A disorder-related variant (E420K) of a PP2A-regulatory subunit (PPP2R5D) causes constitutively active AKT-mTOR signaling and uncoordinated cell growth

Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved..

Functional genomic approaches have facilitated the discovery of rare genetic disorders and improved efforts to decipher their underlying etiology. PPP2R5D-related disorder is an early childhood onset condition characterized by intellectual disability, hypotonia, autism-spectrum disorder, macrocephaly, and dysmorphic features. The disorder is caused by de novo single nucleotide changes in PPP2R5D, which generate heterozygous dominant missense variants. PPP2R5D is known to encode a B'-type (B'56δ) regulatory subunit of a PP2A-serine/threonine phosphatase. To help elucidate the molecular mechanisms altered in PPP2R5D-related disorder, we used a CRISPR-single-base editor to generate HEK-293 cells in which a single transition (c.1258G>A) was introduced into one allele, precisely recapitulating a clinically relevant E420K variant. Unbiased quantitative proteomic and phosphoproteomic analyses of endogenously expressed proteins revealed heterozygous-dominant changes in kinase/phosphatase signaling. These data combined with orthogonal validation studies revealed a previously unrecognized interaction of PPP2R5D with AKT in human cells, leading to constitutively active AKT-mTOR signaling, increased cell size, and uncoordinated cellular growth in E420K-variant cells. Rapamycin reduced cell size and dose-dependently reduced RPS6 phosphorylation in E420K-variant cells, suggesting that inhibition of mTOR1 can suppress both the observed RPS6 hyperphosphorylation and increased cell size. Together, our findings provide a deeper understanding of PPP2R5D and insight into how the E420K-variant alters signaling networks influenced by PPP2R5D. Our comprehensive approach, which combines precise genome editing, isobaric tandem mass tag labeling of peptides generated from endogenously expressed proteins, and concurrent liquid chromatography-mass spectrometry (LC-MS3), also provides a roadmap that can be used to rapidly explore the etiologies of additional genetic disorders.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:296

Enthalten in:

The Journal of biological chemistry - 296(2021) vom: 15. Jan., Seite 100313

Sprache:

Englisch

Beteiligte Personen:

Papke, Cinta M [VerfasserIn]
Smolen, Kali A [VerfasserIn]
Swingle, Mark R [VerfasserIn]
Cressey, Lauren [VerfasserIn]
Heng, Richard A [VerfasserIn]
Toporsian, Mourad [VerfasserIn]
Deng, Liyong [VerfasserIn]
Hagen, Jacob [VerfasserIn]
Shen, Yufeng [VerfasserIn]
Chung, Wendy K [VerfasserIn]
Kettenbach, Arminja N [VerfasserIn]
Honkanen, Richard E [VerfasserIn]

Links:

Volltext

Themen:

AKT-mTOR
EC 2.7.1.1
EC 2.7.11.1
EC 3.1.3.16
Jordan’s syndrome
Journal Article
MTOR protein, human
PP2A
PPP2R5D
PPP2R5D protein, human
PPP2R5D-intellectual disability
PPP2R5D-related neurodevelopmental disorder
Phosphatase
Protein Phosphatase 2
Proto-Oncogene Proteins c-akt
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
TOR Serine-Threonine Kinases

Anmerkungen:

Date Completed 26.08.2021

Date Revised 04.12.2021

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.jbc.2021.100313

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM320444325