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TRAF1 Coordinates Polyubiquitin Signaling to Enhance Epstein-Barr Virus LMP1-Mediated Growth and Survival Pathway Activation.

Greenfeld H, Takasaki K, Walsh MJ, Ersing I, Bernhardt K, Ma Y, Fu B, Ashbaugh CW, Cabo J, Mollo SB, Zhou H, Li S, Gewurz BE - PLoS Pathog. (2015)

Bottom Line: TRAF1 is amongst the most highly TES1-induced target genes and is abundantly expressed in EBV-associated lymphoproliferative disorders.We found that TRAF1 expression enhanced LMP1 TES1 domain-mediated activation of the p38, JNK, ERK and canonical NF-kB pathways, but not non-canonical NF-kB pathway activity.Our results highlight LUBAC as a novel potential therapeutic target in EBV-associated lymphoproliferative disorders.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States of America.

ABSTRACT
The Epstein-Barr virus (EBV) encoded oncoprotein Latent Membrane Protein 1 (LMP1) signals through two C-terminal tail domains to drive cell growth, survival and transformation. The LMP1 membrane-proximal TES1/CTAR1 domain recruits TRAFs to activate MAP kinase, non-canonical and canonical NF-kB pathways, and is critical for EBV-mediated B-cell transformation. TRAF1 is amongst the most highly TES1-induced target genes and is abundantly expressed in EBV-associated lymphoproliferative disorders. We found that TRAF1 expression enhanced LMP1 TES1 domain-mediated activation of the p38, JNK, ERK and canonical NF-kB pathways, but not non-canonical NF-kB pathway activity. To gain insights into how TRAF1 amplifies LMP1 TES1 MAP kinase and canonical NF-kB pathways, we performed proteomic analysis of TRAF1 complexes immuno-purified from cells uninduced or induced for LMP1 TES1 signaling. Unexpectedly, we found that LMP1 TES1 domain signaling induced an association between TRAF1 and the linear ubiquitin chain assembly complex (LUBAC), and stimulated linear (M1)-linked polyubiquitin chain attachment to TRAF1 complexes. LMP1 or TRAF1 complexes isolated from EBV-transformed lymphoblastoid B cell lines (LCLs) were highly modified by M1-linked polyubiqutin chains. The M1-ubiquitin binding proteins IKK-gamma/NEMO, A20 and ABIN1 each associate with TRAF1 in cells that express LMP1. TRAF2, but not the cIAP1 or cIAP2 ubiquitin ligases, plays a key role in LUBAC recruitment and M1-chain attachment to TRAF1 complexes, implicating the TRAF1:TRAF2 heterotrimer in LMP1 TES1-dependent LUBAC activation. Depletion of either TRAF1, or the LUBAC ubiquitin E3 ligase subunit HOIP, markedly impaired LCL growth. Likewise, LMP1 or TRAF1 complexes purified from LCLs were decorated by lysine 63 (K63)-linked polyubiqutin chains. LMP1 TES1 signaling induced K63-polyubiquitin chain attachment to TRAF1 complexes, and TRAF2 was identified as K63-Ub chain target. Co-localization of M1- and K63-linked polyubiquitin chains on LMP1 complexes may facilitate downstream canonical NF-kB pathway activation. Our results highlight LUBAC as a novel potential therapeutic target in EBV-associated lymphoproliferative disorders.

No MeSH data available.


Related in: MedlinePlus

Schematic model.LMP1 recruits TRAF1:TRAF2, which in turn associates with LUBAC. LUBAC attaches M1-pUb chains to LMP1/TRAF1 complexes, which recruits the IKK complex. LMP1 also induces attachment of K63-pUb to TRAF2, which in turn recruits and activates the TAB/TAK1 complex. TAK1 activates downstream MAP kinase and canonical NF-kB pathways.
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ppat.1004890.g011: Schematic model.LMP1 recruits TRAF1:TRAF2, which in turn associates with LUBAC. LUBAC attaches M1-pUb chains to LMP1/TRAF1 complexes, which recruits the IKK complex. LMP1 also induces attachment of K63-pUb to TRAF2, which in turn recruits and activates the TAB/TAK1 complex. TAK1 activates downstream MAP kinase and canonical NF-kB pathways.

Mentions: TRAF1:TRAF2 heterotrimers may also be a target of LMP1 TES1-stimulated K63-pUb chain attachment. LMP1 1–231 induced K63-pUb chain attachment to TRAF2 in 293 TRAF1 cells. K63-pUb chain attachment to TRAF2 may serve important roles in LUBAC recruitment and also in TAK1 activation (Fig 11). LUBAC has multiple zinc finger pUb-binding domains, and K63-pUb chains play an important role in LUBAC recruitment to TNFR1 [56,93,94,95]. LMP1-induced K63-pUb chain attachment to TRAF2 may play a similarly important role in LUBAC recruitment to LMP1 and TRAF1 complexes. Likewise, TNF-alpha induced K63-pUb chain attachment to TRAF2 is important for TAB/TAK1 complex recruitment and downstream MAP kinase and canonical NF-kB activation [99–100]. K63-pUb chain linkage to TRAF2 may play a similar role in activating TAK1 downstream of LMP1 TES1. Colocalization of M1- and K63-linked pUb chains may serve to juxtapose the IKK and TAB/TAK1 complexes at the level of LMP1 complexes, and thereby enhance MAP kinase and canonical NF-kB activation (Fig 11).


TRAF1 Coordinates Polyubiquitin Signaling to Enhance Epstein-Barr Virus LMP1-Mediated Growth and Survival Pathway Activation.

Greenfeld H, Takasaki K, Walsh MJ, Ersing I, Bernhardt K, Ma Y, Fu B, Ashbaugh CW, Cabo J, Mollo SB, Zhou H, Li S, Gewurz BE - PLoS Pathog. (2015)

Schematic model.LMP1 recruits TRAF1:TRAF2, which in turn associates with LUBAC. LUBAC attaches M1-pUb chains to LMP1/TRAF1 complexes, which recruits the IKK complex. LMP1 also induces attachment of K63-pUb to TRAF2, which in turn recruits and activates the TAB/TAK1 complex. TAK1 activates downstream MAP kinase and canonical NF-kB pathways.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4440769&req=5

ppat.1004890.g011: Schematic model.LMP1 recruits TRAF1:TRAF2, which in turn associates with LUBAC. LUBAC attaches M1-pUb chains to LMP1/TRAF1 complexes, which recruits the IKK complex. LMP1 also induces attachment of K63-pUb to TRAF2, which in turn recruits and activates the TAB/TAK1 complex. TAK1 activates downstream MAP kinase and canonical NF-kB pathways.
Mentions: TRAF1:TRAF2 heterotrimers may also be a target of LMP1 TES1-stimulated K63-pUb chain attachment. LMP1 1–231 induced K63-pUb chain attachment to TRAF2 in 293 TRAF1 cells. K63-pUb chain attachment to TRAF2 may serve important roles in LUBAC recruitment and also in TAK1 activation (Fig 11). LUBAC has multiple zinc finger pUb-binding domains, and K63-pUb chains play an important role in LUBAC recruitment to TNFR1 [56,93,94,95]. LMP1-induced K63-pUb chain attachment to TRAF2 may play a similarly important role in LUBAC recruitment to LMP1 and TRAF1 complexes. Likewise, TNF-alpha induced K63-pUb chain attachment to TRAF2 is important for TAB/TAK1 complex recruitment and downstream MAP kinase and canonical NF-kB activation [99–100]. K63-pUb chain linkage to TRAF2 may play a similar role in activating TAK1 downstream of LMP1 TES1. Colocalization of M1- and K63-linked pUb chains may serve to juxtapose the IKK and TAB/TAK1 complexes at the level of LMP1 complexes, and thereby enhance MAP kinase and canonical NF-kB activation (Fig 11).

Bottom Line: TRAF1 is amongst the most highly TES1-induced target genes and is abundantly expressed in EBV-associated lymphoproliferative disorders.We found that TRAF1 expression enhanced LMP1 TES1 domain-mediated activation of the p38, JNK, ERK and canonical NF-kB pathways, but not non-canonical NF-kB pathway activity.Our results highlight LUBAC as a novel potential therapeutic target in EBV-associated lymphoproliferative disorders.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States of America.

ABSTRACT
The Epstein-Barr virus (EBV) encoded oncoprotein Latent Membrane Protein 1 (LMP1) signals through two C-terminal tail domains to drive cell growth, survival and transformation. The LMP1 membrane-proximal TES1/CTAR1 domain recruits TRAFs to activate MAP kinase, non-canonical and canonical NF-kB pathways, and is critical for EBV-mediated B-cell transformation. TRAF1 is amongst the most highly TES1-induced target genes and is abundantly expressed in EBV-associated lymphoproliferative disorders. We found that TRAF1 expression enhanced LMP1 TES1 domain-mediated activation of the p38, JNK, ERK and canonical NF-kB pathways, but not non-canonical NF-kB pathway activity. To gain insights into how TRAF1 amplifies LMP1 TES1 MAP kinase and canonical NF-kB pathways, we performed proteomic analysis of TRAF1 complexes immuno-purified from cells uninduced or induced for LMP1 TES1 signaling. Unexpectedly, we found that LMP1 TES1 domain signaling induced an association between TRAF1 and the linear ubiquitin chain assembly complex (LUBAC), and stimulated linear (M1)-linked polyubiquitin chain attachment to TRAF1 complexes. LMP1 or TRAF1 complexes isolated from EBV-transformed lymphoblastoid B cell lines (LCLs) were highly modified by M1-linked polyubiqutin chains. The M1-ubiquitin binding proteins IKK-gamma/NEMO, A20 and ABIN1 each associate with TRAF1 in cells that express LMP1. TRAF2, but not the cIAP1 or cIAP2 ubiquitin ligases, plays a key role in LUBAC recruitment and M1-chain attachment to TRAF1 complexes, implicating the TRAF1:TRAF2 heterotrimer in LMP1 TES1-dependent LUBAC activation. Depletion of either TRAF1, or the LUBAC ubiquitin E3 ligase subunit HOIP, markedly impaired LCL growth. Likewise, LMP1 or TRAF1 complexes purified from LCLs were decorated by lysine 63 (K63)-linked polyubiqutin chains. LMP1 TES1 signaling induced K63-polyubiquitin chain attachment to TRAF1 complexes, and TRAF2 was identified as K63-Ub chain target. Co-localization of M1- and K63-linked polyubiquitin chains on LMP1 complexes may facilitate downstream canonical NF-kB pathway activation. Our results highlight LUBAC as a novel potential therapeutic target in EBV-associated lymphoproliferative disorders.

No MeSH data available.


Related in: MedlinePlus