Identification of phosphorylated proteins involved in the oncogenesis of prostate cancer via Pin1-proteomic analysis

BACKGROUND

The peptidyl-prolyl isomerase Pin1 regulates a subset of phosphorylated proteins by catalyzing the cis-trans isomerization of their specific phosphorylated Ser/Thr-Pro motifs. Although Pin1 has been shown to be involved in cell transformation and the maintenance of the malignant phenotype in prostate cancer, its specific substrates during these processes have not yet been determined.

METHODS

Cancer-specific phosphorylated proteins were isolated from two human prostate cancer cell lines (PC-3, LNCaP) and the Dunning rat prostate cancer cell lines by GST-pull down analysis with recombinant GST-Pin1 protein. These proteins were then identified by the LC-MS/MS analysis using a Q-Tof micro mass spectrometer and processed for further functional analysis.

RESULTS

We newly identified five prostate cancer-specific Pin1 binding proteins (PINBPs) in this screen. Among these, TRK-fused gene (TFG) was found to be preferentially up-regulated in prostate cancer cell lines and tissues. The targeted inhibition of TFG by specific siRNA resulted in the reduced cell proliferation and the induction of premature senescence in PC3 prostate cancer cells. We further found that TFG can facilitate the cell signaling mediated by NF-kappaB and androgen receptor (AR). Tissue micro-dissection based quantitative RT-PCR analysis of prostate cancer tissues following radical prostatectomy further revealed that TFG expression is closely associated with both a higher probability and shorter period of tumor recurrence following surgery.

CONCLUSIONS

Pin1-based proteomics analysis is a useful tool for the identification of prostate cancer-specific phosphorylated proteins. TFG could be a potential diagnostic and/or prognostic marker and therapeutic target in prostate cancer.

Vaccination with Human Induced Pluripotent Stem Cells Creates an Antigen-Specific Immune Response Against HIV-1 gp160

Induced pluripotent stem cells (iPSCs) are artificially derived from somatic cells that have been transduced with defined reprogramming factors. A previous report has indicated the possibility of using iPSCs as an immune stimulator to generate antigen-specific immunity. In our current study, we have investigated whether human iPSCs (hiPSCs) have the ability to enhance specific immune response against a human immunodeficiency virus type 1 (HIV-1) antigen in a xenogenic mouse model. Our results show that BALB/c mice immunized with hiPSCs transduced with an adenoviral vector encoding HIV-1 gp160 exhibited prominent antigen-specific cellular immune responses. We further found that pre-treatment of hiPSCs with ionizing radiation promotes the secretion of pro-inflammatory cytokines such as interleukin-1 alpha (IL-1α), IL-12, and IL-18. These cytokines might promote the activation of antigen-presenting cells and the effective induction of cellular immunity. Our present findings thus demonstrate that a hiPSCs-based vaccine has the potential to generate cellular immunity against viral antigens such as HIV-1 gp160 in a xenogenic condition.

A distinct role for Pin1 in the induction and maintenance of pluripotency

The prominent characteristics of pluripotent stem cells are their unique capacity to self-renew and pluripotency. Although pluripotent stem cell proliferation is maintained by specific intracellular phosphorylation signaling events, it has not been well characterized how the resulting phosphorylated proteins are subsequently regulated. We here report that the peptidylprolyl isomerase Pin1 is indispensable for the self-renewal and maintenance of pluripotent stem cells via the regulation of phosphorylated Oct4 and other substrates. Pin1 expression was found to be up-regulated upon the induction of induced pluripotent stem (iPS) cells, and the forced expression of Pin1 with defined reprogramming factors was observed to further enhance the frequency of iPS cell generation. The inhibition of Pin1 activity significantly suppressed colony formation and induced the aberrant differentiation of human iPS cells as well as murine ES cells. We further found that Pin1 interacts with the phosphorylated Ser(12)-Pro motif of Oct4 and that this in turn facilitates the stability and transcriptional activity functions of Oct4. Our current findings thus uncover an atypical role for Pin1 as a putative regulator of the induction and maintenance of pluripotency via the control of phosphorylation signaling. These data suggest that the manipulation of Pin1 function could be a potential strategy for the stable induction and proliferation of human iPS cells.

Expression and localization of vascular endothelial growth factor in normal abdominal aorta and abdominal aortic aneurysm

AIM

The genesis of abdominal aortic aneurysms is associated with remodeling of the vascular wall by angiogenesis as well as proteolysis. Vascular endothelial growth factor (VEGF) is known to be a regulator of angiogenesis and to simultaneously stimulate elastolytic proteinases. We analyzed the expression and localization of VEGF in human abdominal aortic aneurysms compared to normal human aorta

METHODS

Eighteen infrarenal aortic aneurysm samples were collected at the time of abdominal aortic aneurysm surgery, while nine normal aortic samples were obtained from autopsy specimens. Immunohistochemical staining was performed to detect VEGF. Immunoenzyme or immunofluorescent double staining was also used to identify those cells presenting VEGF.

RESULTS

VEGF was expressed in 18 (100%) of the 18 abdominal aortic aneurysm samples, while 0 (0%) in the 9 normal abdominal aorta samples. Of the 18 samples of aneurysms, all 18 displayed positive VEGF immunostaining in macrophages, 12 in smooth muscle cells (SMCs), and 9 in endothelial cells (ECs).

CONCLUSION

Our study clearly demonstrated the expression of VEGF in ECs, and SMCs, and macrophages of abdominal aortic aneurysms as well as its absence in those cells of normal abdominal aorta, suggesting that VEGF may play an important role in aneurysm formation via its direct and/or indirect actions.

Effort-reward imbalance and depressive state in nurses

BACKGROUND

The mental health of nurses is an important issue.

AIMS

To examine relationships between effort-reward imbalance (ERI) and depression and anxiety in nurses of a Japanese general hospital.

METHODS

A self-report survey was conducted among 406 nurses. Work stress was measured using a Japanese version of the ERI scale. Depression and anxiety were assessed by an item of the QOL-26. Logistic regression analysis was used to determine the independent contribution of the effort-reward ratios or overcommitment to the depressive state.

RESULTS

Both higher effort-money ratio and higher overcommitment significantly correlated with the depressive state (OR: 2.75; 95% CI: 1.34-5.66 and OR: 1.27; 95% CI: 1.15-1.41, respectively).

CONCLUSIONS

These findings suggest that in addition to effort-money ratio, overcommitment at work is an especially important issue that may be able to be managed in health promotion services for nurses in general hospitals.

Follicular dendritic cells activate HIV-1 replication in monocytes/macrophages through a juxtacrine mechanism mediated by P-selectin glycoprotein ligand 1

Follicular dendritic cells (FDCs) are located in the lymphoid follicles of secondary lymphoid tissues and play a pivotal role in the selection of memory B lymphocytes within the germinal center, a major site for HIV-1 infection. Germinal centers are composed of highly activated B cells, macrophages, CD4(+)T cells, and FDCs. However, the physiological role of FDCs in HIV-1 replication remains largely unknown. We demonstrate in our current study that FDCs can efficiently activate HIV-1 replication in latently infected monocytic cells via an intercellular communication network mediated by the P-selectin/P-selectin glycoprotein ligand 1 (PSGL-1) interaction. Upon coculture with FDCs, HIV-1 replication was significantly induced in infected monocytic cell lines, primary monocytes, or macrophages. These cocultures were found to synergistically induce the expression of P-selectin in FDCs via NF-kappaB activation and its cognate receptor PSGL-1 in HIV-1-infected cells. Consistent with this observation, we find that this response is significantly blocked by antagonistic Abs against PSGL-1 and almost completely inhibited by PSGL-1 small interfering RNA. Moreover, a selective inhibitor for Syk, which is a downstream effector of PSGL-1, blocked HIV-1 replication in our cultures. We have thus elucidated a novel regulatory mechanism in which FDCs are a potent positive bystander that facilitates HIV-1 replication in adjacent infected monocytic cells via a juxtacrine signaling mechanism.

Requirement for microtubule integrity in the SOCS1-mediated intracellular dynamics of HIV-1 Gag

Suppressor of cytokine signaling 1 (SOCS1) is a recently identified host factor that positively regulates the intracellular trafficking and stability of HIV-1 Gag. We here examine the molecular mechanism by which SOCS1 regulates intercellular Gag trafficking and virus particle production. We find that SOCS1 colocalizes with Gag along the microtubule network and promotes microtubule stability. SOCS1 also increases the amount of Gag associated with microtubules. Both nocodazole treatment and the expression of the microtubule-destabilizing protein, stathmin, inhibit the enhancement of HIV-1 particle production by SOCS1. SOCS1 facilitates Gag ubiquitination and the co-expression of a dominant-negative ubiquitin significantly inhibits the association of Gag with microtubules. We thus propose that the microtubule network plays a role in SOCS1-mediated HIV-1 Gag transport and virus particle formation.

Steroid receptor signalling in the brain--lessons learned from molecular imaging

Studies with green fluorescent protein (GFP) have revealed the subcellular distribution of many steroid hormone receptors to be much more dynamic than previously thought. Fluorescence resonance energy transfer (FRET) and fluorescence recovery after photobleaching (FRAP) are powerful techniques with which to examine protein-protein interaction and the mobility of tagged proteins, respectively. FRET analysis revealed that steroid treatment (with corticosterone or testosterone) induces direct interaction of the glucocorticoid receptor (GR) and importin alpha in the cytoplasm and that, shortly after nuclear entry, the GR detaches from importin alpha. The mineralocorticoid receptor (MR) and androgen receptor (AR) show the same trafficking. Upon oestradiol treatment, ERalpha and ERbeta in the same cell are relocalised to form a discrete pattern and are localised in the same discrete cluster (subnuclear foci). FRAP analysis showed that nuclear ERalpha and ERbeta are most dynamic and mobile in the absence of the ligand, and that mobility decreases slightly after ligand treatment. Genomic as well as non-genomic actions of steroid hormones influence the cellular function of target tissues spacio-temporally.

The wheat germ cell-free based screening of protein substrates of calcium/calmodulin-dependent protein kinase II delta

Calcium/calmodulin-dependent protein kinase II (CaMKII) plays a crucial role in mediating calcium signaling. Here, we demonstrate a method for screening substrates phosphorylated by human CaMKII delta using a wheat cell-free system. The cell-free mixture expressing CaMKII delta was incubated with HeLa extracts and radiolabeled ATP. From analysis of two-dimensional electrophoresis gels and mass spectrometry, two proteins were found. The cell-free based in vitro kinase assay revealed that CaMKII delta phosphorylates eukaryotic translation initiation factor 4B and stress-induced phosphoprotein 1 (STIP1), the latter on Ser189. Furthermore, constitutively-active CaMKII delta phosphorylated STIP1 in HeLa cells and dramatically promoted nuclear localization of STIP1, suggesting that calcium signals via CaMKII delta may regulate subcellular localization of STIP1. This approach may be a useful tool for target screening of protein kinases.

A mitochondrial DNA variant at position 16189 is associated with type 2 diabetes mellitus in Asians

AIMS/HYPOTHESIS

This multinational study was conducted to investigate the association between a mitochondrial DNA (mtDNA) T16189C polymorphism and type 2 diabetes in Asians. The mtDNA 16189C variant has been reported to be associated with insulin resistance and type 2 diabetes. However, a recent meta-analysis concluded that it is negatively associated with type 2 diabetes in Europids. Since the phenotype of an mtDNA mutant may be influenced by environmental factors and ethnic differences in the nuclear and mitochondrial genomes, we investigated the association between the 16189C variant and type 2 diabetes in Asians.

METHODS

The presence of the mtDNA 16189C variant was determined in 2,469 patients with type 2 diabetes and 1,205 non-diabetic individuals from Korea, Japan, Taiwan, Hong Kong and China. An additional meta-analysis including previously published Asian studies was performed. Since mtDNA nucleotide position 16189 is very close to the mtDNA origin of replication, we performed DNA-linked affinity chromatography and reverse-phase liquid chromatography/tandem mass spectrometry and chromatin immunoprecipitation to identify protein bound to the 16189 region.

RESULTS

Analysis of participants from five Asian countries confirmed the association between the 16189C variant and type 2 diabetes [odds ratio (OR) 1.256, 95% CI 1.08-1.46, p=0.003]. Inclusion of data from three previously published Asian studies (type 2 diabetes n=3,283, controls n=2,176) in a meta-analysis showed similar results (OR 1.335, 95% CI 1.18-1.51, p=0.000003). Mitochondrial single-stranded DNA-binding protein (mtSSB) was identified as a candidate protein bound to the 16189 region. Chromatin immunoprecipitation in cybrid cells showed that mtSSB has a lower binding affinity for the 16189C variant than the wild-type sequence.

CONCLUSIONS/INTERPRETATION

The mtDNA 16189C variant is associated with an increased risk of type 2 diabetes in Asians.

Last resort for renal transplant recipients, 'restored kidneys' from living donors/patients

Because of the grave shortage of deceased kidney allografts in Japan, we have embarked on a new source of organs, 'Restored kidneys' from living patients. From January 1991 through September 2006, 42 kidneys (eight benign pathology, eight small renal cancers, eight ureteral cancers, six aneurysms, eight severe nephrotic syndrome from four patients and four ureteral stenosis) were obtained from 38 patients/donors after extensive discussion of treatment modalities and risks. All patients/donors agreed to undergo total nephrectomy. The lesions were removed/repaired ex vivo on the back table, then transplanted. All recipients were notified of all possible risks including donor disease recurrence. One, 5 and 10-year patient survival rates of restored transplant patients were 92.9%, 79.3% and 63.8%, respectively. One, 5 and 10-year graft survival rates of restored kidney transplant patients were 78.6%, 51.8% and 42.7%, respectively. There were no recurrences of small renal cell carcinomas. There was one recurrence of ureteral cancer in the transplanted kidney 15 months after operation. In countries where deceased donors are scarce, such as Japan, the restored kidneys can be a last resort for renal allografts.

Direct visualization of glucocorticoid receptor positive cells in the hippocampal regions using green fluorescent protein transgenic mice

The hippocampal formation is a plastic brain structure important for certain types of learning and memory, and also vulnerable to the effects of stress and trauma. Since hippocampal neurons express high levels of corticosteroid receptor, the morphological changes, including alterations in the size of soma, and the length and number of neurites and spines, in response to glucocorticoids released as a result of stress are intriguing. In order to highlight the morphology of neurons that express glucocorticoid receptor (GR), we have generated a transgenic mouse line expressing green fluorescent protein (GFP) under the control of the GR promoter. We found strong green fluorescence in the pyramidal cell layer of the CA1 and CA2 regions and the granule cell layer of the dentate gyrus of the hippocampus in brain sections of the transgenic mice. GFP fluorescence was observed not only in somas, but also in neurites including both dendrites and axons. In dissociated culture, we also observed GFP fluorescence in the soma, neurites including both dendrites and axons, and dendritic spines. Microtubule-associated protein 2 immunopositive pyramidal-shaped neurons clearly showed two different populations, GFP positive and GFP negative neurons. These results indicate that this transgenic mouse line should be useful for live imaging of neuronal structure in animals as well as GR-positive cultured cells using GFP as a specific indicator.

Expression and production of aberrant PAX5 with deletion of exon 8 in B-lineage acute lymphoblastic leukaemia of children

Summary We investigated PAX5 expression in childhood B-lineage acute lymphoblastic leukaemia (ALL). Seven of 21 children with B-lineage ALL had multiple PAX5 variants, while 14 children and healthy controls showed full-length (FL) and one variant PAX5. By Western blotting, healthy controls displayed Pax5-FL, while one short Pax5, derived from the deletion of exon 8 (Pax5-DeltaE8) was produced in 90% of ALL samples, as well as in ALL cell lines. PAX5-DeltaE8 lacked more than 50% of the transactivation domain, indicating that aberrant Pax5 production might lead to the arrest of B-cell differentiation, contributing to the pathogenesis of B-lineage ALL.