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14-3-3 Binding and Sumoylation Concur to the Down-Modulation of β-catenin Antagonist chibby 1 in Chronic Myeloid Leukemia.

Mancini M, Leo E, Takemaru K, Campi V, Castagnetti F, Soverini S, De Benedittis C, Rosti G, Cavo M, Santucci MA, Martinelli G - PLoS ONE (2015)

Bottom Line: Here we demonstrate that it also arises from reduced protein stability upon binding to 14-3-3σ adapter protein.The ubiquitin proteasome system UPS participates in reducing stability of CBY1 bound with 14-3-3σ through enhanced SUMOylation.Our results open new routes towards the research on molecular pathways promoting the proliferative advantage of leukemic hematopoiesis over the normal counterpart.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Diagnostic and Specialty Medicine-DIMES-Institute of Hematology "L. and A. Seràgnoli". University of Bologna-Medical School, Bologna, Italy.

ABSTRACT
The down-modulation of the β-catenin antagonist Chibby 1 (CBY1) associated with the BCR-ABL1 fusion gene of chronic myeloid leukemia (CML) contributes to the aberrant activation of β-catenin, particularly in leukemic stem cells (LSC) resistant to tyrosine kinase (TK) inhibitors. It is, at least partly, driven by transcriptional events and gene promoter hyper-methylation. Here we demonstrate that it also arises from reduced protein stability upon binding to 14-3-3σ adapter protein. CBY1/14-3-3σ interaction in BCR-ABL1+ cells is mediated by the fusion protein TK and AKT phosphorylation of CBY1 at critical serine 20, and encompasses the 14-3-3σ binding modes I and II involved in the binding with client proteins. Moreover, it is impaired by c-Jun N-terminal kinase (JNK) phosphorylation of 14-3-3σ at serine 186, which promotes dissociation of client proteins. The ubiquitin proteasome system UPS participates in reducing stability of CBY1 bound with 14-3-3σ through enhanced SUMOylation. Our results open new routes towards the research on molecular pathways promoting the proliferative advantage of leukemic hematopoiesis over the normal counterpart.

No MeSH data available.


Related in: MedlinePlus

Reduction of JNK and 14-3-3σ post-translational modifications is associated with CBY1 reduced expression and interaction with 14-3-3σ in CML.Bone marrow MCF of 12 CML patients at diagnosis and 8 HDs were compared for CBY1 expression and interaction with 14-3-3σ, JNK phosphorylation at threonine 183 and 14-3-3σ phosphorylation at serine 186. Clinical details of CML patients included in our study are illustrated in the Supplementary section, S1 Table. A pool consisting of equal amounts of proteins from MCF of bone marrow samples of HDs was used as control for IP/IB to avoid individual differences. See legend to Fig 1 for technical details. The two blots shown here have been run separately and confirmed by two additional experiments.
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pone.0131074.g005: Reduction of JNK and 14-3-3σ post-translational modifications is associated with CBY1 reduced expression and interaction with 14-3-3σ in CML.Bone marrow MCF of 12 CML patients at diagnosis and 8 HDs were compared for CBY1 expression and interaction with 14-3-3σ, JNK phosphorylation at threonine 183 and 14-3-3σ phosphorylation at serine 186. Clinical details of CML patients included in our study are illustrated in the Supplementary section, S1 Table. A pool consisting of equal amounts of proteins from MCF of bone marrow samples of HDs was used as control for IP/IB to avoid individual differences. See legend to Fig 1 for technical details. The two blots shown here have been run separately and confirmed by two additional experiments.

Mentions: The participation of JNK and 14-3-3σ phosphorylation in CBY1 interaction with 14-3-3σ and expression was further investigated in MCF from bone marrow samples of 12 CML patients at diagnosis and HD (pooled to avoid individual differences). Clinical characteristics of CML patients included in our study are illustrated in the S1 Table. CBY1 cytoplasmic levels were significantly lower in all patients compared to the normal control pool (p<0.05 or less), confirming our previously published results [15]. Moreover, the interaction of CBY1 with 14-3-3σ was significantly enhanced in BCR-ABL1+ cells compared to the HD pool (p<0.01 or less) (Fig 5). CBY1 reduced expression and enhanced binding with 14-3-3σ were associated with a significant reduction in JNK phosphorylation at threonine 183 and 14-3-3σ phosphorylation at serine 186 (p<0.05 or less) (Fig 5). These results are consistent with the impact of JNK-induced post-transcriptional modification of 14-3-3σ, in addition to AKT-induced CBY1 phosphorylation, on CBY1 interaction with 14-3-3σ and its role in CBY1 down-modulation associated with BCR-ABL1 TK activity.


14-3-3 Binding and Sumoylation Concur to the Down-Modulation of β-catenin Antagonist chibby 1 in Chronic Myeloid Leukemia.

Mancini M, Leo E, Takemaru K, Campi V, Castagnetti F, Soverini S, De Benedittis C, Rosti G, Cavo M, Santucci MA, Martinelli G - PLoS ONE (2015)

Reduction of JNK and 14-3-3σ post-translational modifications is associated with CBY1 reduced expression and interaction with 14-3-3σ in CML.Bone marrow MCF of 12 CML patients at diagnosis and 8 HDs were compared for CBY1 expression and interaction with 14-3-3σ, JNK phosphorylation at threonine 183 and 14-3-3σ phosphorylation at serine 186. Clinical details of CML patients included in our study are illustrated in the Supplementary section, S1 Table. A pool consisting of equal amounts of proteins from MCF of bone marrow samples of HDs was used as control for IP/IB to avoid individual differences. See legend to Fig 1 for technical details. The two blots shown here have been run separately and confirmed by two additional experiments.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492953&req=5

pone.0131074.g005: Reduction of JNK and 14-3-3σ post-translational modifications is associated with CBY1 reduced expression and interaction with 14-3-3σ in CML.Bone marrow MCF of 12 CML patients at diagnosis and 8 HDs were compared for CBY1 expression and interaction with 14-3-3σ, JNK phosphorylation at threonine 183 and 14-3-3σ phosphorylation at serine 186. Clinical details of CML patients included in our study are illustrated in the Supplementary section, S1 Table. A pool consisting of equal amounts of proteins from MCF of bone marrow samples of HDs was used as control for IP/IB to avoid individual differences. See legend to Fig 1 for technical details. The two blots shown here have been run separately and confirmed by two additional experiments.
Mentions: The participation of JNK and 14-3-3σ phosphorylation in CBY1 interaction with 14-3-3σ and expression was further investigated in MCF from bone marrow samples of 12 CML patients at diagnosis and HD (pooled to avoid individual differences). Clinical characteristics of CML patients included in our study are illustrated in the S1 Table. CBY1 cytoplasmic levels were significantly lower in all patients compared to the normal control pool (p<0.05 or less), confirming our previously published results [15]. Moreover, the interaction of CBY1 with 14-3-3σ was significantly enhanced in BCR-ABL1+ cells compared to the HD pool (p<0.01 or less) (Fig 5). CBY1 reduced expression and enhanced binding with 14-3-3σ were associated with a significant reduction in JNK phosphorylation at threonine 183 and 14-3-3σ phosphorylation at serine 186 (p<0.05 or less) (Fig 5). These results are consistent with the impact of JNK-induced post-transcriptional modification of 14-3-3σ, in addition to AKT-induced CBY1 phosphorylation, on CBY1 interaction with 14-3-3σ and its role in CBY1 down-modulation associated with BCR-ABL1 TK activity.

Bottom Line: Here we demonstrate that it also arises from reduced protein stability upon binding to 14-3-3σ adapter protein.The ubiquitin proteasome system UPS participates in reducing stability of CBY1 bound with 14-3-3σ through enhanced SUMOylation.Our results open new routes towards the research on molecular pathways promoting the proliferative advantage of leukemic hematopoiesis over the normal counterpart.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Diagnostic and Specialty Medicine-DIMES-Institute of Hematology "L. and A. Seràgnoli". University of Bologna-Medical School, Bologna, Italy.

ABSTRACT
The down-modulation of the β-catenin antagonist Chibby 1 (CBY1) associated with the BCR-ABL1 fusion gene of chronic myeloid leukemia (CML) contributes to the aberrant activation of β-catenin, particularly in leukemic stem cells (LSC) resistant to tyrosine kinase (TK) inhibitors. It is, at least partly, driven by transcriptional events and gene promoter hyper-methylation. Here we demonstrate that it also arises from reduced protein stability upon binding to 14-3-3σ adapter protein. CBY1/14-3-3σ interaction in BCR-ABL1+ cells is mediated by the fusion protein TK and AKT phosphorylation of CBY1 at critical serine 20, and encompasses the 14-3-3σ binding modes I and II involved in the binding with client proteins. Moreover, it is impaired by c-Jun N-terminal kinase (JNK) phosphorylation of 14-3-3σ at serine 186, which promotes dissociation of client proteins. The ubiquitin proteasome system UPS participates in reducing stability of CBY1 bound with 14-3-3σ through enhanced SUMOylation. Our results open new routes towards the research on molecular pathways promoting the proliferative advantage of leukemic hematopoiesis over the normal counterpart.

No MeSH data available.


Related in: MedlinePlus