Effekte chemisch induzierter β-Arrestin-1-Translokation an die Chemokinrezeptoren CXCR4 und CCR5

Effects of chemically induced β-arrestin 1 translocation to chemokine receptors CXCR4 and CCR5

by Viola Vogt
Doctoral thesis
Date of Examination:2021-07-27
Date of issue:2021-07-19
Advisor:Prof. Dr. Martin Oppermann
Referee:Prof. Dr. Martin Oppermann
Referee:Prof. Dr. Peter Schu
Persistent Address: http://dx.doi.org/10.53846/goediss-8739

 

 

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Abstract

English

Based on heterodimerization of chemokine receptors CXCR4 and CCR5 with β-arrestin 1 in co-expressing HEK 293 cells, this study shows β-arrestin 1-dependent effects without usual ligand induced receptor and G protein activation. These effects were compared to those of a constitutively active β arrestin 1R169E mutant.  In result, ligand-independent effects of chemically induced β-arrestin 1 translocation to unstimulated chemokine receptors were found: β-arrestin 1 desensitizes, internalizes and triggers MAPK signaling without G protein activation. Regarding receptor internalization, the β-arrestin-1R169E mutant exceeds wildtype β-arrestin 1 effects. β-arrestin 1 conformation changes seem to have a relevant impact on cellular process regulation.                                                                                                                                                     First, HEK 293 cells co-expressing CXCR4 / CCR5 with β-arrestin 1 / β-arrestin 1R169E combined with c-terminally added dimerization domains from a heterodimerization system were established. Due to chemically induced contact between chemokine receptor and interacting β-arrestin 1, receptor desensitization occurred. Ligand-independent β-arrestin 1 translocation to CCR5 via heterodimerization reached a similar receptor internalization level compared with usual ligand stimulation. CXCR4 internalization after chemically induced β-arrestin 1 translocation reached a comparable level but did not attain its chemokine induced internalization maximum. Regarding intracellular receptor trafficking, no receptor distribution differences were found between ligand stimulation and chemically induced β-arrestin 1 translocation. Moreover, β-arrestin 1 co-accumulated with both chemokine receptors in intracellular departments via chemically induced translocation. This co-accumulation did not occur in ligand stimulated cells with β-arrestin 1 wildtype but increased after ligand stimulation in cells with β-arrestin 1R169E mutants. In addition, β-arrestin 1R169E had a stronger receptor internalization potential compared to the wildtype. Chemically induced β-arrestin 1 translocation to the chemokine receptors CXCR4 and CCR5 showed ligand-independent ERK1/2 activation, whereas β-arrestin 1R169E mutants did not have stronger effects on ERK1/2 activation compared with wildtype β-arrestin 1.
Keywords: β-arrestin 1; β-arrestin 1R169E; CXCR4; CCR5; heterodimerization; receptor desensitization; receptor internalization; ERK1/2; β-arrestin-dependent
Schlagwörter: β-Arrestin-1; β-Arrestin-1R169E; CXCR4; CCR5; Heterodimerisierung; Rezeptordesensibilisierung; Rezeptorinternalisierung; ERK1/2; β-Arrestin-abhängig
 
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