Article

The La RNA-binding protein interacts with the vault RNA and is a vault-associated protein

Department of Biological Chemistry, The David Geffen School of Medicine, University of California-Los Angeles, 33-131 CHS Mail Code 173717, 10833 Le Conte Avenue, Los Angeles, CA 90095-1737, USA.
Journal of Biological Chemistry (Impact Factor: 4.6). 11/2002; 277(43):41282-6. DOI: 10.1074/jbc.M206980200
Source: PubMed

ABSTRACT Vaults are highly conserved ubiquitous ribonucleoprotein particles with an undefined function. Three protein species (p240/TEP1, p193/VPARP, and p100/MVP) and a small RNA comprise the 13-MDa vault particle. The expression of the unique 100-kDa major vault protein is sufficient to form the basic vault structure. Previously, we have shown that stable association of the vault RNA with the vault particle is dependent on its interaction with the p240/TEP1 protein. To identify other proteins that interact with the vault RNA, we used a UV-cross-linking assay. We find that a portion of the vault RNA is complexed with the La autoantigen in a separate smaller ribonucleoprotein particle. La interacts with the vault RNA (both in vivo and in vitro) presumably through binding to 3'-uridylates. Moreover, we also demonstrate that the La autoantigen is the 50-kDa protein that we have previously reported as a protein that co-purifies with vaults.

0 Followers
 · 
65 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Major vault protein (MVP) is the predominant constituent of the vault particle, the largest known ribonuclear protein complex. Although emerging evidences have been establishing the links between MVP (vault) and multidrug resistance (MDR), little is known regarding exactly how the MDR activity of MVP is modulated during cellular response to drug-induced DNA damage (DDR). Bleomycin (BLM), an anti-cancer drug, induces DNA double-stranded breaks (DSBs) and consequently triggers the cellular DDR. Due to its physiological implications in hepatocellular carcinoma (HCC) and cell fate decision, 14-3-3ε was chosen as the pathway-specific bait protein to identify the critical target(s) responsible for HCC MDR. By using LC-MS/MS-based proteomic approach, MVP was first identified in the BLM-induced 14-3-3ε interactome formed in HCC cells. Biological characterization revealed that MVP possesses specific activity to promote the resistance to the BLM-induced DDR. On the other hand, 14-3-3ε enhances BLM-induced DDR by interacting with MVP. Mechanistic investigation further revealed that 14-3-3ε, in a phosphorylation-dependent manner, binds to the phosphorylated sites at both Thr52 and Ser864 of the monomer of MVP. Consequently, the phosphorylation-dependent binding between 14-3-3ε and MVP inhibits the drug-resistant activity of MVP for an enhanced DDR to BLM treatment. Our findings provide an insight into the mechanism underlying how the BLM-induced interaction between 14-3-3ε and MVP modulates MDR, implicating novel strategy to overcome the chemotherapeutic resistance through interfering specific protein-protein interactions.
    Journal of Proteome Research 04/2013; 12(6). DOI:10.1021/pr301085c · 5.00 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The full potential of vaccines relies on development of effective delivery systems and adjuvants and is critical for development of successful vaccine candidates. We have shown that recombinant vaults engineered to encapsulate microbial epitopes are highly stable structures and are an ideal vaccine vehicle for epitope delivery which does not require the inclusion of an adjuvant. We studied the ability of vaults which were engineered for use as a vaccine containing an immunogenic epitope of Chlamydia trachomatis, polymorphic membrane protein G (PmpG), to be internalized into human monocytes and behave as a “natural adjuvant”. We here show that incubation of monocytes with the PmpG-1-vaults activates caspase-1 and stimulates IL-1β secretion through a process requiring the NLRP3 inflammasome and that cathepsin B and Syk are involved in the inflammasome activation. We also observed that the PmpG-1-vaults are internalized through a pathway that is transiently acidic and leads to destabilization of lysosomes. In addition, immunization of mice with PmpG-1-vaults induced PmpG-1 responsive CD4+ cells upon re-stimulation with PmpG peptide in vitro, suggesting that vault vaccines can be engineered for specific adaptive immune responses. We conclude that PmpG-1-vault vaccines can stimulate NLRP3 inflammasomes and induce PmpG-specific T cell responses.
    Vaccine 11/2014; DOI:10.1016/j.vaccine.2014.11.028 · 3.49 Impact Factor
  • Source
    International journal of cardiology 03/2015; 187:365-368. DOI:10.1016/j.ijcard.2015.03.195 · 6.18 Impact Factor

Leonard H Rome