Zhi-Qin Wang

The Schistosoma japonicum genome reveals features of host-parasite interplay.

Schistosoma japonicum is a parasitic flatworm that causes human schistosomiasis, which is a significant cause of morbidity in China and the Philippines. Here we present a draft genomic sequence for the worm. The genome provides a global insight into the molecular architecture and host interaction of this complex metazoan pathogen, revealing that it can exploit host nutrients, neuroendocrine hormones and signalling pathways for growth, development and maturation. Having a complex nervous system and a well-developed sensory system, S. japonicum can accept stimulation of the corresponding ligands as a physiological response to different environments, such as fresh water or the tissues of its intermediate and mammalian hosts. Numerous proteases, including cercarial elastase, are implicated in mammalian skin penetration and haemoglobin degradation. The genomic information will serve as a valuable platform to facilitate development of new interventions for schistosomiasis control.

Evolutionary and biomedical implications of a Schistosoma japonicum complementary DNA resource.

Schistosoma japonicum causes schistosomiasis in humans and livestock in the Asia-Pacific region. Knowledge of the genome of this parasite should improve understanding of schistosome-host interactions, biomedical aspects of schistosomiasis and invertebrate evolution. We assigned 43,707 expressed sequence tags (ESTs) derived from adult S. japonicum and their eggs to 13,131 gene clusters. Of these, 35% shared no similarity with known genes and 75% had not been reported previously in schistosomes. Notably, S. japonicum encoded mammalian-like receptors for insulin, progesterone, cytokines and neuropeptides, suggesting that host hormones, or endogenous parasite homologs, could orchestrate schistosome development and maturation and that schistosomes modulate anti-parasite immune responses through inhibitors, molecular mimicry and other evasion strategies.

Excretory/Secretory Proteome of the Adult Developmental Stage of Human Blood Fluke, Schistosoma japonicum

Schistosomes are the causative agents of schistosomiasis, one of the most prevalent and serious of the parasitic diseases that currently infects ∼200 million people worldwide. Schistosome excretory/secretory (ES) proteins have been shown to play important roles in modulating mammalian host immune systems. In our current study, we performed a global proteomics identification of the ES proteins from adult worms of Schistosoma japonicum, one of the three major schistosome species. Our results unambiguously identified 101 proteins, including 53 putatively secreted proteins. By quantitative analysis, we revealed fatty acid-binding protein as a major constituent of the in vitro ES proteome. Strikingly the heat shock proteins HSP70s, HSP90, and HSP97 constituted the largest protein family in the ES proteome, implying a central role for these proteins in immunomodulation in the host-parasite relationship. Other important S. japonicum ES proteins included actins, 14-3-3, aminopeptidase, enolase, and glyceraldehyde-3-phosphate dehydrogenase, some of which have been considered as viable vaccine candidates and therapeutic targets. A comparison with previous studies suggests that 48.5% of S. japonicum ES proteins are common to other parasite ES products, indicating that the molecular mechanisms involved in evading the host immune response may be conserved across different parasites. Interestingly seven host proteins, including antimicrobial protein CAP18, immunoglobulins, and a complement component, were identified among in vitro S. japonicum ES products likely originating from the schistosome tegument or gut, indicating that host innate and acquired immune systems could defend against schistosome invasion. Our present study represents the first attempt at profiling S. japonicum ES proteins, provides an insight into host-parasite interactions, and establishes a resource for the development of diagnostic agents and vaccines for the control of schistosomiasis.

The genome of the hydatid tapeworm Echinococcus granulosus

Cystic echinococcosis (hydatid disease), caused by the tapeworm E. granulosus, is responsible for considerable human morbidity and mortality. This cosmopolitan disease is difficult to diagnose, treat and control. We present a draft genomic sequence for the worm comprising 151.6 Mb encoding 11,325 genes. Comparisons with the genome sequences from other taxa show that E. granulosus has acquired a spectrum of genes, including the EgAgB family, whose products are secreted by the parasite to interact and redirect host immune responses. We also find that genes in bile salt pathways may control the bidirectional development of E. granulosus, and sequence differences in the calcium channel subunit EgCavβ1 may be associated with praziquantel sensitivity. Our study offers insights into host interaction, nutrient acquisition, strobilization, reproduction, immune evasion and maturation in the parasite and provides a platform to facilitate the development of new, effective treatments and interventions for echinococcosis control.

ING4 induces G2/M cell cycle arrest and enhances the chemosensitivity to DNA-damage agents in HepG2 cells.

The known members of inhibitor of growth (ING) gene family are considered as candidate tumor suppressor genes. ING4, a novel member of ING family, is recently reported to interact with tumor suppressor p53, p300 (a major component of histone acetyl transferase complexes), and p65(RelA) subunit of NF‐κB. In this study, we investigated the cellular behaviors of HepG2 cells with exogenous ING4. Interestingly, the overexpression of ING4 negatively regulated the cell growth with significant G2/M arrest of cell cycle, and moreover, enhanced the cell apoptosis triggered by serum starvation in HepG2 cells. Furthermore, the exogenous ING4 could upregulate endogenous p21 and Bax in HepG2 cells, not in p53‐deficient Saos‐2 cells, suggesting that G2/M arrest induced by ING4 could be mediated by the increased p21 expression in a p53‐dependent manner, although there is no significant increase of p53 expression in HepG2 cells. Moreover, HepG2 cells with exogenous ING4 could significantly increase cell death, as exposed to some DNA‐damage agents, such as etoposide and doxorubicin, implying that ING4 could enhance chemosensitivity to certain DNA‐damage agents in HepG2 cells.

SjTPdb: integrated transcriptome and proteome database and analysis platform for Schistosoma japonicum

BackgroundSchistosoma japonicum is one of the three major blood fluke species, the etiological agents of schistosomiasis which remains a serious public health problem with an estimated 200 million people infected in 76 countries. In recent years, enormous amounts of both transcriptomic and proteomic data of schistosomes have become available, providing information on gene expression profiles for developmental stages and tissues of S. japonicum. Here, we establish a public searchable database, termed SjTPdb, with integrated transcriptomic and proteomic data of S. japonicum, to enable more efficient access and utility of these data and to facilitate the study of schistosome biology, physiology and evolution.DescriptionAll the available ESTs, EST clusters, and the proteomic dataset of S. japonicum are deposited in SjTPdb. The core of the database is the 8,420 S. japonicum proteins translated from the EST clusters, which are well annotated for sequence similarity, structural features, functional ontology, genomic variations and expression patterns across developmental stages and tissues including the tegument and eggshell of this flatworm. The data can be queried by simple text search, BLAST search, search based on developmental stage of the life cycle, and an integrated search for more specific information. A PHP-based web interface allows users to browse and query SjTPdb, and moreover to switch to external databases by the following embedded links.ConclusionSjTPdb is the first schistosome database with detailed annotations for schistosome proteins. It is also the first integrated database of both transcriptome and proteome of S. japonicum, providing a comprehensive data resource and research platform to facilitate functional genomics of schistosome. SjTPdb is available from URL: http://function.chgc.sh.cn/sj-proteome/index.htm.

hOLF44, a secreted glycoprotein with distinct expression pattern, belongs to an uncharacterized olfactomedin-like subfamily newly identified by phylogenetic analysis☆

Secreted proteins are indispensable for the development and differentiation of multicellular organisms. Cloning and characterization of novel or hypothetical genes encoding these proteins are therefore inviting great incentives. Using bioinformatics tools and experimental approaches, we isolated and characterized a human secreted glycoprotein, hOLF44, which contains a highly conserved olfactomedin‐like (OLF) domain in the C‐terminal. However, phylogenetic analysis revealed that hOLF44 is not clustered into any of the OLF subfamilies containing characterized members, and obviously falls into a newly identified uncharacterized OLF subfamily. Western blot analysis showed that hOLF44 protein is robustly secreted from the transfected COS‐7 cells. Expression levels of hOLF44 mRNA are abundant in placenta, moderate in liver and heart, whereas fairly weak in other tissues examined. Immunohistochemical study on human term placenta demonstrated that hOLF44 is mainly localized extracellularly surrounding the syncytiotrophoblastic cells and very rarely expressed in the maternal decidua layer. These results suggest that hOLF44 may have matrix‐related function involved in human placental and embryonic development, or play a similar role in other physiological processes. The further functional characterization of hOLF44 may provide insights into a better understanding of the newly identified OLF subfamily.

N-glycosylation is required for efficient secretion of a novel human secreted glycoprotein, hPAP21.

The present study reported the isolation and characterization of a novel human secreted protein, named as hPAP21 (human protease‐associated domain‐containing protein, 21 kDa), encoded by the hypothetical gene chromosome 2 open reading frame 7 (C2orf7) that contains signal peptide in its N‐terminus, without transmembrane domain, except for PA domain in its middle. Western blotting assay indicated that the c‐Myc tagged hPAP21 could be secreted into culture medium in the transfected Chinese hamster ovary cells. However, the molecular weights, whatever intracellular (28 kDa) or extracellular (30 kDa) forms, are larger than that of the prediction. To define whether the glycosylation was important process for its secretion, endoglycosidase H (Endo H) and PNGase F (PNG F) were employed to evaluate the effect of glycosylation types on secretion of hPAP21. Interestingly, the extracellular forms were primarily sensitive to PNG F, not Endo H, implying that complex N‐glycosylation could be required for the secretion of hPAP21. Furthermore, N‐glycosylation of Asn171 was confirmed as potential crucial process for the secretory protein via site‐directed mutagenesis assay. All data will be contributed to the understanding of molecular functions of hPAP21.

Insulin receptor tyrosine kinase substrate enhances low levels of MDM2-mediated p53 ubiquitination.

The tumor suppressor p53 controls multiple cellular functions including DNA repair, cell cycle arrest and apoptosis. MDM2-mediated p53 ubiquitination affects both degradation and cytoplasmic localization of p53. Several cofactors are known to modulate MDM2-mediated p53 ubiquitination and proteasomal degradation. Here we show that IRTKS, a novel IRSp53-like protein inhibited p53-induced apoptosis and depressed its transcription activity. IRTKS bound directly to p53 and increased p53 ubiquitination and cytoplasmic localization. Further studies revealed that IRTKS interacted with MDM2 and promoted low levels of MDM2-mediated p53 ubiquitination in vitro and in vivo. In unstressed cells with low levels of MDM2, IRTKS was found to stabilize the interaction of p53 and MDM2. In stressed cells, IRTKS dissociated from p53, and high levels of MDM2 induced by p53 activation mediate IRTKS poly-ubiquitination and subsequent proteasomal degradation. These data suggest that IRTKS is a novel regulator of p53, modulating low level of MDM2-mediated p53 ubiquitination in unstressed cells.

Src-stimulated IRTKS phosphorylation enhances cell migration

Insulin receptor tyrosine kinase substrate (IRTKS) has been demonstrated to be a scaffold protein involved in plasma membrane deformation and actin cytoskeleton remodeling. IRTKS is tyrosine phosphorylated in response to insulin stimulation. However, the mechanism and function of IRTKS phosphorylation remains unclear. Here, we report that overexpression of IRTKS increases the speed of wound closure of HT1080 cells in a Src‐dependent manner. Active Src phosphorylates IRTKS in vivo and in vitro. Deletion mapping and mutation analysis revealed that six tyrosine residues (Y37, Y156, Y163, Y274, Y293 and Y439) were Src‐stimulated phosphorylation sites on IRTKS. Disruption of Src‐stimulated IRTKS phosphorylation abolished the effect of IRTKS on wound closure. Collectively, these data suggest Src‐stimulated IRTKS phosphorylation is essential for its function in cell motility.