Publications by authors named "Jane Findlay"

8 Publications

  • Page 1 of 1

The RanBP2/RanGAP1-SUMO complex gates β-arrestin2 nuclear entry to regulate the Mdm2-p53 signaling axis.

Oncogene 2021 Mar 1;40(12):2243-2257. Epub 2021 Mar 1.

Inserm, U1016, Institut Cochin, Paris, France.

Mdm2 antagonizes the tumor suppressor p53. Targeting the Mdm2-p53 interaction represents an attractive approach for the treatment of cancers with functional p53. Investigating mechanisms underlying Mdm2-p53 regulation is therefore important. The scaffold protein β-arrestin2 (β-arr2) regulates tumor suppressor p53 by counteracting Mdm2. β-arr2 nucleocytoplasmic shuttling displaces Mdm2 from the nucleus to the cytoplasm resulting in enhanced p53 signaling. β-arr2 is constitutively exported from the nucleus, via a nuclear export signal, but mechanisms regulating its nuclear entry are not completely elucidated. β-arr2 can be SUMOylated, but no information is available on how SUMO may regulate β-arr2 nucleocytoplasmic shuttling. While we found β-arr2 SUMOylation to be dispensable for nuclear import, we identified a non-covalent interaction between SUMO and β-arr2, via a SUMO interaction motif (SIM), that is required for β-arr2 cytonuclear trafficking. This SIM promotes association of β-arr2 with the multimolecular RanBP2/RanGAP1-SUMO nucleocytoplasmic transport hub that resides on the cytoplasmic filaments of the nuclear pore complex. Depletion of RanBP2/RanGAP1-SUMO levels result in defective β-arr2 nuclear entry. Mutation of the SIM inhibits β-arr2 nuclear import, its ability to delocalize Mdm2 from the nucleus to the cytoplasm and enhanced p53 signaling in lung and breast tumor cell lines. Thus, a β-arr2 SIM nuclear entry checkpoint, coupled with active β-arr2 nuclear export, regulates its cytonuclear trafficking function to control the Mdm2-p53 signaling axis.
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http://dx.doi.org/10.1038/s41388-021-01704-wDOI Listing
March 2021

Structural insights into TAZ2 domain-mediated CBP/p300 recruitment by transactivation domain 1 of the lymphopoietic transcription factor E2A.

J Biol Chem 2020 03 25;295(13):4303-4315. Epub 2020 Feb 25.

Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada; Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada. Electronic address:

The E-protein transcription factors guide immune cell differentiation, with E12 and E47 (hereafter called E2A) being essential for B-cell specification and maturation. E2A and the oncogenic chimera E2A-PBX1 contain three transactivation domains (ADs), with AD1 and AD2 having redundant, independent, and cooperative functions in a cell-dependent manner. AD1 and AD2 both mediate their functions by binding to the KIX domain of the histone acetyltransferase paralogues CREB-binding protein (CBP) and E1A-binding protein P300 (p300). This interaction is necessary for B-cell maturation and oncogenesis by E2A-PBX1 and occurs through conserved ΦΦΦ motifs (with Φ denoting a hydrophobic amino acid) in AD1 and AD2. However, disruption of this interaction via mutation of the KIX domain in CBP/p300 does not completely abrogate binding of E2A and E2A-PBX1. Here, we determined that E2A-AD1 and E2A-AD2 also interact with the TAZ2 domain of CBP/p300. Characterization of the TAZ2:E2A-AD1(1-37) complex indicated that E2A-AD1 adopts an α-helical structure and uses its ΦΦΦ motif to bind TAZ2. Whereas this region overlapped with the KIX recognition region, key KIX-interacting E2A-AD1 residues were exposed, suggesting that E2A-AD1 could simultaneously bind both the KIX and TAZ2 domains. However, we did not detect a ternary complex involving E2A-AD1, KIX, and TAZ2 and found that E2A containing both intact AD1 and AD2 is required to bind to CBP/p300. Our findings highlight the structural plasticity and promiscuity of E2A-AD1 and suggest that E2A binds both the TAZ2 and KIX domains of CBP/p300 through AD1 and AD2.
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http://dx.doi.org/10.1074/jbc.RA119.011078DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7105314PMC
March 2020

Small-molecule allosteric activators of PDE4 long form cyclic AMP phosphodiesterases.

Proc Natl Acad Sci U S A 2019 07 17;116(27):13320-13329. Epub 2019 Jun 17.

Mironid, Ltd., Newhouse, North Lanarkshire ML1 5UH, Scotland, United Kingdom;

Cyclic AMP (cAMP) phosphodiesterase-4 (PDE4) enzymes degrade cAMP and underpin the compartmentalization of cAMP signaling through their targeting to particular protein complexes and intracellular locales. We describe the discovery and characterization of a small-molecule compound that allosterically activates PDE4 long isoforms. This PDE4-specific activator displays reversible, noncompetitive kinetics of activation (increased with unchanged ), phenocopies the ability of protein kinase A (PKA) to activate PDE4 long isoforms endogenously, and requires a dimeric enzyme assembly, as adopted by long, but not by short (monomeric), PDE4 isoforms. Abnormally elevated levels of cAMP provide a critical driver of the underpinning molecular pathology of autosomal dominant polycystic kidney disease (ADPKD) by promoting cyst formation that, ultimately, culminates in renal failure. Using both animal and human cell models of ADPKD, including ADPKD patient-derived primary cell cultures, we demonstrate that treatment with the prototypical PDE4 activator compound lowers intracellular cAMP levels, restrains cAMP-mediated signaling events, and profoundly inhibits cyst formation. PDE4 activator compounds thus have potential as therapeutics for treating disease driven by elevated cAMP signaling as well as providing a tool for evaluating the action of long PDE4 isoforms in regulating cAMP-mediated cellular processes.
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http://dx.doi.org/10.1073/pnas.1822113116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6613170PMC
July 2019

Targeted disruption of the heat shock protein 20-phosphodiesterase 4D (PDE4D) interaction protects against pathological cardiac remodelling in a mouse model of hypertrophy.

FEBS Open Bio 2014 28;4:923-7. Epub 2014 Oct 28.

Institute of Medical, Veterinary and Life Sciences, University of Glasgow, Wolfson-Link Building, Glasgow G12 8QQ, UK.

Phosphorylated heat shock protein 20 (HSP20) is cardioprotective. Using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and a mouse model of pressure overload mediated hypertrophy, we show that peptide disruption of the HSP20-phosphodiesterase 4D (PDE4D) complex results in attenuation of action potential prolongation and protection against adverse cardiac remodelling. The later was evidenced by improved contractility, decreased heart weight to body weight ratio, and reduced interstitial and perivascular fibrosis. This study demonstrates that disruption of the specific HSP20-PDE4D interaction leads to attenuation of pathological cardiac remodelling.
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http://dx.doi.org/10.1016/j.fob.2014.10.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4239479PMC
November 2014

Eps8 controls Src- and FAK-dependent phenotypes in squamous carcinoma cells.

J Cell Sci 2014 Dec 29;127(Pt 24):5303-16. Epub 2014 Oct 29.

Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road South, EH4 2XR Edinburgh, UK

Eps8 is an actin regulatory scaffold protein whose expression is increased in squamous cell carcinoma (SCC) cells. It forms a complex with both focal adhesion kinase (FAK, also known as PTK2) and Src in SCC cells derived from skin carcinomas induced by administration of the chemical DMBA followed by TPA (the DMBA/TPA model). Here, we describe two new roles for Eps8. Firstly, it controls the spatial distribution of active Src in a FAK-dependent manner. Specifically, Eps8 participates in, and regulates, a biochemical complex with Src and drives trafficking of Src to autophagic structures that SCC cells use to cope with high levels of active Src when FAK is absent. Secondly, when FAK is expressed in SCC cells, thereby meaning active Src becomes tethered at focal adhesion complexes, Eps8 is also recruited to focal adhesions and is required for FAK-dependent polarization and invasion. Therefore, Eps8 is a crucial mediator of Src- and FAK-regulated processes; it participates in specific biochemical complexes and promotes actin re-arrangements that determine the spatial localization of Src, and modulates the functions of Src and FAK during invasive migration.
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http://dx.doi.org/10.1242/jcs.157560DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4265741PMC
December 2014

The UV-B photoreceptor UVR8 promotes photosynthetic efficiency in Arabidopsis thaliana exposed to elevated levels of UV-B.

Photosynth Res 2012 Dec 19;114(2):121-31. Epub 2012 Nov 19.

Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK.

The UV-B photoreceptor UVR8 regulates expression of genes in response to UV-B, some encoding chloroplast proteins, but the importance of UVR8 in maintaining photosynthetic competence is unknown. The maximum quantum yield of PSII (F (v)/F(m)) and the operating efficiency of PSII (Φ(PSII)) were measured in wild-type and uvr8 mutant Arabidopsis thaliana. The importance of specific UVR8-regulated genes in maintaining photosynthetic competence was examined using mutants. Both F (v)/F(m) and Φ(PSII) decreased when plants were exposed to elevated UV-B, in general more so in uvr8 mutant plants than wild-type. UV-B increased the level of psbD-BLRP (blue light responsive promoter) transcripts, encoding the PSII D2 protein. This increase was mediated by the UVR8-regulated chloroplast RNA polymerase sigma factor SIG5, but SIG5 was not required to maintain photosynthetic efficiency at elevated UV-B. Levels of the D1 protein of PSII decreased markedly when plants were exposed to elevated UV-B, but there was no significant difference between wild-type and uvr8 under conditions where the mutant showed increased photoinhibition. The results show that UVR8 promotes photosynthetic efficiency at elevated levels of UV-B. Loss of the DI polypeptide is probably important in causing photoinhibition, but does not entirely explain the reduced photosynthetic efficiency of the uvr8 mutant compared to wild-type.
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http://dx.doi.org/10.1007/s11120-012-9785-yDOI Listing
December 2012

Compaction of a prokaryotic signal-anchor transmembrane domain begins within the ribosome tunnel and is stabilized by SRP during targeting.

J Mol Biol 2012 Nov 4;423(4):600-12. Epub 2012 Aug 4.

Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.

Cotranslational targeting of membrane proteins is mediated by the universally conserved signal recognition particle (SRP). In eukaryotes, SRP attenuates translation during targeting; however, in prokaryotes, a simplified SRP is believed to carry out targeting during continuing translation. Here, we show a detailed stepwise analysis of the targeting of subunit c of the F(0) component of the bacterial ATP synthase (F(0)c) to the inner membrane. We show that the first transmembrane (TM) signal-anchor domain of F(0)c forms a compacted structure within the distal portion of the ribosome tunnel. This structure is formed just prior to the interaction with SRP. In the absence of SRP this structure is lost as the TM domain exits the tunnel; however in the presence of SRP it is stabilized. Our results suggest differences in early protein folding of substrates for prokaryotic SRP-dependent membrane protein targeting pathways, from that of eukaryotic SRP targeting. These results imply that early TM domain recognition by targeting factors acts to ensure that the efficiency of membrane targeting is maintained.
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http://dx.doi.org/10.1016/j.jmb.2012.07.023DOI Listing
November 2012

Cyclic AMP-specific phosphodiesterase, PDE8A1, is activated by protein kinase A-mediated phosphorylation.

FEBS Lett 2012 Jun 3;586(11):1631-7. Epub 2012 May 3.

Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.

The cyclic AMP-specific phosphodiesterase PDE8 has been shown to play a pivotal role in important processes such as steroidogenesis, T cell adhesion, regulation of heart beat and chemotaxis. However, no information exists on how the activity of this enzyme is regulated. We show that under elevated cAMP conditions, PKA acts to phosphorylate PDE8A on serine 359 and this action serves to enhance the activity of the enzyme. This is the first indication that PDE8 activity can be modulated by a kinase, and we propose that this mechanism forms a feedback loop that results in the restoration of basal cAMP levels.
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http://dx.doi.org/10.1016/j.febslet.2012.04.033DOI Listing
June 2012