Up-regulated uridine kinase gene identified by RLCS in the ventral horn after crush injury to rat sciatic nerves

Impact of the Uridine⁻Cytidine Kinase Like-1 Protein and IL28B rs12979860 and rs8099917 SNPs on the Development of Hepatocellular Carcinoma in Cirrhotic Chronic Hepatitis C Patients-A Pilot Study

Background and objectives: The hepatitis C virus (HCV) is the major causative agent of hepatocellular carcinoma (HCC) in the western world. The efficacy of surveillance programs for early detection of HCC is not satisfactory: many tumors are diagnosed at the late, incurable stages. Therefore, there is a need in reliable prognostic markers for the proper follow-up of HCV-positive patients. The aim of the present study was to assess the prognostic value of the uridine⁻cytidine kinase-like protein 1 (UCKL-1), a putative oncoprotein, together with genetically determined polymorphisms in the interleukin 28B (IL28B) gene (rs12979860, rs8099917) in the development of HCC in HCV-positive cirrhotic patients. Materials and Methods: We included 32 HCV cirrhotic patients, 21 (65.6%) of whom had HCC. The expression of UCKL-1 was assessed in liver tissue sections, using immunohistochemistry. For IL28B rs12979860 and rs8099917 genotype analysis, the corresponding genomic regions were amplified by polymerase chain reaction (PCR) with appropriate primers. Results: We have found that UCKL-1 expression was significantly increased in HCC (p = 0.003). The presence of rs8099917 TT single-nucleotide polymorphism (SNP) elevated the chances of HCC manifestation more than sevenfold (OR = 7.3, p = 0.0273). The presence of rs12979860 CC SNP also heightened HCC chances more than sevenfold (OR = 7.5, p = 0.0765). Moreover, in the HCC group, a combination of IL28B rs12979860 non-TT and rs8099917 TT genotypes was observed more often, compared with the non-HCC group. Other combinations of IL28B rs12979860 and rs8099917 SNIPs were associated with a reduced risk of HCC development, approximately at the same extent. Conclusions: The presence of IL28B rs8099917 TT and rs12979860 CC SNPs, but not the intensity of UCKL-1 expression, is strongly associated with increased chances of HCC development in HCV-positive cirrhotic patients.

Characterization of the rat cerebrospinal fluid proteome following acute cerebral ischemia using an aptamer-based proteomic technology

The limited accessibility to the brain has turned the cerebrospinal fluid (CSF) into a valuable source that may contribute to the complete understanding of the stroke pathophysiology. Here we have described the CSF proteome in the hyper-acute phase of cerebral ischemia by performing an aptamer-based proteomic assay (SOMAscan) in CSF samples collected before and 30 min after male Wistar rats had undergone a 90 min Middle Cerebral Artery Occlusion (MCAO) or sham-surgery. Proteomic results indicated that cerebral ischemia acutely increased the CSF levels of 716 proteins, mostly overrepresented in leukocyte chemotaxis and neuronal death processes. Seven promising candidates were further evaluated in rat plasma and brain (CKB, CaMK2A, CaMK2B, CaMK2D, PDXP, AREG, CMPK). The 3 CaMK2 family-members and CMPK early decreased in the infarcted brain area and, together with AREG, co-localized with neurons. Conversely, CKB levels remained consistent after the insult and specifically matched with astrocytes. Further exploration of these candidates in human plasma revealed the potential of CKB and CMPK to diagnose stroke, while CaMK2B and CMPK resulted feasible biomarkers of functional stroke outcome. Our findings provided insights into the CSF proteome following cerebral ischemia and identified new outstanding proteins that might be further considered as potential biomarkers of stroke.

Spatiotemporal patterns of expression of IGSF4 in developing mouse nervous system

IGSF4 is a novel immunoglobulin (Ig)-like intercellular adhesion molecule. Since IGSF4 has been characterized by several independent research groups, this molecule is called by three names, TSLC1, SgIGSF and SynCAM. In the experiments to study global changes of gene expression in fetal murine brains after prenatal exposure to low-doses of X-rays, we have found IGSF4 as one of down-regulated genes after X-irradiation. In order to elucidate the expression of spatiotemporal expression of IGSF4 in the developing brain, we have produced polyclonal antibody against IGSF4 and studied the expression of IGSF4 with immunohistochemistry and Western blot analysis. At embryonic day (E) 12.5, IGSF4-immunoreactivity (IR) was observed diffusely in the telencephalic wall, whereas it became rather confined to the subplate, the cortical plate and the subventricular zone as the development proceeded. Noteworthy was a distinct radial pattern found in the cortical plate of E16.5. IGSF4-IR gradually decreased after birth and disappeared in adulthood. In the cerebellum, IGSF4 was expressed in the molecular layer at postnatal day (P) 0 through P14. By Western blot analysis, IGSF4 remained at low levels throughout embryonic stage, whereas it increased after birth. These spatiotemporal patterns of the expression suggest that IGSF4 plays crucial roles in the development of both telencephalon and cerebellum.

Epstein-Barr virus encoded nuclear protein EBNA-3 binds a novel human uridine kinase/uracil phosphoribosyltransferase

BACKGROUND

Epstein-Barr virus (EBV) infects resting B-lymphocytes and transforms them into immortal proliferating lymphoblastoid cell lines (LCLs) in vitro. The transformed immunoblasts may grow up as immunoblastic lymphomas in immuno-suppressed hosts.

RESULTS

In order to identify cellular protein targets that may be involved in Epstein-Barr virus mediated B-cell transformation, human LCL cDNA library was screened with one of the transformation associated nuclear antigens, EBNA-3 (also called EBNA-3A), using the yeast two-hybrid system. A clone encoding a fragment of a novel human protein was isolated (clone 538). The interaction was confirmed using in vitro binding assays. A full-length cDNA clone (F538) was isolated. Sequence alignment with known proteins and 3D structure predictions suggest that F538 is a novel human uridine kinase/uracil phosphoribosyltransferase. The GFP-F538 fluorescent fusion protein showed a preferentially cytoplasmic distribution but translocated to the nucleus upon co-expression of EBNA-3. A naturally occurring splice variant of F538, that lacks the C-terminal uracil phosphoribosyltransferase part but maintain uridine kinase domain, did not translocate to the nucleus in the presence of EBNA3. Antibody that was raised against the bacterially produced GST-538 protein showed cytoplasmic staining in EBV negative Burkitt lymphomas but gave a predominantly nuclear staining in EBV positive LCL-s and stable transfected cells expressing EBNA-3.

CONCLUSION

We suggest that EBNA-3 by direct protein-protein interaction induces the nuclear accumulation of a novel enzyme, that is part of the ribonucleotide salvage pathway. Increased intranuclear levels of UK/UPRT may contribute to the metabolic build-up that is needed for blast transformation and rapid proliferation.

Phosphorylation of uridine and cytidine nucleoside analogs by two human uridine-cytidine kinases

Uridine-cytidine kinases (UCK) have important roles for the phosphorylation of nucleoside analogs that are being investigated for possible use in chemotherapy of cancer. We have cloned the cDNA of two human UCKs. The approximately 30-kDa proteins, named UCK1 and UCK2, were expressed in Escherichia coli and shown to catalyze the phosphorylation of Urd and Cyd. The enzymes did not phosphorylate deoxyribonucleosides or purine ribonucleosides. UCK1 mRNA was detected as two isoforms of approximately 1.8 and approximately 2.7 kb. The 2.7-kb band was ubiquitously expressed in the investigated tissues. The band of approximately 1.8 kb was present in skeletal muscle, heart, liver, and kidney. The two isoforms of UCK2 mRNA of 1.2 and 2.0 kb were only detected in placenta among the investigated tissues. The genes encoding UCK1 and UCK2 were mapped to chromosome 9q34.2-9q34.3 and 1q22-1q23.2, respectively. We tested 28 cytidine and uridine nucleoside analogs as possible substrates of the enzymes. The enzymes phosphorylated several of the analogs, such as 6-azauridine, 5-fluorouridine, 4-thiouridine, 5-bromouridine, N(4)-acetylcytidine, N(4)-benzoylcytidine, 5-fluorocytidine, 2-thiocytidine, 5-methylcytidine, and N(4)-anisoylcytidine. The cloning and recombinant expression of the two human UCKs will be important for development of novel pyrimidine ribonucleoside analogs and the characterization of their pharmacological activation.

Nifedipine and nimodipine competitively inhibit uridine kinase and orotidine-phosphate decarboxylase: theoretical relevance to poor outcome in stroke

Nifedipine and nimodipine, dihydropyridine calcium channel blockers, are commonly used as antihypertensive and antianginal agents in patients at risk for stroke. At least one stroke trial suggests that patients receiving calcium channel blockers at the time of an acute stroke have worse outcomes than those receiving other or no antihypertensive medications. We hypothesize that the poor outcome may not be related to blood pressure changes but instead may be mediated by competitive inhibition of important enzymes of pyrimidine synthesis whose products are needed to repair nerve cell membranes after an acute stroke. Both drugs acted as competitive inhibitors of the only enzymes that are known to synthesize the nucleotide uridine-5'-phosphate: uridine kinase and orotidine-5'-phosphate decarboxylase. Nifedipine produced Ki values of 28 microM for uridine kinase and 105 microM for orotidine-5'-phosphate decarboxylase. Nimodipine produced Ki values of 20 microM for uridine kinase and 18 microM for orotidine-5'-phosphate decarboxylase. For uridine kinase, these inhibitors bound more tightly than the physiologic substrates uridine or cytidine. For the decarboxylase, the inhibitors bound less tightly than the normal physiologic substrate orotidine-5'-phosphate. Additional experiments are needed to determine whether the concentrations of nifedipine or nimodipine, and of cytidine, uridine, and orotidine-5'-phosphate in human brain, are such that this inhibition would affect stroke outcome.