Showing papers by "Hong Zhang published in 2018"
TL;DR: It is revealed that mTORC1-mediated LLPS of PGL-1/-3 acts as a switch-like stress sensor, coupling phase separation to autophagic degradation and adaptation to stress during development.
150 citations
TL;DR: This study reveals that VAPs directly interact with multiple ATG proteins, thereby contributing to ER/IM contact formation for autophagosome biogenesis.
115 citations
TL;DR: It is reported that a low dose of metformin upregulates the endoplasmic reticulum‐localized glutathione peroxidase 7 (GPx7) and increases the nuclear accumulation of nuclear factor erythroid 2‐related factor 2 (Nrf2), which binds to the antioxidant response elements in the GPX7 gene promoter to induce its expression.
Abstract: Metformin, an FDA-approved antidiabetic drug, has been shown to elongate lifespan in animal models. Nevertheless, the effects of metformin on human cells remain unclear. Here, we show that low-dose metformin treatment extends the lifespan of human diploid fibroblasts and mesenchymal stem cells. We report that a low dose of metformin upregulates the endoplasmic reticulum-localized glutathione peroxidase 7 (GPx7). GP×7 expression levels are decreased in senescent human cells, and GPx7 depletion results in premature cellular senescence. We also indicate that metformin increases the nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2), which binds to the antioxidant response elements in the GPX7 gene promoter to induce its expression. Moreover, the metformin-Nrf2-GPx7 pathway delays aging in worms. Our study provides mechanistic insights into the beneficial effects of metformin on human cellular aging and highlights the importance of the Nrf2-GPx7 pathway in pro-longevity signaling.
109 citations
TL;DR: Experimental results reveal that 1) transfer learning improves the detection accuracy and overall performance and reduces the false positives, and 2) compared with the faster RCNN and other SSD models, the SSD-512 model with transfer learning achieves the best overall performance, which demonstrates the effectiveness of the approach.
Abstract: With the capabilities of constant use in any weather condition and a wide coverage area, synthetic aperture radar (SAR) technology is widely used in marine transportation safety and fishing law enf...
75 citations
TL;DR: Potent pan-Atg8 or GABARAP-selective inhibitory peptides derived from giant neuronal ankyrin-B and -G effectively block autophagy in cell cultures and in C. elegans spatiotemporally in living animals.
Abstract: The mammalian Atg8 family proteins are central drivers of autophagy and contain six members, classified into the LC3 and GABARAP subfamilies. Due to their high sequence similarity and consequent functional overlaps, it is difficult to delineate specific functions of Atg8 proteins in autophagy. Here we discover a super-strong GABARAP-selective inhibitory peptide harbored in 270/480 kDa ankyrin-G and a super-potent pan-Atg8 inhibitory peptide from 440 kDa ankyrin-B. Structural studies elucidate the mechanism governing the Atg8 binding potency and selectivity of the peptides, reveal a general Atg8-binding sequence motif, and allow development of a more GABARAP-selective inhibitory peptide. These peptides effectively blocked autophagy when expressed in cultured cells. Expression of these ankyrin-derived peptides in Caenorhabditis elegans also inhibited autophagy, causing accumulation of the p62 homolog SQST-1, delayed development and shortened life span. Thus, these genetically encodable autophagy inhibitory peptides can be used to occlude autophagy spatiotemporally in living animals.
56 citations
TL;DR: It is found that loss of rnst-2 causes accumulation of rRNA and ribosomal proteins in enlarged lysosomes and both phenotypes are suppressed by blocking autophagy, which indicates that RNST-2 mediates autophagic degradation of ribosome RNA in lyssomes.
Abstract: Ribosome degradation through the autophagy-lysosome pathway is crucial for cell survival during nutrient starvation, but whether it occurs under normal growth conditions and contributes to animal physiology remains unaddressed. In this study, we identified RNST-2, a C. elegans T2 family endoribonuclease, as the key enzyme that degrades ribosomal RNA in lysosomes. We found that loss of rnst-2 causes accumulation of rRNA and ribosomal proteins in enlarged lysosomes and both phenotypes are suppressed by blocking autophagy, which indicates that RNST-2 mediates autophagic degradation of ribosomal RNA in lysosomes. rnst-2(lf) mutants are defective in embryonic and larval development and are short-lived. Remarkably, simultaneous loss of RNST-2 and de novo synthesis of pyrimidine nucleotides leads to complete embryonic lethality, which is suppressed by supplements of uridine or cytidine. Our study reveals an essential role of autophagy-dependent degradation of ribosomal RNA in maintaining nucleotide homeostasis during animal development.
38 citations
TL;DR: The data release (DR) 5 catalogue of white dwarf-main sequence (WDMS) binaries from the Large Area Multi-Object Spectroscopic Telescope (LAMOST) was published in this article.
Abstract: We present the data release (DR) 5 catalogue of white dwarf-main sequence (WDMS) binaries from
the Large Area Multi-Object fiber Spectroscopic Telescope (LAMOST). The catalogue contains
876 WDMS binaries, of which 757 are additions to our previous LAMOST DR1 sample and 357
are systems that have not been published before. We also describe a LAMOST-dedicated survey
that aims at obtaining spectra of photometrically-selected WDMS binaries from the Sloan Digital
Sky Survey (SDSS) that are expected to contain cool white dwarfs and/or early type M dwarf
companions. This is a population under-represented in previous SDSS WDMS binary catalogues. We
determine the stellar parameters (white dwarf effective temperatures, surface gravities and masses,
and M dwarf spectral types) of the LAMOST DR5 WDMS binaries and make use of the parameter
distributions to analyse the properties of the sample. We find that, despite our efforts, systems
containing cool white dwarfs remain under-represented. Moreover, we make use of LAMOST DR5
and SDSS DR14 (when available) spectra to measure the Na I λλ 8183.27, 8194.81 absorption doublet
and/or Hα emission radial velocities of our systems. This allows identifying 128 binaries displaying
significant radial velocity variations, 76 of which are new. Finally, we cross-match our catalogue
with the Catalina Surveys and identify 57 systems displaying light curve variations. These include
16 eclipsing systems, two of which are new, and nine binaries that are new eclipsing candidates. We
calculate periodograms from the photometric data and measure (estimate) the orbital periods of 30
(15) WDMS binaries.
27 citations
TL;DR: Findings for HSDs provide a new insight not only into the mechanistic studies of the dynamics and functions of LDs in multiple organisms, but also into understanding the evolutionary history of the organelle.
26 citations
TL;DR: It is discovered that the TVEEVD sequence of Saccharomyces cerevisiae cytoplasmic Hsp70 (Ssa1) functions as a SUMO-interacting motif, and highlighted that the C-terminal GGAP motif of HSp70 is important for substrate recognition and mediation of the heat shock response.
23 citations
TL;DR: The results suggest that Sec61β may stabilize protein translocation by linking translocon complex to microtubule and provide insight into the physiological function of ER-microtubule interaction.
Abstract: Sec61β, a subunit of the Sec61 translocon complex, is not essential in yeast and commonly used as a marker of endoplasmic reticulum (ER). In higher eukaryotes, such as Drosophila, deletion of Sec61β causes lethality, but its physiological role is unclear. Here, we show that Sec61β interacts directly with microtubules. Overexpression of Sec61β containing small epitope tags, but not a RFP tag, induces dramatic bundling of the ER and microtubule. A basic region in the cytosolic domain of Sec61β is critical for microtubule association. Depletion of Sec61β induces ER stress in both mammalian cells and Caenorhabditis elegans, and subsequent restoration of ER homeostasis correlates with the microtubule binding ability of Sec61β. Loss of Sec61β causes increased mobility of translocon complexes and reduced level of membrane-bound ribosomes. These results suggest that Sec61β may stabilize protein translocation by linking translocon complex to microtubule and provide insight into the physiological function of ER-microtubule interaction.
23 citations
TL;DR: This review focuses on the application of exosomes as nanocarriers and the current status of the application in cancer therapy, and the most promising candidates for targeted drug or gene delivery vehicles.
Abstract: Exosomes are nanoscale vesicles shed from all cell types and play a major role in communication and transportation of materials between cells due to their ability to transfer proteins and nucleic acids from one cell to another. Analogous in size and function to synthetic nanoparticles, exosomes offer many advantages, rendering them the most promising candidates for targeted drug or gene delivery vehicles. Exosomes can also induce chemoresistance or radioresistance of tumor cells. Studies about the related mechanisms help overcome cancer therapy resistance to some extent. In this review, we focus on the application of exosomes as nanocarriers and the current status of the application of exosomes to cancer therapy.
TL;DR: This strategy was successfully used for detecting of A549 cancer cells in complex media such as human serum and clinical pleural effusion, which strong indicated that the proposed method could be applied for the early diagnosis of lung cancer.
TL;DR: The in vitro results found that sulfated and benzoylated derivatives could reverse the decreased mitochondrial activity and decreased lactate dehydrogenase (LDH) and reactive oxygen species (ROS) release induced by 6-hydroxydopamine (6-OHDA), which provides further evidence that sulfate and Benzoylate groups could enhance the neuroprotective activity of fucoidan.
22 Jul 2018
TL;DR: In this paper, the Sentinel-1 ScanSAR IR GRD products are used for sea ice mapping using convolutional neural networks (CNN) and the results are promising.
Abstract: In this paper, the Sentinel-1 ScanSAR IR GRD products are used for sea ice mapping using convolutional neural networks (CNN). The sea and ice are classified as 2 types and 4 types respectively according to their SAR image textures. They are smooth sea, rough sea, granular ice, massive ice, smooth ice and striped ice. The Sentinel-1 SAR images are firstly pre-processed using ESA SNAP software. Then the classes are interpreted manually for chip preparation and annotations. Chips with 3 spatial scales $(32\mathrm{x}32,64\mathrm{x}64,128\mathrm{x}128)$ are used for training input of the CNN. The trained CNN is then used for generation of sea ice map from the ScanSAR image. The results are promising. Further work is still going on.
TL;DR: It is found that the ER-localized autophagy protein EPG-3/VMP1 plays an essential role in controlling ER-phagophore dissociation and also the disassembly of ER contacts with LDs, mitochondria and endolysosomes.
Abstract: The ER forms contacts with other endomembrane systems to exchange materials (e.g., calcium and lipids) and also to modulate dynamic organelle processes, including fission, cargo sorting and movement. During autophagosome formation, dynamic contacts between the ER and the phagophore membrane are crucial for phagophore expansion and closure. Little is known about the mechanisms underlying the formation and disassembly of the ER contacts. We found that the ER-localized autophagy protein EPG-3/VMP1 plays an essential role in controlling ER-phagophore dissociation and also the disassembly of ER contacts with LDs, mitochondria and endolysosomes. VMP1 regulates the ER contact by activating the ER calcium channel ATP2A/SERCA (ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting). CALM (calmodulin) acts as one of the downstream calcium effectors that controls the PIK3C3/VPS34 phosphatidylinositol (PtdIns) 3-kinase (PtdIns3K) activity to maintain these contacts. Our study provides insights into the molecular mechanisms which regulate ER contacts and generate autophagosomes.
TL;DR: This study provides a scientific rationale for the clinical use of heavy ion as radiotherapy in patients with p53‐deficient tumors, which are often resistant to radiotherapy.
Abstract: Deletion of p53, most common genetic alteration, is observed in human tumors and reported to lead to improve in cell radioresistance. Heavy-ion irradiation (IR) could induce p53-/- cancer cells apoptosis. However, little is known regarding the molecular mechanism in this type of cell apoptosis. The present studies have focused on mechanisms state of signaling pathways as an activator of the cell fate decisions induced by heavy ion IR without p53. Carbon ion IR could induce up-regulation of E2F1 expression in cancer cells. This phenomenon was not observed in X-ray IR group. Up-regulation of E2F1 could cause a higher reduction in clonogenic survival, low level of cellular activity, G2 /M phase arrest, promotion of apoptosis rate, up-regulation of phosphor-Rb, Bax, and cleaved-caspase 3 proteins expressions without p53. Changes of E2F1 expressions could partly alter radioresistance in cancer cells. The results were suggested that heavy ion IR could induce p53-/- cancer cells apoptosis via E2F1 signal pathway. Our study provides a scientific rationale for the clinical use of heavy ion as radiotherapy in patients with p53-deficient tumors, which are often resistant to radiotherapy.
TL;DR: The differentially expressed miRNAs described here provided a novel perspective for the role ofMiRNAs in testis toxicity following CIR and helped validate miRNA sequencing data.
Abstract: This study investigated the toxicity of heavy ion radiation to mice testis by microRNA (miRNA) sequencing and bioinformatics analyses. Testicular indices and histology were measured following enterocoelia irradiation with a 2 Gy carbon ion beam, with the testes exhibiting the most serious injuries at 4 weeks after carbon ion radiation (CIR) exposure. Illumina sequencing technology was used to sequence small RNA libraries of the control and irradiated groups at 4 weeks after CIR. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses implicated differential miRNAs in the regulation of target genes involved in metabolism, development, and reproduction. Here, 8 miRNAs, including miR-34c-5p, miR-138, and 6 let-7 miRNA family members previously reported in testis after radiation, were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to validate miRNA sequencing data. The differentially expressed miRNAs described here provided a novel perspective for the role of miRNAs in testis toxicity following CIR.
TL;DR: This work uses the yeast [PSI+] system and SBD-targeted mutagenesis to investigate how allosteric changes within key structural regions of the Hsp70 SBD result in functional changes in the protein that translate to phenotypic defects in prion propagation and ability to grow at elevated temperatures.
Abstract: Hsp70 is a highly conserved chaperone that in addition to providing essential cellular functions and aiding in cell survival following exposure to a variety of stresses is also a key modulator of prion propagation. Hsp70 is composed of a nucleotide-binding domain (NBD) and substrate-binding domain (SBD). The key functions of Hsp70 are tightly regulated through an allosteric communication network that coordinates ATPase activity with substrate-binding activity. How Hsp70 conformational changes relate to functional change that results in heat shock and prion-related phenotypes is poorly understood. Here, we utilised the yeast [PSI +] system, coupled with SBD-targeted mutagenesis, to investigate how allosteric changes within key structural regions of the Hsp70 SBD result in functional changes in the protein that translate to phenotypic defects in prion propagation and ability to grow at elevated temperatures. We find that variants mutated within the β6 and β7 region of the SBD are defective in prion propagation and heat-shock phenotypes, due to conformational changes within the SBD. Structural analysis of the mutants identifies a potential NBD:SBD interface and key residues that may play important roles in signal transduction between domains. As a consequence of disrupting the β6/β7 region and the SBD overall, Hsp70 exhibits a variety of functional changes including dysregulation of ATPase activity, reduction in ability to refold proteins and changes to interaction affinity with specific co-chaperones and protein substrates. Our findings relate specific structural changes in Hsp70 to specific changes in functional properties that underpin important phenotypic changes in vivo. A thorough understanding of the molecular mechanisms of Hsp70 regulation and how specific modifications result in phenotypic change is essential for the development of new drugs targeting Hsp70 for therapeutic purposes.
TL;DR: A new method to conduct whole-genome RNAi screen using LD resident protein DHS-3 as a LD marker, and identified 78 genes involved in significant LD morphologic changes, including mthf-1, as well as a series of methylation-related genes, was found dramatically influencing lipid metabolism.
TL;DR: It is demonstrated that the ubiquitin-binding protein Vps13D functions downstream of the fission factor Drp1 to control mitochondrial size and autophagic clearance in Drosophila midgut cells.
TL;DR: While functional changes in Hsp70 can result in phenotypic consequences for both the stress response and prion propagation, there can be significant differences in the levels of phenotypesic impact that such changes illicit.
Abstract: The Hsp70 chaperone machinery is a key component of the heat-shock response and a modulator of prion propagation in yeast. A major factor in optimizing Hsp70 function is the highly coordinated activities of the nucleotide-binding and substrate-binding domains of the protein. Hsp70 inter-domain communication occurs through a bidirectional allosteric interaction network between the two domains. Recent findings identified the β6/β7 region of the substrate-binding domain as playing a critical role in optimizing Hsp70 function in both the stress response and prion propagation and highlighted the allosteric interaction interface between the domains. Importantly, while functional changes in Hsp70 can result in phenotypic consequences for both the stress response and prion propagation, there can be significant differences in the levels of phenotypic impact that such changes illicit.
University of New Mexico1, University of Massachusetts Medical School2, Ludwig Maximilian University of Munich3, University of Rome Tor Vergata4, Paris Descartes University5, French Institute of Health and Medical Research6, Academia Sinica7, Weizmann Institute of Science8, University of Turku9, University of Pretoria10, Sabancı University11, Agency for Science, Technology and Research12, Harvard University13, Broad Institute14, Chungnam National University15, University of Tromsø16, Hungarian Academy of Sciences17, Babraham Institute18, University of Tokyo19, University of Zurich20, University Medical Center Groningen21, University of Cambridge22, University of Queensland23, University of Oslo24, Francis Crick Institute25, University of Buenos Aires26, Osaka University27, Centre for Life28, Chinese Academy of Sciences29, University of Michigan30
TL;DR: The AIM Center of Biomedical Research Excellence is focused on autophagy and its intersections with other processes, with emphasis on both fundamental discoveries and applied translational research.
Abstract: Recently, NIH has funded a center for autophagy research named the Autophagy, Inflammation, and Metabolism (AIM) Center of Biomedical Research Excellence, located at the University of New Mexico Health Science Center (UNM HSC), with aspirations to promote autophagy research locally, nationally, and internationally. The center has 3 major missions: (i) to support junior faculty in their endeavors to develop investigations in this area and obtain independent funding; (ii) to develop and provide technological platforms to advance autophagy research with emphasis on cellular approaches for high quality reproducible research; and (iii) to foster international collaborations through the formation of an International Council of Affiliate Members and through hosting national and international workshops and symposia. Scientifically, the AIM center is focused on autophagy and its intersections with other processes, with emphasis on both fundamental discoveries and applied translational research.
TL;DR: This study reveals the pathogenesis of tumors in respect to stem cells and indicates that the evolved heterogeneous cell clusters can lead to cancer.
Abstract: Background: The generation of cancer stem cells is essential for the formation of tumor tissues; insightful understanding of the process may offer breakthroughs in tumor research and treatment. It is hypothesized that somatic stem cells (SSC) undergoing abnormal differentiation and evolution are able to form heterogeneous cell clusters, leading to onset of tumors.
Methods: Bone marrow mesenchymal stem cells (BMSCs) were isolated and cultured, then BMSCs were induced to differentiate into osteoblasts, adipocytes and neuroblasts. The differentiation process of BMSCs was interrupted at certain time points, and the cells at various stages of maturation were obtained. The resulting cells were further cultured to their fourth generation, then they were subject to the soft agar colony forming assay to screen the mutated cells that form clusters after losing their contact inhibition. The mutant cells were cultured for 5 days, then inoculated on the renal fascia of mice, which were pre-treated with immunosuppress reagent cyclophosphamide (CTX). Results: Tissue biopsies confirmed a generation of heterogeneous cell clusters in the mice. These clusters morphologically resemble Hela cells, as they share similar pathophysiology, histomorphology and cell biology features with cancer tissues. These findings indicate that the evolved heterogeneous cell clusters can lead to cancer. Conclusions: This study reveals the pathogenesis of tumors in respect to stem cells. Tumor stem cells may arise from the abnormal differentiation and evolution of SSC. From then on, tumor production evolves including heterogeneity, metastasis, immune escape and infinite increment.
TL;DR: The hypothesis that HRG expression may define a drug tolerant cancer cell phenotype characterized by poor response to multiple classes of cytotoxic and targeted therapies, including aromatase inhibitors and SERDs is supported.
Abstract: Background: The receptor tyrosine kinase, HER3 and its ligand, heregulin (HRG), have been implicated in the initiation and progression of multiple cancer types including: breast, lung, and head & neck cancers. Seribantumab is a fully human, monoclonal IgG2 antibody that binds to the ligand-binding domain of HER3 and inhibits HRG-mediated signaling. Previously, seribantumab was tested in combination with exemestane in a placebo-controlled, Phase 2 study in post-menopausal women with ER/PR+, HER2 negative metastatic breast cancer (mBC). Although the trial failed to meet its primary efficacy objective of a 50% reduction in hazard ratio in the seribantumab/exemestane treatment vs. the placebo/exemestane control group, a positive trend in PFS and a statistically significant improvement in median OS was observed in patients in the seribantumab/exemestane treatment group. Seribantumab has also been tested in three randomized Phase 2 studies adding to standard of care (SOC) in non-small cell lung, ER/PR+ mBC, and platinum resistant/refractory ovarian cancer. These studies were retrospectively analyzed to determine correlation between HRG mRNA levels in tumor tissue and PFS. In each of these studies, the presence of tumor cell HRG mRNA was prognostic for shortened PFS with SOC treatment. Further, the addition of seribantumab to SOC therapy improved PFS for patients with HRG+ tumors. These data support the hypothesis that HRG expression may define a drug tolerant cancer cell phenotype characterized by poor response to multiple classes of cytotoxic and targeted therapies, including aromatase inhibitors and SERDs. Additionally, blockade of HRG-induced HER3 signaling by seribantumab may counter such protective effects of HRG on cancer cells, with the potential for improved outcomes in HRG+ patients. It is estimated that ˜45% of hormone-receptor positive, HER2 negative advanced breast cancers are HRG+ and that HRG expression may contribute to accelerated clinical progression observed in this subset of patients. Trial design: In the upcoming randomized, double-blinded, multi-center, Phase 2 study, ER/PR receptor-positive, HER2 negative mBC patients with HRG+ tumors will be prospectively selected using a HRG RNA in situ hybridization assay. Approximately 200 women will be screened to enroll 80 HRG+ subjects. Eligible subjects will be randomized in a 1:1 ratio to receive seribantumab/fulvestrant or placebo/fulvestrant until investigator-assessed disease progression or unacceptable toxicity, whichever comes first. Subjects will have progressed on one or two prior hormonal therapies, one of which must have been a CDKi-containing regimen. The goal of this study is to determine if the combination of seribantumab + fulvestrant is more effective than placebo + fulvestrant based on PFS (primary end point) in HRG positive subjects. Secondary endpoints include OS, objective response rate, and time to progression. Safety will also be assessed. Enrollment is expected to begin in 2017 at approximately 80 sites globally. Citation Format: Kaufman PA, Pipas M, Finn GJ, Mathews SE, Zhang H, Richards J, Kudla AJ, Bloom T, Zalutskaya AA, Llorin-Sangalang J, Pinto AC, Ettl J. SHERBOC: A double-blind, placebo-controlled, phase 2 trial of seribantumab (MM-121) plus fulvestrant in postmenopausal women with hormone receptor-positive, heregulin positive, HER2 negative metastatic breast cancer whose disease progressed after prior systemic therapy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT3-06-01.
01 Jul 2018
TL;DR: This study shows that elevated JNK and IDO1 expression induced by Fe ion IR could result in dysfunction of BMDCs via p-p38/MAPK and p-ERK1/2 signal pathway, and it may represent a new mechanism in radiation-induced immune tolerance.
Abstract: High linear energy transfer radiation is known to deposit higher energy in tissues and cause greater toxicity compared to low-LET irradiation. Local immunosuppression is frequently observed after irradiation (IR). Dendritic cells (DCs) play important roles in the initiation and maintenance of the immune response. The dysfunction of DCs contributes to tumor evasion and growth. However, molecular mechanisms underlying the establishment of immune tolerance induced by heavy ion IR through this DC population are poorly understood. Therefore, here we report our findings on the dysfunction of bone marrow-derived dendritic cells (BMDCs) induced by 1 Gy iron ion radiation and promotions of expressions of JNK1/2/3, indoleamine 2,3-dioxygenase 1 (IDO1), p-ERK1/2 and p38/MAPK; and decrease of IDO2, MHC class II, CD40, CD80 expressions and IFN-γ and TNF-α secretion after total-body IR in mice. JNK+IDO1+ BMDCs showed up-expression of p-ERK1/2 and p-p38/MAPK, reduced expression of MHC class II and CD80, and were not able to effectively stimulate allogeneic spleen T cells. The inhibition of IDO1 expressions could partly restore the function of BMDCs. In all, our study shows that elevated JNK and IDO1 expression induced by Fe ion IR could result in dysfunction of BMDCs via p-p38/MAPK and p-ERK1/2 signal pathway, and it may represent a new mechanism in radiation-induced immune tolerance.