Ubiquitin E3 Ligase, Tripartite Motif Protein 68 (TRIM68) Inhibits TCP-1 b Function by Proteasome-Mediated Degradation and May Overcome Imatinib-Resistance.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3789-3789
Author(s):  
Yasuhito Terui ◽  
Ryoko Kuniyoshi ◽  
Yuji Mishima ◽  
Yuko Mishima ◽  
Kiyohiko Hatake
Keyword(s):  
Differential Display ◽  
Ring Finger ◽  
E3 Ligase ◽  
K562 Cells ◽  
Wild Type ◽  
Mcf7 Cells ◽  
Spry Domain ◽  
Ubiquitin E3 Ligase ◽  
Imatinib Resistant

Abstract Abstract 3789 Poster Board III-725 [Background] Imatinib mesylate is effective therapy against Philadelphia chromosome-positive leukemia, but the resistance develops in all phases of the disease. The identification of new proteins induced by imatinib may lead to find the novel potent molecular targets in imatinib-resistant CML. [Methods] K562 cells were treated with or without 1 mM imatinib for 24 hours, and then differential display between them was performed. TRIM68 expression was examined by RT-PCR, and in vivo ubiquitination or sumoylation assay was performed by transfection experiment and Western blot analysis. The substrates for TRIM68 were analyzed by mass spectorometry. [Results] As the results of RNA differential display, we found that the expression of TRIM68 mRNA was increased when the K562 cells were treated with 1 mM imatinib for 24 hours. TRIM68 protein possesses a RING finger domain at its N-terminal site. Since many RING-finger proteins have been identified as E3 ligases for ubiquitination or sumoylation (Meroni G, Diez-Roux G. TRIM/RBCC, a novel class of esingle protein RING finger' E3 ubiquitin ligases. Bioessays 2005; 27: 1147-57.), we examined whether TRIM68 functions as an E3 ligase for ubiquitination or sumoylation. To examine the function of TRIM68 as an E3 ligase, wild type TRIM68 and a RING domain deletion mutant of TRIM68 (TRIM68/¢R) genes were constructed into a mammalian expression vector and they were transfected into MCF7 cells. TRIM68 had auto-ubiquitination activity but not auto-sumoylation activity on the in vivo assays, suggesting that TRIM68 can be an ubiquitin E3 ligase but not sumo ligase. Moreover, wild type TRIM68 promoted the whole ubiqutination in the cells, whereas TRIM68/¢R prevented the ubiquitination inside of the cells. To identify the TRIM68-interacting proteins, we transfected FLAG-tagged wild type TRIM68 gene or B30.2/SPRY domain of TRIM68 gene into MCF7 cells, and immunoprecipitation with FLAG-M2 agarose was performed and mass spectrometric analysis was performed. As the results, we revealed that the members of molecular chaperone T-complex polypeptide 1 (TCP-1) complex, TCP-1 b and heat shock protein 70 (HSP70) interacted with TRIM68 at the B30.2/SPRY domain. Then, we examined whether TCP-1 b is one of the substrates for TRIM68-related ubiqutination. TCP-1 b was ubiquitinated by wild type TRIM68, but not by TRIM68/¢R. Furthermore, the ubiquitination of TCP-1 b was accumulated by the treatment with a proteasome inhibitor MG132. These suggested that TCP-1 b is one of the substrates for TRIM68. [Conclusions] We found that TRIM68 is induced by the treatment with imatinib and functions as an ubiquitin E3 ligase. Furthermore, we identified that TCP-1 b is a substrate of TRIM68. TRIM68 may inhibit the function of TCP-1 b as a chaperone by ubiquitination and proteasome-mediated degradation. TRIM68 is possible for a new target in the imatinib-resistant CML. Disclosures: No relevant conflicts of interest to declare.

Arsenic Sulfide Binds c-CBL to Promote BCR-ABL Ubiquitination and Degradation In Chronic Myelogenous Leukemia.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1200-1200
Author(s):  
Jian-Hua Mao ◽  
Xiao-Yan Sun ◽  
Jian-Xiang Liu ◽  
Qun-Ye Zhang ◽  
Ping Liu ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Conflicts Of Interest ◽  
Ring Finger ◽  
E3 Ligase ◽  
K562 Cells ◽  
Myelogenous Leukemia ◽  
Arsenic Sulfide ◽  
Cbl Protein

Abstract Abstract 1200 Using immunoprecipitation (IP)-2D-nano-HPLC-MALDI-MS-MS, we identified c-CBL in association with BCR-ABL in a multi-protein complex in K562 cells. In vitro ubiquitination and mutagenesis analyses show that c-CBL serves as a specific E3 ligase for ubiquitination of BCR-ABL at K1517. Arsenic sulfide (As4S4) treatment results in increased c-CBL protein level, which promotes ubiquitination and subsequent degradation of BCR-ABL and apoptosis of K562 cells. Elevated c-CBL is necessary and sufficient to recapitulate the effect of As4S4. Interestingly, arsenic directly binds the RING finger domain of c-CBL, inhibiting its self-ubiquitination and degradation, thus leading to accumulation of c-CBL. However, this interaction between As4S4 and c-CBL does not interfere with its E3 ligase activity towards BCR-ABL. Increased c-CBL protein and BCR-ABL degradation are also observed in vivo after As4S4 administration in BCR-ABL leukemia mice. These findings provide insights into the molecular mechanisms of arsenic and its potential therapeutic applications in CML. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Critical Contribution of the MDM2 Acidic Domain to p53 Ubiquitination

2003 ◽  
Vol 23 (14) ◽  
pp. 4939-4947 ◽  
Author(s):  
Hidehiko Kawai ◽  
Dmitri Wiederschain ◽  
Zhi-Min Yuan
Keyword(s):  
Nuclear Export ◽  
Critical Role ◽  
Ring Finger ◽  
E3 Ligase ◽  
Chimeric Protein ◽  
Chimeric Proteins ◽  
Ring Finger Domain ◽  
Acidic Domain ◽  
Ubiquitin E3 Ligase

ABSTRACT MDM2 is an E3 ubiquitin ligase that targets p53 for proteasomal degradation. Recent studies have shown, however, that the ring-finger domain (RFD) of MDM2, where the ubiquitin E3 ligase activity resides, is necessary but not sufficient for p53 ubiquitination, suggesting that an additional activity of MDM2 might be required. To test this possibility, we generated a series of MDM2/MDMX chimeric proteins to assess the contribution of each domain of MDM2 to the ubiquitination process. MDMX is a close structural homolog of MDM2 that nevertheless lacks the E3 ligase activity in vivo. We demonstrate here that MDMX gains self-ubiquitination activity and becomes extremely unstable upon introduction of the MDM2 RFD, indicating that the RFD is essential for self-ubiquitination. This MDMX chimeric protein, however, is unable to ubiquitinate p53 in vivo despite its E3 ligase activity and binding to p53, separating the self-ubiquitination activity of MDM2 from its ability to ubiquitinate p53. Significantly, fusion of the central acidic domain (AD) of MDM2 to the MDMX chimeric protein renders the protein fully capable of ubiquitinating p53, and p53 ubiquitination is associated with p53 degradation and nuclear export. Moreover, the AD mini protein expressed in trans can functionally rescue the AD-lacking MDM2 mutant, further supporting a critical role for the AD in MDM2-mediated p53 ubiquitination.

scholarly journals Inhibition of Ubiquitination and Stabilization of Human Ubiquitin E3 Ligase PIRH2 by Measles Virus Phosphoprotein

2005 ◽  
Vol 79 (18) ◽  
pp. 11824-11836 ◽  
Author(s):  
Mingzhou Chen ◽  
Jean-Claude Cortay ◽  
Ian R. Logan ◽  
Vasileia Sapountzi ◽  
Craig N. Robson ◽  
...  
Keyword(s):  
Binding Site ◽  
Measles Virus ◽  
Fluorescent Protein ◽  
E3 Ligase ◽  
Yeast Two Hybrid ◽  
Ubiquitin E3 Ligase ◽  
P Protein ◽  
Two Hybrid

ABSTRACT Using a C-terminal domain (PCT) of the measles virus (MV) phosphoprotein (P protein) as bait in a yeast two-hybrid screen, a cDNA identical to the recently described human p53-induced-RING-H2 (hPIRH2) cDNA was isolated. A glutathione S-transferase-hPIRH2 fusion protein expressed in bacteria was able to pull down P protein when mixed with an extract from P-expressing HeLa cells in vitro, and myc-tagged hPIRH2 could be reciprocally coimmunoprecipitated with MV P protein from human cells. Additionally, immunoprecipitation experiments demonstrated that hPIRH2-myc, MV P, and nucleocapsid (N) proteins form a ternary complex. The hPIRH2 binding site was mapped to the C-terminal X domain region of the P protein by using a yeast two-hybrid assay. The PCT binding site was mapped on hPIRH2 by using a novel yeast two-hybrid tagged PCR approach and by coimmunoprecipitation of hPIRH2 cysteine mutants and mouse/human PIRH2 chimeras. The hPIRH2 C terminus could mediate the interaction with MV P which was favored by the RING-H2 motif. When coexpressed with an enhanced green fluorescent protein-tagged hPIRH2 protein, MV P alone or in a complex with MV N was able to redistribute hPIRH2 to outside the nucleus, within intracellular aggregates. Finally, MV P efficiently stabilized hPIRH2-myc expression and prevented its ubiquitination in vivo but had no effect on the stability or ubiquitination of an alternative ubiquitin E3 ligase, Mdm2. Thus, MV P protein is the first protein from a pathogen that is able to specifically interact with and stabilize the ubiquitin E3 ligase hPIRH2 by preventing its ubiquitination.

scholarly journals Cysteine protease RD21A regulated by E3 ligase SINAT4 is required for drought-induced resistance to Pseudomonas syringae in Arabidopsis

2020 ◽  
Vol 71 (18) ◽  
pp. 5562-5576
Author(s):  
Yi Liu ◽  
Kunru Wang ◽  
Qiang Cheng ◽  
Danyu Kong ◽  
Xunzhong Zhang ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Cysteine Protease ◽  
Plant Immunity ◽  
Stomatal Closure ◽  
Bacterial Pathogen ◽  
E3 Ligase ◽  
Biotic Stresses ◽  
Ubiquitin E3 Ligase ◽  
Induced Immunity

Abstract Plants can be simultaneously exposed to multiple stresses. The interplay of abiotic and biotic stresses may result in synergistic or antagonistic effects on plant development and health. Temporary drought stress can stimulate plant immunity; however, the molecular mechanism of drought-induced immunity is largely unknown. In this study, we demonstrate that cysteine protease RD21A is required for drought-induced immunity. Temporarily drought-treated wild-type Arabidopsis plants became more sensitive to the bacterial pathogen-associated molecular pattern flg22, triggering stomatal closure, which resulted in increased resistance to Pseudomonas syringae pv. tomato DC3000 (Pst-DC3000). Knocking out rd21a inhibited flg22-triggered stomatal closure and compromised the drought-induced immunity. Ubiquitin E3 ligase SINAT4 interacted with RD21A and promoted its degradation in vivo. The overexpression of SINAT4 also consistently compromised the drought-induced immunity to Pst-DC3000. A bacterial type III effector, AvrRxo1, interacted with both SINAT4 and RD21A, enhancing SINAT4 activity and promoting the degradation of RD21A in vivo. Therefore, RD21A could be a positive regulator of drought-induced immunity, which could be targeted by pathogen virulence effectors during pathogenesis.

TRIM37 defective in mulibrey nanism is a novel RING finger ubiquitin E3 ligase

2005 ◽  
Vol 308 (1) ◽  
pp. 146-155 ◽  
Author(s):  
Jukka Kallijärvi ◽  
Ulla Lahtinen ◽  
Riikka Hämäläinen ◽  
Marita Lipsanen-Nyman ◽  
Jorma J. Palvimo ◽  
...  
Keyword(s):  
Ring Finger ◽  
E3 Ligase ◽  
Ubiquitin E3 Ligase ◽  
Mulibrey Nanism

Dasatinib (BMS-354825) Overcomes Multiple Mechanisms of Imatinib Resistance in Chronic Myeloid Leukemia (CML).

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1994-1994 ◽  
Author(s):  
Francis Y. Lee ◽  
Mei-Li Wen ◽  
Rajeev Bhide ◽  
Amy Camuso ◽  
Stephen Castenada ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kinase Inhibitor ◽  
Leukemic Cell ◽  
K562 Cells ◽  
Src Family Kinases ◽  
Imatinib Resistance ◽  
Over Expression ◽  
Imatinib Resistant

Abstract Resistance to imatinib is a growing concern in CML, particularly in advanced disease. The most common cause of resistance is mutations in BCR-ABL, but other mechanisms have also been identified, including over-expression of BCR-ABL, activation of SRC family kinases and the P-glycoprotein (PGP) efflux pump (via MDR1 over-expression). Dasatinib (BMS-354825) is a novel, oral, multi-targeted tyrosine kinase inhibitor that targets BCR-ABL and SRC kinases. Dasatinib has 325-fold greater potency versus imatinib in cell lines transduced with wild-type BCR-ABL and is active against 18 out of 19 BCR-ABL mutations tested that confer imatinib resistance (Shah et al, Science305:399, 2004; O’Hare et al, Cancer Res65:4500–5, 2005), and preliminary results from a Phase I study show that it is well tolerated and has significant activity in imatinib-resistant patients in all phases of CML (Sawyers et al, J Clin Oncol23:565s, 2005; Talpaz et al, J Clin Oncol23:564s, 2005). We assessed the ability of dasatinib to overcome a variety of mechanisms of imatinib resistance. First, the leukemic-cell killing activity of dasatinib was tested in vitro in three human imatinib-resistant CML cell lines (K562/IM, MEG-01/IM and SUP-B15/IM). Based on IC50 values, dasatinib had >1000-fold more potent leukemic-cell killing activity compared with imatinib versus all three cell lines. Furthermore, in mice bearing K562/IM xenografts, dasatinib was curative at doses >5 mg/kg, while imatinib had little or no impact at doses as high as 150 mg/kg, its maximum tolerated dose. We determined that the MEG-01/IM and SUP-B15/IM cell lines carried BCR-ABL mutations known to confer imatinib resistance to imatinib clinically (Q252H and F359V, respectively). In K562/IM cells, BCR-ABL mutations or BCR-ABL over-expression were not detected, but the SRC family member FYN was over-expressed. PP2, a known inhibitor of SRC family kinases but not BCR-ABL, could reverse the imatinib resistance in these cells. Together, these data suggest that activation of FYN may be a cause of imatinib resistance in K562/IM. Based on cell proliferation IC50, we found that the anti-leukemic activity of dasatinib in K562/IM cells was 29-fold more potent compared with AMN107 (a tyrosine kinase inhibitor that inhibits BCR-ABL but not SRC family kinases). Given that the human serum protein binding of dasatinib, imatinib and AMN107 were 93, 92 and >99% respectively, the difference in potency between dasatinib and AMN107 in vivo may be far greater than the simple fold-difference in the in vitro IC50 values. Finally, in K562 cells over-expressing PGP (K562/ADM), we found that dasatinib was only 6-fold less active than in parental K562 cells. Because of the extreme potency of dasatinib in K562 cells, this reduced potency still afforded an IC50 of 3 nM, which is readily achievable in vivo. Indeed, in mice bearing K562/ADM xenografts, dasatinib was curative at 30 mg/kg, with significant anti-leukemic activity at 15 mg/kg. In conclusion, the rational design of dasatinib as a multi-targeted kinase inhibitor allows this agent to overcome a variety of mechanisms of resistance to imatinib in CML, including mechanisms that are not overcome by agents with a narrower spectrum of inhibition, such as AMN107. Dasatinib is currently in Phase II evaluation in imatinib-resistant/-intolerant patients in the ‘START’ program, and in Phase I evaluation in solid tumors.

KW-2449, a Novel Multi-Kinase Inhibitor, Suppresses the Growth of Imatinib-Resistant Ph+ Leukemia Including BCR-ABL/T315I Both in Vitro and in Vivo.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1640-1640 ◽  
Author(s):  
Yukimasa Shiotsu ◽  
Hitoshi Kiyoi ◽  
Ryohei Tanizaki ◽  
Yosuke Minami ◽  
Akihiro Abe ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Kinase Inhibitor ◽  
Imatinib Treatment ◽  
Wild Type ◽  
Growth Inhibitory ◽  
Imatinib Resistant ◽  
Blast Cells ◽  
T315i Mutation

Abstract Background: KW-2449 is a multi-kinase inhibitor against FLT3, ABL and ABL/T315I and Aurora kinases with IC50 values of 0.007, 0.014, 0.004 and 0.048 micro mol/L, respectively. We reported a possible mode of action of KW-2449 with respect to its anti-leukemic effects on FLT3-mutated and FLT3-wild type leukemia cells via FLT3 and Aurora inhibition, respectively (1). Currently KW-2449 is being investigated in a Phase 1/2 study in patients with acute myeloid leukemia. In this report, we investigated the activity of KW-2449 or imatinib in imatinib-resistant leukemia with the T315I mutation. Methods and results: We evaluated the effects of KW-2449 in vitro and in vivo on imatinib-resistant Ph+ leukemia. While imatinib suppressed the growth of K562 (Ph+CML with wild-type BCR-ABL) and TCC-Y (Ph+ALL with wild-type BCR-ABL) with GI50 values of 0.20 and 0.18 micro mol/L, it had little inhibitory effects on TCC-Y/sr (Ph+ALL with BCR-ABL/T315I) with a GI50 value of 24 micro mol/L. On the other hand, KW-2449 showed equivalent growth inhibitory activities against K562, TCC-Y and TCC-Y/sr giving the GI50 values of 0.2–0.6 micro mol/L. In addition, KW-2449 showed potent growth inhibitory activity against IL-3 dependent cells transfected with BCR-ABL and BCR-ABL/T315I with GI50 values below 0.50 micro mol/L, whereas imatinib had no growth inhibition in BCR-ABL/T315I cells. When we examined the ABL-signaling pathway, imatinib had no effects on the expression of phosphorylated BCR-ABL (P-BCR-ABL) and STAT5 (P-STAT5), a key downstream signal molecules of BCR-ABL in TCC-Y/sr cells. Furthermore, no obvious apoptosis or cell cycle effects were observed in BCR-ABL/T315I cells after imatinib treatment. In addition, the exposure to KW-2449 induced reduction of P-BCR-ABL and P-STAT5 at 0.25 micro mol/L and induced G2/M arrest and apoptosis over the GI50 value (0.50–1.0 micro mol/L). These data provide the evidence that BCR-ABL inhibition at a lower concentration of KW-2449 modulates its signaling pathway and that Aurora inhibition at a higher concentration may play a critical role in the anti-proliferative effects in imatinib-resistant CML and Ph+ALL. To assess the anti-leukemia activity of KW-2449 in vivo, the SCID mice intravenously inoculated with TCC-Y/sr leukemia were orally treated with KW-2449 or imatinib. While KW-2449 prolonged the survival, imatinib treatment had no effects in this model. Furthermore, anti-proliferative activity of KW-2449 was examined in primary samples from blast crisis CML patients who had BCR-ABL/T315I mutation. After inoculation of blast cells into NOG mice, KW-2449 or imatinib treatment started. In this model, oral treatments with KW-2449 decreased peripheral copy number of BCR-ABL mRNA and CD45+ blast cells in the bone marrow, though imatinib treatment showed limited activity. Conclusion: KW-2449 demonstrated anti-leukemia activity against imatinib resistant leukemia both in vitro and in vivo. These results suggest that KW-2449 would be effective against imatinib-resistant CML or Ph+ALL because of its potent and unique kinase inhibition profile.

scholarly journals Muscle ring finger 1 mediates cardiac atrophy in vivo

2009 ◽  
Vol 296 (4) ◽  
pp. H997-H1006 ◽  
Author(s):  
Monte S. Willis ◽  
Mauricio Rojas ◽  
Luge Li ◽  
Craig H. Selzman ◽  
Ru-Hang Tang ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Transcriptional Activation ◽  
Smooth Muscle Actin ◽  
Ring Finger ◽  
Left Ventricular ◽  
Cardiac Mass ◽  
Wild Type ◽  
Cardiac Atrophy ◽  
Pathological Cardiac Hypertrophy

Pathological cardiac hypertrophy, induced by various etiologies such as high blood pressure and aortic stenosis, develops in response to increased afterload and represents a common intermediary in the development of heart failure. Understandably then, the reversal of pathological cardiac hypertrophy is associated with a significant reduction in cardiovascular event risk and represents an important, yet underdeveloped, target of therapeutic research. Recently, we determined that muscle ring finger-1 (MuRF1), a muscle-specific protein, inhibits the development of experimentally induced pathological; cardiac hypertrophy. We now demonstrate that therapeutic cardiac atrophy induced in patients after left ventricular assist device placement is associated with an increase in cardiac MuRF1 expression. This prompted us to investigate the role of MuRF1 in two independent mouse models of cardiac atrophy: 1) cardiac hypertrophy regression after reversal of transaortic constriction (TAC) reversal and 2) dexamethasone-induced atrophy. Using echocardiographic, histological, and gene expression analyses, we found that upon TAC release, cardiac mass and cardiomyocyte cross-sectional areas in MuRF1−/− mice decreased ∼70% less than in wild type mice in the 4 wk after release. This was in striking contrast to wild-type mice, who returned to baseline cardiac mass and cardiomyocyte size within 4 days of TAC release. Despite these differences in atrophic remodeling, the transcriptional activation of cardiac hypertrophy measured by β-myosin heavy chain, smooth muscle actin, and brain natriuretic peptide was attenuated similarly in both MuRF1−/− and wild-type hearts after TAC release. In the second model, MuRF1−/− mice also displayed resistance to dexamethasone-induced cardiac atrophy, as determined by echocardiographic analysis. This study demonstrates, for the first time, that MuRF1 is essential for cardiac atrophy in vivo, both in the setting of therapeutic regression of cardiac hypertrophy and dexamethasone-induced atrophy.

scholarly journals NEDD4 Regulates Ubiquitination and Stability of the Cell adhesion Molecule IGPR-1 via Lysosomal Pathway

2021 ◽  
Author(s):  
Linzi Sun ◽  
Razie Amraei ◽  
Nader Rahimi
Keyword(s):  
Cell Adhesion ◽  
Adhesion Molecule ◽  
Cell Adhesion Molecule ◽  
Molecular Mechanisms ◽  
E3 Ligase ◽  
Cell Surface Expression ◽  
Significant Implication ◽  
Ubiquitin E3 Ligase

ABSTRACTThe cell adhesion molecule immunoglobulin and proline-rich receptor-1 (IGPR-1) regulates various critical cellular processes including, cell-cell adhesion, mechanosensing and autophagy. However, the molecular mechanisms governing IGPR-1 cell surface expression levels remains unknown. In the present study, we used an in vitro ubiquitination assay and identified ubiquitin E3 ligase NEDD4 and the ubiquitin conjugating enzyme UbcH6 involved in the ubiquitination of IGPR-1. In vitro GST-pulldown and in vivo co-immunoprecipitation assays demonstrated that NEDD4 binds to IGPR-1. Over-expression of wild-type NEDD4 downregulated IGPR-1 and deletion of WW domains (1-4) of NEDD4 revoked its effects on IGPR-1. Similarly, knockdown of NEDD4 increased IGPR-1 levels in A375 melanoma cells. Furthermore, deletion of 57 amino acids encompassing polyproline rich (PPR) motif on the C-terminus of IGPR-1 nullified the binding of NEDD4 with IGPR-1. Moreover, we demonstrate that NEDD4 promotes K48- and K63-dependent polyubiquitination of IGPR-1. The NEDD4-mediated polyubiquitination of IGPR-1 stimulated lysosomal degradation of IGPR-1 as the treatment of cells with the lysosomal inhibitors, bafilomycine and ammonium chloride increased IGPR-1 levels in the HEK-293 cells ectopically expressing IGPR-1 and in multiple human skin melanoma cell lines. Hence, these findings suggest that ubiquitin E3 ligase NEDD4 is a key regulator of IGPR-1 with a significant implication in the therapeutic targeting of IGPR-1.

Protein kinase A mediates novel serine-584 phosphorylation of HDAC4

2019 ◽  
Vol 97 (5) ◽  
pp. 526-535 ◽  
Author(s):  
Shanmukha K. Doddi ◽  
Githavani Kummari ◽  
Jagannadham M.V. ◽  
Arunasree M. Kalle
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Cell Line ◽  
Target Genes ◽  
K562 Cells ◽  
Pcr Analysis ◽  
Wild Type ◽  
Kinase A

Given the well-established diversified signaling pathways for histone deacetylase 4 (HDAC4) and the regulation of HDAC4 by several post-translational modifications (PTMs), including phosphorylation, sumoylation, and ubiquitination, an unbiased and detailed analysis of HDAC4 PTMs is needed. In this study, we used matrix-assisted laser desorption/ionization time of flight (MALDI-TOF/TOF) to describe phosphorylation at serine 584 (Ser584) along with already-known dual phosphorylation at serines 265 and 266 (Ser265/266), that together regulate HDAC4 activity. Overexpression of site-specific HDAC4 mutants (S584A, S265/266A) in HEK 293T cells, followed by HDAC activity assays, revealed the mutants to be less active than the wild-type protein. In vitro kinase assays have established that Ser584 and Ser265/266 are phosphorylated by protein kinase A (PKA). Luciferase assays driven by the myocyte enhancer factor 2 (MEF2) promoter and real-time PCR analysis of the MEF2 target genes show that the S584A and S265/266A mutants are less repressive than the wild-type. Furthermore, treatment with PKA activators such as 8-Bromo-cAMP and forskolin, and silencing either by shRNA or its inhibitor H-89 in a mouse myoblast cell line (C2C12) and in a non-muscle human cell line (K562), confirmed in vivo phosphorylation of HDAC4 in C2C12 but not in K562 cells, indicating the specific functional significance of HDAC4 phosphorylation in muscle cells. Thus, we identified PKA-induced Ser584 phosphorylation of HDAC4 as a yet unknown regulatory mechanism of the HDAC4–MEF2 axis.

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