BMP2K as a signaling effector of Atypical chemokine receptor 3 (2023)

Undergraduate: Saisha Dhar

Faculty Advisor: Sudarshan Rajagopal
Department: Biochemistry & Biophysics

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G protein-coupled receptors (GPCRs) are seven-transmembrane receptors that mediate the majority of cellular responses and are the target of 1/3 of all FDA-approved drugs. GPCRs are known to signal through two main protein pathways, G-proteins and β-arrestins, however Atypical chemokine receptor 3 (ACKR3) is a GPCR that was found to signal without G-protein, making it a protein of interest to study GPCR signaling through alternative pathways. To investigate what other signaling effectors may be responsible for regulating ACKR3 signaling, we conducted ACKR3-APEX2 proximity labeling in a β-arrestin knockout cell line, and found that the protein BMP2K is significantly upregulated with ACKR3 and is conserved across multiple GPCR data sets. Using a NanoBiT protein-protein interaction assay, we found that BMP2K recruits to ACKR3 independent of the β-arrestins, while other GPCRs (AT1R, B2AR, and V2R) recruit BMP2K with or through β-arrestin. To investigate the specific sites on ACKR3 that may be involved with signaling, we created five separate ACKR3 phosphodeficient mutants through site-directed mutagenesis. BMP2K recruitment to ACKR3 and ACKR3 internalization was significantly reduced with the proximal and C-tail truncation mutants, while β-arrestin 1 and 2 recruitment was reduced with the medial and C-tail truncation mutants. The similar pattern of BMP2K recruitment and ACKR3 internalization suggests that BMP2K recruitment either promotes ACKR3 internalization, or that ACKR3 internalization is necessary for BMP2K recruitment. We hope to further explore BMP2K’s function with ACKR3 to understand non-canonical signaling of GPCRs and create more efficient therapeutics.

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