Structural basis of protein phosphatase 2A stable latency

Li, Jiang; Stanevich, Vitali; Satyshur, Kenneth A.; Kong, Mei; Watkins, Guy R.; Wadzinski, Brian E.; Sengupta, Rituparna; Xing, Yongna

doi:10.1038/ncomms2663

Cited by 65 publications

(132 citation statements)

References 43 publications

Supporting

Mentioning

116

Contrasting

Unclassified

Order By: Relevance

“…The A-subunit binding site is also formed by protein loops directly connected to the central β-sheets, but is located on a surface opposite to the active site [17]. This architecture explains a recent observation that eviction of catalytic metal ions led to local unfolding of the PP2Ac active site and a relay of conformational changes via central β-sheets that perturbed the scaffold subunit binding site at the opposite surface [18]. Due to a direct binding of LCMT-1 to the PP2Ac active site, perturbation of the PP2Ac active site also hindered LCMT-1-mediated PP2A methylation [11].…”

Section: Introductionmentioning

confidence: 90%

Mechanisms of the Scaffold Subunit in Facilitating Protein Phosphatase 2A Methylation

et al. 2014

Self Cite

View full text Add to dashboard Cite

The function of the biologically essential protein phosphatase 2A (PP2A) relies on formation of diverse heterotrimeric holoenzymes, which involves stable association between PP2A scaffold (A) and catalytic (C or PP2Ac) subunits and binding of variable regulatory subunits. Holoenzyme assembly is highly regulated by carboxyl methylation of PP2Ac-tail; methylation of PP2Ac and association of the A and C subunits are coupled to activation of PP2Ac. Here we showed that PP2A-specific methyltransferase, LCMT-1, exhibits a higher activity toward the core enzyme (A–C heterodimer) than free PP2Ac, and the A-subunit facilitates PP2A methylation via three distinct mechanisms: 1) stabilization of a proper protein fold and an active conformation of PP2Ac; 2) limiting the space of PP2Ac-tail movement for enhanced entry into the LCMT-1 active site; and 3) weak electrostatic interactions between LCMT-1 and the N-terminal HEAT repeats of the A-subunit. Our results revealed a new function and novel mechanisms of the A-subunit in PP2A methylation, and coherent control of PP2A activity, methylation, and holoenzyme assembly.

show abstract

Section: Introductionmentioning

confidence: 90%

Mechanisms of the Scaffold Subunit in Facilitating Protein Phosphatase 2A Methylation

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…The exact function of α4 on PP2Ac has been difficult to unravel. Our recent structural evidence suggests it preferentially binds to the partially folded PP2Ac and stabilizes it for stable latency (Jiang et al ., 2013). α4 stabilizes PP2Ac in part by protecting it from ubiquitination by Midline 1 (MID1) and preventing its subsequent degradation (Liu et al ., 2001; Short et al ., 2002).…”

Section: Protein Phosphatase 2a: a Complex And Diverse Family Of Phosmentioning

confidence: 99%

“…α4 stabilizes PP2Ac in part by protecting it from ubiquitination by Midline 1 (MID1) and preventing its subsequent degradation (Liu et al ., 2001; Short et al ., 2002). This provides a pool of latent PP2Ac for the biogenesis of diverse heterotrimeric holoenzymes while simultaneously preventing the unregulated phosphatase activity of free PP2Ac and protecting cells from nontargeted dephosphorylation (Jiang et al ., 2013). …”

Section: Protein Phosphatase 2a: a Complex And Diverse Family Of Phosmentioning

confidence: 99%

“…The core of PP2Ac contains two central β-sheets flanked by α-helices, with the loops connecting to the β-sheets forming the active site, and the active site loops harbor six conserved residues that chelate catalytic metal ions. The active site loops are highly dynamic (Guo et al ., 2014; Jiang et al ., 2013). As such, all holoenzyme (and core enzyme) structures solved to date required potent inhibitors such as microcystin LR (MCLR) or okadaic acid (OA) to stabilize the active site for crystallization (Wlodarchak et al ., 2013; Xing et al ., 2006; Xu et al ., 2006,2008,2009).…”

Section: Protein Phosphatase 2a: a Complex And Diverse Family Of Phosmentioning

confidence: 99%

See 1 more Smart Citation

PP2A as a master regulator of the cell cycle

Wlodarchak

Xing

2016

Critical Reviews in Biochemistry and Molecular Biology

Self Cite

306

273

View full text Add to dashboard Cite

Protein phosphatase 2A (PP2A) plays a critical multi-faceted role in the regulation of the cell cycle. It is known to dephosphorylate over 300 substrates involved in the cell cycle, regulating almost all major pathways and cell cycle checkpoints. PP2A is involved in such diverse processes by the formation of structurally distinct families of holoenzymes, which are regulated spatially and temporally by specific regulators. Here, we review the involvement of PP2A in the regulation of three cell signaling pathways: wnt, mTOR and MAP kinase, as well as the G1→S transition, DNA synthesis and mitotic initiation. These processes are all crucial for proper cell survival and proliferation and are often deregulated in cancer and other diseases.

show abstract

“…Besides the prototypic heterotrimers, "atypical" PP2A complexes consisting of PP2Ac and ␣4 protein exist wherein, PP2A is maintained in an inactive state (30,31). Our identification of the PP2Ac-CIN85 complex and the in vitro finding that CIN85 restrains PP2A activity (Fig.…”

Section: Discussionmentioning

confidence: 59%

A Novel Interaction of the Catalytic Subunit of Protein Phosphatase 2A with the Adaptor Protein CIN85 Suppresses Phosphatase Activity and Facilitates Platelet Outside-in αIIbβ3 Integrin Signaling

Khatlani¹,

Pradhan²,

Da³

et al. 2016

Journal of Biological Chemistry

View full text Add to dashboard Cite

The transduction of signals generated by protein kinases and phosphatases are critical for the ability of integrin ␣ IIb ␤ 3 to support stable platelet adhesion and thrombus formation. Unlike kinases, it remains unclear how serine/threonine phosphatases engage the signaling networks that are initiated following integrin ligation. Because protein-protein interactions form the backbone of signal transduction, we searched for proteins that interact with the catalytic subunit of protein phosphatase 2A (PP2Ac). In a yeast two-hybrid study, we identified a novel interaction between PP2Ac and an adaptor protein CIN85 (Cbl-interacting protein of 85 kDa). Truncation and alanine mutagenesis studies revealed that PP2Ac binds to the P3 block ( 396 PAIPPKKPRP 405 ) of the proline-rich region in CIN85. The interaction of purified PP2Ac with CIN85 suppressed phosphatase activity. Human embryonal kidney 293 ␣ IIb ␤ 3 cells overexpressing a CIN85 P3 mutant, which cannot support PP2Ac binding, displayed decreased adhesion to immobilized fibrinogen. Platelets contain the ϳ85 kDa CIN85 protein along with the PP2Ac-CIN85 complex. A myristylated cell-permeable peptide derived from residues 395-407 of CIN85 protein (P3 peptide) disrupted the platelet PP2Ac-CIN85 complex and decreased ␣ IIb ␤ 3 signaling dependent functions such as platelet spreading on fibrinogen and thrombin-mediated fibrin clot retraction. In a phospho-profiling study P3 peptide treated platelets also displayed decreased phosphorylation of several signaling proteins including Src and GSK3␤. Taken together, these data support a role for the novel PP2Ac-CIN85 complex in supporting integrindependent platelet function by dampening the phosphatase activity.An ischemic vascular event ensues when a blood vessel is occluded by platelet-rich thrombi at the site of ruptured atherosclerotic plaque. Exposure of platelets to collagen and/or von Willebrand factor under high shear stress within the milieu of plaque initiates the inside-out signaling processes that activates integrin ␣ IIb ␤ 3 (1). The activated integrin can engage fibrinogen and generate outside-in signals that facilitate cytoskeletal reorganization and support a cascade of functional changes, including platelet spreading, stable adhesion, granule secretion, and clot retraction; all processes that augment the size of the platelet thrombi (2, 3).The coordinated signaling networks that are initiated by the engagement of agonists and integrin receptors on platelets are essential to the development of thrombi (4, 5). Spatial and temporal assembly of multiprotein signaling complexes by adaptor proteins relay signals following the engagement of integrin. The reversible phosphorylation of proteins on tyrosine, serine, and threonine residues, under the control of kinases and phosphatases, is an essential component of signaling. Because the outside-in signaling process greatly amplifies the size of platelet thrombi, there is a desire to selectively target this signaling process in a new class of antithrombotic agents (6). ...

show abstract

Structural basis of protein phosphatase 2A stable latency

Cited by 65 publications

References 43 publications

Mechanisms of the Scaffold Subunit in Facilitating Protein Phosphatase 2A Methylation

Mechanisms of the Scaffold Subunit in Facilitating Protein Phosphatase 2A Methylation

PP2A as a master regulator of the cell cycle

A Novel Interaction of the Catalytic Subunit of Protein Phosphatase 2A with the Adaptor Protein CIN85 Suppresses Phosphatase Activity and Facilitates Platelet Outside-in αIIbβ3 Integrin Signaling

Contact Info

Product

Resources

About