PD-L1 (Programmed Death Ligand 1) Regulates T-Cell Differentiation to Control Adaptive Venous Remodeling.

OBJECTIVE: Patients with end-stage renal disease depend on hemodialysis for survival. Although arteriovenous fistulae (AVF) are the preferred vascular access for hemodialysis, the primary success rate of AVF is only 30% to 50% within 6 months, showing an urgent need for improvement. PD-L1 (programmed death ligand 1) is a ligand that regulates T-cell activity. Since T cells have an important role during AVF maturation, we hypothesized that PD-L1 regulates T cells to control venous remodeling that occurs during AVF maturation. Approach and results: In the mouse aortocaval fistula model, anti-PD-L1 antibody (200 mg, 3×/wk intraperitoneal) was given to inhibit PD-L1 activity during AVF maturation. Inhibition of PD-L1 increased T-helper type 1 cells and T-helper type 2 cells but reduced regulatory T cells to increase M1-type macrophages and reduce M2-type macrophages; these changes were associated with reduced vascular wall thickening and reduced AVF patency. Inhibition of PD-L1 also inhibited smooth muscle cell proliferation and increased endothelial dysfunction. The effects of anti-PD-L1 antibody on adaptive venous remodeling were diminished in nude mice; however, they were restored after T-cell transfer into nude mice, indicating the effects of anti-PD-L1 antibody on venous remodeling were dependent on T cells. CONCLUSIONS: Regulation of PD-L1 activity may be a potential therapeutic target for clinical translation to improve AVF maturation.

Inhibition of T-Cells by Cyclosporine A Reduces Macrophage Accumulation to Regulate Venous Adaptive Remodeling and Increase Arteriovenous Fistula Maturation.

OBJECTIVE: Arteriovenous fistulae (AVF) are the preferred vascular access for hemodialysis, but the primary success rate of AVF remains poor. Successful AVF maturation requires vascular wall thickening and outward remodeling. A key factor determining successful AVF maturation is inflammation that is characterized by accumulation of both T-cells and macrophages. We have previously shown that anti-inflammatory (M2) macrophages are critically important for vascular wall thickening during venous remodeling; therefore, regulation of macrophage accumulation may be an important mechanism promoting AVF maturation. Since CD4+ T-cells such as T-helper type 1 cells, T-helper type 2 cells, and regulatory T-cells can induce macrophage migration, proliferation, and polarization, we hypothesized that CD4+ T-cells regulate macrophage accumulation to promote AVF maturation. Approach and Results: In a mouse aortocaval fistula model, T-cells temporally precede macrophages in the remodeling AVF wall. CsA (cyclosporine A; 5 mg/kg, sq, daily) or vehicle (5% dimethyl sulfoxide) was administered to inhibit T-cell function during venous remodeling. CsA reduced the numbers of T-helper type 1 cells, T-helper type 2, and regulatory T-cells, as well as M1- and M2-macrophage accumulation in the wall of the remodeling fistula; these effects were associated with reduced vascular wall thickening and increased outward remodeling in wild-type mice. However, these effects were eliminated in nude mice, showing that the effects of CsA on macrophage accumulation and adaptive venous remodeling are T-cell-dependent. CONCLUSIONS: T-cells regulate macrophage accumulation in the maturing venous wall to control adaptive remodeling. Regulation of T-cells during AVF maturation may be a strategy that can improve AVF maturation. Graphic Abstract: A graphic abstract is available for this article.

The dysfunctional innate immune response triggered by Toll-like receptor activation is restored by TLR7/TLR8 and TLR9 ligands in cutaneous lichen planus.

BACKGROUND: Lichen planus (LP) is a chronic inflammatory mucocutaneous disease. Toll-like receptors (TLRs) bind numerous exogenous and endogenous antigens by recognizing conserved pathogen-associated molecular patterns (PAMPs) and have the ability to induce the production of proinflammatory cytokines. Therefore, alterations in innate immunity could explain the inflammation and T-cell autoreactivity leading to the development of LP disease. OBJECTIVES: To evaluate how the host innate immune response to PAMPs is affected by cutaneous LP, primarily by using TLR agonists to induce proinflammatory cytokine secretion from peripheral blood mononuclear cells (PBMCs). METHODS: PBMCs from patients with LP and healthy control (HC) individuals were stimulated with agonists of TLR2/TLR1 (pam3csk4), TLR3 [poly(I:C)-RIG], TLR4 (lipopolysaccharide), TLR5 (flagellin), TLR7 (imiquimod), TLR7/TLR8 (CL097) and TLR9 (CpG). Cytokines from culture supernatants (n = 10-12) and serum chemokines and cytokines (n = 22-24) were measured using flow cytometry. RESULTS: Activation through the TLR2, TLR4 and TLR5 pathways induced increased tumour necrosis factor (TNF)-α secretion by PBMCs from individuals with LP compared with the HC group. In contrast, activation through TLR3 and TLR7 was impaired in the LP group, leading to decreased TNF-α secretion. Moreover, intracellular TLR activation resulted in reduced interleukin (IL)-1ß and IL-6 secretion. Notably, individuals with LP became responders on stimulation with TLR7/TLR8 and TLR9 agonists; responses were measured as increases in interferon (IFN)-α production. Detectable TNF-α and high CXCL9 and CXCL10 serum levels were observed in patients with LP, suggesting their potential use as markers of the inflammatory status in LP. CONCLUSIONS: These findings point to a defect in the TLR signalling pathways in cutaneous LP. Agonists of TLR7/TLR8 or TLR9 overcame impaired IFN-α secretion in LP, strategically acting as adjuvants to improve the type I response.

Ischaemic colitis during interferon treatment for chronic hepatitis C: report of two cases and literature review.

Ischaemic colitis is known to be a severe emergency complication of interferon (IFN) therapy. However, as ischaemic colitis is an infrequent complication of IFN therapy, limited information is available regarding the safety of resuming IFN therapy after resolution of ischaemic colitis and subsequent recurrence. Here, we report two cases of ischaemic colitis during IFN therapy for chronic hepatitis C. Ischaemic colitis was fully healed within 1 week after its onset and IFN withdrawal, and IFN therapy was resumed following patients' wishes to do so. Ischaemic colitis did not recur after the resumption of IFN therapy, and sustained virological response was achieved in both patients. In this report, we also summarize the findings of 11 cases of IFN-associated ischaemic colitis (nine previously published cases plus our two cases) and review the clinical characteristics of ischaemic colitis during IFN therapy in patients with chronic hepatitis C.

Biodistribution of BPA and BSH after single, repeated and simultaneous administrations for neutron-capture therapy of cancer.

The effect of administration mode of L-BPA and BSH on the biodistribution in the melanoma-bearing hamsters was investigated. In single intravenous (i.v.) administration, BSH (100 mg BSH/kg) showed no significant retention of (10)B in all the tissues, including tumors, while long-term retention of (10)B in the tumor, muscle and brain was observed with L-BPA (500 mg BPA/kg). The dose escalation of L-BPA and the simultaneous single administration of L-BPA and BSH were not so effective at increasing boron accumulation in tumor after bolus i.v. injection. The boron concentration in tumor was 41 microg B/g after single bolus i.v. injection even at the dose of 1000 mg BPA/kg. In contrast, two sequential bolus i.v. injections of l-BPA with the dose of 500 mg BPA/kg each was found to be effective at increasing (10)B accumulation in the tumor; the maximum (10)B concentration in the tumor reached 52 microg B/g at 3 h after the second i.v. injection.

PDGFR-A is a therapeutic target in alveolar rhabdomyosarcoma.

Alveolar rhabdomyosarcoma is an aggressive skeletal muscle cancer of childhood. Our initial studies of rhabdomyosarcoma gene expression for patients enrolled in a national clinical trial suggested that platelet-derived growth factor receptor A (PDGFR-A) may be a mediator of disease progression and metastasis. Using our conditional mouse tumor models that authentically recapitulate the primary mutations and metastatic progression of alveolar rhabdomyosarcomas in humans, we found by immunoblotting and immunokinase assays that PDGFR-A and its downstream effectors, mitogen-activated protein kinase and Akt, were highly activated in both primary and metastatic tumors. Inhibition of PDGFR-A by RNA interference, small molecule inhibitor or neutralizing antibody had a dramatic effect on tumor cell growth both in vitro and in vivo, although resistance evolved in one-third of tumors. These results establish proof-of-principal for PDGFR-A as a therapeutic target in alveolar rhabdomyosarcoma.

Mastopathic fibroadenoma of the breast: a pitfall of aspiration cytology.

OBJECTIVE: To assess the correlation between cytological diagnoses and histological subtypes of fibroadenoma (FA) and to clarify the cytological features of a specific group of FA displaying variable features similar to fibrocystic disease (mastopathic type, MFA), and to evaluate the significance of this subtype in cytological diagnosis. METHODS: A review of 141 cases of histologically proven FA was performed. We re-classified them into four subtypes according to Kinoshita's criteria [Jpn J Breast Cancer6 (1991) 377] and further selected 92 cases for which both fine needle aspiration (FNA) smears and histological specimens were available. Among them, 18 cases of MFA and their cytological smears were selected for the present study. RESULTS: There was significant correlation between MFA and cytological diagnosis of 'indeterminate' or 'suspicious for malignancy' (P < 0.01). Although no false-positive diagnosis was experienced in our series, 56% of the MFAs (10/18) had cytological diagnoses of indeterminate or were included in the category 'suspicious for malignancy'. Smears from MFA revealed high cellularity (9/18 smears had more than 10 epithelial clusters each composed of more than 50 cells), presence of cellular discohesiveness (13/18, 72.2%), but only mild nuclear atypia (5/18, 27.8%). Anisonucleosis was present in fewer than half the cases and no apparent condensed chromatin was identified. CONCLUSION: We highlight the significance of subclassification of MFA in aspiration cytology of breast. MFA had a significantly higher chance of falling into the 'suspicious for malignancy' or 'indeterminate' diagnostic category in aspiration cytology. It might be a diagnostic challenge for cytopathologist to identify this subtype of FA in FNA smears.

Bystander effect in synergy to anergy in oral tolerance of Blomia tropicalis/ovalbumin murine co-immunization model.

Oral tolerance is an important approach in allergic diseases and murine model can provide useful information to improve its understanding and therapeutic measures. To address the influence of non-related allergen sensitization in immunized mice with the mite Blomia tropicalis (Bt) or ovalbumin (OVA) or with both Bt/OVA allergens. Furthermore, we sought to verify oral tolerance effect in the Bt/OVA co-immunization model. Mice sensitized with Bt and then exposed to OVA developed an enhanced IgE response to both allergens; contrariwise, this effect was not observed when OVA-sensitization was prior to Bt-sensitization. Co-injection of Bt and OVA led to a dominant IgE response towards OVA over Bt, which was not observed when co-immunization was performed with a 240-fold less amount of OVA. Induction of oral tolerance with OVA, prior to co-immunization, suppressed IgE response to both allergens, probably as a consequence of the increased levels of IFN-gamma found in these animals. The results evidenced that, depending on allergenic potential, new allergen exposure may exert an adjuvant effect to the first allergen used in the sensitization. The bystander suppression to non-related allergens through oral tolerance should be a useful mechanism to control sensitization to new allergens.

[Multiple primary lung cancer diagnosed by thoracic computed tomography; report of 2 cases].

Two cases of bilateral multiple primary lung cancers are presented. One is synchronous, and another is metachronous. Case 1: An abnormal shadow in the left lower lobe was found on the chest radiograph of 40-year-old female during a regular check-up. Chest computed tomography (CT) film showed a micronodule in the right S2. Left lower lobectomy was performed, followed by second-staged right S2 segmentectomy 1 month after the initial operation. Case 2: A 62-year-old female underwent left lower lobectomy for lung cancer in April 1997. Follow-up CT showed a nodule in right S8. In March 2000, right basal segmentectomy was performed for second lung cancer. Moreover, follow-up CT showed a nodule in right S3. Right wedge resection was performed for third lung cancer in July 2002. It is important to carefully examine a synchronous lesion before the operation of a primary lung cancer and to perform close follow-up surveillance for early detection of a metachronous lesion.

Is laparoscopic colorectal surgery less invasive than classical open surgery? Quantitation of physical activity using an accelerometer to assess postoperative convalescence.

BACKGROUND: With the technical advances of recent years, the number of operative manipulations in the abdominal cavity by laparoscopic surgery is now considered to be the same as that using classical open surgery. The question has been raised whether laparoscopic colorectal surgery with lymphadenectomy improves the recovery compared to open surgery. METHODS: We compared patients' physical activity for 7 days postoperatively as measured with an accelerometer between laparoscopic-assisted colorectal resection (LAC, n = 32) and classical open colorectal surgery (OC, n = 30). RESULTS: Physical activity expressed as cumulative acceleration was significantly higher in the LAC than in the OC group on each postoperative day. The recovery time, defined as the day on which the cumulative acceleration recovered to 90% of the preoperative level, was significantly shorter (p < 0.05) in the LAC (3.4 +/- 1.2 days) than in the OC group (6.8 +/- 1.7 days). CONCLUSION: Our results showed that the duration of convalescence with LAC was significantly shorter than that with the OC procedure. Laparoscopic colorectal surgery appears to allow an earlier recovery after the operation than the classical open procedure, and it is less invasive as assessed by convalescence.

Effects of N-methyl-N'-nitro-N-nitrosoguanidine on the human colorectal polyps consecutively maintained in SCID mice.

N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatments for a long period induced morphological and molecular alterations in the benign human colorectal polyps which were maintained in the severe combined immunodeficient C.B17/N-scid/scid mice. Thirty four xenografts of colorectal polyps from five solitary polyp and three familial polyposis patients were examined for K-ras and p53 mutations. Six K-ras mutations were induced in 16 grafts treated with MNNG more than five times, while no K-ras mutations were detected in 14 untreated grafts (P<0.05). Additional and new K-ras mutations were also induced in two polyps in which K-ras mutation had pre-existed. p53 mutations were not observed in both MNNG-treated and untreated groups. The mutations in K-ras gene were induced at codon 12 (GGT-->GAT) except one at codon 13 (GGC-->GGT). The results indicate that K-ras mutation plays an important role in human colorectal carcinogenesis as is the case in experimental animals.

Three-dimensional pressure imaging: a novel method for intraoperative manometry during laparoscopic esophagomyotomy for esophageal achalasia.

With the introduction of computerized manometry, the creation of the three-dimensional (3-D) pressure image with measurement of pressure vector volume (PVV) has become available to assess the pressure structure of the high-pressure zone (HPZ) of the distal esophagus. We have applied this technique to intraoperative manometry during laparoscopic surgery for esophageal achalasia (EA). A laparoscopic esophagomyotomy with anterior fundoplication was performed in a 12-year-old boy with EA. Computerized 3-D images were obtained by a stepwise pullback of a manometric assembly with eight radial side-holes to quantitate the PVV of the HPZ of the distal esophagus in each stage of the operation for EA. Virtual abolishment of the peak pressure image and a marked reduction in the PVV after esophagomyotomy suggested appropriate decompression of the HPZ. Intraoperative manometry using computerized 3-D pressure imaging with measurement of the PVV is thus useful to assess the HPZ during laparoscopic surgery for EA.

Identification of novel inhibitors of calling and in vitro [14C]acetate incorporation by pheromone glands of Plodia interpunctella.

Some octopamine agonists were found to suppress in vitro biosynthesis of the calling pheromone of the Indian meal moth, Plodia interpunctella. Isolated pheromone-gland preparations incorporated sodium [14C]acetate at a linear rate for 3 h when incubated with the pheromone biosynthesis activating neuropeptide (PBAN). This incorporation was dependent on the dose of PBAN (up to 0.5 microM). Thin-layer chromatography of a pheromone-gland extract revealed quantitative incorporation of radioactivity into a product exhibiting the same mobility as (Z,E)-9,12-tetradecadienyl acetate, the main component of the calling pheromone of P interpunctella. Twenty-seven octopamine agonists were initially screened using a calling behaviour bioassay of female P interpunctella. Four derivatives with activity in the nanomolar range were identified which were, in order of decreasing pheromonostatic activity: 2-(2,6-diethylphenylimino)thiazolidine > 2-(2,6-diethylphenylimino)oxazolidine > 2-(2,6-dimethylphenylimino)thiazolidine > 2-(2-ethylphenylimino)oxazolidine. These compounds also showed in vitro inhibitory activity in intracellular de novo pheromone biosynthesis. The results of the present study indicate that these derivatives could provide useful information in the characterization and differentiation of octopaminergic receptor types and subtypes.

Morphometric characterization of endometrial glands using quantitative cytology.

OBJECTIVE: To determine the usefulness of the combination of confocal laser scanning microscopy (CLSM), image cytometry and three-dimensional (3D) imaging for analyzing architectural changes indicative of endometrial hyperplasia and grade 1 adenocarcinoma. STUDY DESIGN: Papanicolaou-stained endometrial samples (n = 180) were analyzed for specific cellular characteristics and analyzed by CLSM. Confocal images were obtained and then analyzed cytometrically and used for 3D reconstruction. RESULTS: Values obtained after image cytometry and 3D imaging increased significantly (P < .01) with the degree of cellular atypia. CONCLUSION: The combination of CLSM, image cytometry and 3D imaging is a valuable method for differential diagnosis of endometrial hyperplasia and grade 1 adenocarcinoma.

Alterations in tight junctions differ between primary biliary cirrhosis and primary sclerosing cholangitis.

Tight junctions (TJ) of biliary epithelial cells (BEC) and hepatocytes prevent bile regurgitation from the biliary tract. Alterations in these TJs may participate in chronic cholestatic liver diseases such as primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). We examined the localization of 2 TJ proteins, ZO-1 and 7H6, in these diseases. Frozen sections from livers of PBC, PSC, extrahepatic cholestasis (Ex-C), and hepatitis C-associated cirrhosis (LC-C), as well as histologically normal livers, were processed for double-fluorescence immunohistochemistry. In controls and cirrhosis, 7H6 and ZO-1 colocalized surrounding the luminal space of the bile ducts and outlined the bile canalicular spaces between hepatocytes. In untreated PBC, immunostaining for ZO-1 in BEC of bile ducts 40 to 80 microm in diameter was preserved, but that for 7H6 was diminished to absent. In PBC treated with ursodeoxycholic acid (UDCA), immunostaining for 7H6 was well preserved. In PSC as well as in Ex-C, immunostaining for both 7H6 and ZO-1 was well preserved in bile ducts. In hepatocytes, ZO-1 showed preserved immunoreactivity, but immunostaining for 7H6 frequently disappeared. The percentage of bile ducts with immunostaining for 7H6 in all bile ducts with immunostaining for ZO-1 was significantly reduced in PBC compared with that in control, LC-C, Ex-C, and PSC (all P <.0001). Substantial alteration in the TJ protein occurs predominantly in bile ducts in PBC and in hepatocytes in PSC, suggesting increased paracellular permeability along different paracellular routes for bile regurgitation in these chronic cholestatic liver diseases.

Correlation between nuclear grade and biological prognostic variables in invasive breast cancer.

BACKGROUND: Grading of carcinomas is an estimation of differentiation. Nuclear grading is the cytological evaluation of tumor nuclei in comparison with the nuclei of normal mammary epithelial cells. Because nuclear grading does not involve an assessment of the growth pattern of the tumor, it applies not only to invasive ductal carcinoma but also to other subtypes of breast carcinoma. METHODS: A total of 215 primary breast carcinomas obtained from the Affiliated Kihoku Hospital of Wakayama Medical College were enrolled in our present study. Nuclear grade was evaluated according to the criteria of the National Surgical Adjuvant Study of Breast Cancer (NSAS-B) protocol. Immunohistochemistry was also performed to determine Bcl-2, p53, c-erbB-2, estrogen receptor (ER) and MIB-1 expression in paraffin-embedded tissues for all cases. RESULTS: Thirty-two (14.9%) of the patients were graded as 1,124 (57.7%) as 2, and 59 (27.4%) as 3. Nuclear grade displayed a negative correlation with Bcl-2 expression (r=-0.308, p<0.0001), and a positive correlation with c-erbB-2 overexpression (r= 0.172, p=0.0117) and tumor proliferative index labeling by MIB-1 (r=0.485, p<0.0001). CONCLUSIONS: These results imply that nuclear grade is related to the characteristics of tumor biology, indicating that the morphology and biology of breast cancer are tightly linked. Our present results also suggest that adding the nuclear grade to the pathological diagnosis of invasive breast carcinoma may be clinically useful for predicting tumor behavior, for example aggressiveness, and for prognostication.

Involvement of p21(WAF1/Cip1), p27(Kip1), and p18(INK4c) in troglitazone-induced cell-cycle arrest in human hepatoma cell lines.

Peroxisome proliferator-activated receptor gamma (PPARgamma) regulates cell growth and differentiation. Recent evidence has suggested that PPARgamma ligands had anti-tumor effects through inhibiting cell growth and inducing cell differentiation in several types of malignant neoplasm. In the present study, we investigated: 1) the expression of PPARgamma in both human hepatoma cell lines and 5 resected human hepatocellular carcinoma (HCC) tissues; 2) the growth-inhibitory effect of troglitazone, a PPARgamma ligand, on those hepatoma cells; and 3) the molecular mechanisms of troglitazone-induced cell-cycle arrest. Five hepatoma cell lines, HLF, HuH-7, HAK-1A, HAK-1B, and HAK-5, were used. The mRNA expression levels of PPARgamma, p21(WAF1/Cip1), and p27(Kip1) were determined by real-time quantitative reverse transcription-polymerase chain reaction. The expression of cell cycle-regulating proteins, such as p21, p27, p18(INK4c), cyclin E, and pRb, was examined using Western blotting. PPARgamma was constitutively expressed in all the cell lines and the HCC tissues used in this study. A cytostatic effect of troglitazone was found in those cell lines, and this inhibition of cell growth was dosage-dependent. G0/G1 arrest was apparently demonstrated in flow cytometric analysis in HLF, HAK-1A, HAK-1B, and HAK-5, all of which showed an increased expression of p21 protein. However, HuH-7, lacking p21 protein expression, did not demonstrate clear arrest in the cell-cycle analysis. HLF, which was deficient in the protein product of the retinoblastoma tumor-suppressor gene (pRb), responded most profoundly to troglitazone, showing an increased expression in not only p21, but also in p27 and in p18. These findings suggested that p21, p27, and p18 might be involved in troglitazone-induced cell-cycle arrest in human hepatoma cells.

Endotoxin increases paracellular permeability of isolated rat hepatocyte couplets.

Hyperbilirubinemia is frequently associated with endotoxemia. Regurgitation of bile constituents including bilirubin into the sinusoidal space is prevented by tight junctions which maintain paracellular permeability between hepatocytes. To investigate the mechanism of endotoxin-associated hyperbilirubinemia, we have studied the changes in paracellular permeability of primary hepatocyte couplets treated with endotoxin. In addition, we examined the effects of ursodeoxycholic acid (UDCA), which has been widely used for various liver diseases, on endotoxin-associated changes in paracellular permeability. The paracellular permeability of hepatocyte couplets was evaluated by paracellular penetration of fluorescein isothiocyanate (FITC)-dextran with molecular weights of 3, 10 and 70K using confocal laser scanning microscopy. Endotoxin increased the paracellular penetration of FITC-dextran 3 and 10K. These changes were prevented by treatment with UDCA. There was little paracellular penetration of FITC-dextran 70K under any conditions. These results suggested that endotoxin increased the paracellular permeability of hepatocyte couplets and these changes were prevented by treatment with UDCA. Furthermore, bile regurgitation through the paracellular route is involved in endotoxin-associated hyperbilirubinemia, and UDCA might be a potential therapeutic agent for endotoxin-associated hyperbilirubinemia.

A mutation of the Wilson disease protein, ATP7B, is degraded in the proteasomes and forms protein aggregates.

BACKGROUND & AIMS: Wilson disease is a genetic disorder characterized by the accumulation of copper in the body as a result of a defect of copper excretion from hepatocytes. The intracellular localization of the Wilson disease gene product, ATP7B, was recently identified as the late endosomes. Various mutations have been documented in patients with Wilson disease. The clinical manifestations vary greatly among the patients; however, there is little information on the genotype-phenotype correlation. METHODS: We investigated the distribution of a common ATP7B mutant His1069Gln and a mutant Asp1270Ser by expressing the mutants tagged with green fluorescent protein in Huh7 and HEK293 cells. Intracellular organelles were visualized by fluorescence microscopy. RESULTS: Although the wild-type ATP7B and Asp1270Ser mutant localized in the late endosomes, His1069Gln mutant did not locate in the late endosomes and was degraded by the proteasomes in the cytoplasm. Furthermore, His1069Gln formed aggresomes composed of the degradates and intermediate filaments at the microtubule-organizing center. These aggresomes were similar to Mallory bodies on electron microscopy. CONCLUSIONS: The different protein properties of ATP7B mutants may explain the variety of clinical spectrums in patients with Wilson disease.

Polo-like kinase 1 phosphorylates cyclin B1 and targets it to the nucleus during prophase.

In vertebrate cells, the nuclear entry of Cdc2-cyclin B1 (MPF) during prophase is thought to be essential for the induction and coordination of M-phase events. Phosphorylation of cyclin B1 is central to its nuclear translocation, but the kinases that are responsible remain unknown. Here we have purified a protein kinase from Xenopus M-phase extracts that phosphorylates a crucial serine residue (S147) in the middle of the nuclear export signal sequence of cyclin B1. We have identified this kinase as Plx1 (ref. 16), a Xenopus homologue of Polo-like kinase (Plk)-1. During cell-cycle progression in HeLa cells, a change in the kinase activity of endogenous Plk1 toward S147 and/or S133 correlates with a kinase activity in the cell extracts. An anti-Plk1 antibody depletes the M-phase extracts of the kinase activity toward S147 and/or S133. An anti-phospho-S147 antibody reacts specifically with cyclin B1 only during G2/M phase. A mutant cyclin B1 in which S133 and S147 are replaced by alanines remains in the cytoplasm, whereas wild-type cyclin B1 accumulates in the nucleus during prophase. Co-expression of constitutively active Plk1 stimulates nuclear entry of cyclin B1. Our results indicate that Plk1 may be involved in targeting MPF to the nucleus during prophase.