A PIN1 polymorphism that prevents its suppression by AP4 associates with delayed onset of Alzheimer's disease

Alzheimer's disease (AD), the most common form of dementia, is characterized by the presence of neurofibrillary tangles composed of tau and senile plaques of amyloid-beta peptides (Aβ) derived from amyloid precursor protein (APP). Pin1 is a unique prolyl isomerase that has been shown to protect against age-dependent neurodegeneration by acting on phosphorylated tau and APP to suppress tangle formation and amyloidogenic APP processing. Here we report a functional polymorphism, rs2287839, in the Pin1 promoter that is significantly associated with a 3-year delay in the average age at onset (AAO) of late-onset AD in a Chinese population. More significantly, the Pin1 polymorphism rs2287839 is located within the consensus binding motif for the brain-selective transcription factor, AP4 (CAGCTG) and almost completely abolishes the ability of AP4 to bind and suppress the Pin1 promoter, as shown by chromatin immunoprecipitation, electrophoretic mobility shift assay, and promoter luciferase assay. Moreover, overexpression or knockdown of AP4 resulted in an 80% reduction or 2-fold increase in endogenous Pin1 levels, respectively. Thus, AP4 is a novel transcriptional repressor of Pin1 expression and the Pin1 promoter single nucleotide polymorphism (SNP) identified in this study that prevents such suppression is associated with delayed onset of AD. These results indicate that regulation of Pin1 by AP4 plays a critical role in determining age at onset of AD and might be a novel therapeutic target to delay the onset of AD.

Toward flexibility-activity relationships by NMR spectroscopy: dynamics of Pin1 ligands

Drug design involves iterative ligand modifications. For flexible ligands, these modifications often entail restricting conformational flexibility. However, defining optimal restriction strategies can be challenging if the relationship between ligand flexibility and biological activity is unclear. Here, we describe an approach for ligand flexibility-activity studies using Nuclear Magnetic Resonance (NMR) spin relaxation. Specifically, we use (13)C relaxation dispersion measurements to compare site-specific changes in ligand flexibility for a series of related ligands that bind a common macromolecular receptor. The flexibility changes reflect conformational reorganization resulting from formation of the receptor-ligand complex. We demonstrate this approach on three structurally similar but flexibly differentiated ligands of human Pin1, a peptidyl-prolyl isomerase. The approach is able to map the ligand dynamics relevant for activity and expose changes in those dynamics caused by conformational locking. Thus, NMR flexibility-activity studies can provide information to guide strategic ligand rigidification. As such, they help establish an experimental basis for developing flexibility-activity relationships (FAR) to complement traditional structure-activity relationships (SAR) in molecular design.

Non-natural amino acid fluorophores for one- and two-step fluorescence resonance energy transfer applications

Fluorescence resonance energy transfer (FRET) provides a powerful means to study protein conformational changes. However, the incorporation of an exogenous FRET pair into a protein could lead to undesirable structural perturbations of the native fold. One of the viable strategies to minimizing such perturbations is to use non-natural amino acid-based FRET pairs. Previously, we showed that p-cyanophenylalanine (Phe(CN)) and tryptophan (Trp) constitute such a FRET pair, useful for monitoring protein folding-unfolding transitions. Here we further show that 7-azatryptophan (7AW) and 5-hydroxytryptophan (5HW) can also serve as a FRET acceptor to Phe(CN), and the resultant FRET pairs offer certain advantages over Phe(CN)-Trp. For example, the fluorescence spectrum of 7AW is sufficiently separated from that of Phe(CN), making it straightforward to decompose the FRET spectrum into donor and acceptor contributions. Moreover, we show that Phe(CN), Trp, and 7AW can be used together to form a multi-FRET system, allowing more structural information to be extracted from a single FRET experiment. The applicability of these FRET systems is demonstrated in a series of studies where they are employed to monitor the urea-induced unfolding transitions of the villin headpiece subdomain (HP35), a designed betabetaalpha motif (BBA5), and the human Pin1 WW domain.

Promyelocytic leukemia protein controls cell migration in response to hydrogen peroxide and insulin-like growth factor-1

Promyelocytic leukemia protein (PML) was originally identified as part of a chromosomal translocation that contributes to the development of acute promyelocytic leukemia (APL). Since its discovery, PML has been found to play diverse roles in different cellular processes. Notably, PML has anti-proliferative and pro-apoptotic activity that supports its role as a tumor suppressor. We have previously shown that the peptidyl-prolyl isomerase Pin1 is able to affect cell proliferation and hydrogen peroxide (H(2)O(2))-mediated cell death through modulation of the steady-state levels of PML. We have extended these studies to show that the interaction between PML and Pin1 is targeted by multiple extracellular signals in the cell. We show that H(2)O(2) up-regulates and IGF-1 down-regulates PML expression in a Pin1-dependent manner. Interestingly, we found that H(2)O(2)- and IGF-1-mediated alteration in PML accumulation regulate MDA-MB-231 cell migration. Furthermore, we show that the control of cell migration by PML, and thus H(2)O(2) and IGF-1, results from PML-dependent decreased expression of integrin beta1 (ITGB1). Knockdown of Pin1 leads to decreased cell migration, lower levels of ITGB1 expression and resistance to IGF-1- and H(2)O(2)-induced changes in cell migration and ITGB1 expression. Taken together, our work identifies PML as a common target for H(2)O(2) and IGF-1 and supports a novel tumor suppressive role for PML in controlling cell migration through the expression of ITGB1.

Inhibition of peptidyl-prolyl cis/trans isomerase Pin1 induces cell cycle arrest and apoptosis in vascular smooth muscle cells

This study was undertaken to determine the in vitro effect of lentivirus-mediated siPin1 on cell cycle and apoptosis of vascular smooth muscle cells (VSMCs). Further we sought to provide insight into the mechanisms behind these processes. Human umbilical artery smooth muscle cells (HUASMCs) were transfected with lentiviral siPin1. Real-time RT-PCR and Western blotting were used to examine Pin1 mRNA and protein expression. MTT and [(3)H]thymidine incorporation assays were employed to observe cell proliferation status. The apoptotic rate and cell cycle were analyzed by Hoechst33258 staining and flow cytometry. Finally we measured the expression of cyclin D1, beta-catenin, CDK4, cytochrome c, procaspase-3, cleaved caspase-3, procaspase-9, cleaved caspase-9, Bcl-2, Bax, STAT3, phosphorylated STAT3 and VEGF in lentiviral siPin1 infected VSMCs. Lentivirus-mediated siPin1 effectively diminished endogenous Pin1 expression in VSMCs resulting in cell cycle arrest and enhancement of apoptosis. This was accompanied by downregulation of cyclin D1, beta-catenin, CDK4, increase of Bax/Bcl-2 ratio, release of cytochrome c, and activation of caspase-3 and -9. We concluded that this effect was mediated, at least in part, via the beta-catenin/cyclin D1/CDK4 cascade, and that the mitochondrial pathway was responsible for VSMC apoptosis in the absence of Pin1. Our observations raised the possibility that Pin1 might be a potential therapeutic target to prevent stenosis.

Pin1 facilitates the phosphorylation-dependent ubiquitination of SF-1 to regulate gonadotropin beta-subunit gene transcription

Pin1 is a peptidyl-prolyl cis-trans isomerase which catalyzes the isomerization of phosphorylated Ser/Thr-Pro peptide bonds. Pin1 knockout mice have marked abnormalities in their reproductive development and function. However, the molecular mechanisms underlying their reproductive defects are poorly understood. Herein, we demonstrate that Pin1 is required for both basal and GnRH-induced gonadotropin beta-subunit gene transcription, through interactions with the transcription factors SF-1, Pitx1, and Egr-1. Pin1 activates transcription of the gonadotropin beta-subunit genes synergistically with these transcription factors, either by modulating their stability or by increasing their protein-protein interactions. Notably, we provide evidence that Pin1 is required for the Ser203 phosphorylation-dependent ubiquitination of SF-1, which facilitates SF-1-Pitx1 interactions and therefore results in an enhancement of SF-1 transcriptional activity. Furthermore, we demonstrate that in gonadotrope cells, sufficient levels of activated Pin1 are maintained through transcriptional and posttranslational regulation by GnRH-induced signaling cascades. Our results suggest that Pin1 functions as a novel player in GnRH-induced signal pathways and is involved in gonadotropin beta-subunit gene transcription by modulating the activity of various specific transcription factors.

[The expression and significance of Pin1 and CyclinD1 in adult papilloma of larynx]

OBJECTIVE

To study the expression and relationship of Pin1 and CyclinD1 in adult papilloma of larynx, and the effect of both in laryngeal papilloma's canceration.

METHOD

Ninety-two cases of paraffin section with immunoperoxidase (SP) staining method was used to detect the distribution of Pin1 and CyclinD1 in 10 cases of laryngeal normal epithelial tissue, 39 cases of laryngeal papilloma, 27 cases of laryngeal papilloma with middle, severe atypical hyperplasia and 16 cases of laryngeal carcinoma.

RESULT

The distribution of Pin1 and CyclinD1 increased gradually from laryngeal normal epithelial tissue to laryngeal carcinoma (P<0.05); No difference of the expression of CyclinD1 (not including Pin1, for Pin1, P=0.009) was found between laryngeal papilloma and laryngeal papilloma with middle, severe atypical hyperplasia (P>0.0125), but there had significant difference of the expression of Pin1 and CyclinD1 among the rest groups; There was significantly direct correlation between the expression of Pin1 and CyclinD1 (P<0.05).

CONCLUSION

The hyper-expressions of Pin1 and CyclinD1 may play a key role in laryngeal papilloma's malignant change. Pin1 up-regulating the expressions of cyclinD1 possibly participate in its malignant change.

Interpretation of Pin-1 and VEGF-C expression in breast infiltrating duct carcinoma

Pin-1 has been shown to regulate several phases of the cell cycle and is strikingly overexpressed in many human cancers. Vascular endothelial growth factor (VEGF)-C is a potent lymphangiogenic factor produced by tumor and stromal cells. However, little is known about the roles of Pin-1 and VEGF-C in breast carcinoma. p53 protein and cyclin D1 overexpressions have been shown to play a role as prognostic factors in many human cancers. To better understand the roles of Pin-1 and VEGF-C in breast carcinoma, we evaluated the immunohistochemical expression of Pin-1 and VEGF-C in relationship with p53 protein or cyclin D1 overexpression and clinicopathological parameters in 128 mammary infiltrating duct carcinomas. There was a positive expression in 100% of Pin-1, 88% of VEGF-C, 35% of p53 protein, and 66% of cyclin D1 in the breast carcinoma. Correlation of the positive expression of Pin-1 with tumor grade (p<0.01) and lymph node metastasis or cyclin D1 overexpression (p<0.05, respectively) was statistically significant. Significant correlation was observed between VEGF-C and tumor grade, lymph node metastasis or clinical stage (p<0.01, respectively). These results indicate that elevated Pin-1 or VEGF-C expression is more common in infiltrating duct carcinomas with poor prognostic characteristics and is partly associated with an unfavorable outcome. Given the role of cyclin D1 overexpression in oncogenesis of breast, these results suggest that overexpression of Pin-1 and VEGF-C may promote tumor progression and metastasis.

The Ess1 prolyl isomerase is required for transcription termination of small noncoding RNAs via the Nrd1 pathway

Genome-wide studies have identified abundant small, noncoding RNAs, including small nuclear RNAs, small nucleolar RNAs (snoRNAs), cryptic unstable transcripts (CUTs), and upstream regulatory RNAs (uRNAs), that are transcribed by RNA polymerase II (pol II) and terminated by an Nrd1-dependent pathway. Here, we show that the prolyl isomerase Ess1 is required for Nrd1-dependent termination of noncoding RNAs. Ess1 binds the carboxy-terminal domain (CTD) of pol II and is thought to regulate transcription by conformational isomerization of Ser-Pro bonds within the CTD. In ess1 mutants, expression of approximately 10% of the genome was altered, due primarily to defects in termination of snoRNAs, CUTs, stable unannotated transcripts, and uRNAs. Ess1 promoted dephosphorylation of Ser5 (but not Ser2) within the CTD, most likely by the Ssu72 phosphatase. We also provide evidence for a competition between Nrd1 and Pcf11 for CTD binding that is regulated by Ess1. These data indicate that a prolyl isomerase is required for specifying the "CTD code."

Novel role of Pin1 induction in type II collagen-mediated rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation in joints and subsequent destruction of cartilage and bone. Inflammatory mediators such as PGs and proinflammatory cytokines contribute to RA progress. Pin1, a peptidyl prolyl isomerase, plays important pathophysiological roles in several diseases, including cancer and neurodegeneration. We found that both Pin1 and cyclooxygenase-2 (COX-2) were highly expressed in ankle tissues of type II collagen-induced RA mice. HTB-94 cells overexpressing Pin1 and primary cultured human chondrocytes showed increased basal expression of proinflammatory proteins (COX-2, inducible NO synthase, TNF-alpha, and IL-1beta). Site-directed mutagenesis revealed that Pin1-mediated transcriptional activation of COX-2 was coordinately regulated by NF-kappaB, CREB, and C/EBP. Gel shift, reporter gene, and Western blot analyses confirmed that NF-kappaB, CREB, and C/EBP were consistently activated in chondrocytes overexpressing Pin1. Treatment of RA mice with juglone, a chemical inhibitor of Pin1, significantly reduced RA progress and COX-2 expression in the ankle tissues. Moreover, juglone dose dependently decreased the basal COX-2 expression in primary cultured chondrocytes from RA patients. These results demonstrate that Pin1 induction during RA progress stimulates proinflammatory protein expression by activating NF-kappaB, CREB, and C/EBP, and suggest that Pin1 is a potential therapeutic target of RA.

Cep55 stabilization is required for normal execution of cytokinesis

Cep55 is a mitotic phosphoprotein that plays an important role in cytokinesis, the final stage of cell division during which physical separation of the two daughter cells is accomplished. We recently demonstrated that the peptidyl-prolyl isomerase Pin1 regulates this cell cycle event by enhancing the Plk1-dependent phosphorylation of Cep55. We show here that Cep55 is stabilized post-translationally during mitosis and that siRNA-mediated knockdown of Pin1 prevents this stabilization. Consistent with this, Cep55 is unstable in Pin1 knockout mouse embryonic fibroblasts. Moreover, mutation of the Pin1 binding sites in Cep55 reduces its stability during mitosis. Mutation of the Plk1 phosphorylation site also lowers Cep55 stability, whereas overexpression of Plk1 increases Cep55 levels, in keeping with Pin1 regulating Plk1-mediated phosphorylation of Cep55. Importantly, expression of wild-type Cep55 at levels similar to that of the phosphorylation mutants only partially reverts the cytokinesis defect induced by depletion of Cep55, indicating that inadequate levels of Cep55 prevent proper execution of cytokinesis. Taken together, these data provide more insight into the regulation of the final stages of cell division. As cytokinesis defects can cause chromosomal instability, knowledge about the processes that regulate normal cytokinesis adds to our understanding of events that lead to tumorigenesis.

Involvement of Pin1 induction in epithelial-mesenchymal transition of tamoxifen-resistant breast cancer cells

Acquisition of resistance to tamoxifen is a critical therapeutic problem in breast cancer patients. Epithelial-mesenchymal transition (EMT), where cells undergo a developmental switch from a polarized epithelial phenotype to a highly motile mesenchymal phenotype, is associated with invasion and motility of cancer cells. Here, we found that tamoxifen-resistant (TAMR)-MCF-7 cells had undergone EMT, as evidenced by mesenchymal-like cell shape, downregulation of basal E-cadherin expression, and overexpression of N-cadherin and vimentin, as well as increased Snail transcriptional activity and protein expression. Given the roles of glycogen synthase kinase (GSK)-3beta and nuclear factor (NF)-kappaB in Snail-mediated E-cadherin deregulation during EMT, we examined the role of these signaling pathways in the EMT of TAMR-MCF-7 cells. Both Ser9-phosphorylated GSK-3beta (inactive form) and NF-kappaB reporter activity were increased in TAMR-MCF-7 cells, as was activation of the phosphatase and tensin homolog depleted on chromosome ten (PTEN)-phosphoinositide 3 (PI3)-kinase-Akt pathway. Pin1, a peptidyl-prolyl isomerase, was overexpressed in TAMR-MCF-7 cells, and Snail transcription and the expression of EMT markers could be decreased by Pin1 siRNA treatment. These results imply that Pin1 overexpression in TAMR-MCF-7 cells is involved in the EMT process via PTEN-PI3-kinase-Akt-GSK-3beta and/or GSK-3beta-NF-kappaB-dependent Snail activation, and suggest the potential involvement of Pin1 in EMT during breast cancer development.

Mapping the dynamics of ligand reorganization via 13CH3 and 13CH2 relaxation dispersion at natural abundance

Flexible ligands pose challenges to standard structure-activity studies since they frequently reorganize their conformations upon protein binding and catalysis. Here, we demonstrate the utility of side chain (13)C relaxation dispersion measurements to identify and quantify the conformational dynamics that drive this reorganization. The dispersion measurements probe methylene (13)CH(2) and methyl (13)CH(3) groups; the latter are highly prevalent side chain moieties in known drugs. Combining these side chain studies with existing backbone dispersion studies enables a comprehensive investigation of mus-ms conformational dynamics related to binding and catalysis. We perform these measurements at natural (13)C abundance, in congruence with common pharmaceutical research settings. We illustrate these methods through a study of the interaction of a phosphopeptide ligand with the peptidyl-prolyl isomerase, Pin1. The results illuminate the side-chain moieties that undergo conformational readjustments upon complex formation. In particular, we find evidence that multiple exchange processes influence the side chain dispersion profiles. Collectively, our studies illustrate how side-chain relaxation dispersion can shed light on ligand conformational transitions required for activity, and thereby suggest strategies for its optimization.

The peptidyl-prolyl isomerase, Pin1, facilitates NF-kappaB binding in hepatocytes and protects against hepatic ischemia/reperfusion injury

BACKGROUND/AIMS

Our previous work suggested an important role for the peptidyl-prolyl isomerase, Pin1, in hepatic NF-kappaB activation and liver injury during ischemia/reperfusion (I/R). In this study, we sought to determine the function of Pin1 in the injury response to hepatic I/R.

METHODS

Wild-type and Pin1(-/-) mice were subjected to partial hepatic I/R. In addition, hepatocytes and Kupffer cells were isolated from these mice.

RESULTS

Pin1(-/-) mice had reduced hepatic NF-kappaB activation and more liver injury after I/R than wild-type mice. The increased injury was not a result of enhanced inflammation as Pin1(-/-) mice had the same level of proinflammatory cytokine production and less neutrophil accumulation in the liver. The reduced NF-kappaB activation was not a result of a defect in nuclear translocation of NF-kappaB. In fact, hepatic nuclear p65 protein expression was higher in Pin1(-/-) mice than wild-type mice. This suggests that Pin1 is important for NF-kappaB-DNA binding. This effect was specific to hepatocytes as isolated Kupffer cells from wild-type and Pin1(-/-) mice were identical in their activation of NF-kappaB and production of cytokines after stimulation. In contrast, hepatocytes stimulated with TNFalpha had greatly reduced NF-kappaB activation, reduced production of the CXC chemokine, MIP-2, and increased cell death.

CONCLUSIONS

These data suggest that Pin1 is a critical regulator of NF-kappaB activation in hepatocytes and its role in these cells appears to confer direct protective effects.

The peptidyl-prolyl isomerase Pin1 regulates cytokinesis through Cep55

Failure of cytokinesis results in tetraploidy and can increase the genomic instability frequently observed in cancer. The peptidyl-prolyl isomerase Pin1, which is deregulated in many tumors, regulates several processes, including cell cycle progression. Here, we show a novel role for Pin1 in cytokinesis. Pin1 knockout mouse embryonic fibroblasts show a cytokinesis delay, and depletion of Pin1 from HeLa cells also causes a cytokinesis defect. Furthermore, we provide evidence that Pin1 localizes to the midbody ring and regulates the final stages of cytokinesis by binding to centrosome protein 55 kDa (Cep55), an essential component of this ring. This interaction induces Polo-like kinase 1-mediated phosphorylation of Cep55, which is critical for the function of Cep55 during cytokinesis. Importantly, Pin1 knockdown does not enhance the cytokinesis defect in Cep55-depleted cells, indicating that Pin1 and Cep55 act in the same pathway. These data are the first evidence that Pin1 regulates cytokinesis and may provide a mechanistic explanation as to how pathologic levels of Pin1 can stimulate tumorigenesis.

Molecular and biochemical characterization of the parvulin-type PPIases in Lotus japonicus

The cis/trans isomerization of the peptide bond preceding proline is an intrinsically slow process, although important in many biological processes in both prokaryotes and eukaryotes. In vivo, this isomerization is catalyzed by peptidyl-prolyl cis/trans-isomerases (PPIases). Here, we present the molecular and biochemical characterization of parvulin-type PPIase family members of the model legume Lotus japonicus, annotated as LjPar1, LjPar2, and LjPar3. Although LjPar1 and LjPar2 were found to be homologous to PIN1 (Protein Interacting with NIMA)-type parvulins and hPar14 from human, respectively, LjPar3 represents a novel multidomain parvulin, apparently present only in plants, that contains an active carboxyl-terminal sulfurtransferase domain. All Lotus parvulins were heterologously expressed and purified from Escherichia coli, and purified protein verification measurements used a liquid chromatography-mass spectrometry-based proteomic method. The biochemical characterization of the recombinant Lotus parvulins revealed that they possess PPIase activity toward synthetic tetrapeptides, although they exhibited different substrate specificities depending on the amino acid amino terminal to proline. These differences were also studied in a structural context using molecular modeling of the encoded polypeptides. Real-time reverse transcription-polymerase chain reaction revealed that the three parvulin genes of Lotus are ubiquitously expressed in all plant organs. LjPar1 was found to be up-regulated during the later stages of nodule development. Subcellular localization of LjPar-enhanced Yellow Fluorescence Protein (eYFP) fusions expressed in Arabidopsis (Arabidopsis thaliana) leaf epidermal cells revealed that LjPar1- and LjPar2-eYFP fusions were localized in the cytoplasm and in the nucleus, in contrast to LjPar3-eYFP, which was clearly localized in plastids. Divergent substrate specificities, expression profiles, and subcellular localization indicate that plant parvulin-type PPIases are probably involved in a wide range of biochemical and physiological processes.

Effect of Pin1 or microtubule binding on dephosphorylation of FTDP-17 mutant Tau

Neurodegenerative tauopathies, including Alzheimer disease, are characterized by abnormal hyperphosphorylation of the microtubule-associated protein Tau. One group of tauopathies, known as frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17), is directly associated with mutations of the gene tau. However, it is unknown why mutant Tau is highly phosphorylated in the patient brain. In contrast to in vivo high phosphorylation, FTDP-17 Tau is phosphorylated less than wild-type Tau in vitro. Because phosphorylation is a balance between kinase and phosphatase activities, we investigated dephosphorylation of mutant Tau proteins, P301L and R406W. Tau phosphorylated by Cdk5-p25 was dephosphorylated by protein phosphatases in rat brain extracts. Compared with wild-type Tau, R406W was dephosphorylated faster and P301L slower. The two-dimensional phosphopeptide map analysis suggested that faster dephosphorylation of R406W was due to a lack of phosphorylation at Ser-404, which is relatively resistant to dephosphorylation. We studied the effect of the peptidyl-prolyl isomerase Pin1 or microtubule binding on dephosphorylation of wild-type Tau, P301L, and R406W in vitro. Pin1 catalyzes the cis/trans isomerization of phospho-Ser/Thr-Pro sequences in a subset of proteins. Dephosphorylation of wild-type Tau was reduced in brain extracts of Pin1-knockout mice, and this reduction was not observed with P301L and R406W. On the other hand, binding to microtubules almost abolished dephosphorylation of wild-type and mutant Tau proteins. These results demonstrate that mutation of Tau and its association with microtubules may change the conformation of Tau, thereby suppressing dephosphorylation and potentially contributing to the etiology of tauopathies.

Dipentamethylene thiuram monosulfide is a novel inhibitor of Pin1

Pin1 is involved in eukaryotic cell proliferation by changing the structure and function of phosphorylated proteins. PiB, the Pin1 specific inhibitor, blocks cancer cell proliferation. However, low solubility of PiB in DMSO has limited studies of its effectiveness. We screened for additional Pin1 inhibitors and identified the DMSO-soluble compound dipentamethylene thiuram monosulfide (DTM) that inhibits Pin1 activity with an EC50 value of 4.1 microM. Molecular modeling and enzyme kinetic analysis indicated that DTM competitively inhibits Pin1 activity, with a K(i) value of 0.05 microM. The K(D) value of DTM with Pin1 was determined to be 0.06 microM by SPR technology. Moreover, DTM specifically inhibited peptidyl-prolyl cis/trans isomerase activity in HeLa cells. FACS analysis showed that DTM induced G0 arrest of the HCT116 cells. Our results suggest that DTM has the potential to guide the development of novel antifungal and/or anticancer drugs.

Peptidylproline cis-trans-isomerase Pin1 interacts with human T-cell leukemia virus type 1 tax and modulates its activation of NF-kappaB

Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus etiologically causal of adult T-cell leukemia (ATL). The virus encodes a Tax oncoprotein that functions in transcriptional regulation, cell cycle control, and transformation. ATL is a highly virulent cancer that is resistant to chemotherapeutic treatments. To understand this disease better, it is important to comprehend how HTLV-1 promotes cellular growth and survival. Tax activation of NF-kappaB is important for the proliferation and transformation of virus-infected cells. We show here that prolyl isomerase Pin1 is over expressed in HTLV-1 cell lines; Pin1 binds Tax and regulates Tax-induced NF-kappaB activation.

[Recent advance in the study of novel anti-tumor targets and drugs--aurora kinase and Pin1]

Malignant tumor, one of the most refractory diseases, plays a threaten role in human health, the therapy and research on malignant tumor have taken a long way to go. The anti-tumor drugs which are the essential therapy strategies upgrade with the development of new anti-tumor targets and the research on tumor pathogenesis. Aurora kinase and Pin1, the novel anti-tumor targets, maintain the important relationship with tumor. Many new compounds designed on these targets have excellent anti-tumor effects and also enter into phase I or phase II clinical trial.

Expression and significance of Pin1 mRNA in circulating mononuclear cells from non-small cell lung cancer patients during perioperative period

BACKGROUND AND OBJECTIVE

The catalytic reaction of Pin1 (peptidylprolyl cis/trans isomerase NIMA-interacting 1) is a signal pathway for changing the functions of phosphorylated proteins, which plays an important role in tumorigenesis. Pin1 is called the catalytic molecule for tumorigenesis. This study was to detect the expression of Pin1 mRNA in blood samples from non-small cell lung cancer (NSCLC) patients, and explore its significance.

METHODS

Twenty-six NSCLC patients who underwent radical resection were assigned to pulmonary artery first ligation group (PA-first group) and pulmonary vein first ligation group (PV-first group). The blood samples were collected before operation (after anesthesia), during operation from the proximal part and distal part of the pulmonary vein when it was ligated, and at 7 days later. Additionally, ten patients with benign lung disease who underwent resection served as disease control, and ten healthy subjects served as negative control. The expression of Pin1 in the blood samples was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The mRNA level of Pin1 was obviously higher in blood samples from NSCLC patients than in those from benign lung disease patients and healthy subjects: it in NSCLC group was 1.69-34.78 times of that in negative control group. It was associated with lymph node metastasis and clinical stage of NSCLC (p=0.043, p=0.038). The mRNA level of Pin1 was significantly higher in the distal part of the pulmonary vein than in the proximal part (p=0.019), and was significantly lower at 7 days after operation than before operation (p=0.031). There was no significant difference between PA-first group and PV-first group (p=0.082, p=0.106).

CONCLUSION

Pin1 is overexpressed in circulation of NSCLC, and may be used as a tumor marker or as a target for cancer therapy.

The prolyl isomerase Pin1 interacts with a ribosomal protein S6 kinase to enhance insulin-induced AP-1 activity and cellular transformation

Phosphorylation of proteins on serine or threonine residues that immediately precede proline (pSer/Thr-Pro) is specifically catalyzed by the peptidyl-prolyl cis-trans isomerase Pin1 and is a central signaling mechanism in cell proliferation and transformation. Although Pin1 is frequently overexpressed in hepatocellular carcinoma (HCC), the molecular mechanism of Pin1 in HCC has not been completely elucidated. Here, we show that Pin1 interacts with p70S6K in vitro and ex vivo. Overexpression of Pin1 resulted in enhanced p70S6K phosphorylation induced by insulin in SK-HEP-1 cells. In contrast, Pin1(-/-) mouse embryonic fibroblasts (MEFs) exhibited significantly decreased insulin-induced p70S6K phosphorylation compared with Pin1(+/+) MEFs. Furthermore, Pin1 enhanced the insulin-induced extracellular signal-regulated protein kinase (ERK)1/2 phosphorylation through its interaction with p70S6K, whereas the inhibition of p70S6K activity by rapamycin suppressed insulin-induced ERK1/2 phosphorylation in SK-HEP-1 cells. Hence, Pin1 affected activator protein-1 activity through p70S6K-ERK1/2 signaling in SK-HEP-1 cells. Most importantly, Pin1-overexpressing JB6 Cl41 cells enhanced neoplastic cell transformation promoted by insulin much more than green fluorescent protein-overexpressing JB6 Cl41 control cells. These results imply that Pin1 amplifies insulin signaling in hepatocarcinoma cells through its interaction with p70S6K, suggesting that Pin1 plays an important role in insulin-induced tumorigenesis and is a potential therapeutic target in hepatocarcinoma.

Nuclear import of Pin1 is mediated by a novel sequence in the PPIase domain

Pin1 actively regulates diverse biological/pathological processes, but little is known about the regulatory mechanisms of its cellular localization. In this study, we report that the endogenous Pin1 is distributed in both nucleus and cytoplasm. We found that point mutations of several basic amino acids in the PPIase domain of Pin1 significantly compromise its nuclear localization. Such inhibition is independent of Pin1 enzymatic activity, and is mainly due to the defects in the nuclear import. A novel sequence harboring these residues was identified as a putative nuclear localization signal (NLS) of Pin1. Importin alpha5 of the nuclear import machinery was found to interact with Pin1.

[Effect of yizhi jiannao granules on the expression of Pin1 and HMGB1 mRNA in the hippocampus of SAMP8 mice]

OBJECTIVE

To investigate the effect of yizhi jiannao granule concentration fluid (YCF) on the expression of peptidyl-prolyl-cis-trans isomerase A (Pin1) and high mobility group box 1 (HMGB1) mRNA in the hippocampus of senescence accelerated mice Senile-Prone8(SAMP8).

METHODS

Six-month old SAMP8 mice were randomly divided into a YCF group and a model group. Six-month old SAMP8 mice were served as a normal control group. The YCF group was ravaged, while the model group and the normal control group were gavaged with double-distilled water for 8 weeks. The hippocampus was taken out for examination. The expression of Pin1 and HMGB1 mRNA was measured by RT-PCR.

RESULTS

In the YCF group, the level of Pin1 mRNA increased, and the level of HMGB1 mRNA decreased compared with that of the model group.

CONCLUSION

Yizhi jiannao granules can prevent Alzheimer's disease by increasing the Pin1 level and decreasing the HMGB1 level.

[Expression of pin1 mRNA in the circulation of non-small cell lung cancer patients and influence of sequence of vessel ligation]

OBJECTIVE

To detect the expression of peptidylprolyl cis/trans isomerase NIMA-interacting l (pin1 mRNA) in the circulation of non-small cell lung cancer (NSCLC) and to investigate the effect of ligating pulmonary vein first or ligating pulmonary artery first during operation on haematogenous dissemination of cancer cells.

METHODS

Twenty-six consecutive patients with NSCLC who underwent surgical resection with curative intention were randomly assigned into pulmonary artery first-ligation group (PA group) and pulmonary vein first-ligation group (PV group). Blood samples were collected just before and 7 days after the operation. During the lobectomy, blood samples of the proximal part and distal part of the pulmonary vein when it was ligated were collected. Another 10 patients with benign lung disease served as control subjects undergoing surgical resection, and 10 healthy persons served as negative controls. All blood samples were subjected to real-time RT-PCR with pin1 mRNA as the marker.

RESULTS

Compared with the benign lung disease and healthy persons, pin1 mRNA in NSCLC was overexpressed (1.45 to approximately 29.86 vs.0.83 to approximately 1.26 vs 1, P<0.05). pin1 mRNA in stage III NSCLC and lymph node positive were significantly higher than in stage I to approximately II and lymph node negative(18.48+/-1.64 vs.10.57+/-1.05, P<0.05;18.93+/-2.10 vs.10.02+/-1.23, P<0.05). Expression of pin1 mRNA in the distal part of the pulmonary vein was significantly higher than that of the proximal part (30.56+/-1.37 vs.20.31+/-1.48, P<0.05); the expression 7 days after the operation was significantly lower than that of preoperation (20.68+/-1.17 vs.29.43+/-2.62, P<0.05). There was no significant difference between the PA group and PV group (9.95+/-0.91 vs.14.71+/-1.64, P>0.05; 16.84+/-2.36 vs.13.36+/-1.78, P>0.05).

CONCLUSION

pin1 mRNA was overexpressed in the circulation of NSCLC. Ligation of pulmonary vein before the ligation of the pulmonary artery may decrease the expression of pin1 mRNA in the circulation, which can prevent the release of tumor cells into the bloodstream.