Normal Cell Protein Research Articles

Pseudotumor Cerebri in a Turkish Boy With Fanconi Anemia

Pseudotumor cerebri (PC) is a clinical syndrome characterized by increased intracranial pressure with a normal cerebrospinal fluid cell count and protein level in the absence of a space-occupying lesion or apparent obstruction to the cerebrospinal fluid pathway. Although PC is described in patients with various hematological diseases including iron-deficiency anemia, megaloblastic anemia, acquired aplastic anemia, hemolytic anemia, sickle cell disease, and paroxysmal nocturnal hemoglobinuria, there is no case of PC with Fanconi anemia in the English literature. Here, we report a first case of PC in an 11-year-old boy with a diagnosis of Fanconi anemia.

Abstract 2073: Parthenolide-mediated redox modification of Keap1 leads to differential effects on radiosensitivities of prostate cancer and normal cells

Abstract Elevated oxidative stress is more frequently observed in cancer cells than in normal cells. Thus, further exposure to exogenous reactive oxygen species (ROS) is expected to push cancer to cell death, whereas normal cells may maintain redox homeostasis through ROS mediated adaptive responses. We previously demonstrated that parthenolide selectively enhances radiosensitivity of prostate cancer cells through activation of a NADPH oxidase-dependent redox signaling pathway. Our present study identifies the status of the redox sensitive Kelch-like ECH-associated protein-1 (Keap1) as a central regulator responsible for the parthenolide-mediated differential redox modification. This results in both a radiosensitization effect in prostate cancer cells and a radioresistance effect in normal prostate epithelial cells. Mechanistically, parthenolide increases the reduced state of Keap1 in prostate cancer cells in a thioredoxin-dependent manner but causes oxidation of Keap1 in normal prostate epithelial cells. Selective knock-down of thioredoxin leads to Keap1 oxidation and subsequent activation of the NF-E2-related factor 2 (Nrf2). These results suggest that redox modification of Keap1 is a major mechanism for the parthenolide effect on radiation therapy in cancer and normal cells. Consistent with the differential effect of parthenolide in cancer and normal cells, the levels of superoxide, hydrogen peroxide and peroxynitrite were selectively increased in parthenolide treated prostate cancer cells but not in normal prostate epithelial cells, indicating the selective increase of ROS in cancer cells. Parthenolide reduces the levels of Nrf2 targets, antioxidant proteins including manganese superoxide dismutase and heme oxygenase in prostate cancer cells, but increases the levels of these proteins in normal cells. This suggests that an antioxidant response is critical for the protection of normal cells against ROS generated from parthenolide. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2073. doi:1538-7445.AM2012-2073

Abstract 2072: Distinct antioxidant profiles of human prostate carcinoma cell lines and tissues: Implications for rational design of redox therapy

Abstract Several cancer chemotherapeutic drugs and radiation mediate their effects, at least in part, by generation of reactive oxygen/nitrogen species. Therefore, the levels of antioxidants and status of cellular redox state have tremendous influence on the outcome of these therapies. We analyzed antioxidant proteins in normal prostate epithelial cells and tissues as well as prostate cancer cell lines and tissues. Highly aggressive androgen-independent prostate cancer PC3 and LNCAP-C42B cells demonstrated significantly higher levels of superoxide dismutase (SOD) 2, peroxyredoxin (Prx) 1, 2, 3, and 4, thioredoxin (Trx) 1 and 2, and thioredoxin reductase (TR) 1 and 2, relative to normal prostate epithelial PrEC cells and immortalized RWPE1 human prostate epithelial cells. Similarity, the highly aggressive human prostate cancer tissues (Gleason scores 4+4 and 4+5) demonstrated significantly higher levels of SOD1 and 2, Prx 3 and 4, Trx 1 and 2, and TR 1 and 2 relative to adjacent normal prostate tissues. In contrast, the expression levels of these antioxidant proteins were lower or were not altered in less aggressive human prostate cancer tissues (Gleason score 3+3) relative to adjacent normal prostate tissues. Utilizing Trx1 redox western as a marker of cellular redox states, we found more oxidized form of Trx1 in PC3 and LNCAP-C42B cells and human prostate cancer tissues (Gleason scores 4+4 and 4+5) despite their higher levels of Trx1 protein expression. Our data suggest that alteration in antioxidant proteins and cellular redox state may differentiate cancers from non-cancer tissues. Additionally, knowledge of redox state profiles can help to predict the response of each cancer cell type to chemotherapeutic drugs and radiation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2072. doi:1538-7445.AM2012-2072

Proteomic analysis of Trichinella spiralis proteins in intestinal epithelial cells after culture with their larvae by shotgun LC–MS/MS approach

Although it has been known for many years that Trichinella spiralis initiates infection by invading intestinal epithelium, the mechanisms by which the parasite invades the intestinal epithelium are unknown. The purpose of this study was to screen the invasion-related proteins among the increased proteins of intestinal epithelial cells after culture with T. spiralis and to study their molecular functions. The proteins of HCT-8 cells which cultured with T. spiralis infective larvae were analyzed by SDS-PAGE and Western blot. Results showed that compared with proteins of normal HCT-8 cells, four additional protein bands (115, 61, 35 and 24 kDa) of HCT-8 cells cultured with the infective larvae were recognized by sera of the mice infected with T. spiralis, which may be the invasion-related proteins released by the infective larvae. Three bands (61, 35 and 24 kDa) were studied employing shotgun LC-MS/MS. Total 64 proteins of T. spiralis were identified from T. spiralis protein database by using SEQUEST searches, of which 43 (67.2%) proteins were distributed in a range of 10-70 kDa, and 26 proteins (40.6%) were in the range of pI 5-6. Fifty-four proteins were annotated according to Gene Ontology Annotation in terms of molecular function, biological process, and cellular localization. Out of 54 annotated proteins, 43 proteins (79.6%) had binding activity and 23 proteins (42.6%) had catalytic activity (e.g. hydrolase, transferase, etc.), which might be related to the invasion of intestinal epithelial cells by T. spiralis. The protein profile provides a valuable basis for further studies of the invasion-related proteins of T. spiralis.

Myc Posttranscriptionally Induces HIF1 Protein and Target Gene Expression in Normal and Cancer Cells

c-Myc is frequently overexpressed in tumors and plays an important role in the regulation of cancer metabolism. Hypoxia-inducible factor-1 (HIF1), the master regulator of the hypoxic response, enhances tumorigenesis and influences metabolism via upregulation of the glycolytic pathway and suppression of mitochondrial respiration. Together, deregulated Myc and HIF1 cooperate to lend metabolic advantages to proliferating cancer cells and contribute to the Warburg effect. Here we show that overexpression of Myc significantly stabilizes the α subunit of HIF1 (HIF1α) under normoxic conditions and enhances HIF1α accumulation under hypoxic conditions in cells. Posttranscriptional regulation of HIF1α by Myc led to the induction of HIF1α gene targets. Normoxic HIF1α protein expression was also dependent on Myc. Functionally, HIF1α expression was required for Myc-induced anchorage-independent growth and cell proliferation. Myc-dependent stabilization of HIF1α involved either disruption of binding to the VHL complex or posttranslational protein modifications. Taken together, our findings uncover a previously uncharacterized regulatory relationship between Myc and HIF1 that has important implications for cancer metabolism and development.

Quantitative Analysis of the Chromatin Proteome in Disease Reveals Remodeling Principles and Identifies High Mobility Group Protein B2 as a Regulator of Hypertrophic Growth

A fundamental question in biology is how genome-wide changes in gene expression are enacted in response to a finite stimulus. Recent studies have mapped changes in nucleosome localization, determined the binding preferences for individual transcription factors, and shown that the genome adopts a nonrandom structure in vivo. What remains unclear is how global changes in the proteins bound to DNA alter chromatin structure and gene expression. We have addressed this question in the mouse heart, a system in which global gene expression and massive phenotypic changes occur without cardiac cell division, making the mechanisms of chromatin remodeling centrally important. To determine factors controlling genomic plasticity, we used mass spectrometry to measure chromatin-associated proteins. We have characterized the abundance of 305 chromatin-associated proteins in normal cells and measured changes in 108 proteins that accompany the progression of heart disease. These studies were conducted on a high mass accuracy instrument and confirmed in multiple biological replicates, facilitating statistical analysis and allowing us to interrogate the data bioinformatically for modules of proteins involved in similar processes. Our studies reveal general principles for global shifts in chromatin accessibility: altered linker to core histone ratio; differing abundance of chromatin structural proteins; and reprogrammed histone post-translational modifications. Using small interfering RNA-mediated loss-of-function in isolated cells, we demonstrate that the non-histone chromatin structural protein HMGB2 (but not HMGB1) suppresses pathologic cell growth in vivo and controls a gene expression program responsible for hypertrophic cell growth. Our findings reveal the basis for alterations in chromatin structure necessary for genome-wide changes in gene expression. These studies have fundamental implications for understanding how global chromatin remodeling occurs with specificity and accuracy, demonstrating that isoform-specific alterations in chromatin structural proteins can impart these features.

L-arginine intake effect on adenine nucleotide metabolism in rat parenchymal and reproductive tissues.

L-arginine is conditionally essetcial amino acid, required for normal cell growth, protein synthesis, ammonia detoxification, tissue growth and general performance, proposed in the treatment of men sterility and prevention of male impotence. The aim of the present paper was to estimate the activity of the enzymes of adenine nucleotide metabolism: 5′-nucleotidase (5′-NU), adenosine deaminase (ADA), AMP deaminase, and xanthine oxidase (XO), during dietary intake of L-arginine for a period of four weeks of male Wistar rats. Adenosine concentration in tissues is maintained by the relative activities of the adenosine-producing enzyme, 5′-NU and the adenosine-degrading enzyme-ADA adenosine deaminase. Dietary L-arginine intake directed adenine nucleotide metabolism in liver, kidney, and testis tissue toward the activation of adenosine production, by increased 5′-NU activity and decreased ADA activity. Stimulation of adenosine accumulation could be of importance in mediating arginine antiatherosclerotic, vasoactive, immunomodulatory, and antioxidant effects. Assuming that the XO activity reflects the rate of purine catabolism in the cell, while the activity of AMP deaminase is of importance in ATP regeneration, reduced activity of XO, together with the increased AMP-deaminase activity, may suggest that adenine nucleotides are presumably directed to the ATP regenerating process during dietary L-arginine intake.

Thunderclap headache as the primary clinical feature of a supratentorial embolic cerebral infarct

A formula for the diagnostic assessment of thunderclap headache (TCH) should be established. The management of this type of headache is controversial. The established diagnostic assessment of TCH includes a computer tomography (CT) of the head and cerebrospinal fluid (CSF) examination to exclude a subarachnoid haemorrhage. In patients whose CT scans and CSF analyses are normal, further testing is rarely considered to be indicated by most clinicians [1]. However, others suggest that in circumstances where CT and CSF are normal, further diagnostic assessment with magnetic resonance imaging (MRI), magnetic resonance angiography (MRA) of the brain and neck, and magnetic resonance venography is necessary [2]. Articles differ in their conclusions and recommendations. A MRI-verified supratentorial embolic cerebral infarct with TCH as the primary clinical feature is to my knowledge not hitherto reported. Here is described a patient who experienced a TCH as the primary clinical feature of an embolic insula/temporal lobe infarct. A 41-year-old woman appeared in the emergency department following an acute and sudden onset of severe headache. The pain was located in the left temporal region, it reached its maximum intensity in \1 min and lasted for about 7 h. At the time of admission to hospital, the patient reported that the headache had waned. There was no previous history of headaches. Vital signs and physical examination were normal. Neurological examination was normal. Laboratory testing was within the normal range. Blood pressure monitoring was normal. An electrocardiogram (ECG) showed sinus rhythm. Cerebrospinal fluid (CSF) examination revealed a normal opening pressure (140 mmH2O), a normal closing pressure, a normal cell count, glucose and protein. Spectrophotometry disclosed no bilirubin. A CT scan of the head was normal. A magnetic resonance imaging (MRI) of the brain was carried out to exclude other causes of TCHs. It revealed an acute ischaemic lesion in the left insula/ temporal lobe (Fig. 1). A magnetic resonance angiography (MRA) was ordered to exclude intracranial aneurysms, cerebral venous thrombosis, dissection and reversible cerebral vasoconstriction syndrome. These investigations revealed an acute embolic occlusion of a main M2 segment branch of the left middle cerebral artery (Fig. 2). No dissection, reversible cerebral vasoconstriction syndrome or other abnormalities could be detected. Further investigations with ECG telemetry and echocardiography were normal. An additional MRI and MRA of the cervical arteries/intracerebral circulation 2 days later confirmed the cerebral infarct and the occlusion. An extensive laboratory testing revealed normal results. No source of the cerebral embolus could be found. The patient could be discharged and remains well. At follow-up after 6 months, she reported no headache. TCH is a very rare manifestation of a cerebral infarct. In 2006, a case report was published where a TCH was the presenting clinical feature of embolic cerebellar infarcts, in the absence of neurological findings [3]. Gossrau et al. [4] presented a similar case (cerebellar infarct) in 2008. Headache is not uncommon in ischaemic stroke, but is usually overshadowed by other manifestations such as aphasia and neglect [5]. It is usually focal and mild [5]. The character of the headache is throbbing [5]. The severity of the headache is not related to the size of the infarct or the location of the lesion [5]. B. Edvardsson (&) Department of Neurology, Faculty of Medicine, Lund University Hospital, 221 85 Lund, Sweden e-mail: Bengt.Edvardsson@med.lu.se

Seroconversion of anti-aquaporin-4 antibody in NMO spectrum disorder: a case report

Dear Sirs,Anti-aquaporin-4 (AQP4) antibodies are known to be pres-ent both in patients with neuromyelitis optica (NMO) andNMO spectrum disorders (NMOsd), some limited forms ofNMO [1, 2]. The antibodies are considered to have animportant role in the pathogenesis of those disorders [3, 4].We had a patient with NMOsd who had acute longitudinallyextensive myelitis. Her serum anti-AQP4 antibody waspositive at the time myelitis developed, but was negative 8and 9 years before myelitis onset and seroconverted 3 yearsbefore the onset. Her case provides insight into when andhow anti-AQP4 antibody is produced.A 55-year-old Japanese woman developed numbnessand dysesthesia on April 10, 2010 which thereafter exten-ded symmetrically below the eighth cervical segment andcaused slight staggering gait in the dark. Spinal cord MRIT2-weighted images revealed longitudinally extensivemyelitis from the C4 to T2 vertebral segments with gado-linium-enhanced lesion from C7 to T1. She was referred tous, and admitted on May 18, 2010.Actually, she had visited us regularly for the follow-up ofanti-acetylcholine receptor (AChR) antibody-positivemyasthenia gravis (MG) since 1994. She had been treatedwith oral high-dose prednisolone from January 1995. InAugust 1995, she underwent extended thymectomy andhistological examination had revealed hyperplasia. Thosetreatmentshadrelievedallneurologicaldeficits by7 monthsafter surgery. From December 1998, the prednisolone dosewas maintained at 5 mg/day every second day with tempo-rary cessations. By May 2002, prednisolone therapy hadended, and she remained symptom-free.On her present admission, neurological examinationrevealed hypopallesthesia and hyperreflexia in her lowerlimbs, and mild weakness in her left adductor digiti miniand bilateral iliopsoas muscles. Cerebrospinal fluid exam-ination showed a normal cell count and protein levels witha negative oligoclonal band. Brain MRI detected noabnormality consistent with Barkhof’s criteria [5]. Anti-AQP4 antibodies, measured by enzyme-linked immuno-sorbent assays [6] in a serum sample obtained on May 18,2010 were positive. Our diagnosis was NMOsd.Serum samples had been stocked for MG researchbefore the onset of NMO. After receiving her informedconsent, we measured the presence of anti-AQP4 anti-bodies in her stocked serum samples. Figure 1 shows thelongitudinal change in the anti-AQP4 and anti-AChRantibodies before and after NMOsd onset. Anti-AQP4antibody remained negative 8 and 9 years before the onsetof longitudinally extensive myelitis and was seroconverted3 years before myelitis onset. Her anti-AQP4 antibody titrehad increased, and myelitis emerged.Recently, the case of a patient with NMO whose serumhad remained positive for anti-AQP4 antibody for morethan 10 years before onset was reported [7], but it is notclear whether all patients with NMO have anti-AQP4antibody ten or more years before onset. Our patient’s caseshows that seroconversion is possible and that elevation ofanti-AQP4 antibody does not cause NMO onset. Onset mayrequire long-term elevation of anti-AQP4 antibody or someother mechanism.We previously reported two patients with MG whopresented with NMO after thymectomy [8]. In that report,

Cell adhesion, spreading, and proliferation on surface functionalized with RGD nanopillar arrays

In this paper, a method was introduced for the fabrication of vertically and spatially-controlled peptide nanostructures that enhance cell adhesion, proliferation, spreading on artificial surfaces. The RGD nanostructures with different heights were fabricated on gold surfaces by self-assembly technique through a nanoporous alumina mask composed of nanoscale-controlled pores. Pore diameter and spatial distribution were controlled by manipulating the pore widening time at a constant voltage during the mask fabrication process. Two-dimensional RGD nanodot, three-dimensional RGD nanorod, and RGD nanopillar arrays were carried out using various concentrations of RGD peptide solution, self-assembly times, and pore sizes, which were 74 nm, 63 nm, and 43 nm in diameter, respectively. The fabricated RGD nanodot, nanorod, and nanopillar arrays were utilized as a cell adhesion layer to evaluate the cell adhesion force, adhesion speed, spreading assay, and phosphorylation of cofilin protein in PC12, HeLa, and HEK293T normal cells. Among the three different nanostructures, RGD nanopillar arrays were found to be suitable for cellular attachment, spreading, and proliferation due to the proper arrangement of the RGD motif, which mimics in vivo conditions. Hence, our newly fabricated RGD nanostructured array can be successfully applied as a bio-platform for improving cellular functions and in in vitro tissue engineering.

Macrocycles That Inhibit the Binding between Heat Shock Protein 90 and TPR-Containing Proteins

Heat shock protein 90 (Hsp90) accounts for 1-2% of the total proteins in normal cells and functions as a molecular chaperone that folds, assembles, and stabilizes client proteins. Hsp90 is overexpressed (3- to 6-fold increase) in stressed cells, including cancer cells, and regulates over 200 client and co-chaperone proteins. Hsp90 client proteins are involved in a plethora of cellular signaling events including numerous growth and apoptotic pathways. Since pathway-specific inhibitors can be problematic in drug-resistant cancers, shutting down multiple pathways at once is a promising approach when developing new therapeutics. Hsp90's ability to modulate many growth and signaling pathways simultaneously makes this protein an attractive target in the field of cancer therapeutics. Herein we present evidence that a small molecule modulates Hsp90 via binding between the N and middle domain and allosterically inhibiting the binding interaction between Hsp90 and four C-terminal binding client proteins: IP6K2, FKBP38, FKBP52, and HOP. These last three clients contain a tetratricopeptide-repeat (TPR) region, which is known to interact with the MEEVD sequence on the C-terminus of Hsp90. Thus, this small molecule modulates the activity between co-chaperones that contain TPR motifs and Hsp90's MEEVD region. This mechanism of action is unique from that of all Hsp90 inhibitors currently in clinical trials where these molecules have no effect on proteins that bind to the C-terminus of Hsp90. Further, our small molecule induces a Caspase-3 dependent apoptotic event. Thus, we describe the mechanism of a novel scaffold that is a useful tool for studying cell-signaling events that result when blocking the MEEVD-TPR interaction between Hsp90 and co-chaperone proteins.

A DNA methylation microarray-based study identifies ERG as a gene commonly methylated in prostate cancer

DNA methylation of promoter regions is a common event in prostate cancer, one of the most common cancers in men worldwide. Because prior reports demonstrating that DNA methylation is important in prostate cancer studied a limited number of genes, we systematically quantified the DNA methylation status of 1505 CpG dinucleotides for 807 genes in 78 paraffin-embedded prostate cancer samples and three normal prostate samples. The ERG gene, commonly repressed in prostate cells in the absence of an oncogenic fusion to the TMPRSS2 gene, was one of the most commonly methylated genes, occurring in 74% of prostate cancer specimens. In an independent group of patient samples, we confirmed that ERG DNA methylation was common, occurring in 57% of specimens, and cancer-specific. The ERG promoter is marked by repressive chromatin marks mediated by polycomb proteins in both normal prostate cells and prostate cancer cells, which may explain ERG’s predisposition to DNA methylation and the fact that tumors with ERG DNA methylation were more methylated, in general. These results demonstrate that bead arrays offer a high-throughput method to discover novel genes with promoter DNA methylation such as ERG, whose measurement may improve our ability to more accurately detect prostate cancer.

E2FBP1 antagonizes the p16INK4A‐Rb tumor suppressor machinery for growth suppression and cellular senescence by regulating promyelocytic leukemia protein stability

Cellular senescence is an irreversible cell cycle arrest triggered by the activation of oncogenes or mitogenic signaling as well as the enforced expression of tumor suppressors such as p53, p16INK4A and promyelocytic leukemia protein (PML) in normal cells. E2F-binding protein 1 (E2FBP1), a transcription regulator for E2F, induces PML reduction and suppresses the formation of PML-nuclear bodies, whereas the down-regulation of E2FBP1 provokes the PML-dependent premature senescence in human normal fibroblasts. Here we report that the depletion of E2FBP1 induces the accumulation of PML through the Ras-dependent activation of MAP kinase signaling. The cellular levels of p16INK4A and p53 are elevated during premature senescence induced by depletion of E2FBP1, and the depletion of p16INK4A, but not p53 rescued senescent cells from growth arrest. Therefore, the premature senescence induced by E2FBP1 depletion is achieved through the p16INK4A-Rb pathway. Similar to human normal fibroblasts, the growth inhibition induced by E2FBP1 depletion is also observed in human tumor cells with intact p16INK4A and Rb. These results suggest that E2FBP1 functions as a critical antagonist to the p16INK4A-Rb tumor suppressor machinery by regulating PML stability.

Ubc9 mediates nuclear localization and growth suppression of BRCA1 and BRCA1a proteins.

BRCA1 gene mutations are responsible for hereditary breast and ovarian cancers. In sporadic breast tumors, BRCA1 dysfunction or aberrant subcellular localization is thought to be common. BRCA1 is a nuclear-cytoplasm shuttling protein and the reason for cytoplasmic localization of BRCA1 in young breast cancer patients is not yet known. We have previously reported BRCA1 proteins unlike K109R and cancer-predisposing mutant C61G to bind Ubc9 and modulate ER-α turnover. In the present study, we have examined the consequences of altered Ubc9 binding and knockdown on the subcellular localization and growth inhibitory function of BRCA1 proteins. Our results using live imaging of YFP, GFP, RFP-tagged BRCA1, BRCA1a and BRCA1b proteins show enhanced cytoplasmic localization of K109 R and C61G mutant BRCA1 proteins in normal and cancer cells. Furthermore, down-regulation of Ubc9 in MCF-7 cells using Ubc9 siRNA resulted in enhanced cytoplasmic localization of BRCA1 protein and exclusive cytoplasmic retention of BRCA1a and BRCA1b proteins. These mutant BRCA1 proteins were transforming and impaired in their capacity to inhibit growth of MCF-7 and CAL51 breast cancer cells. Interestingly, cytoplasmic BRCA1a mutants showed more clonogenicity in soft agar and higher levels of expression of Ubc9 than parental MCF7 cells. This is the first report demonstrating the physiological link between cytoplasmic mislocalization of mutant BRCA1 proteins, loss of ER-α repression, loss of ubiquitin ligase activity and loss of growth suppression of BRCA1 proteins. Thus, binding of BRCA1 proteins to nuclear chaperone Ubc9 provides a novel mechanism for nuclear import and control of tumor growth.

The Human Protein Atlas as a proteomic resource for biomarker discovery

The analysis of tissue-specific expression at both the gene and protein levels is vital for understanding human biology and disease. Antibody-based proteomics provides a strategy for the systematic generation of antibodies against all human proteins to combine with protein profiling in tissues and cells using tissue microarrays, immunohistochemistry and immunofluorescence. The Human Protein Atlas project was launched in 2003 with the aim of creating a map of protein expression patterns in normal cells, tissues and cancer. At present, 11,200 unique proteins corresponding to over 50% of all human protein-encoding genes have been analysed. All protein expression data, including underlying high-resolution images, are published on the free and publically available Human Protein Atlas portal (http://www.proteinatlas.org). This database provides an important source of information for numerous biomedical research projects, including biomarker discovery efforts. Moreover, the global analysis of how our genome is expressed at the protein level has provided basic knowledge on the ubiquitous expression of a large proportion of our proteins and revealed the paucity of cell- and tissue-type-specific proteins.

Importin α-Mediated Nuclear Import of Cytoplasmic Poly(A) Binding Protein Occurs as a Direct Consequence of Cytoplasmic mRNA Depletion

Recent studies have found the cytoplasmic poly(A) binding protein (PABPC) to have opposing effects on gene expression when concentrated in the cytoplasm versus in the nucleus. PABPC is predominantly cytoplasmic at steady state, where it enhances protein synthesis through simultaneous interactions with mRNA and translation factors. However, it accumulates dramatically within the nucleus in response to various pathogenic and nonpathogenic stresses, leading to an inhibition of mRNA export. The molecular events that trigger relocalization of PABPC and the mechanisms by which it translocates into the nucleus to block gene expression are not understood. Here, we reveal an RNA-based mechanism of retaining PABPC in the cytoplasm. Expression either of viral proteins that promote mRNA turnover or of a cytoplasmic deadenylase drives nuclear relocalization of PABPC in a manner dependent on the PABPC RNA recognition motifs (RRMs). Using multiple independent binding sites within its RRMs, PABPC interacts with importin α, a component of the classical import pathway. Finally, we demonstrate that the direct association of PABPC with importin α is antagonized by the presence of poly(A) RNA, supporting a model in which RNA binding masks nuclear import signals within the PABPC RRMs, thereby ensuring efficient cytoplasmic retention of this protein in normal cells. These findings further suggest that cells must carefully calibrate the ratio of PABPC to mRNA, as events that offset this balance can dramatically influence gene expression.

Prions and protein-folding diseases

Prions represent a group of proteins with a unique capacity to fold into different conformations. One isoform is rich in beta-pleated sheets and can aggregate into amyloid that may be pathogenic. This abnormal form propagates itself by imposing its confirmation on the homologous normal host cell protein. Pathogenic prions have been shown to cause lethal neurodegenerative diseases in humans and animals. These diseases are sometimes infectious and hence referred to as transmissible spongiform encephalopathies. In the present review, the remarkable evolution of the heterodox prion concept is summarized. The origin of this phenomenon is based on information transfer between homologous proteins, without the involvement of nucleic acid-encoded mechanisms. Historically, kuru and Creutzfeldt-Jakob disease (CJD) were the first infectious prion diseases to be identified in man. It was their relationship to scrapie in sheep and experimental rodents that allowed an unravelling of the particular molecular mechanism that underlie the disease process. Transmission between humans has been documented to have occurred in particular contexts, including ritual cannibalism, iatrogenic transmission because of pituitary gland-derived growth hormone or the use in neurosurgical procedures of dura mater from cadavers, and the temporary use of a prion-contaminated protein-rich feed for cows. The latter caused a major outbreak of bovine spongiform encephalopathy, which spread to man by human consumption of contaminated meat, causing approximately 200 cases of variant CJD. All these epidemics now appear to be over because of measures taken to curtail further spread of prions. Recent studies have shown that the mechanism of protein aggregation may apply to a wider range of diseases in and possibly also outside the brain, some of which are relatively common such as Alzheimer's and Parkinson's diseases. Furthermore, it has become apparent that the phenomenon of prion aggregation may have a wider physiological importance, but a full understanding of this remains to be defined. It may involve maintaining neuronal functions and possibly contributing to the establishment of long-term memory.

Heterogeneity in expression of antimicrobial proteins in normal and crohn's disease small intestinal paneth cells

IntroductionPaneth cells are normally located at the base of small intestinal crypts and express a number of antimicrobial factors that are believed to be important in host protection against luminal...

Recent progress in the epigenetics and chromatin field

Recent progress in the epigenetics and chromatin field

Inhibition of Anchorage‐Independent Proliferation and G0/G1 Cell‐Cycle Regulation in Human Colorectal Carcinoma Cells by 4,7‐Dimethoxy‐5‐Methyl‐l,3‐Benzodioxole Isolated from the Fruiting Body of Antrodia camphorate

In this study, 4,7-dimethoxy-5-methyl-l,3-benzodioxole (SY-1) was isolated from three different sources of dried fruiting bodies of Antrodia camphorate (AC). AC is a medicinal mushroom that grows on the inner heartwood wall of Cinnamomum kanehirai Hay (Lauraceae), an endemic species that is used in Chinese medicine for its anti-tumor and immunomodulatory properties. In this study, we demonstrated that SY-1 profoundly decreased the proliferation of human colon cancer cells (COLO 205) through G0/G1 cell-cycle arrest (50–150 μM) and induction of apoptosis (>150 μM). Cell-cycle arrest induced by SY-1 was associated with a significant increase in levels of p53, p21/Cip1 and p27/Kip1, and a decrease in cyclins D1, D3 and A. In contrast, SY-1 treatment did not induce significant changes in G0/G1 phase cell-cycle regulatory proteins in normal human colonic epithelial cells (FHC). The cells were cultured in soft agar to evaluate anchorage-independent colony formation, and we found that the number of transformed colonies was significantly reduced in the SY-1-treated COLO 205 cells. These findings demonstrate for the first time that SY-1 inhibits human colon cancer cell proliferation through inhibition of cell growth and anchorage-independent colony formation in soft agar. However, the detailed mechanisms of these processes remain unclear and will require further investigation.