The prolyl isomerase Pin1 binds to the phosphorylated Ser/Thr-Pro motif of target proteins and enhances their cis-trans conversion. This report is the first to show that Pin1 expression in pancreatic β cells is markedly elevated by high-fat diet feeding and in ob/ob mice. To elucidate the role of Pin1 in pancreatic β cells, we generated β-cell-specific Pin1 KO (βPin1 KO) mice. These mutant mice showed exacerbation of glucose intolerance but had normal insulin sensitivity. We identified two independent factors underlying impaired insulin secretion in the βPin1 KO mice. Pin1 enhanced pancreatic β-cell proliferation, as indicated by a reduced β-cell mass in βPin1 KO mice compared with control mice. Moreover, a diet high in fat and sucrose failed to increase pancreatic β-cell growth in the βPin1 KO mice, an observation to which up-regulation of the cell cycle protein cyclin D appeared to contribute. The other role of Pin1 was to activate the insulin-secretory step: Pin1 KO β cells showed impairments in glucose- and KCl-induced elevation of the intracellular Ca2+ concentration and insulin secretion. We also identified salt-inducible kinase 2 (SIK2) as a Pin1-binding protein that affected the regulation of Ca2+ influx and found Pin1 to enhance SIK2 kinase activity, resulting in a decrease in p35 protein, a negative regulator of Ca2+ influx. Taken together, our observations demonstrate critical roles of Pin1 in pancreatic β cells and that Pin1 both promotes β-cell proliferation and activates insulin secretion.

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.

BACKGROUND

Recent evidence suggests that the peptidyl-prolyl isomerase Pin1 is an oncoprotein that acts as a novel therapeutic target in a variety of tumors. In this study, we investigated the clinical significance of Pin1 and its function in prostate cancer (PCa) tumor progression.

METHODS

Immunohistochemical and quantitative RT-PCR analyses were performed to detect the expression of Pin1 in 86 PCa tissue samples. The functional role of Pin1 was evaluated by small interfering RNA-mediated depletion in PCa cells followed by analyses of cell proliferation and migration. Furthermore, the association between expression of Pin1 and levels of β-catenin and cyclin D1 was also evaluated.

RESULTS

Our results showed that the high expression of Pin1 staining was 66 of 86 (76.74 %) PCa samples, and in 25 of 86 (29.07 %) BPH tissues, the difference was statistically significant (P < 0.001). Pin1 was significantly elevated in all PCa cell lines when compared to the normal RWPE-1 cells. We observed that proliferation and migration of LNCaP cells were inhibited by Pin1 knockdown. The levels of β-catenin and cyclin D1 in clinical PCa specimens were positively associated with Pin1 expression.

CONCLUSIONS

Our results suggest that Pin1 plays an important role in tumorigenesis of PCa, suggesting that targeting Pin1 pathway could represent a potential modality for treating PCa.

HPV-transformed cells exhibit activation of NF-κB and STAT3 (mediators of inflammation), but very little is known about their regulation under inflammatory conditions before HPV integration. This study reports that cervical tissues with stromal inflammation and intact HPV16 E2 gene show increased expression of target genes of NF-κB and/or STAT3 which can regulate cell survival (cyclin D1, c-Myc, survivin and Bcl2) and inflammatory responses (TNF-α, IL-1β, IL-6, IL-8 and CCR2). Increased expression of RelA, p-IκBα, STAT3, p-STAT3 (Ser727), Pin1 (peptidyl-prolyl cis/trans isomerase) and MCM2 in the squamous epithelia of cervices with stromal inflammation supports early activation of NF-κB-STAT3. Furthermore, HPV16 E2 potentiated NF-κB activation induced by inflammatory mediators, IL-1β and SDF-1α, in HEK293 cells. These results reveal a novel role for E2 in regulating the activities of NF-κB and STAT3 that may have implications in carcinogenic progression of HPV16-infected cells under conditions of stromal inflammation.

BACKGROUND

Prolyl isomerase Pin1 may be involved in innate immunity against microbial infection, but the mechanism how Pin1 controls the innate immunity is poorly understood.

RESULTS

Injection of lipopolysaccharide (LPS) into the mice induces inflammatory pulmonary disorder and sometimes the serious damages lead to death. Comparing to the wild-type (WT) mice, the Pin1⁻/⁻ mice showed more serious damages in lung and the lower survival rate after the LPS injection. We compared the levels of typical inflammatory cytokines. Pin1⁻/⁻ mice overreacted to the LPS injection to produce inflammatory cytokines, especially IL-6 more than WT mice. We showed that Pin1 binds phosphorylated PU.1 and they localize together in a nucleus. These results suggest that Pin1 controls the transcriptional activity of PU.1 and suppresses overreaction of macrophage that causes serious damages in lung.

CONCLUSIONS

Pin1 may protect the mice from serious inflammation by LPS injection by attenuating the increase of IL-6 transcription of the mouse macrophages.

SUMMARY Proteinase inhibitors (PIs) are established markers for wound- and especially jasmonate-mediated signalling in dicot species such as tomato and potato. Differential screening of a cDNA library constructed from RNA isolated from wounded leaves of the grass Brachypodium distachyon led to the identification of a proteinase inhibitor gene (Bdpin1). Bdpin1 exhibited the highest homology to the subtilisin/chymotrypsin-inhibiting subgroup of the pin1 class of plant PIs. Northern analyses indicated that Bdpin1 was induced within 6 h at the site of wounding and systemically, by 24 h, thereby providing evidence for long-distance signalling in grasses. Bdpin1 also proved to be more rapidly induced in susceptible than in resistant ecotypes of B. distachyon following challenge with the Rice blast pathogen, Magnaporthe grisea. Screening with chemical signals indicated that Bdpin1 could be induced with MeJA but not with the putative mimic of salicylic acid, benzothiadiazole. Genomic Southern hybridization was consistent with Bdpin1 existing at a single locus, which was isolated following screening of a genomic cosmid library. DNA upstream of the Bdpin1 coding sequence was characterized via fusion to a GUS reporter and was found to confer wound-responsive transcription in B. distachyon and other cereals following biolistic bombardment. Both wound- and TMV-activated Bdpin1-GUS activity was detected in transgenic tobacco. Given that B. distachyon represents an ancestral grass species, our data suggest that there is considerable conservation in defence-associated signalling between dicots and grasses.

Homologues of the p23 co-chaperone of HSP90 are present in all eukaryotes, suggesting conserved functions for this protein throughout evolution. Although p23 has been extensively studied in animal systems, little is known about its function in plants. In the present study, the functional characterization of the two isoforms of p23 in Arabidopsis thaliana is reported, suggesting a key role of p23 in the regulation of root development. Arabidopsis p23 mutants, for either form, show a short root length phenotype with a reduced meristem length. In the root meristem a low auxin level associated with a smaller auxin gradient was observed. A decrease in the expression levels of PIN FORMED PROTEIN (PIN)1, PIN3, and PIN7, contextually to an inefficient polar localization of PIN1, was detected. Collectively these results suggest that both Arabidopsis p23 isoforms are required for root growth, in particular in the maintenance of the root meristem, where the proteins are located.

The prolyl isomerase Pin1, which isomerizes the p-Ser/Thr-Pro peptide bonds and effects conformational and functional changes of the bound proteins, has been identified as a regulator of phosphorylation signaling in several diseases including cancer. The aim of this study is to determine the expression status of Pin1 in gastric cancer, its relationship between clinicopathologic features and patients' outcome. The mRNA levels of Pin1 in human normal and gastric cancer tissues were analyzed using the datasets from the publicly available Oncomine database ( www.oncomine.org ). Pin1 protein levels in human gastric cancer cells and tissues were analyzed by Western blot and immunohistochemistry staining, respectively. The Pin1 protein expression levels and its clinicopathologic correlations were investigated using tumor tissue microarray including 182 cases of human gastric cancer samples with survival information. Pin1 mRNA expression was found to be overexpressed in gastric cancer by using several datasets of Oncomine database analyzing. Pin1 protein expression is higher in 10 gastric cancer cell lines than that in normal gastric epithelial cell line GES-1. Pin1 positive expression was observed in 109 of 182 (59.9 %) gastric cancer samples and in 55 of 182 (30.2 %) normal gastric tissues (P < 0.001). Correlation analysis showed that high expression of Pin1 was significantly associated with pT (P = 0.017), pN (P = 0.043), TNM staging (P = 0.027), Lauren's classification (P < 0.001), as well as shorter overall survival in gastric cancer patients (29 mos vs. 47 mos. P = 0.048). Moreover, Pin1 expression, pT, and differentiation were independent prognostic factors of gastric cancer in Cox regression analysis. Pin1 is overexpressed in gastric cancer and correlates with clinicopathologic features, which might predict poor prognosis of gastric cancer patients.

The tumor suppressor p53 and the prolyl isomerase Pin1 are both highly connected proteins, lying at the crossroads between many signaling pathways that control cell proliferation and transformation. By catalyzing conformational changes in a large number of phosphorylated proteins, Pin1 has been implicated in the regulation of major cellular events, such as cell cycle progression, transcription, proliferation and differentiation. Recently, a role for Pin1 has emerged also in the DNA damage response, through modulation of p53 functions upon genotoxic stress. A further level of control has now been unveiled by showing that also the p53 sibling p73 requires Pin1 for its apoptotic activity.

Enzymes catalyze a plethora of chemical reactions that are tightly regulated and intricately coupled in biology. Catalysis of phosphorylation-dependent cis-trans isomerization of peptidyl-prolyl bonds, which act as conformational switches in regulating many post-phosphorylation processes, is considered to be one of the most critical. Pin1 is a cis-trans isomerase of peptidyl-prolyl(ω-) bonds of phosphorylated-Ser/Thr-Pro motifs and has been implicated in many diseases. Structural and experimental studies are still unable to resolve the mechanistic role and protonation states of two adjacent histidines (His59 and His157) and a cysteine (Cys113) in the active site of Pin1. Here, we show that the protonation state of Cys113 mediates a dynamic hydrogen-bonding network in the active site of Pin1, involving the two adjacent histidines and several other residues that are highly conserved and necessary for catalysis. We have used detailed free energy calculations and molecular dynamics simulations, complementing previous experiments, to resolve the ambiguities in the orientations of the histidines and protonation states of these key active site residues, details that are critical for fully understanding the mechanism of Pin1 and necessary for developing potent inhibitors. Importantly, Cys113 is shown to alternate between the unprotonated and neutral states, unprotonated in free Pin1 and neutral in substrate-bound Pin1. Our results are consistent with experiments and provide an explanation for the chemical reactivity of free Pin1 that is suggested to be necessary for the regulation of the enzyme.

Alzheimer's disease (AD) manifests with progressive memory loss and decline of spatial awareness and motor skills. Neurofibrillary tangles (NFTs) represent one of the pathological hallmarks of AD. Previous studies suggest that the enzyme prolyl-peptidyl cis-trans isomerase PIN1 [protein interacting with NIMA (never in mitosis A)-1] recognizes hyperphosphorylated tau (in NFTs) and facilitates its dephosphorylation, thereby recovering its function. This study aims to determine the frequency, severity and distribution of PIN1 immunoreactivity and its relationship to NFTs and other neuropathological markers of neurodegeneration such as amyloid-β (Aβ) plaques and transcription-responsive DNA-binding protein of M(r) 43 kDa (TDP-43). Immunohistochemical analysis of 194 patients (46 with AD, 43 with Parkinson's disease/dementia with Lewy bodies, 12 with progressive supranuclear palsy/corticobasal degeneration, 36 with frontotemporal lobar degeneration, 21 with motor neuron disease and 34 non-demented (ND) individuals) revealed an increased frequency and severity of PIN1 immunoreactive inclusions in AD as compared to all diagnostic groups (P < 0.001). The hippocampal and cortical distribution of PIN1 granules was distinct from that of NFTs, Aβ and TDP-43 pathologies, though the frequency of neurons with PIN1 immunoreactivity increased with increasing NFT pathology. There was a progressive increase in PIN1 changes in ND individuals as the degree of AD-type pathological changes increased. Present findings indicate that PIN1 changes are a constant feature of AD pathology and could serve as a biomarker of the onset or spread of AD neuropathology independent of tau or Aβ.

Parvulins are a conserved group of peptidyl-prolyl cis/trans isomerases (PPIases) that catalyze the cis/trans isomerization of proline-preceding peptide bonds. Parvulin-class PPIases are structurally unrelated to cyclophilins and FK506-binding proteins that are defined as receptors for immunosuppressive drugs. In Trypanosoma cruzi we identified parvulin TcPIN1 as a homolog of the human hPin1 PPIase. The 117 amino acids of the TcPIN1 display 40% identity with the catalytic core of hPin1 and exhibit prolyl cis/trans isomerase activity. TcPIN1 lacks the WW domain at the N-terminus, and is able to rescue the temperature-sensitive phenotype on a mutation in the Saccharomyces cerevisiae hPin1 homolog, ESS1/PTF1. Western blot analysis revealed that the enzyme was present both in dividing and non-dividing forms of T. cruzi. In epimastigote cells neither cell growth kinetics nor cell morphology was affected by the overexpression of the small parvulin TcPIN1. These results suggest the occurrence of a supplementary conserved level of post-translational control in trypanosomatids.

The Unifoliata (Uni) gene plays a major role in development of the compound leaf in pea, but its regulation is unknown. In this study, we examined the effects of plant hormones on the expression of Uni, PsPK2 (the gene for a pea homolog of Arabidopsis PID, a regulator of PIN1 targeting), PsPIN1 (the major gene for a putative auxin efflux carrier) and LE (a gibberellin biosynthesis gene, GA3ox), and also examined mutual hormonal regulation of these genes, in pea shoot tips, including a number of mutants. The Uni promoter possessed putative auxin and gibberellin response elements. The PsPIN1 mRNA levels were increased in afila, which replaces leaflets with branched tendrils; and reduced in tendrilless, which replaces tendrils with leaflets, compared with the wild type (WT). In contrast, mRNA levels of LE were increased in uni and tendrilless and decreased in afila compared with the WT. Uni, PsPK2 and PsPIN1 are positively regulated by gibberellin and auxin, and were induced to higher levels by simultaneous application of auxin and gibberellin. Auxin induction of Uni, PsPK2 and PsPIN1 did not require de novo protein synthesis. LE was positively regulated by auxin and cytokinin. In conclusion, these results support the hypothesis that auxin and gibberellin positively regulate Uni, which controls pea compound leaf development. Also, Uni, PsPIN1, PsPK2 and LE are expressed differentially in the leaf mutants, suggesting that mutual regulation by auxin and gibberellin promotes compound leaf development.

CCAAT/enhancer-binding proteins (C/EBPs) are transcriptional regulators implicated in cell proliferation, differentiation, survival, and tumorigenesis. Their biological activities require interactions with several protein partners. This report presents insights from in silico analysis aimed at identifying phosphorylation-dependent protein recognition motifs in C/EBPs. (1) All C/EBP variants contain intrinsically disordered Ser/Thr- and Pro-rich segments with potential docking sites for WW and Polo-box domains of prolyl isomerase Pin1 and Polo-like kinases (Plks), respectively. (2) Consensus phosphorylation sequences for Plks are located in a highly conserved region of transactivation domains, suggesting that Plks might modulate transcriptional activities of C/EBPs in a cell cycle-dependent manner. (3) Phosphorylation at these positions, as well as at conserved Ser in the extended basic region, would create phosphoserine-containing motifs (pSXXF/Y/I/L), which could be recognized by BRCT repeats containing proteins such as the PAX-transactivation-domain-interacting protein (PTIP), and the breast cancer-associated protein (BRCA1). Proteins containing BRCT domains serve as scaffolds, mediating protein-protein interactions and formation of functional multiprotein complexes involved in DNA repair and cell cycle control. These findings add a new perspective to studies aimed at elucidation of molecular mechanisms underlying the diverse functions of C/EBPs.

Osterix is an essential transcription factor for osteoblast differentiation and bone formation. The mechanism of regulation of Osterix by post-translational modification remains unknown. Peptidyl-prolyl isomerase 1 (Pin1) catalyzes the isomerization of pSer/Thr-Pro bonds and induces a conformational change in its substrates, subsequently regulating diverse cellular processes. In this study, we demonstrated that Pin1 interacts with Osterix and influences its protein stability and transcriptional activity. This regulation is likely due to the suppression of poly-ubiquitination-mediated proteasomal degradation of Osterix. Collectively, our data demonstrate that Pin1 is a novel regulator of Osterix and may play an essential role in the regulation of osteogenic differentiation.

Tri-phosphorylated trifluridine (FTD) incorporation into DNA is TAS-102's main anti-tumor action. We tested whether genetic polymorphisms in homologous recombination (HR) and cell cycle checkpoint pathway for DNA repair is associated with outcomes in refractory metastatic colorectal cancer (mCRC) patients treated with TAS-102.

We analyzed genomic DNA extracted from 233 samples of three cohorts: an evaluation cohort of 52 patients receiving TAS-102, a validation cohort of 129 patients receiving TAS-102 and a control cohort of 52 patients receiving regorafenib. Single nucleotide polymorphisms of genes involved in HR (ATM, BRCA1, BRCA2, XRCC3, FANCD2, H2AX, RAD51) and cell cycle checkpoint (ATR, CHEK1, CHEK2, CDKN1A, TP53, CHE1, PIN1, PCNA) were analyzed by PCR-based direct sequencing.

In univariate analysis for the evaluation cohort, patients with any G allele in ATM rs609429 had longer overall survival (OS) than those with the C/C variant (8.7 vs. 4.4 months, HR 0.37, 95% CI: 0.14-0.99, P = 0.022). Patients carrying any A allele in XRCC3 rs861539 had significantly longer progression-free survival (PFS) (3.8 vs. 2.3 months, HR 0.44, 95% CI: 0.21-0.92, P = 0.024) and OS (15.6 vs. 6.3 months, HR 0.25, 95% CI: 0.08-0.79, P = 0.012) than those with the G/G variant. In multivariable analysis, ATM rs609429 remained significant for OS (P = 0.020). In the validation cohort, patients having ATM rs609429 with any G allele showed longer OS and PFS; the G/A variant in XRCC3 rs861539 showed longer OS, though without statistical significance.

Genetic variants in the HR pathway may predict clinical outcome in mCRC patients receiving TAS-102.

Long-term memories are thought to be maintained by persistent changes in the strength of synaptic connections among neurons, but how such changes can persist for days to years has been one of the fundamental enigmas of neuroscience. Recently, however, one mechanism that is dependent on the persistent increased activity of an enzyme has been shown to be necessary for the persistence of long-term memory. The transient inhibition of the brain-specific, constitutively active protein kinase C isoform PKMzeta erases memories that are even months old. This finding raises a number of issues; chief among them is the question, how can PKMzeta maintain memories for months when its half-life is probably much shorter? New data suggest how the high abundance of PKMzeta can be maintained over long periods of time. The synthesis of PKMzeta is inhibited by Pin1 (protein interacting with NIMA 1), a peptidyl-prolyl isomerase that represses dendritic translation. Signals mediated by the excitatory neurotransmitter glutamate, which induces long-term potentiation (LTP) and memory formation, inhibit Pin1, enabling PKMzeta synthesis. PKMzeta, once translated, in turn inhibits Pin1, permitting persistent PKMzeta synthesis. In this way, PKMzeta may be up-regulated to the appropriate amounts for maintaining LTP and perpetuating our mental representations of the past.

While the role of the prolyl isomerase Pin1 in dividing cells has long been recognized, Pin1's function in postmitotic neurons is poorly understood. We have identified a novel mechanism by which Pin1 mediates activation of the mitochondrial cell death machinery specifically in neurons. This perspective presents a sophisticated signaling pathway that triggers neuronal apoptosis upon JNK-mediated phosphorylation of the BH3-only protein BIM(EL) at serine 65. Pin1 is enriched at the mitochondria in neurons together with BIM(EL) and components of a neuron-specific JNK signaling complex and functions as a molecular switch that couples the phosphorylation of BIM(EL) by JNK to apoptosis specifically in neurons. We discuss how these findings relate to our understanding of the development of the nervous system and the pathogenesis of neurologic disorders.

The peptidyl-prolyl isomerase Pin1 is overexpressed in many human cancers, including melanoma. To investigate its possible role in oncogenesis of melanoma and as a therapeutic target, we suppressed Pin1 expression in the human melanoma cell line A375 by microRNA (miRNA) interference technology. Two stable clones with suppressed Pin1 were established by stable transfection of miRNA plasmid targeting Pin1 into A375 cells. Both clones showed reduced proliferation and invasion in vitro and suppressed tumorigenic potential in athymic mice. Furthermore, Pin1 inhibition also resulted in decreased phosphorylation of Akt and repressed expression of C-Jun N-terminal kinase and pro-matrix metalloproteinase 2, which were associated closely with the development of melanoma. These findings indicate that Pin1 plays an important role in the tumorigenesis of melanoma and might serve as a promising therapeutic target.

Heat shock proteins (HSPs), which are members of the chaperone family of proteins, are essential factors for cellular responses to environmental stressors, such as hyperthermia, and are antiapoptotic. The transcription of HSPs is mainly controlled by heat shock transcription factor 1 (HSF1). In response to environmental stress, HSF1 forms a trimer, undergoes hyperphosphorylation, and is translocated to the nucleus. In this study, we show that upon heat shock treatment of cells, a WW domain-containing propyl-isomerase, PIN1, is able to colocalize to and associate with phospho-HSF1 at Ser(326) in the nucleus via its WW domain. This interaction is required for the DNA-binding activity of HSF1 and is consistent with the lower induction of HSPs in PIN1-deficient cells. This function of PIN1 is further demonstrated by in vivo refolding and survival assays, which have shown that PIN1-deficient cells are temperature sensitive and develop apoptosis upon exposure to an environmental challenge. Moreover, the reduced levels of HSPs in PIN1-deficient cells resulted in less efficient refolding of denatured proteins. Based on our results, we propose a novel role for PIN1 whereby it acts as a stress sensor regulating HSF1 activity in response to stress on multiple levels through the transcriptional activation of stress response elements in embryonic fibroblast cells, tumor cells, and neurons.

The evolution of hepatocellular carcinoma (HCC) is a compound process which involves many kinds of genes and transductional pathways. The expression of the peptidyl-proplyl-isomerase PIN1 gene, the mutation in exon 3 of beta-catenin and its correspondent abnormal expression and their roles in the hepatocellular carcinogeneisis were investigated. Among 29 pair cases of HCC and non-carcinoma tissues, the expression of PIN1 gene was detected by immunochemical staining. Mutations in exon 3 of beta-catenin gene and differential expression of beta-catenin gene were investigated by the methods of PCR-SSCP, direct sequencing and immunohistochemical technique as well. The results indicated: (1) 44.8% (13/29) cases of HCC presented higher level of PIN1 gene expression than non-cancerous tissues (chi2=32.63, P<0.05), especially in cytoplasm and nucleus, while there was lower level of PIN1 expression in non-cancerous tissues; (2) 58.6% (17/29) HCC tissues showed beta-catenin protein accumulation in cytoplasm and nucleus. 46.2% (6/13) HCC tissues indicated beta-catenin protein accumulation with higher level of PIN1 expression, while 53.8% (7/13) HCC tissues indicated beta-catenin protein accumulation with lower level or trace of PIN1 expression (chi2=0.00, P>0.05); (3) 24.1% (7/29) of primary tumor lesions carried gene mutations in exon 3 of beta-catenin, and accompanied by beta-catenin protein accumulation. There was no mutation in non-cancerous tissues. All the mutation presented in tissues with low level of PIN1 expression. There was no mutation of beta-catenin gene in tissues with high PIN1 expression level (chi2=58.12, P<0.05). So it was postulated that the increase of PIN1 gene expression could promote hepatocellular carcinogenesis via a way different from beta-catenin gene mutation.

Induction of adventitious roots (ARs) in recalcitrant plants often culminates in cell division and callus formation rather than root differentiation. Evidence is provided here to suggest that microtubules (MTs) play a role in the shift from cell division to cell differentiation during AR induction. First, it was found that fewer ARs form in the temperature-sensitive mutant mor1-1, in which the MT-associated protein MOR1 is mutated, and in bot1-1, in which the MT-severing protein katanin is mutated. In the two latter mutants, MT dynamics and form are perturbed. By contrast, the number of ARs increased in RIC1-OX3 plants, in which MT bundling is enhanced and katanin is activated. In addition, any1 plants in which cell walls are perturbed made more ARs than wild-type plants. MT perturbations during AR induction in mor1-1 or in wild-type hypocotyls treated with oryzalin led to the formation of amorphous clusters of cells reminiscent of callus. In these cells a specific pattern of polarized light retardation by the cell walls was lost. PIN1 polarization and auxin maxima were hampered and differentiation of the epidermis was inhibited. It is concluded that a fine-tuned crosstalk between MTs, cell walls, and auxin transport is required for proper AR induction.