Database Resources of the National Genomics Data Center, China National Center for Bioinformation in 2024

The National Genomics Data Center (NGDC), which is a part of the China National Center for Bioinformation (CNCB), provides a family of database resources to support the global academic and industrial communities. With the rapid accumulation of multi-omics data at an unprecedented pace, CNCB-NGDC continuously expands and updates core database resources through big data archiving, integrative analysis and value-added curation. Importantly, NGDC collaborates closely with major international databases and initiatives to ensure seamless data exchange and interoperability. Over the past year, significant efforts have been dedicated to integrating diverse omics data, synthesizing expanding knowledge, developing new resources, and upgrading major existing resources. Particularly, several database resources are newly developed for the biodiversity of protists (P10K), bacteria (NTM-DB, MPA) as well as plant (PPGR, SoyOmics, PlantPan) and disease/trait association (CROST, HervD Atlas, HALL, MACdb, BioKA, BioKA, RePoS, PGG.SV, NAFLDkb). All the resources and services are publicly accessible at https://ngdc.cncb.ac.cn.

Mycobacteriaceae Phenome Atlas (MPA): A Standardized Atlas for the Mycobacteriaceae Phenome Based on Heterogeneous Sources

The bacterial family Mycobacteriaceae includes pathogenic and nonpathogenic bacteria, and systematic research on their genome and phenome can give comprehensive perspectives for exploring their disease mechanism. In this study, the phenotypes of Mycobacteriaceae were inferred from available phenomic data, and 82 microbial phenotypic traits were recruited as data elements of the microbial phenome. This Mycobacteriaceae phenome contains five categories and 20 subcategories of polyphasic phenotypes, and three categories and eight subcategories of functional phenotypes, all of which are complementary to the existing data standards of microbial phenotypes. The phenomic data of Mycobacteriaceae strains were compiled by literature mining, third-party database integration, and bioinformatics annotation. The phenotypes were searchable and comparable from the website of the Mycobacteriaceae Phenome Atlas (MPA, https://www.biosino.org/mpa/). A topological data analysis of MPA revealed the co-evolution between Mycobacterium tuberculosis and virulence factors, and uncovered potential pathogenicity-associated phenotypes. Two hundred and sixty potential pathogen-enriched pathways were found by Fisher's exact test. The application of MPA may provide novel insights into the pathogenicity mechanism and antimicrobial targets of Mycobacteriaceae.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-023-00101-5.

Placental homing peptide guides HIF1α‑silenced exosomes conjugates for targeted enhancement of invasion of trophoblast cells

There is a current lack of availability of therapeutics to treat Preeclampsia (PE), primarily due to the risk of harm to the fetus. Hypoxia‑inducible factor‑1α (HIF1α) is highly expressed in trophoblast cells and suppresses their invasive ability. Extensive studies have confirmed the positive effects of mesenchymal stem cell (MSC)‑derived exosomes on PE. The aim of the present study was to develop a method for targeted delivery of HIF1α‑silenced exosomes to the placenta. HIF1α was overexpressed in JEG‑3 cells. Then, the glucose uptake, lactate production, proliferation and invasion of HIF1α‑elevated JEG‑3 cells were detected. Exosomal membrane protein lysosome‑associated membrane glycoprotein 2b and placental homing peptide CCGKRK gene sequence amplified by PCR were conjugated using short hairpin RNA‑HIF1α (sh‑HIF1α) sequence (exo‑pep‑sh‑HIF1α), which were then transfected into MSCs cultured in vitro. Exosomes were isolated from the supernatant of the aforementioned MSCs and identified by determining the size and exosomal markers. Finally, the invasion ability of MSCs‑derived exosomes treated JEG‑3 cells were detected using Transwell assays. HIF1α was demonstrated to remarkably promote the uptake of glucose and the production of lactate in JEG‑3 cells. In addition, high levels of HIF1α facilitated the proliferation of JEG‑3 cells, while suppressing their invasion ability. Bone marrow derived MSCs were cultured in vitro and exosomes were successfully isolated from these cells. Exo‑pep‑sh‑HIF1α significantly reduced placental HIF1α expression, and induced significant enhancement of placental invasion. Overall, placental homing peptide‑guided HIF1α‑silenced exosomes effectively facilitated the invasion of placental trophoblasts, which could be used for the targeted delivery of payloads to the placenta and serve as a novel placenta‑specific therapeutic approach.

The relationship between hsa_circ_0051326 and HLA-G expression in the blood of patients with pre-eclampsia

OBJECTIVES

To investigate the relationship between hsa_circ_0051326 and HLA-G expression in the blood of patients with pre-eclampsia.

MATERIAL AND METHODS

Real-time PCR (qRT-PCR) was used to detect the hsa_circ_0051326 expression level. Enzyme-linked immunosorbent assay (ELISA), qRT-PCR, and western blotting were used to detect HLA-G expression in blood in 50 patients with pre-eclampsia and 50 normal pregnant women.

RESULTS

HLA-G protein expression level was decreased significantly in the blood of patients with pre-eclampsia. hsa_circ_0051326 and HLA-G mRNA in blood were decreased significantly in the pre-eclampsia patients compared with normal pregnant women. There was a positive correlation between the expression of serum hsa_circ_0051326 with HLA-G mRNA.

CONCLUSIONS

Serum hsa_circ_0051326 was a new diagnostic biomarker for pre-eclampsia with equivalent efficiency of HLA-G. Maternal serum hsa_circ_0051326 level may pre-diagnose potentially pre-eclampsia before delivery.

MicroRNA‑524‑5p regulates the proliferation and invasion of HTR‑8/SVneo trophoblasts by targeting NUMB in the Notch signaling pathway

Preeclampsia is a pregnancy disorder that is primarily associated with maternal and neonatal or fetal morbidity and mortality. The discovery of dysregulated microRNAs (miRs) and their roles in preeclampsia has provided new insight into the mechanisms involved in pregnancy‑related disorders. In the present study, quantitative PCR demonstrated that the expression levels of miR‑524‑5p were lower in patients with preeclampsia than those in normal pregnant women. Cell Counting Kit‑8 and Transwell assays indicated that overexpression of miR‑524‑5p promoted the proliferation and invasion of HTR‑8/SVneo cells, whereas inhibition of miR‑524‑5p suppressed HTR‑8/SVneo cell proliferation and invasion. Furthermore, NUMB endocytic adaptor protein (NUMB), a negative regulator of the Notch signaling pathway and a target gene of miR‑524‑5p, limited the effects of miR‑524‑5p on HTR‑8/SVneo cell invasion and migration. The present study demonstrated that miR‑524‑5p regulated the proliferation and invasion of HTR‑8/SVneo cells at least partly by targeting NUMB to regulate the Notch signaling pathway.

[Regulatory relationship between lncRNA KCNQ1OT1 and miR-146a-3p in preeclampsia]

Objective: To observe the changes of the expression level of long non-coding RNA (lncRNA) KCNQ1OT1 and microRNA (miR)-146a-3p in placenta tissues of preeclampsia (PE) patients, as well as their effect and mechanism on the biological functions of trophoblast cells. Methods: A total of 45 cases of hospitalized PE patients in Hainan General Hospital from July 2017 to July 2018 were selected as the PE group, 55 normal pregnant women during the same period were chosed as the control group. The expression level of KCNQ1OT1 mRNA and miR-146a-3p in the placenta tissues between two groups were detected by using quantitative real time (qRT)-PCR. Pearson's test was furtherly analyzed the correlation between them. Human trophoblast cell line (HTR8/SVneo) were randomly divided into control and lipopolysaccharide (LPS) groups, and then LPS group were divide into four sub-groups,included LPS group, short hairpin RNA (sh)-KCNQ1OT1 (after silencing the expression of KCNQ1OT1), miR-146a-3p inhibitor and sh-KCNQ1OT1+miR-146a-3p inhibitor. The targeting relationship between KCNQ1OT1 and miR-146a-3p were predicted by bioinformatics software and confirmed by luciferase assay. The cell proliferation and invasion capacities were respectively detected by cell counting kit-8 (CCK-8) and transwell assay. The expression level of KCNQ1OT1 mRNA and miR-146a-3p were detected by qRT-PCR and the protein expression level of CXC chemokine ligand 12 （CXCL12） and CXC chemokine receptor type 4 (CXCR4) were tested by western blot. Results: (1) The mRNA expression level of KCNQ1OT1 in the placenta of PE group was lower than that of control group (0.23±0.03 vs 0.51±0.04, P<0.05), and the miR-146a-3p expression level was higher than that of the control group (0.49±0.03 vs 0.31±0.03, P<0.05), there were statistical significant differences between the two groups. (2) Luciferase assay showed that there was a targeting relationship between KCNQ1OT1 and mir-146a-3p. Compared with the control group, the mRNA expression level of KCNQ1OT1 in the LPS group were significantly decreased (0.91±0.03 vs 0.35±0.03, P<0.05), and the expression level of miR-146a-3p were significantly increased (0.22±0.03 vs 0.63±0.04, P<0.05). The cell proliferation, invasion and migration capacities and the protein expression of CXCL12 and CXCR4 significantly reduced in the LPS group compared with control group (all P<0.05). The mRNA expression level of KCNQ1OT1 (0.23±0.03) in the sh-KCNQ1OT1 group were further decreased, the expression of miR-146a-3p (0.85±0.03) were further increased, and the cell proliferation, invasion and migration capacities and the protein expression of CXCL12 and CXCR4 were all further reduced compared with control group，there were significant difference between two groups (all P<0.05). Comparing the miR-146a-3p inhibitor group, and sh-KCNQ1OT1+miR-146a-3p inhibitor group with the sh-KCNQ1OT1 group, respectively, the expression level of KCNQ1OT1 mRNA (0.78±0.04 vs 0.50±0.03) increased, and the expression level of miR-146a-3p (0.42±0.03 vs 0.46±0.03) decreased, the cell proliferation, invasion and migration capacities and the protein expression of CXCL12 and CXCR4 were all increased ,there were statistically significant differences (all P<0.05). Conclusion: KCNQ1OT1 could target the regulation of miR-146a-3p through CXCL12/CXCR4 pathway in the proliferation, invasion an migration of HTR8/SVneo cells, which may be involved in the pathogenesis of PE.

β-TrCP suppresses the migration and invasion of trophoblast cells in preeclampsia by down-regulating Snail

Insufficient trophoblast invasion has been shown to contribute to the occurrence and progression of preeclampsia (PE). Recently, beta-transducin repeat containing E3 ubiquitin protein (β-TrCP) was shown to function as a ubiquitination regulator in regulating the proliferation and invasion of various cell types. In this study, we employed an in vitro model of trophoblasts to investigate the role played by β-TrCP in the pathogenesis of PE. The levels of β-TrCP in newly delivered placentas from 15 pregnant women with PE and 15 healthy pregnant women were detected by quantitative real-time PCR and western blot assays. The effects of β-TrCP on cell migration, invasion, and epithelial-mesenchymal transition (EMT) in two trophoblast cell lines (HTR-8/SVneo and TEV-1) were examined using wound healing assays, Transwell assays, and western blot assays, respectively. Rescue experiments were performed by treating β-TrCP knockdown or β-TrCP expressing trophoblasts with si-Snail transfection or a proteasome inhibitor (MG132). β-TrCP mRNA and protein expression levels were significantly increased in the PE placentas when compared to the normal control placentas. β-TrCP overexpression significantly inhibited cell migration and invasion, while silencing of β-TrCP promoted cell migration and invasion of the two trophoblast cell lines. Furthermore, we demonstrated that β-TrCP-mediated ubiquitination might inhibit the EMT process of trophoblasts by down-regulating Snail expression. Our results suggest that both β-TrCP mRNA and protein expression were up-regulated in the PE placentas. β-TrCP impeded the migration and invasion of trophoblasts by suppressing Snail expression. This implicates the ubiquitin-proteasome pathway in the pathogenesis of PE, and suggests β-TrCP as a potential target for treating PE.

MiR-135a-5p promotes the migration and invasion of trophoblast cells in preeclampsia by targeting β-TrCP

BACKGROUND

MiR-135a-5p is an important regulator of cell migration and invasion in several diseases. However, the biological functions and mechanisms of miR-135a-5p in women with preeclampsia (PE) remain unclear.

METHODS

The levels of miR-135a-5p and beta-transducin repeat containing E3 ubiquitin protein ligase (β-TrCP) expression in samples of placenta tissue from PE patients and healthy control subjects were determined by quantitative real-time PCR. The effects of miR-135a-5p and β-TrCP on cell migration, invasion, and epithelial-mesenchymal transition (EMT) in two trophoblast cell lines (HTR-8/SVneo and TEV-1) were examined using wound healing, Transwell, and western blot assays, respectively. A luciferase reporter assay was performed to confirm the association between miR-135a-5p and β-TrCP, and an in vivo mouse model was established and used to analyze the effect of β-TrCP on PE clinical phenotypes.

RESULTS

We found that miR-135a-5p expression was significantly decreased and negatively correlated with β-TrCP expression in the placental tissues of pregnant women with PE. Cellular function experiments showed that overexpression of miR-135a5p promoted the migration and invasion of trophoblast cells in vitro. Furthermore, β-TrCP was confirmed as a target gene of miR-135a-5p in trophoblast cells. Notably, overexpression of β-TrCP significantly reversed the effect of miR-135a-5p on migration and invasion of trophoblast cells. At the molecular level, decreases in E-cadherin levels and increases in N-cadherin, Vimentin, and β-catenin levels that were induced by miR-135a-5p overexpression were attenuated by β-TrCP overexpression.

CONCLUSIONS

Our findings demonstrate that miR-135a-5p promotes the migration and invasion of trophoblast cells by targeting β-TrCP.

Relationship between the IL-4 gene promoter -590C/T (rs2243250) polymorphism and susceptibility to autoimmune diseases: a meta-analysis

OBJECTIVE

Studies investigating the association between interleukin (IL)-4 gene promoter -590C/T (rs2243250) polymorphism and autoimmune diseases report conflicting results. To derive a more precise estimation of the relationship, a meta-analysis was performed.

METHODS

A systematic literature search was conducted to identify relevant studies. Pooled odds ratio (OR) with 95% confidence interval (CI) was used to estimate the strength of association.

RESULTS

A total of 6001 cases and 6788 controls from 24 studies were analysed. Significant association of the C allele of IL-4 rs2243250 polymorphism with rheumatoid arthritis (RA) was detected (odds ratio (OR) = 0.696, 95% confidence interval (CI) = 0.601-0.807). Stratification by ethnicity indicated an association between the IL-4 rs2243250 polymorphism and RA in Caucasians. Furthermore, the overall ORs of the associations between the C allele and multiple scleorosis (MS) were 1.340 (95% CI = 1.102-1.630). However, we failed to reveal any association between IL-4 rs2243250 polymorphism and systemic lupus erythematosus (SLE), type 1 diabetes (T1D) or Graves' disease (GD).

CONCLUSIONS

The present study suggests that the IL-4 rs2243250 polymorphism might be associated with genetic susceptibility to autoimmune diseases, including RA and MS.

Cell transformation by ras and regulation of its protein product

We are studying the biological activity and regulation of mammalian Ras protein in tumours and in physiological signalling. We have shown that GAP (the GTPase-activating protein) is a potent negative regulator of normal Ras in cells. Reduction or loss of the NF1 gene product neurofibromin, in association with genetic abnormalities of the NF1 locus, has been identified in schwannoma cell lines from patients with neurofibromatosis and in melanoma and neuroblastoma lines from patients without neurofibromatosis. Although loss of neurofibromin in the schwannoma lines was associated with a high proportion of normal Ras protein in the active GTP-bound state, Ras-GTP appeared to be appropriately regulated in the melanoma and neuroblastoma lines, which contain normal levels of GAP. Therefore the GTPase-activating activity of neurofibromin is not essential for negative regulation of Ras in some cell types and the putative tumour suppressor function of neurofibromin in such cell types is independent of its GTPase-activating activity. Mitogen activation of Ras in fibroblasts is mediated primarily by exchange factors, which probably interact with a region on the Ras protein distinct from the region required for interaction with GAP. Multiple full-length cDNAs have identified a mouse gene whose products are related to yeast CDC25 guanine nucleotide exchange factor.

Induction of HSF1 expression is associated with sporadic colorectal cancer

AIM: To explore the activation of signal transduction pathways related with the carcinogenesis of sporadic colon cancers.

METHODS: A gene array monitoring the activation of 8 signal transduction pathways (PathwayFinder GEArray) was used to screen the differentially expressed genes between colorectal cancer and normal colon tissues. The differentially expressed genes were further analyzed by RT-PCR, using RNA derived from colorectal cancer and normal colon tissue of 35 patients.

RESULTS: The expression of HSF1, HSF27, HSP90 and iNOS was increased in colon cancer tissues compared to normal colon tissue using PathwayFinder GEArray. The RT-PCR results showed that the expression of HSF1 was increased in 86% (30/35) patients and the expression of iNOS was increased in 63% (22/35) patients.

CONCLUSION: The induction of HSF1 gene expression is associated with sporadic colon cancer. HSF1 induces heat shock stress signaling pathway, which might play a role in the carcinogenesis of sporadic colorectal cancer.

[Induction of HSF1 expression and sporadic colorectal cancer]

OBJECTIVE

To explore the activation of the signal transduction pathways related with the carcinogenesis of sporadic colon cancers.

METHODS

A gene microarray monitoring activation of 8 signal transduction pathways (PathwayFinder GEArray) was used to screen the differentially expressed genes between colorectal cancer and normal colon tissue. The differentially expressed genes were further analyzed by RT-PCR, using RNA extracted from cancer tissue and matched normal colon mucosa of 35 patients with colorectal cancer.

RESULTS

The expression of hsf1, hsf27 and inos was increased in colon cancer compared with normal colon mucosa using PathwayFinder GEArray. The RT-PCR results showed that the expression of hsf1 was detected in 86% of patients(30/35)and the expression of inos detected in 63% patients(22/35).

CONCLUSION

Hsf1 induces heat shock stress signaling pathway, which might play a role in the carcinogenesis of sporadic colorectal cancer.

Prevention of murine acute graft-versus-host disease by recipient-derived TGFβ1-treated dendritic cells

Acute graft-versus-host disease (GVHD) remains the major barrier to allogeneic bone marrow transplantation (allo-BMT). Evidence has accumulated that transforming growth factor beta1-treated dendritic cells (TGFbeta-DC), deficient in surface costimulatory molecules, inhibit alloantigen-specific T-cell responses and induce graft hyporeactivity. To analyze the effect of TGFbeta-DC on GVHD after allo-BMT, 5.0 x 10(6) recipient-derived TGFbeta-DC were injected into C57BL/6 (H-2b) with bone marrow-splenocyte grafts from major histocompatibility complex (MHC) disparate BALB/c mice (H-2d). Survival analysis showed TGFbeta-DC cotransplantation resulted in significant prolongation of allograft survival, namely a mean survival time (MST) of 44.3 +/- 4.5 days, versus the untreated MST of 9.5 +/- 0.6 days (P < .01). However, mature DC aggravated the GVHD with an MST of 6.6 +/- 0.6 days (P < .01). In addition, the third-party C3H-derived TGFbeta-DC did not enhance the survival rate (MST = 9.7 +/- 0.5 days). Furthermore, serum IFN-gamma, IL-12, and IL-18 levels in TGFbeta-DC cotransplanted mice were reduced compared with untreated BMT hosts, while serum IL-10 levels were not changed. These results suggest that TGFbeta-DC cotransplantation may attenuate the severity of GVHD after BMT.

High-throughput screening for ligand-induced c-fos mRNA expression by branched DNA assay in Chinese hamster ovary cells

We have developed a generally useful screening assay for receptor agonists and antagonists in Chinese Hamster Ovary (CHO) cells. Three key features of the assay make it applicable to a broad range of receptors: (1) the use of CHO cells as host cells to overexpress receptors, (2) measurement of endogenous c-fos mRNA, which responds to a wide spectrum of stimuli, and (3) the use of branched chain DNA assay which is highly sensitive, quantifiable, amenable to high-throughput analysis, and easy to execute. The combination of these features provides a powerful means to screen rapidly for peptide and small molecule ligands for a variety of receptors. CHO cells overexpressing insulin receptor were used as a test system to compare conventional signaling assays with the high-throughput c-fos branched DNA assay.

[Primary epididymal tumors: report of 24 cases]

24 cases of primary epididymal tumors including 23 benign and 1 malignant tumors were treated. In these cases, 66.7% situated at epididymal tail, and 12.5% involved both tail and body. Smooth muscle tumor of one case was bilateral, and adenomatoid tumor of another one was multiple. The symptoms of primary epididymal tumors were mild even absent, so the tumor was easily confused with non-tumorous mass of epididymis. Benign epididymal tumor should be differentiated from tuberculosis, chronic inflammation or granuloma. Besides signs of malignant mass, malignant epididymal tumor usually showed thickened spermatic cord, especially enlarged ductus deferens. The removal of the tumor mass or whole epididymis of the same side could cure benign epididymal tumor without recurrence. Malignant epididymal tumor should be treated as malignancy of testis or spermatic cord, with adjuvant chemotherapy or radiotherapy as indicated by the pathological type.

EBV gene expression, EBNA antibody responses and EBV+ peripheral blood lymphocytes in post-transplant lymphoproliferative disease

Epstein-Barr virus (EBV) is associated with the development of several B cell malignancies including Burkitt's lymphoma (BL), post-transplant lymphoproliferative disease (PTLD), and AIDS-related lymphomas. The latter two diseases result from EBV-driven B cell proliferation in the absence of normal immunosurveillance and as such, represent a heterogenous family of lymphoproliferative disorders. This article reviews studies on EBV gene expression and antibody development in PTLD and introduces recent information on the levels of EBV+ peripheral blood lymphocytes to discuss possible mechanisms of pathogenesis under varying conditions of immunosuppression.

EBV-immortalized isogenic human B-cell clones exhibit differences in DNA-protein complex formation on the BZLF1 and BRLF1 promoter regions among latent, lytic and TPA-activated cell lines

The reactivation of Epstein-Barr virus from latency requires the transcriptional induction of the viral encoded lytic cycle initiator gene, BZLF1, and a concomitant switch from OriP to OriLyt directed viral DNA replication. To investigate the role of host cell factors in these events, a series of EBV-immortalized clonal lymphoblastoid cell lines (LCL) were derived from the spontaneous outgrowth of peripheral blood lymphocytes from a single EBV-seropositive individual. We show that the state of virus activation among this family of isogenic clonal LCL differs, suggesting that each B-cell clone expresses a different complement of cellular factors that influence the state of viral activation. As a first step in the identification of factors involved in EBV reactivation, nuclear extracts were prepared from tightly latent, spontaneously replicating and latent LCL treated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and sodium butyrate. The extracts were used in gel mobility shift analyses to compare DNA-protein complex formation among a series of target DNA sequences, including OriLyt and promoter sequences from BZLF1 and BRLF1. The DNA-protein complex patterns were reproducible and indistinguishable among extracts obtained from the latent LCL, but differed from those observed in extracts obtained from the spontaneously replicating LCL, particularly in regard to the binding of a CREB protein to the BZLF1 promoter. Moreover, extracts prepared from LCL treated with TPA to induce virus reactivation resulted in the formation of complexes that differed from those prepared from the spontaneously replicating LCL. Taken together, these data suggest that B-cell factors govern the state of viral activation and that EBV may be reactivated by more than one pathway.

Regulated and constitutive activity by CDC25Mm (GRF), a Ras-specific exchange factor

Serum stimulates cells to increase their proportion of Ras protein in the active GTP-bound state. We have recently identified four types (I to IV) of apparently full-length cDNAs from a single mammalian gene, called CDC25Mm or GRF, which is homologous to the Ras-specific exchange factor CDC25 of S. cerevisiae. The largest cDNA (type IV) is brain specific, with the other three classes, although they have distinct 5' ends, essentially representing progressive N-terminal deletions of this cDNA. When placed in a retroviral expression vector, all four types of cDNAs induced morphologic transformation of NIH 3T3 cells and an increase in the basal level of GTP.Ras. Serum stimulation of these transformants lead to a further increase in GTP.Ras only in cells expressing the type IV cDNA. Each type of GRF protein was found in cytosolic and membrane fractions, and the protein in each fraction could stimulate guanine nucleotide release from GDP.Ras in vitro. When NIH 3T3 cells and cells expressing the type IV protein were transfected with two versions of a mutant ras gene, one encoding membrane-associated Ras protein and the other encoding a cytosolic Ras protein, the basal levels of GTP bound to both forms of the mutant Ras protein were significantly higher in the cells expressing the type IV protein. However, serum increased the level of GTP bound to the membrane-associated mutant Ras protein in NIH 3T3 cells and in cells expressing the type IV protein but not in cells expressing the cytosolic version of the Ras protein. We conclude that each type of CDC25Mm induces cell transformation via the ability of its C terminus to stimulate guanine nucleotide exchange on Ras, the presence of N-terminal sequences is associated with a serum-dependent change in GTP.Ras, and the serum-dependent increase in GTP.Ras by exogenous CDC25Mm or by endogenous exchange factors probably requires membrane association of both Ras and the exchange factor.

Evidence for restricted Epstein-Barr virus latent gene expression and anti-EBNA antibody response in solid organ transplant recipients with posttransplant lymphoproliferative disorders

Epstein-Barr virus (EBV) is associated with the development of two human B-cell malignancies, Burkitt's lymphoma and lymphomas that occur in the immunosuppressed host. The latter category of disease has become important recently as it is seen primarily in organ transplant recipients and individuals with acquired immunodeficiency syndrome. One possible mechanism for lymphoma development involves a reduction in or lack of EBV-specific cytotoxic T-cell recognition. In support of this model are previous observations that the expression of EBV nuclear antigen 2 (EBNA2) and latent membrane protein, two viral antigens associated with major histocompatibility complex class I-restricted T-cell killing, are downregulated in Burkitt's lymphoma and in early passage lymphoblastoid cell lines (LCL) derived from the malignant lesions. To determine whether a similar mechanism could occur in the development of posttransplant lymphoproliferative disorders (PTLD), we compared EBV gene expression among 23 PTLD tumor lesions obtained from 11 solid organ transplant recipients and among LCL derived from 3 of these lesions. In this report, we demonstrate, by Southern blot, Western blot, and immunofluorescence analysis, that (1) the tumor lesions exhibit varying patterns of restricted viral gene expression; (2) LCL derived from these lesions may represent the in vitro selection of cell subpopulations; and (3) immunosuppressed individuals have a markedly reduced antibody response to the latent cycle antigens, EBNA1, EBNA2, and EBNA-LP, but not to the lytic cycle viral capsid antigen when compared with normal immunocompetent controls.

Isolation of multiple mouse cDNAs with coding homology to Saccharomyces cerevisiae CDC25: identification of a region related to Bcr, Vav, Dbl and CDC24

In Saccharomyces cerevisiae, the product of the CDC25 gene is an essential Ras activator that appears to function by stimulating guanine nucleotide exchange on Ras. Using the ability of a mouse cDNA expression library to complement yeast cells lacking functional CDC25, Martegani et al. have identified a 1.7 kb partial cDNA from a gene, designated CDC25Mm, with homology to CDC25. We have now screened a mouse brain cDNA library to identify full-length clones of CDC25Mm. This cloning has led to the isolation of six distinct full-length cDNAs, each of which appear to be derived from the CDC25Mm gene, since their 3' 2 kb appear to be identical and to encode the same 661 C-terminal amino acids. Three cDNAs are predicted to encode protein products of 666 or 667 amino acids. The other three cDNAs encode products that are 836, 1120 and 1260 amino acids, respectively. A 241 amino acid region near the N-terminus of the two largest products was found to have homology to a domain shared by Bcr, Vav, Dbl and CDC24. Polyclonal antibodies raised to a peptide encoded by all the cDNAs have identified at least two protein products in NIH3T3 fibroblasts. Their apparent molecular weights are 75 and 95 kDa, which correspond closely to those predicted to be encoded, respectively, by the two shorter classes of cDNAs. In NIH3T3, the 95 kDa form is much more abundant than the 75 kDa form, while PC-12 pheochromocytoma cells contain relatively high levels of the 75 kDa form. We conclude that CDC25Mm is a complex gene whose protein products are regulated in a tissue-specific manner.

Epstein-Barr virus transmission via the donor organs in solid organ transplantation: polymerase chain reaction and restriction fragment length polymorphism analysis of IR2, IR3, and IR4

Two organ transplant recipients who received organs from a common donor and were diagnosed as having an Epstein-Barr virus (EBV)-associated posttransplant lymphoproliferative disorder were studied to determine the mode of EBV transmission. The results of restriction fragment length polymorphism, polymerase chain reaction, and minisatellite DNA analyses demonstrate that both patients had a common strain of EBV and that this strain was transmitted from the donor's organs to both recipients. Posttransplant lymphoproliferative disorder resulted from the proliferation of EBV-immortalized B lymphocytes of the recipient, not those of the donor.