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At least 289 records · Page 16Linked to original sources
PubMed2002

Preferential loss of Death Associated Protein kinase expression in invasive pituitary tumours is associated with either CpG island methylation or homozygous deletion.

Death Associated Protein kinase (DAP kinase) a novel calmodulin-dependent serine/threonine kinase was first identified as a positive mediator of programmed cell death. Loss of DAP kinase expression was first demonstrated in highly metastatic cells, whilst re-expression of the protein resulted in delayed local tumour growth and a decreased incidence of metastasis. Although loss of DAP kinase expression has been reported in several cell lines derived from human malignancies the mechanisms responsible have not been defined. In this study we have examined 32 sporadic pituitary tumours for expression of the DAP kinase protein and transcript. In addition, we examined the methylation and deletion status of the DAP kinase CpG island as possible mechanisms for the inactivation of the DAP kinase gene. Eleven of 32 (34%) tumours had undetectable DAP kinase expression, by Western blot and/or RT-PCR analysis. Loss of DAP kinase expression was significantly (P=0.004) associated with invasive tumours (10 of 17; 59%) compared to their non-invasive (1 of 15; 7%) counterparts. Of 11 tumours that failed to express DAP kinase, five (45%) showed de novo methylation of the CpG island contained within the promoter region, while four (36%) had evidence of homozygous deletion of this region. Statistical analysis showed that loss of DAP kinase expression was significantly (P=<0.001) associated with methylation or deletion of the DAP kinase CpG island. With two exceptions, none of the remaining tumours or five histologically normal post-mortem pituitaries examined had evidence of methylation or deletion within this region. To our knowledge this is the first report that describes two mutually exclusive mechanisms associated with loss of DAP kinase gene expression. In addition, we also show that loss of the DAP kinase protein and associated genetic aberrations preferentially segregates with tumours that show an invasive phenotype.

Apoptosis Regulatory Proteins↗
PubMed2002

Myelin-associated glycoprotein modulates expression and phosphorylation of neuronal cytoskeletal elements and their associated kinases.

Decreased phosphorylation of neurofilaments in mice lacking myelin-associated glycoprotein (MAG) was shown to be associated with decreased activities of extracellular-signal regulated kinases (ERK1/2) and cyclin-dependent kinase-5 (cdk5). These in vivo changes could be caused directly by the absence of a MAG-mediated signaling pathway or secondary to a general disruption of the Schwann cell-axon junction that prevents signaling by other molecules. Therefore, in vitro experimental paradigms of MAG interaction with neurons were used to determine if MAG directly influences expression and phosphorylation of cytoskeletal proteins and their associated kinases. COS-7 cells stably transfected with MAG or with empty vector were co-cultured with primary dorsal root ganglion (DRG) neurons. Total amounts of the middle molecular weight neurofilament subunit (NF-M), microtubule-associated protein 1B (MAP1B), MAP2, and tau were up-regulated significantly in DRG neurons in the presence of MAG. There was also increased expression of phosphorylated high molecular weight neurofilament subunit (NF-H), NF-M, and MAP1B. Additionally, in similar in vitro paradigms, total and phosphorylated NF-M were increased significantly in PC12 neurons co-cultured with MAG-expressing COS cells or treated with a soluble MAG Fc-chimera. The increased expression of phosphorylated cytoskeletal proteins in the presence of MAG in vitro was associated with increased activities of ERK 1/2 and cdk5. We propose that interaction of MAG with an axonal receptor(s) induces a signal transduction cascade that regulates expression of cytoskeletal proteins and their phosphorylation by these proline-directed protein kinases.

Animals↗
PubMed2000

TTRAP, a novel protein that associates with CD40, tumor necrosis factor (TNF) receptor-75 and TNF receptor-associated factors (TRAFs), and that inhibits nuclear factor-kappa B activation.

CD40 belongs to the tumor necrosis factor (TNF) receptor family. CD40 signaling involves the recruitment of TNF receptor-associated factors (TRAFs) to its cytoplasmic domain. We have identified a novel intracellular CD40-binding protein termed TRAF and TNF receptor-associated protein (TTRAP) that also interacts with TNF-R75 and CD30. The region of the CD40 cytoplasmic domain that is required for TTRAP association overlaps with the TRAF6 recognition motif. Association of TTRAP with CD40 increases profoundly in response to treatment of cells with CD40L. Interestingly, TTRAP also associates with TRAFs, with the highest affinity for TRAF6. In transfected cells, TTRAP inhibits in a dose-dependent manner the transcriptional activation of a nuclear factor-kappaB (NF-kappaB)-dependent reporter mediated by CD40, TNF-R75 or Phorbol 12-myristate 13-acetate (PMA) and to a lesser extent by TRAF2, TRAF6, TNF-alpha, or interleukin-1beta (IL-1beta). TTRAP does not affect stimulation of NF-kappaB induced by overexpression of the NF-kappaB-inducing kinase (NIK), the IkappaB kinase alpha (IKKalpha), or the NF-kappaB subunit P65/RelA, suggesting it acts upstream of the latter proteins. Our results indicate that we have isolated a novel regulatory factor that is involved in signal transduction by distinct members of the TNF receptor family.

Amino Acid Sequence↗
PubMed2003

DAP-like kinase, a member of the death-associated protein kinase family, associates with centrosomes, centromers, and the contractile ring during mitosis.

DAP-like kinase (Dlk) is a nuclear serine/threonine-specific kinase which has been implicated in apoptosis. However, induction of apoptosis by Dlk requires its relocation to the cytoplasm, particularly association with the actin cytoskeleton, which is achieved through interaction with pro-apoptotic protein Par-4. On the other hand, nuclear Dlk does not induce apoptosis and has rather been implicated in transcription. To further explore the biological functions of Dlk, we established a cell clone of MCF-7 cells stably expressing a GFP-Dlk fusion protein at low level. Ectopic expression of GFP-Dlk did not affect the growth properties of the cells. During interphase, GFP-Dlk showed a diffuse nuclear distribution with punctate staining in a subpopulation of cells. During mitosis, however, Dlk was associated with centrosomes, centromeres, and the contractile ring, but not with the mitotic spindle. Association with centrosomes, as confirmed by colocalization with gamma-tubulin and pericentrin persisted throughout mitosis but was also seen in interphase cells. Interestingly, GFP-Dlk and gamma-tubulin could be co-immunoprecipitated indicating that they are present in the same protein complex. Association of Dlk with centromeres, as verified by confocal fluorescence microscopy with centromere-specific antibodies was more restricted and discernable from prophase to early anaphase. Centromere association of Dlk coincides with H3 phosphorylation at Thr11 that is specifically phosphorylated by Dlk in vitro (U. Preuss, G. Landsberg, K. H. Scheidtmann, Nucleic Acids Res. 31, 878-885, 2003). During cytokinesis, Dlk was enriched in the contractile acto-myosin ring and colocalized with Ser19-phosphorylated myosin light chain, which is an in vitro substrate of Dlk. Strikingly, a C-terminal truncation mutant of Dlk generated multi-nucleated cells. Together, these data suggest that Dlk participates in regulation and, perhaps, coordination of mitotis and cytokinesis.

Actins↗
PubMed2005

Buffalo hump seen in HIV-associated lipodystrophy is associated with hyperinsulinemia but not dyslipidemia.

Accumulation of dorsocervical fat, or a "buffalo hump" (BH), is commonly reported in adults with HIV-associated lipodystrophy (HIVLD). The pathogenesis underlying this aspect of a syndrome characterized by loss of subcutaneous fat from other body sites is poorly understood. We aimed to identify risk factors for a BH in HIV-infected adults in cross-sectional analyses of 2 HIV-infected ambulatory populations. The first group (Australian Lipodystrophy Prevalence Survey [APS]) consisted of 1348 Australian HIV-infected adults (95% male) irrespective of changes in body composition. The second group (Lipodystrophy Case Definition [LDCD] study) comprised 417 subjects (83% male) with at least 1 reported moderate or severe feature of HIVLD. A BH was reported in 24 (2%) APS subjects and 79 (19%) LDCD study subjects. A BH was not an isolated finding. Patients with a BH had a high prevalence of other features of HIVLD, similar to lipodystrophic patients without a BH, such as facial lipoatrophy reported in 100% and 61% BH-positive subjects from the APS and LDCD study, respectively. In both groups, those with a BH had higher fasting insulin (P<or=0.007), a higher body mass index (P<or=0.003), a higher waist/hip ratio (P<or=0.001), higher limb fat (P<or=0.003), and higher systolic blood pressure (P<0.05). On multivariate analysis, higher serum insulin, systolic blood pressure, age, and duration of exposure to ritonavir were independently associated with a BH in the APS group. In the LDCD group, higher insulin, diastolic blood pressure, and duration of exposure to zidovudine were independently associated with a BH. There was no association between a BH and hyperlipidemia. These data show that a BH is associated with other physical features of the lipodystrophy phenotype and suggest that hyperinsulinemia, a feature common to HIVLD, obesity, and hypercortisolism, is an important component of this phenotype, thus warranting closer monitoring of BH-positive patients for glucose intolerance and diabetes.

Adult↗
PubMed2002

Mot1 associates with transcriptionally active promoters and inhibits association of NC2 in Saccharomyces cerevisiae.

Mot1 stably associates with the TATA-binding protein (TBP), and it can dissociate TBP from DNA in an ATP-dependent manner. Mot1 acts as a negative regulator of TBP function in vitro, but genome-wide transcriptional profiling suggests that Mot1 positively affects about 10% of yeast genes and negatively affects about 5%. Unexpectedly, Mot1 associates with active RNA polymerase (Pol) II and III promoters, and it is rapidly recruited in response to activator proteins. At Pol II promoters, Mot1 association requires TBP and is strongly correlated with the level of TBP occupancy. However, the Mot1/TBP occupancy ratio at both Mot1-stimulated and Mot1-inhibited promoters is high relative to that at typical promoters, strongly suggesting that Mot1 directly affects transcriptional activity in a positive or negative manner, depending on the gene. The effect of Mot1 at the HIS3 promoter region depends on the functional quality and DNA sequence of the TATA element. Unlike TBP, Mot1 association is largely independent of the Srb4 component of Pol II holoenzyme, and it also can occur downstream of the promoter region. Mot1 removes TBP, but not TBP complexes or preinitiation complexes, from inappropriate genomic locations. Mot1 inhibits the association of NC2 with promoters, suggesting that the TBP-Mot1 and TBP-NC2 complexes compete for promoter occupancy in vivo. We speculate that Mot1 does not form transcriptionally active TBP complexes but rather regulates transcription in vivo by modulating the activity of free TBP and/or by affecting promoter DNA structure.

Adenosine Triphosphatases↗
PubMed2005

Whole-genome association analysis to identify markers associated with recombination rates using single-nucleotide polymorphisms and microsatellites.

Recombination during meiosis is one of the most important biological processes, and the level of recombination rates for a given individual is under genetic control. In this study, we conducted genome-wide association studies to identify chromosomal regions associated with recombination rates. We analyzed genotype data collected on the pedigrees in the Collaborative Study on the Genetics on Alcoholism data provided by Genetic Analysis Workshop 14. A total of 315 microsatellites and 10,081 single-nucleotide polymorphisms from Affymetrix on 22 autosomal chromosomes were used in our association analysis. Genome-wide gender-specific recombination counts for family founders were inferred first and association analysis was performed using multiple linear regressions. We used the positive false discovery rate (pFDR) to account for multiple comparisons in the two genome-wide scans. Eight regions showed some evidence of association with recombination counts based on the single-nucleotide polymorphism analysis after adjusting for multiple comparisons. However, no region was found to be significant using microsatellites.

Female↗
PubMed2026

Suggestive genome-wide associations with inflammatory biomarkers in an admixed population, including a missense variant in the OR6K6 olfactory receptor gene associated with MCP-1.

BACKGROUND: Chronic low-grade inflammation drives cardiometabolic diseases and has a strong genetic basis. Most genome-wide association studies (GWAS) have focused on European populations, limiting knowledge of the genetic influences on inflammation in admixed populations such as those in Brazil. METHODS: This study is part of the cross-sectional ISA Capital Health Survey. It uses data from the 2015 ISA Nutrition cohort, which measured biochemical, genetic, anthropometric, and lifestyle factors in a probabilistic sample of S&#xe3;o Paulo residents. Genomic DNA was extracted from 841 individuals. Genotyping was performed using the Axiom 2.0 Precision Medicine Research Array. After quality control and missing data exclusion, 244,338 SNPs from 638 individuals remained for GWAS-based association analysis with eight inflammatory biomarkers. Models were adjusted for sex, age, age2, overweight, and the first two principal components of ancestry. RESULTS: Most participants were male (53%) and not overweight (55%). The median age was 49, and 38% were older adults. In the genome-wide analysis of TNF-&#x3b1;, IL-10, IL-1&#x3b2;, monocyte chemoattractant protein-1 (MCP-1), and adiponectin, 12 SNPs were significantly associated, most of which were intronic. Notably, one signal mapped to the missense variant rs16841009 in the olfactory receptor gene OR6K6. This variant was associated with MCP-1, suggesting a possible involvement in inflammatory responses. CONCLUSIONS: We identified new SNPs linked to inflammatory biomarkers in a highly admixed Brazilian population, including a missense variant in an olfactory receptor gene linked to MCP-1. This association may be biologically important for inflammation and could affect the risk of cardiometabolic diseases.

Humans↗
PubMed2006

[Study on the association of INT4 and 3'UTR polymorphism of natural-resistance-associated macrophage protein 1 gene with susceptibility to pulmonary tuberculosis].

OBJECTIVE: To investigate the association between natural-resistance-associated macrophage protein 1 (NRAMP1) gene polymorphisms and susceptibility to pulmonary tuberculosis (TB) in Han nationality from Northern part of China. METHODS: A 1:1 matched case-control study was adopted. Polymerase chain reaction and restriction fragment length polymorphism technique were used to type the two NRAMP1 polymorphisms: INT4 and 3'UTR. Information on environmental-related risk factors and pathological changes of tuberculosis was collected using a pre-tested standard questionnaire. Univariate and multivariate conditional logistic analyses were conducted using SPSS for window software. RESULTS: A sample consisting 124 pairs of cases and controls was studied. Univariate analysis demonstrated that the 3'UTR TGTG+/del genotype occurred more frequently in the cases than in the controls, with crude OR (95% CI) being 2.923 (1.557 - 5.487). No significant association was observed between TB and INT4 polymorphism. In multivariate analysis, associations of TB and 3'UTR TGTG+/del genotype remained, after adjusting for scar of bacillus Calmette-Guérin vaccine, marriage status, body mass index and exposure history. Adjusted OR (95% CI) was 2.955 (1.369 - 6.381). Again, no significant association between INT4 polymorphism and TB was found. Among different INT4 genotypes, the pathological characters of pulmonary tuberculosis were also found different (chi(2) = 9.634, P < 0.05). CONCLUSION: Polymorphism of 3'UTR locus in NRAMP1 gene might affect their susceptibility to TB in Han nationality living in the northern part of China, and polymorphism of INT4 might affect the pathological characters of tuberculosis.

Analysis of Variance↗
PubMed1988

Relationship of serum CA125 and lipid-associated sialic acid tumor-associated antigen levels to the disease status of patients with gynecologic malignancies.

Serum samples obtained from 133 patients with gynecologic malignancies were assayed for two tumor-associated antigen markers: CA125, an ovarian marker, and lipid-associated sialic acid, a nonspecific marker. In the patient population, there were 77 papillary serous and 19 unspecified ovarian adenocarcinomas, and 24 miscellaneous ovarian carcinomas. Thirteen patients had nonovarian malignancies. Sixty-nine percent (74 of 108) of the patients with known disease had abnormal CA125 levels, whereas only 32% (20 of 63) had abnormal lipid-associated sialic acid levels. Changes in CA125 serum levels reflected the disease status of the patients for whom there were serial serum samples. Normal levels of CA125 corresponded to no evidence of disease in 100% (six of six) surgically evaluated patients and 75% (30 of 40) of clinically evaluated patients. Changes in CA125 levels from normal to abnormal corresponded to disease progression in 80% (12 of 15) of the patients. Decreases in CA125 levels from abnormal to normal corresponded to complete clinical response in 55% (11 of 20), and partial clinical response in 45% (nine of 20). No such correlations were available for lipid-associated sialic acid antigen levels. For tumors that express CA125 antigen, serum levels appear to be a good marker for the extent of malignant gynecologic disease. Levels of CA125 that rose from normal to abnormal were usually associated with recurrent disease.

Adenocarcinoma↗
PubMed1995

Stimulation of NK-like YT cells via leukocyte function-associated antigen (LFA)-1. Possible involvement of LFA-1-associated tyrosine kinase in signal transduction after recognition of NK target cells.

The YTA-1 anti-LFA-1 alpha mAb activates protein tyrosine kinase (PTK), augments NK cytotoxicity, and induces proliferation of fresh CD3- large granular lymphocytes. We demonstrate here that LFA-1 is physically associated in the YT human NK-like cell line cells with a PTK(s) that is distinct from Src family PTKs such as Lck, Fyn, or Lyn. In vitro kinase assays revealed similar association of protein kinase activity with LFA-1 in normal CD3- large granular lymphocytes. Tyrosine phosphorylation of the proteins associated with LFA-1 drastically increased in YT cells after stimulation with NK-sensitive K562 cells but not with NK-resistant P815 cells. Furthermore, pretreatment of YT cells with TS1/22 anti-LFA-1 alpha and TS1/18 anti-LFA-1 beta mAbs abrogated not only the cytotoxicity against K562 cells but also an increase in tyrosine phosphorylation of LFA-1-associated molecules induced by K562 stimulation. These results provide biochemical evidence that the PTK(s) associated with LFA-1 is involved in the signal transduction that follows the recognition of NK target cells.

Antibodies, Monoclonal↗
PubMed1995

Staphylococcus aureus catheter-associated bacteremia. Minimal effective therapy and unusual infectious complications associated with arterial sheath catheters.

OBJECTIVE: To determine factors that predict complications and examine outcomes of Staphylococcus aureus bacteremia according to the duration of antibiotic therapy. METHODS: Clinical data were extracted from charts of patients with positive blood cultures for S aureus at a single institution during a 2-year period. RESULTS: Of 102 patients with S aureus bacteremia, 55 were considered to have bacteremia attributable to an intravascular catheter, including five patients who were bacteremic after percutaneous transluminal coronary angioplasty. Among the other 50 patients with S aureus catheter-associated bacteremia, infection was community acquired in 18 and nosocomial in 32. Septic pulmonary emboli were more common in patients with community-acquired S aureus catheter-associated bacteremia, most of whom had Hickman catheters or venous access disks. Delayed removal of the infected catheter was associated with persistence of bacteremia (P = .01). With patients with early complications excluded, patients treated for 10 to 15 days had clinical characteristics similar to those of patients treated with longer courses of antibiotics and had similarly low rates of relapse (0% vs 4.7%). In contrast, treatment with parenteral antibiotics for less than 10 days appeared to be inadequate in that relapse occurred in two of three such patients. Staphylococcus aureus catheter-associated bacteremia associated with percutaneous transluminal coronary angioplasty was complicated by a femoral artery mycotic aneurysm in two of five patients. CONCLUSION: Approximately one third of S aureus catheter-related bacteremias were community acquired, reflecting increased usage of intravascular devices for home parenteral support. A 10- to 15-day course of parenteral antibiotics was equivalent to longer courses of therapy in patients without early complications.

Adult↗
PubMed2001

Family-based association study of serotonin transporter promoter in suicidal adolescents: no association with suicidality but possible role in violence traits.

The serotonin transporter-linked promoter region polymorphism (5-HTTLPR) is thought to be associated with some serotonin dysfunction-related psychopathologies such as depression and anxiety disorders. Suicide and suicide-related behaviors such as violence, aggression, and impulsivity have been reproducibly associated with serotonin dysfunction and are partially genetic. This study examined the association of 5-HTTLPR with suicidal behavior and related traits in Israeli suicidal adolescent inpatients using the haplotype relative risk (HRR) method that controls for artifacts caused by population stratification. Forty-eight inpatient adolescents who recently attempted suicide were assessed by structured interviews for detailed clinical history, diagnoses, suicide intent, suicide risk, impulsivity, violence, and depression. Blood samples were collected and DNA extracted from patients and their biological parents. The 5-HTTLPR allele frequencies were tested for association with suicidality by the HRR method. In addition, the relationship between genotypes and phenotypic severity of several clinical parameters was analyzed. No significant allelic association of the 5-HTTLPR polymorphism with suicidal behavior was found (chi square = 0.023; P = 0.88). Analysis of variance of the suicide-related trait measures for the three genotypes demonstrated a significant difference in violence measures between patients carrying the LL and LS genotypes (9.50+/-4.04 vs. 5.36+/-4.03; P = 0.029). This study suggests that the 5-HTTLPR polymorphism is unlikely to have major relevance to the pathogenesis of suicidal behavior in adolescence but may contribute to violent behavior in this population.

Adolescent↗
PubMed2001

Association of a polymorphism of the dopamine transporter gene with externalizing behavior problems and associated temperament traits: a longitudinal study from infancy to the mid-teens.

There have been reports that a variable number of tandem repeats (VNTR) polymorphism situated in the 3' untranslated region of the dopamine transporter gene is associated with attention-deficit hyperactivity disorder. On the basis of these findings, we predicted an association of this polymorphism with hyperactivity, other externalizing behavior problems, and related temperament traits in a general population sample. The association was investigated using children participating in a longitudinal study of childhood temperament and development. DNA was taken from 660 children who had been assessed for temperament from 4-8 months to 15-16 years, and for behavior problems from 3-4 to 15-16 years. No significant associations were found at any age. There are a number of methodological differences from earlier studies that might explain the lack of associations with hyperactivity. It is also possible that the earlier findings are not replicable.

Adolescent↗
PubMed2006

Lipoprotein-associated phospholipase A2 is associated with risk of dementia.

OBJECTIVE: High levels of the inflammatory marker lipoprotein-associated phospholipase A2 (Lp-PLA2) have been proposed to be a predictor of coronary heart disease and stroke. Because both inflammation and vascular disease are associated with dementia, the objective of the present study was to examine the association between Lp-PLA2 and the risk of dementia. METHODS: Within the Rotterdam Study, a population-based prospective cohort study, we performed a case-cohort study. Of the 6,713 participants at risk for dementia, a random sample of 1,742 individuals was drawn. During follow-up (mean, 5.7 years), 302 incident dementia cases were identified. Cox proportional hazard models were used to estimate the association of Lp-PLA2 and dementia. RESULTS: We found that subjects with higher levels of Lp-PLA2 had an increased risk of dementia. Compared with the first quartile of Lp-PLA2, age- and sex-adjusted hazard ratios (HRs; 95% confidence interval [CI]) for dementia for the second, third, and fourth quartiles were 1.19 (0.78-1.81), 1.15 (0.74-1.79), and 1.56 (1.03-2.37), respectively (p value for trend 0.04). Additional adjustment for cardiovascular and inflammatory factors did not change the estimates. INTERPRETATION: This is the first study to our knowledge that shows that Lp-PLA2 is associated with the risk of dementia independent of cardiovascular and inflammatory factors and provides evidence for a potential role of Lp-PLA2 in identifying subjects at risk for dementia.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1983

Professional association membership of nurses: factors affecting membership and the decision to join an association.

In this article factors such as education, employment characteristics, and association benefits which are associated with nurses joining and remaining in professional nursing associations are identified. The impact of these factors on association membership was determined through a survey of 225 nurses in one midwestern state. On the basis of these empirical results recommendations are made which should be useful to professional associations seeking to attract new members and keep their present ones.

Economics, Nursing↗
PubMed1993

Post-translational processing and membrane association of the two early endosome-associated rab GTP-binding proteins (rab4 and rab5).

The two early endosome-associated rab GTP-binding proteins, rab4 and rab5, are suggested to regulate endocytosis. In this report, we examined post-translational processing and membrane association of the two rab proteins. Human rab4 and rab5 were expressed in chicken embryo fibroblasts using a Sindbis virus expression vector. Cells were labeled with either [35S]methionine or [3H]mevalonolactone. Cell lysates were immunoprecipitated with antisera specific for rab4 and rab5, respectively, and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was found that both rab4 and rab5 contained at least three forms: the precursor form, the isoprenylated intermediate, and the isoprenylated mature form of faster mobility. The rab5 intermediate comigrated with the precursor form, whereas the rab4 intermediate migrated slightly faster than the precursor form. The intermediate form of rab4, but not rab5, accumulated in the presence of a chymotrypsin-like protease inhibitor (N-acetyl Tyr ethyl ester), suggesting that proteolysis was required for generation of the mature form. Furthermore, the intermediate and mature forms of rab4, but not rab5, were carboxyl-methylated as demonstrated by incorporation of alkali-labile counts from [methyl-3H]methionine. Membrane association of the distinct rab4 and rab5 forms was examined by subcellular fractionation and Triton X-114 partitioning. The precursor forms were found in the cytosol and partitioned into the aqueous phase. The mature forms were membrane-associated and partitioned into the detergent phase. Unexpectedly, the isoprenylated intermediate forms of both rab4 and rab5 partitioned exclusively into the aqueous phase. Taken together, the data indicate that the entire post-translational processing, which includes isoprenylation, carboxyl methylation (rab4), and possibly proteolysis, confers the competency for membrane association of rab4 and rab5.

Animals↗
PubMed1999

The latency-associated nuclear antigen tethers the Kaposi's sarcoma-associated herpesvirus genome to host chromosomes in body cavity-based lymphoma cells.

Viruses that establish latent infection must maintain their DNA in the host nucleus through many cellular generations. Here we identify a novel mechanism by which the gammaherpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV) may achieve this persistence in latently infected body cavity-based lymphoma (BCBL) cells. We find that KSHV genomic DNA is associated with host chromosomes and colocalizes with the latency-associated nuclear antigen (LANA). Furthermore, a region at the left end of the KSHV genome binds strongly to LANA and can colocalize to the host chromosomes with LANA. Additionally, we found that LANA associates with histone H1 in KSHV-infected BCBL cells. We propose that this chromosomal association of the KSHV genome is mediated by LANA and involves a tethering mechanism by which viral episomes are linked to host chromatin through simultaneous interaction with host chromosomal proteins including histone H1 and cis-acting KSHV DNA elements. This strategy may be employed by other viruses in establishment of latency in the infected cells.

Antigens, Viral↗