A Diagnostic Test Combining Molecular Testing with Phenotypic Pooled Antibiotic Susceptibility Improved the Clinical Outcomes of Patients with Non-E. coli or Polymicrobial Complicated Urinary Tract Infections.

Purpose: Complicated UTIs (cUTIs) cause significant morbidity and healthcare resource utilization and cost. Standard urine culture has limitations in detecting polymicrobial and non-E. coli infections, resulting in the under-diagnosis and under-treatment of cUTIs. In this study, patient-reported outcomes were compared between treated and untreated patients when an advanced diagnostic test combining multiplex-polymerase chain reaction (M-PCR) with a pooled antibiotic susceptibility method (P-AST) was incorporated into the patients' clinical management. Methods: Patients who had symptoms typical of cUTI and positive M-PCR/P-AST test results were recruited from urology clinics. Symptom reduction and clinical cure rates were measured from day 0 through day 14 using the American English Acute Cystitis Symptom Score (ACSS) Questionnaire. Clinical cure was defined based on the sum of the scores of four US Food and Drug Administration (FDA) symptoms and the absence of visible blood in the urine. Results: Of 264 patients with suspected cUTI, 146 (55.4%) had exclusively non-E. coli infections (115 treated and 31 untreated) and 190 (72%) had polymicrobial infections (162 treated and 28 untreated). Treated patients exhibited greater symptom reduction compared to untreated ones on day 14 for those with exclusively non-E. coli organisms (3.18 vs 1.64, p = 0.006) and polymicrobial infections (3.52 vs 1.41, p = 0.002), respectively. A higher percentage of treated patients than of untreated patients achieved clinical cure for polymicrobial infections on day 14 (58.7% vs 36.4%, p = 0.049). Conclusion: Patients with cUTIs treated based on the M-PCR/P-AST diagnostic test had significantly improved symptom reduction and clinical cure rates compared to untreated patients among those with non-E. coli or polymicrobial infections.

Analytical Performance of a 15-Gene Prognostic Assay for Early-Stage Non-Small-Cell Lung Carcinoma Using RNA-Stabilized Tissue.

A 15-gene prognostic signature for early-stage, completely resected, non-small-cell lung carcinoma, (which distinguishes between patients with good and poor prognoses) was clinically validated in prior studies. To achieve operational efficiencies, this study was designed to evaluate the assay's performance in RNA-stabilized tissue as an alternative to the fresh-frozen tissue format originally used to develop the assay. The percent concordance between matched tissue formats was 84% (95% Wilson CI, 70%-92%), a level of agreement comparable to the inherent reproducibility of the assay observed within biological replicates of fresh-frozen tissue. Furthermore, the analytical performance of the assay using the RNA-stabilized tissue format was evaluated. When compared to an accredited reference laboratory, the clinical laboratory achieved a concordance of 94% (95% Wilson CI, 81%-98%), and there was no evidence of bias between the laboratories. The lower limit of quantitation for the target RNA concentration was confirmed to be, at most, 12.5 ng/µL. The assay reportable range defined in terms of risk score units was determined to be -4.295 to 4.210. In a large-scale precision study, the assay showed high reproducibility and repeatability. When subjected to a maximal amount of genomic DNA, a potential contaminant, the assay still produced the expected results. The 15-gene signature was confirmed to produce reliable results and, thus, is suitable for its intended use.

In vitro chemoresponse in metachronous pairs of ovarian cancers.

BACKGROUND/AIM: An in vitro chemoresponse assay may aid effective therapy selection in epithelial ovarian cancer (EOC). This study explores changes in chemoresponse between paired primary and recurrent EOC tumors. PATIENTS AND METHODS: RESULTS from metachronous tumors were examined in 242 patients. Changes in in vitro chemoresponse, measured by the area under the dose response curve (AUC) between paired tumors were assessed. RESULTS: A significant increase in AUC was identified in most first-line therapies over time. No significant difference was observed in most recurrent therapies. When the elapsed time between occurrences was <17 months, no difference was observed for any recurrent therapies, and half of first-line therapies exhibited significant increases in AUC. When ≥17 months, all 7 therapies showed significant increases. CONCLUSION: These results suggest an increase in chemoresistance over time, which is more pronounced for first-line therapies. This is consistent with clinical observations and suggests the biologic concordance between assay results and response to chemotherapy.

Analytical performance of a formalin-fixed paraffin-embedded tissue-based 634-probe prognostic assay for predicting outcome of patients with stage II colon cancer.

A formalin-fixed paraffin-embedded tissue-based prognostic assay to assess the risk for recurrence in stage II colon cancer has recently been clinically validated. This study describes the analytical performance and quality control measures of the assay. The reportable range was determined to be [-1.129, 1.414] in risk score units. The accuracy was evaluated with a split sample comparison within the production lab and between the production lab and a reference lab. The concordance between the replicates within the production lab was 79% (95% confidence interval, 64%-91%). There was no evidence of bias, and the concordance was 78% (95% confidence interval, 61%-90%) between the labs. The lab-to-lab concordance was further evaluated by simulating risk scores from the full reportable range. The simulation suggested a higher concordance. The sensitivity study demonstrated that the percentage of tumor tissue did not impact the risk score and that RNA concentration of 9.5 ng/µL was a conservative determination of the analyte lower limit of quantification. From the precision study, the repeatability and reproducibility estimates were 0.1267 and 0.0548 in risk score units, respectively. Furthermore, multifaceted quality control measures were implemented, such as proper tissue processing steps, high-risk and low-risk controls, nontemplate control, and a gene expression-based classifier to evaluate the cDNA amplification kit, a key reagent in the assay. In conclusion, this study demonstrates the strong analytical performance of the assay and further supports its use as an objective standardized prognostic test for stage II colon cancer.

[Basic biological characteristics of mesenchymal stem cells derived from bone marrow and human umbilical cord].

Bone marrow (BM) and umbilical cord (UC) are the major sources of mesenchymal stem cells for therapeutics. This study was aimed to compare the basic biologic characteristics of bone marrow-derived and umbilical cord derived-mesenchymal stem cells (BM-MSC and UC-MSC) and their immunosuppressive capability in vitro. The BM-MSC and UC-MSC were cultured and amplified under same culture condition. The growth kinetics, phenotypic characteristics and immunosuppressive effects of UC-MSC were compared with those of BM-MSC.Gene chip was used to compare the genes differentially expressed between UC-MSC and BM-MSC. The results showed that UC-MSC shared most of the characteristics of BM-MSC, including morphology and immunophenotype. UC-MSC could be ready expanded for 30 passages without visible changes. However, BM-MSC grew slowly, and the mean doubling time increased notably after passage 6. Both UC-MSC and BM-MSC could inhibit phytohemagglutinin-stimulated peripheral blood mononuclear cell proliferation, in which BM-MSC mediated more inhibitory effect. Compared with UC-MSC, BM-MSC expressed more genes associated with immune response. Meanwhile, the categories of up-regulated genes in UC-MSC were concentrated in organ development and growth. It is concluded that the higher proliferation capacity, low human leukocyte antigen-ABC expression and immunosuppression make UC-MSC an excellent alternative to BM-MSC for cell therapy. The differences between BM-MSC and UC-MSC gene expressions can be explained by their ontogeny and different microenvironment in origin tissue. These differences can affect their efficacy in different therapeutic applications.

[Immunomodulatory ability of senile mesenchymal stem cells].

This study was aimed to investigate the immunomodulatory ability of human umbilical cord mesenchymal stem cells (UB-MSC) along with prolonging of culture time and increasing of passages in vitro. Mesenchymal stem cells (MSC) were isolated from human umbilical cord and cultured in vitro. The morphological changes and nucleocytoplasmic ratio of MSC were observed using Giemsa staining. MSC of the 5th passage were selected as control group, and MSC of the 13th passage were taken as senile group. The degree of cell senescence was detected by aging cells in situ test kit. Cell Counting Kit-WST-8 was used to determine the proliferation of lymphocytes in mixed lymphocytes coculture system with different passages of MSC. The expression of immunomodulation-related genes was detected by RT-PCR. The results showed that the length-breadth ratio of MSC increased and nucleocytoplasmic ratio decreased along with the increasing of passages. The senium degree of cells of the 13th passage was higher than that of the 5th passage cells. The capacity of suppressing lymphocyte proliferation of the 13th passage MSC was enhanced, compared with the 5th passage. Moreover, the expression of immunosuppression-related genes of senile MSC increased and the expression of most anti-inflammation associated genes declined as compared with young MSC by RT-PCR. It is concluded that the degree of MSC senescence gradually develops with increasing of culture passage, but the immunosuppressive ability of MSC strengthens with continuous culture.

Adaptation of a chemosensitivity assay to accurately assess pemetrexed in ex vivo cultures of lung cancer.

PURPOSE: Pemetrexed is the only FDA approved treatment for mesothelioma and is a second line agent for treatment of non-small cell lung carcinoma (NSCLC). Pemetrexed is inhibited by folate and its analogs, which are components of many culture media, making it challenging to study pemetrexed in vitro. In order to accurately evaluate pemetrexed's effects in vitro, the protocol for a standard chemosensitivity assay, the ChemoFx drug response marker, had to be modified. EXPERIMENTAL DESIGN: Novel rinse and media change steps were assessed and then added to the assay protocol in order to observe pemetrexed activity. The intraday and interday stability of pemetrexed were also established under the adapted protocol. Then, the modified protocol was used to examine pemetrexed in 65 ex vivo lung cancer specimens. RESULTS: Substituting 5% RPMI + EGF for BEGM allowed pemetrexed to exert its anticancer activity in the ChemoFx DRM. ChemoFx classified 6.2% of the lung specimens as responsive, 9.2% as intermediate responsive and 84.6% as non-responsive to pemetrexed. CONCLUSIONS: Adapting the ChemoFx protocol allowed for the accurate evaluation of pemetrexed anticancer activity in ex vivo lung specimens. ChemoFx evaluation may provide an indication of a patient's clinical response to the drug prior to pemetrexed treatment. Having this information when treatment options are being considered could avoid wasted time, unnecessary costs and needless side effects that are the result of an inappropriate chemotherapy regimen.

The Birt-Hogg-Dubé tumor suppressor Folliculin negatively regulates ribosomal RNA synthesis.

Birt-Hogg-Dubé syndrome (BHD) is a human cancer disorder caused by mutations in the tumor suppressor gene Folliculin (FLCN) with unknown biological functions. Here, we show that the Drosophila homolog of FLCN, dFLCN (a.k.a. dBHD) localizes to the nucleolus and physically interacts with the 19S proteasomal ATPase, Rpt4, a nucleolar resident and known regulator of rRNA transcription. Downregulation of dFLCN resulted in an increase in nucleolar volume and upregulation of rRNA synthesis, whereas dFLCN overexpression reduced rRNA transcription and counteracted the effects of Rpt4 on rRNA production by preventing the association of Rpt4 with the rDNA locus. We further show that human FLCN exhibited evolutionarily conserved function and that Rpt4 knockdown inhibits the growth of FLCN-deficient human renal cancer cells in mouse xenografts. Our study suggests that FLCN functions as a tumor suppressor by negatively regulating rRNA synthesis.

Distinct genes related to drug response identified in ER positive and ER negative breast cancer cell lines.

Breast cancer patients have different responses to chemotherapeutic treatments. Genes associated with drug response can provide insight to understand the mechanisms of drug resistance, identify promising therapeutic opportunities, and facilitate personalized treatment. Estrogen receptor (ER) positive and ER negative breast cancer have distinct clinical behavior and molecular properties. However, to date, few studies have rigorously assessed drug response genes in them. In this study, our goal was to systematically identify genes associated with multidrug response in ER positive and ER negative breast cancer cell lines. We tested 27 human breast cell lines for response to seven chemotherapeutic agents (cyclophosphamide, docetaxel, doxorubicin, epirubicin, fluorouracil, gemcitabine, and paclitaxel). We integrated publicly available gene expression profiles of these cell lines with their in vitro drug response patterns, then applied meta-analysis to identify genes related to multidrug response in ER positive and ER negative cells separately. One hundred eighty-eight genes were identified as related to multidrug response in ER positive and 32 genes in ER negative breast cell lines. Of these, only three genes (DBI, TOP2A, and PMVK) were common to both cell types. TOP2A was positively associated with drug response, and DBI was negatively associated with drug response. Interestingly, PMVK was positively associated with drug response in ER positive cells and negatively in ER negative cells. Functional analysis showed that while cell cycle affects drug response in both ER positive and negative cells, most biological processes that are involved in drug response are distinct. A number of signaling pathways that are uniquely enriched in ER positive cells have complex cross talk with ER signaling, while in ER negative cells, enriched pathways are related to metabolic functions. Taken together, our analysis indicates that distinct mechanisms are involved in multidrug response in ER positive and ER negative breast cells.

[Influence of vascular endothelial growth factor on endothelial components in human bone marrow and umbilical cord mesenchymal stem cells].

This study was aimed to compare the proportion of endothelial cells (EC) in human bone marrow mesenchymal stem cell (BM-MSC) and human umbilical cord mesenchymal stem cells (UC-MSC), and to investigate the influence of vascular endothelial growth factor (VEGF) on proportion of EC in MSC. Flow cytometry was used to detect the proportion of CD34(+)CD133(+) and vWF(+)CD31(+) double positive cells in MSC. Wright's staining was employed to observe the influence of VEGF on morphology of MSC. The expressions of CD34, CD133, CD31, vWF were detected by immunofluorescence. qRT-PCR was performed to detect the influence of VEGF on EC marker genes' expression of MSC. The results showed that there were a small amount of EC and endothelial progenitor cells (EPC) in obtained BM-MSC and UC-MSC. After exposed to VEGF 10 ng/ml for 24 h, aspect ratio of MSC and the proportion of EC increased, while proportion of EPC decreased. Expression of EC related marker genes such as Tie-2 and ecNOS up-regulated, especially in UC-MSC. It is concluded that small amount of EC and EPC exists in cultured BM-MSC and UC-MSC, VEGF can enhance the proportion and function of EC in MSC.

[Changes of biological characteristics and gene expression profile of umbilical cord mesenchymal stem cells during senescence in culture].

This study was purposed to investigate the changes of biological properties and expression patterns of the aging related genes in umbilical cord mesenchymal stem cells (UC-MSC) during in vitro culture. UC-MSC at passage 3 were served as the control cells and those at passage 15 were considered as the aged cells. The biological features of those two kinds of cells including morphology, proliferation activity and phenotypic profile were observed, and the differences of gene expression were analysed by the whole human genome oligo microarray. Several differential genes were selected for further confirmation by quantitative reverse transcription-polymerase chain reaction. The results showed that UC-MSC at passage 15 were larger in size and their proliferation rate was slower compared with those of cells at passage 3, while the positivity of CD44 and CD105 remained unchanged. Compared with UC-MSC at passage 3, relatively aged cells expressed higher levels of genes that are associated with small subunit of ribosome. Further analysis with Gene Ontology functional categories showed that the up-regulated genes were concentrated in those related to steroid biosynthesis, galactose metabolism and the development of autoimmune diseases and degenerative diseases and the down-regulated genes in UC-MSC at passage 15 were concentrated in cytoskeleton molecules, DNA structure binding, mRNA binding and protein function. Functional analysis with Kyoto Encyclopedia of Genes and Genomes functional pathway revealed that the expression of some genes responsible for ribosome composition was elevated while those of associated with extracellular matrix, focal adhesion and cell cycle progression were down-regulated. It is concluded that UC-MSC become senescent due to the declines in metabolism and proliferation activities.

Hepatitis B virus infection and replication in human bone marrow mesenchymal stem cells.

BACKGROUND: Hepatitis B virus (HBV) infection is a blood borne infectious disease that affects the liver. Human bone marrow mesenchymal stem cells (BMSCs) may serve as a cell source for adult stem cell transplantation in liver repair. However, the susceptibility of human BMSCs to HBV infection is poorly understood. The aim of this study was to investigate the infection and replication of HBV in cultures of human BMSCs. RESULTS: Human BMSCs were confirmed using flow cytometry. Intracellular HBV DNA was detected at d 2 after infection and maintained at relatively high levels from d 6 to d 12. The maximal level of intracellular HBV DNA was 9.37 × 105 copies/mL. The extracellular HBV DNA was observed from d 3 to d 15, and the levels ranged from 3.792 × 102 copies/mL to 4.067 × 105 copies/mL. HBsAg in the culture medium was detected from d 2 to d 16. HBeAg secretion was positive from d 5 to d 13. HBcAg constantly showed positive signals in approximately 7%-20% of BMSCs from 2 days after exposure. Intracellular HBV covalently closed circular DNA (cccDNA) could be detected as early as 2 days postinfection, and strong signals were obtained with increasing time. CONCLUSION: HBV can infect and replicate in human BMSCs. Human BMSCs may be a useful tool for investigating HBV life-cycle and the mechanism of initial virus-cell interactions.

Chemoresponse assay for evaluating response to sunitinib in primary cultures of breast cancer.

PURPOSE: Not all patient tumors respond equally to the same type of therapy. An in vitro chemoresponse assay that can suggest individualized tumor response to therapies, in this case sunitinib, can be a valuable guide for clinical decision-making. RESULTS: The assay was shown to be sensitive and reproducible while differentiating renal cell lines based on sunitinib sensitivity and evaluating vendors' supply of the compound. Of the cultured breast cancer tumor specimens treated with sunitinib, ChemoFx classified 7.6% as responsive (R), 20.5% of specimens as intermediate responsive (IR), and 71.7% as non-responsive (NR). EXPERIMENTAL DESIGN: The ChemoFx(®) drug response marker (DRM) (Precision Therapeutics, Inc.) was carried out on SK-OV-3 cells treated with sunitinib to establish appropriate dose ranges and assay thresholds, and to evaluate vendor supplies of sunitinib. Once reference values were determined, the assay was applied to eight different renal cell lines treated with sunitinib, each of which was subsequently classified into responsive, intermediate responsive, and non-responsive groups. Next, ex vivo tumor samples from 39 clinically diagnosed breast cancer patients were grown in culture and assayed for their response to sunitinib using ChemoFx. CONCLUSIONS: Chemoresponse assay assessment is an effective tool for evaluating sunitinib sensitivity in cultured cell lines as well as ex vivo breast cancer samples. An in vitro assay that may indicate an individual patient's clinical response to a chemotherapeutic agent can be beneficial in time, cost, and clinical outcome when therapeutic options are considered.

[Influence of penicillin and streptomycin on gene expression of extracellular secretion from human umbilical cord tissue derived mesenchymal stem cells in vitro].

The study was aimed to investigate the influence of penicillin and streptomycin on proliferation, apoptosis and extracellular secretion (ECS) produced from human umbilical cord derived mesenchymal stem cells (MSC). MSC were isolated from umbilical cord tissue, then the immunotyping, multipotent differentiation and proliferation of these cells were assayed by cytometry, cytochemistry and MTT respectively. The expressions of ECS and apoptosis-related genes (bcl-2, bax) were detected by quantitative RT-PCR. The results showed that the phenotype of these cells matched with the characteristics of MSC. Penicillin and streptomycin of low concentrations promoted MSC proliferation, with the most effective concentration of 100 U/ml. Expressions of ECS cultured in addition of penicillin and streptomycin were down-regulated. Furthermore, apoptosis-related factor (bcl-2/bax) expression levels in low concentrations penicillin and streptomycin groups were higher than that in the control group. It is concluded that low concentrations penicillin and streptomycin can promote the proliferation and reduce the apoptotic rate, but high dose can inhibit the ECS component expression of MSC.

Analysis of chemotherapeutic response heterogeneity and drug clustering based on mechanism of action using an in vitro assay.

BACKGROUND: Cancer chemotherapeutic treatment is a complex scientific task. The ChemoFx Drug Response Marker (DRM) assists physicians in identifying treatment protocols likely to be effective for specific patients. MATERIALS AND METHODS: The ChemoFx DRM was used to study drug response in vitro. Established human cancer cell lines and primary cultures of patient tumor specimens were challenged with chemotherapeutic agents to observe response of multiple tumor samples and determine whether drugs with similar mechanisms of action elicit similar response. RESULTS: These studies demonstrated heterogeneous response among patient tumor samples and clustering of drug response with similar mechanisms of action. Also highlighted was the reproducibility of ChemoFx DRM and its utility in characterizing tumor response to chemotherapy. CONCLUSION: Heterogeneous drug responses observed in vitro were similar to those observed clinically. Response characteristics were similar for drugs with similar mechanisms of action, suggesting response heterogeneity is determined at a cellular and molecular level.

Identification and characterization of functional CD154 (CD40 ligand) in the Pekin duck.

Binding of CD154, a member of the TNF ligand superfamily, to its receptor CD40 is essential for the development and regulation of adaptive immune responses in mammals. The duck CD154 (DuCD154) encoding gene was isolated from activated splenocytes using RT-PCR. Sequence analysis of the cloned DuCD154 gene revealed an open reading frame of 819 base pairs encoding a 272 amino acid protein. The extracellular domain of DuCD154 was identified and expressed for characterization and generation of antibodies. DuCD154 mRNA was predominantly expressed in spleen, thymus and duodenum. DuCD154 protein generated in cell culture was secreted and formed dimers. DuCD154 markedly enhanced proliferative responses in duck splenocytes when used alone or in conjunction with LPS or PHA. These observations suggest that DuCD154 has functional equivalence with mammalian CD154 and that the central role of CD154 as an immunoregulatory protein had already evolved before the divergence of birds and mammals.

VHL protein-interacting deubiquitinating enzyme 2 deubiquitinates and stabilizes HIF-1alpha.

Hypoxia-inducible factor (HIF)-1alpha is a short-lived protein and is ubiquitinated and degraded through the von Hippel-Lindau protein (pVHL)-E3 ubiquitin ligase pathway at normoxia. Deubiquitination, by reversing ubiquitination, has been recognized as an important regulatory step in ubiquitination-related processes. Here, we show that pVHL-interacting deubiquitinating enzyme 2, VDU2, but not VDU1, interacts with HIF-1alpha. VDU2 can specifically deubiquitinate and stabilize HIF-1alpha and, therefore, increase expression of HIF-1alpha targeted genes, such as vascular endothelial growth factor (VEGF). These findings suggest that ubiquitination of HIF-1alpha is a dynamic process and that ubiquitinated HIF-1alpha might be rescued from degradation by VDU2 through deubiquitination. Although pVHL functions as a master control for HIF-1alpha stabilization, as pVHL-E3 ligase mediates the ubiquitination of both HIF-1alpha and VDU2, the balance between the pVHL-mediated ubiquitination and VDU2-mediated deubiquitination of HIF-1alpha provides another level of control for HIF-1alpha stabilization.

The SPRY domain-containing SOCS box protein 1 (SSB-1) interacts with MET and enhances the hepatocyte growth factor-induced Erk-Elk-1-serum response element pathway.

The suppressor of cytokine signaling (SOCS) protein family includes a SPRY (repeats in splA and RyR) domain-containing SOCS box protein (SSB) subfamily, which consists of four members, SSB-1, SSB-2, SSB-3, and SSB-4. These proteins contain a central SPRY domain and a C-terminal SOCS box. Although some of the SOCS protein subfamilies function as adaptors for a large family of ubiquitin-protein isopeptide ligases to regulate certain signaling pathways, the function of the SSB subfamily remains to be determined. In our previous studies, we have found that two SPRY domain-containing proteins, RanBP9 and RanBP10, interact with MET through the SPRY domain. In the present study, we explored the function of SSB proteins in the regulation of the hepatocyte growth factor (HGF)-MET signaling. Our results showed that all four SSB proteins also interacted with the MET. The MET interaction with SSB-1 was further investigated. We demonstrated that SSB-1 bound to MET tyrosine kinase domain through its SPRY domain. MET interacted with SSB-1 in both the absence and the presence of HGF, but HGF treatment resulted in the recruitment of more SSB-1 by MET. We showed that overexpression of SSB-1 but not other SSB proteins enhanced the HGF-induced serum response element (SRE)-luciferase activity. Overexpression of SSB-1 exhibited no effect on the basal level or epidermal growth factor-induced SRE-luciferase activity. SSB-1 also enhanced HGF-induced Erk phosphorylation. Suppression of SSB-1 by the RNA interference method down-regulated HGF-induced SRE-luciferase activity and decreased Elk-1 activation. These results suggest that SSB-1 may play an important role in enhancing the HGF-induced Erk-Elk-1-SRE pathway. Furthermore, we demonstrated that in response to HGF stimulation, the SSB-1 protein became phosphorylated at tyrosine residue 31. The phosphorylated SSB-1 protein bound to p120Ras-GTPase-activating protein (GAP) but did not promote the degradation of p120RasGAP, indicating that enhanced HGF-MET signaling by overexpression of SSB-1 was not dependent on p120RasGAP degradation.

A novel MET-interacting protein shares high sequence similarity with RanBPM, but fails to stimulate MET-induced Ras/Erk signaling.

MET is a receptor protein tyrosine kinase for hepatocyte growth factor, a multifunctional cytokine controlling cell growth, morphogenesis, and motility. In our previous study, RanBPM/RanBP9, whose name originated from its ability to interact with Ran, was identified as a MET-interacting protein. RanBPM/RanBP9 activates the Ras/Erk signaling pathway by serving as an adaptor protein of MET to recruit Sos. In this study, we identify a protein sharing a high amino acid sequence identity with RanBPM/RanBP9, especially in its SPRY domain, the region responsible for MET binding. This protein lacks the N-terminal poly-proline and poly-glutamine (Poly-PQ) stretch present in RanBPM/RanBP9 and has less homology with RanBPM/RanBP9 in its mid-region. We subsequently named this protein RanBP10 after demonstrating its interaction with Ran. We show that, like RanBPM/RanBP9, RanBP10 interacts with the tyrosine kinase domain of MET via its SPRY domain and these two proteins can compete with each other to bind to MET. Interestingly, unlike RanBPM/RanBP9, overexpression of RanBP10 cannot induce Erk1/2 phosphorylation and serum response element-luciferase (SRE-LUC) reporter gene expression. More importantly, co-transfection of RanBPM/RanBP9 and RanBP10 significantly represses SRE-LUC reporter gene expression induced by overexpression of RanBPM/RanBP9. Additional binding assays demonstrate that RanBP10 fails to interact with Sos, which explains its inability to activate the Ras/Erk pathway. Furthermore, we show that the N-terminus of RanBPM/RanBP9 with the Poly-PQ stretch is required for recruiting Sos and a truncated RanBPM/RanBP9 lacking this region fails to recruit Sos, indicating that the functional difference between RanBP10 and RanBPM/RanBP9 lies in their sequence difference in their N-termini.

The VHL protein recruits a novel KRAB-A domain protein to repress HIF-1alpha transcriptional activity.

The von Hippel-Lindau tumor suppressor (pVHL) is a component of an E3 ubiquitin ligase and targets hypoxia-inducible factor-1alpha (HIF-1alpha) for ubiquitylation and degradation under normoxic conditions. pVHL also directly inhibits HIF-1alpha transactivation by recruiting histone deacetylases. Here, we report a novel pVHL-interacting protein that functions as a negative regulator of HIF-1alpha transactivation. This protein, generated from the ZnF197 locus by alternative splicing, contains a Kruppel-associated box (KRAB)-A domain and a SCAN domain, but lacks the 22 C2H2-type zinc fingers present in ZnF197. Therefore, we named this protein pVHL-associated KRAB-A domain-containing protein (VHLaK). We demonstrate that the KRAB-A domain in VHLaK mediates pVHL binding and functions as a transcriptional repression module. The SCAN domain mediates VHLaK homo-oligomerization, which enhances VHLaK repressive activity. pVHL can recruit VHLaK to repress HIF-1alpha transcriptional activity and HIF-1alpha-induced VEGF expression. Finally, we demonstrate that pVHL, VHLaK and KAP1/TIF-1beta can be recruited into a single complex, indicating that KAP1/TIF-1beta may participate in pVHL-mediated transcriptional repression of HIF-1alpha. Our findings provide a novel mechanism for the modulation of HIF-1alpha transactivation by pVHL.