Browsing by Subject "Immunoprecipitation"

Now showing 1 - 5 of 5
  • Thumbnail Image
    ItemOpen Access
    A recessive variant of XRCC4 predisposes to non- BRCA1/2 breast cancer in chinese women and impairs the DNA damage response via dysregulated nuclear localization.
    (Oncotarget, 2014-12) He, Min; Hu, Xin; Chen, Li; Cao, A-Yong; Yu, Ke-Da; Shi, Ting-Yan; Kuang, Xia-Ying; Shi, Wen-Biao; Ling, Hong; Li, Shan; Qiao, Feng; Yao, Ling; Wei, Qingyi; Di, Gen-Hong; Shao, Zhi-Ming
    XRCC4 plays a crucial role in the non-homologous end joining pathway that maintains genome stability. In this two-stage case-control study with 1,764 non-BRCA1/2 breast cancer patients and 1,623 cancer-free controls, we investigated the contribution of genetic variants of XRCC4 to breast cancer susceptibility in Chinese women. We identified a recessive missense variant, rs3734091 (c.739G>T, p.Ala247Ser), of XRCC4 that was significantly associated with an increased risk of breast cancer (odds ratio [OR] = 3.92, P = 0.007), particularly with the risk of developing triple-negative breast cancer (OR = 18.65, P < 0.0001). This p.Ala247Ser variant disturbed the nuclear localization of XRCC4 in cells homozygous for the rs3734091-T allele but not in heterozygous cells at both the cellular and tissue levels. In heterozygous cells, wild-type XRCC4 facilitated the nuclear localization of the XRCC4A247S mutant, thus compensating for the impaired localization of XRCC4A247S. This provided a biological mechanism by which rs3734091 conferred an increased susceptibility to non-BRCA1/2 breast cancer exclusively under a recessive model. Further functional analyses revealed that p.Ala247Ser impaired the DNA damage repair capacity and ultimately perturbed genomic stability. Taken together, our findings document the role of XRCC4 in non-BRCA1/2 breast cancer predisposition and reveal its underlying biological mechanism of action.
  • Thumbnail Image
    ItemOpen Access
    Dectin 1 activation on macrophages by galectin 9 promotes pancreatic carcinoma and peritumoral immune tolerance.
    (Nature medicine, 2017-05) Daley, Donnele; Mani, Vishnu R; Mohan, Navyatha; Akkad, Neha; Ochi, Atsuo; Heindel, Daniel W; Lee, Ki Buom; Zambirinis, Constantinos P; Pandian, Gautam Sd Balasubramania; Savadkar, Shivraj; Torres-Hernandez, Alejandro; Nayak, Shruti; Wang, Ding; Hundeyin, Mautin; Diskin, Brian; Aykut, Berk; Werba, Gregor; Barilla, Rocky M; Rodriguez, Robert; Chang, Steven; Gardner, Lawrence; Mahal, Lara K; Ueberheide, Beatrix; Miller, George
    The progression of pancreatic oncogenesis requires immune-suppressive inflammation in cooperation with oncogenic mutations. However, the drivers of intratumoral immune tolerance are uncertain. Dectin 1 is an innate immune receptor crucial for anti-fungal immunity, but its role in sterile inflammation and oncogenesis has not been well defined. Furthermore, non-pathogen-derived ligands for dectin 1 have not been characterized. We found that dectin 1 is highly expressed on macrophages in pancreatic ductal adenocarcinoma (PDA). Dectin 1 ligation accelerated the progression of PDA in mice, whereas deletion of Clec7a-the gene encoding dectin 1-or blockade of dectin 1 downstream signaling was protective. We found that dectin 1 can ligate the lectin galectin 9 in mouse and human PDA, which results in tolerogenic macrophage programming and adaptive immune suppression. Upon disruption of the dectin 1-galectin 9 axis, CD4+ and CD8+ T cells, which are dispensable for PDA progression in hosts with an intact signaling axis, become reprogrammed into indispensable mediators of anti-tumor immunity. These data suggest that targeting dectin 1 signaling is an attractive strategy for developing an immunotherapy for PDA.
  • Thumbnail Image
    ItemOpen Access
    Interaction of Cryptococcus neoformans Rim101 and protein kinase A regulates capsule.
    (PLoS Pathog, 2010-02-19) O'Meara, Teresa R; Norton, Diana; Price, Michael S; Hay, Christie; Clements, Meredith F; Nichols, Connie B; Alspaugh, J Andrew
    Cryptococcus neoformans is a prevalent human fungal pathogen that must survive within various tissues in order to establish a human infection. We have identified the C. neoformans Rim101 transcription factor, a highly conserved pH-response regulator in many fungal species. The rim101 multiply sign in circle mutant strain displays growth defects similar to other fungal species in the presence of alkaline pH, increased salt concentrations, and iron limitation. However, the rim101 multiply sign in circle strain is also characterized by a striking defect in capsule, an important virulence-associated phenotype. This capsular defect is likely due to alterations in polysaccharide attachment to the cell surface, not in polysaccharide biosynthesis. In contrast to many other C. neoformans capsule-defective strains, the rim101 multiply sign in circle mutant is hypervirulent in animal models of cryptococcosis. Whereas Rim101 activation in other fungal species occurs through the conserved Rim pathway, we demonstrate that C. neoformans Rim101 is also activated by the cAMP/PKA pathway. We report here that C. neoformans uses PKA and the Rim pathway to regulate the localization, activation, and processing of the Rim101 transcription factor. We also demonstrate specific host-relevant activating conditions for Rim101 cleavage, showing that C. neoformans has co-opted conserved signaling pathways to respond to the specific niche within the infected host. These results establish a novel mechanism for Rim101 activation and the integration of two conserved signaling cascades in response to host environmental conditions.
  • Thumbnail Image
    ItemOpen Access
    Tenascin-C is an innate broad-spectrum, HIV-1-neutralizing protein in breast milk.
    (Proceedings of the National Academy of Sciences of the United States of America, 2013-11) Fouda, Genevieve G; Jaeger, Frederick H; Amos, Joshua D; Ho, Carrie; Kunz, Erika L; Anasti, Kara; Stamper, Lisa W; Liebl, Brooke E; Barbas, Kimberly H; Ohashi, Tomoo; Moseley, Martin Arthur; Liao, Hua-Xin; Erickson, Harold P; Alam, S Munir; Permar, Sallie R
    Achieving an AIDS-free generation will require elimination of postnatal transmission of HIV-1 while maintaining the nutritional and immunologic benefits of breastfeeding for infants in developing regions. Maternal/infant antiretroviral prophylaxis can reduce postnatal HIV-1 transmission, yet toxicities and the development of drug-resistant viral strains may limit the effectiveness of this strategy. Interestingly, in the absence of antiretroviral prophylaxis, greater than 90% of infants exposed to HIV-1 via breastfeeding remain uninfected, despite daily mucosal exposure to the virus for up to 2 y. Moreover, milk of uninfected women inherently neutralizes HIV-1 and prevents virus transmission in animal models, yet the factor(s) responsible for this anti-HIV activity is not well-defined. In this report, we identify a primary HIV-1-neutralizing protein in breast milk, Tenascin-C (TNC). TNC is an extracellular matrix protein important in fetal development and wound healing, yet its antimicrobial properties have not previously been established. Purified TNC captured and neutralized multiclade chronic and transmitted/founder HIV-1 variants, and depletion of TNC abolished the HIV-1-neutralizing activity of milk. TNC bound the HIV-1 Envelope protein at a site that is induced upon engagement of its primary receptor, CD4, and is blocked by V3 loop- (19B and F39F) and chemokine coreceptor binding site-directed (17B) monoclonal antibodies. Our results demonstrate the ability of an innate mucosal host protein found in milk to neutralize HIV-1 via binding to the chemokine coreceptor site, potentially explaining why the majority of HIV-1-exposed breastfed infants are protected against mucosal HIV-1 transmission.
  • Thumbnail Image
    ItemOpen Access
    The Trim39 ubiquitin ligase inhibits APC/CCdh1-mediated degradation of the Bax activator MOAP-1.
    (J Cell Biol, 2012-04-30) Huang, Nai-Jia; Zhang, Liguo; Tang, Wanli; Chen, Chen; Yang, Chih-Sheng; Kornbluth, Sally
    Proapoptotic Bcl-2 family members, such as Bax, promote release of cytochrome c from mitochondria, leading to caspase activation and cell death. It was previously reported that modulator of apoptosis protein 1 (MOAP-1), an enhancer of Bax activation induced by DNA damage, is stabilized by Trim39, a protein of unknown function. In this paper, we show that MOAP-1 is a novel substrate of the anaphase-promoting complex (APC/C(Cdh1)) ubiquitin ligase. The influence of Trim39 on MOAP-1 levels stems from the ability of Trim39 (a RING domain E3 ligase) to directly inhibit APC/C(Cdh1)-mediated protein ubiquitylation. Accordingly, small interfering ribonucleic acid-mediated knockdown of Cdh1 stabilized MOAP-1, thereby enhancing etoposide-induced Bax activation and apoptosis. These data identify Trim39 as a novel APC/C regulator and provide an unexpected link between the APC/C and apoptotic regulation via MOAP-1.