). Since only E282C lacked plasma membrane expression, EL3 amino acids predominantly fulfill critical functional roles during transport. Oppositely charged membrane-impermeant MTS (methanethiosulfonate) reagents {MTSET [(2-trimethylammonium) ethyl MTS] and MTSES [(2-sulfonatoethyl) MTS]} produced mostly similar inhibition profiles wherein only middle and descending loop segments (residues Thr267–Val286) displayed significant MTS sensitivity. The presence of bile acid substrate significantly reduced the rates of MTS modification for all MTS-sensitive mutants, suggesting a functional association between EL3 residues and bile acids. Activity assessments at equilibrative [Na+] revealed numerous Na+-sensitive residues, possibly performing auxiliary functions during transport such as transduction of protein conformational changes during translocation. Integration of these data suggests ligand interaction points along EL3 via electrostatic interactions with Arg256, Glu261 and probably Glu282 and a potential cation-π interaction with Phe278. We conclude that EL3 amino acids are essential for hASBT activity, probably as primary substrate interaction points using long-range electrostatic attractive forces.

scholarly journals Human bile acid transporter ASBT (SLC10A2) forms functional non-covalent homodimers and higher order oligomers

2018 ◽  
Vol 1860 (3) ◽  
pp. 645-653 ◽  
Author(s):  
Paresh P. Chothe ◽  
Lindsay C. Czuba ◽  
Robyn H. Moore ◽  
Peter W. Swaan
Keyword(s):  
Bile Acid ◽  
Higher Order ◽  
Human Bile ◽  
Bile Acid Transporter ◽  
Acid Transporter

Resveratrol promotes degradation of the human bile acid transporter ASBT (SLC10A2)

2014 ◽  
Vol 459 (2) ◽  
pp. 301-312 ◽  
Author(s):  
Paresh P. Chothe ◽  
Peter W. Swaan
Keyword(s):  
Bile Acid ◽  
Human Bile ◽  
Ubiquitin Proteasome ◽  
Bile Acid Transporter ◽  
Acid Transporter

hASBT is negatively regulated by resveratrol, which acts by promoting ubiquitin–proteasome-mediated degradation of hASBT. The effect was specific, SIRT1-independent and does not require phosphorylation.

scholarly journals Transmembrane Domain V Plays a Stabilizing Role in the Function of Human Bile Acid Transporter SLC10A2

Biochemistry ◽  
2013 ◽  
Vol 52 (30) ◽  
pp. 5117-5124 ◽  
Author(s):  
Robyn H. Moore ◽  
Paresh Chothe ◽  
Peter W. Swaan
Keyword(s):  
Bile Acid ◽  
Transmembrane Domain ◽  
Human Bile ◽  
Bile Acid Transporter ◽  
Acid Transporter ◽  
Domain V

scholarly journals Transmembrane Domain II of the Human Bile Acid Transporter SLC10A2 Coordinates Sodium Translocation

2013 ◽  
Vol 288 (45) ◽  
pp. 32394-32404 ◽  
Author(s):  
Hairat Sabit ◽  
Sairam S. Mallajosyula ◽  
Alexander D. MacKerell ◽  
Peter W. Swaan
Keyword(s):  
Bile Acid ◽  
Transmembrane Domain ◽  
Human Bile ◽  
Bile Acid Transporter ◽  
Acid Transporter
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