Molecular mechanism of PP2A/B55α phosphatase inhibition by IER5
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Abstract
PP2A serine/threonine phosphatases are heterotrimeric complexes that execute many essential physiologic functions. These activities are modulated by additional regulatory proteins, such as ARPP19, FAM122A, and IER5. Here, we report the cryoelectron microscopy (cryo-EM) structure of a complex of PP2A/B55α with the N-terminal structured region of IER5 (IER5-N50), which occludes a surface on B55α used for substrate recruitment, and show that IER5-N50 inhibits PP2A/B55α catalyzed dephosphorylation of pTau in biochemical assays. Mutations of full-length IER5 that disrupt its PP2A/B55α interface interfere with co-immunoprecipitation of PP2A/B55α. IER5 antagonism of B55α in keratinocytes is required for expression of KRT1, a differentiation marker. Mini-IER5 composed of IER5-N50 and a nuclear localization sequence restores this activity in IER5 knockout cells. Using structural bioinformatics, we identify homology of IER5-N50 with SERTA (SEI-1, RBT-1, and TARA) domain containing proteins. These studies define the molecular basis of PP2A/B55α nuclear inhibition by IER5 and suggest a roadmap for selective pharmacologic modulation of PP2A/B55α complexes.
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- Authors
- Cao, R., Jones, D. T. D., Pan, L., Yang, A., Wang, S., Padi, S. K. R., Rawson, S., Aster, J. C., & Blacklow, S. C.
- Affiliations
- Harvard University (US)
- Brigham and Women's Hospital (US)
- UConn Health (US)
- Corresponding author
- Aster, Jon C.
- Blacklow, Stephen C.
- ORCID
- Venue
- Cell Chemical Biology
- Publisher
- Elsevier BV
- Published
- 2025-04
- Volume
- 32
- Issue
- 4
- Pages
- 631-642.e7
- ISSN
- 2451-9448 (ISSN-L)
- 2451-9456
- PMC
- PMC12067903
- OpenAlex
- W4409283374
- Cited by
- 7
- References
- 63
- Citations by year
- 2026: 1 · 2025: 5 · 2024: 1
- FWCI
- 0.62
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- www.elsevier.com/tdm/userlicense/1.0/ (tdm)
- www.elsevier.com/legal/tdmrep-license (tdm)
- www.elsevier.com/open-access/userlicense/1.0/ (am, 381 d)
- doi.org/10.15223/policy-017 (stm-asf)
- doi.org/10.15223/policy-037 (stm-asf)
- doi.org/10.15223/policy-012 (stm-asf)
- doi.org/10.15223/policy-029 (stm-asf)
- doi.org/10.15223/policy-004 (stm-asf)
- Locations
- Cell chemical biology (acceptedVersion)
- bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- PubMed Central (submittedVersion, cc-by-nc-nd)
- Funders
- National Institutes of Health Office of Extramural Research (1R35 CA220340, 1R01 CA272484)
- Ludwig Center at Harvard
- National Institutes of Health
- Charles H. Revson Foundation
- Warren Alpert Foundation
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Tyrosine Phosphatases
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Kinase Regulation and GTPase Signaling
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Signaling Pathways in Disease
- Keywords
- IER5, phosphatase inhibition, substrate recruitment, tau dephosphorylation, keratinocyte differentiation, keratin 1, protein complex structure, nuclear localization, phosphatase regulation
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