Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form

The role of G protein-coupled receptor kinases in modulating γ-secretase activity and amyloid-β generation

Todd, Nicholas (2021) The role of G protein-coupled receptor kinases in modulating γ-secretase activity and amyloid-β generation. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

Download (5MB) | Preview


Pathological changes in the Alzheimer’s disease (AD) brain begin up to 20 years prior to
the clinical onset of dementia, initially with the aggregation of amyloid-β (Aβ) peptides generated
via processive proteolytic cleavage of the amyloid precursor protein (APP) by β-secretase followed
by γ-secretase. The γ-secretase complex is a four-subunit aspartyl protease complex that consists
of a catalytic presenilin 1 or 2 (PS1 or PS2) subunit, nicastrin (NCT), presenilin enhancer 2
(PEN2), and anterior pharynx-defective 1 (APH1) A or B (APH1A or APH1B). The orphan G
protein-coupled receptor (GPCR) GPR3 is a regulator of γ-secretase activity and Aβ generation in
AD. GPR3-mediated γ-secretase activity requires GPR3 C-terminal phosphorylation and
recruitment of the multifunctional scaffolding protein β-arrestin 2 (βarr2). Canonical GPCR
phosphorylation is regulated via the family of kinases known as GPCR kinases (GRKs).
Interestingly, βarr2 has been shown to interact directly with the APH1A subunit of γ-secretase,
independent of a specific GPCR, to regulate γ-secretase activity. Furthermore, emerging evidence
suggests that GRKs regulate both Aβ and tau pathology in AD. Similar to GPCRs, APH1A
contains seven transmembrane domains and putative phosphorylation sites in intracellular loop 2
and the carboxy-terminus. Therefore, we hypothesized that the GRK family of kinases can directly
regulate γ-secretase activity via modulating non-canonical APH1A phosphorylation and
interaction with βarr2 and that specific GRKs can regulate GPR3-mediated Aβ via canonical
regulation of the GPCR GPR3. Here, we uncover a novel and constitutive role of the GRK family
of kinases in regulating APH1A phosphorylation and βarr2 interactions. We determine that distinct
GRK-mediated phosphorylation barcodes differentially regulate βarr2 binding and γ-secretase
cleavage of APP. Computational docking and molecular dynamic simulations reveal that βarr2
binds to APH1A in a similar fashion as a GPCR. Additionally, we discover that GRK2 kinase
activity specifically regulates GPR3-mediated Aβ generation. While the exact downstream
mechanisms of GPR3-βarr2 signaling that regulate Aβ generation are still undetermined, we
propose a model whereby both GPR3 trafficking and regulation of APH1A-βarr2 interaction are
involved. Together, this work suggests that drugs targeting the APH1A-βarr2 interaction and
GPR3 biased ligands may be therapeutically beneficial in AD.


Social Networking:
Share |


Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Todd, Nicholasnkt11@pitt.edunkt110000-0002-3924-1464
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairAizenman, Eliasredox@pitt.eduredox
Thesis AdvisorThathiah, Amanthaamantha@pitt.eduamantha
Committee MemberKoldamova, Radosvetaradak@pitt.eduradak
Committee MemberBrodsky, Jeffreyjbrodsky@pitt.edujbrodsky
Committee MemberFriedman, Peterpaf10@pitt.edupaf10
Date: 17 December 2021
Date Type: Publication
Defense Date: 28 October 2021
Approval Date: 17 December 2021
Submission Date: 30 November 2021
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 181
Institution: University of Pittsburgh
Schools and Programs: School of Medicine > Molecular Pharmacology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: GRK GPCR Kinase G protein-coupled receptor kinase Gamma secretase Amyloid beta APH1A
Date Deposited: 17 Dec 2021 14:29
Last Modified: 17 Dec 2021 14:29


Monthly Views for the past 3 years

Plum Analytics

Actions (login required)

View Item View Item