野生型和突变型p16在H460细胞株的表达

应用ＰＣＲ体外定点突为技术,构建了ｐ１６－Ｐ４８Ｌ和ｐ１６－Ｄ７４ｎ突变体。野生型和突变型ｐ１６ｃＤＮＡ克隆地ｐｃＤＮＡ３真核表达载体,导入纯合缺失ｐ１６基因的人肺癌细胞株Ｈ４６０,经ＲＮＡ点杂交初筛吴Ｇ４１８抗性的细胞株,再用Ｎｏｒｔｈｅｒｎ印迹证实外源ｐ１６表达。     

宫颈异倍体细胞Ki67和P16蛋白的表达

目的通过测定宫颈上皮同一异倍体细胞内Ki67和P16蛋白的表达,了解宫颈病变的严重程度。方法将宫颈细胞经DABI,Ki67和P16蛋白的免疫荧光处理,通过不同的激发光测定着色的细胞数。结果在8例宫颈病变中（2例宫颈炎,1例CIN1,2例CIN2,2例CIN3及1例宫颈癌）,除2例宫颈炎病例外,其余6例均可见〉5c的异倍体细胞。在6例中共发现有55个〉5c异倍体细胞,其中有38个Ki67阳性细胞（69％）和12个P16阳性细胞（21．8％）。10个Ki67和P16共阳性的细胞（18．2％）。结论高级别宫颈鳞状上皮内瘤变中异倍体细胞,可出现Ki67和P16蛋白阳性表达。     

The Specificity and Patterns of Staining in Human Cells and Tissues of p16INK4a Antibodies Demonstrate Variant Antigen Binding

The validity of the identification and classification of human cancer using antibodies to detect biomarker proteins depends upon antibody specificity. Antibodies that bind to the tumour-suppressor protein p16INK4a are widely used for cancer diagnosis and research. In this study we examined the specificity of four commercially available anti-p16INK4a antibodies in four immunological applications. The antibodies H-156 and JC8 detected the same 16 kDa protein in western blot and immunoprecipitation tests, whereas the antibody F-12 did not detect any protein in western blot analysis or capture a protein that could be recognised by the H-156 antibody. In immunocytochemistry tests, the antibodies JC8 and H-156 detected a predominately cytoplasmic localised antigen, whose signal was depleted in p16INK4a siRNA experiments. F-12, in contrast, detected a predominately nuclear located antigen and there was no noticeable reduction in this signal after siRNA knockdown. Furthermore in immunohistochemistry tests, F-12 generated a different pattern of staining compared to the JC8 and E6H4 antibodies. These results demonstrate that three out of four commercially available p16INK4a antibodies are specific to, and indicate a mainly cytoplasmic localisation for, the p16INK4a protein. The F-12 antibody, which has been widely used in previous studies, gave different results to the other antibodies and did not demonstrate specificity to human p16INK4a. This work emphasizes the importance of the validation of commercial antibodies, aside to the previously reported use, for the full verification of immunoreaction specificity.     

Localization and subcellular distribution of smg p25A, a ras p21-like GTP-binding protein, in rat brain

We have made a monoclonal antibody which specifically recognizes smg p25A among many ras p21/ras p21-like GTP-binding proteins thus far purified from bovine brain membranes. By use of this antibody, we have investigated the localization and subcellular distribution of smg p25A in rat brain by light and electron microscopic immunocytochemistry and by immunoblotting. By light microscopic immunocytochemistry, specific immunoreactivity is widely distributed, most abundant in neuropil, weak in neuronal somata, and absent from white matter. By electron microscopic immunocytochemistry, intense labeling is demonstrated on most of the synapses and concentrated in the presynaptic area where synaptic vesicles are observed. Presynaptic plasma membranes are weakly labeled but mitochondria, postsynaptic plasma membranes, and postsynaptic densities are unlabeled. In subcellular fractionation analysis of cerebrum, about one-fifth of smg p25A is found in the soluble cytosol fraction and the rest is found in the particulate fraction. About half of the particulate-bound smg p25A is recovered in the P2 fraction containing synaptosomes, mitochondria, and myelin, among which a major portion of smg p25A is recovered in the synaptosomal fraction. In the synaptosomal fraction, smg p25A is concentrated about 8-fold in the fraction containing synaptic vesicles and about 3-fold in the fraction containing synaptic plasma membranes compared with the original homogenate. smg p25A is present at a low level in the fraction containing synaptosomal soluble substances but almost absent from the fractions containing intrasynaptosomal mitochondria or post-synaptic densities. These results suggest that smg p25A plays important roles in the regulation of synaptic functions such as exo-endocytotic recycling of synaptic vesicles during neurotransmitter release.     

P16(INK4a) immunocytochemistry in liquid-based cytology samples in equivocal Pap smears: added value in management of women with equivocal Pap smear

OBJECTIVE: To test whether p1l6(INK4a) immunocytochemistry (ICC) in liquid-based cytology (LBC) is useful with colposcopy in abnormal Pap smears. STUDY DESIGN: A series of 248 women with abnormal Pap smear were analyzed for oncogenic (HR) human papillomavirus (HPV) types using the Hybrid Capture II assay and for p16(INK4a) expression using ICC on cervical samples in PreservCyt liquid media. Colposcopic and loop electrosurgical excision procedure (LEEP) cone biopsy were the gold standard. RESULTS: p16(INK4a) ICC did best as predictor of high-grade squamous intraepithelial lesion, with OR 12.18 (2.72-54.57) (p = 0.0001), showing 88.2% sensitivity (SE), 61.9% specificity (SP), 14.6% positive predictive value (PPV) and 98.6% negative predictive value (NPV). In sorting discrepant cases, p16(INK4a) ICC results in 100% SE and 100% NPV in detecting cervical intraepithelial neoplasia (CIN) 2 lesions among Pap+/biopsy- women. In atypical squamous cells undetermined significance (ASCUS) cytology, adding p16(INK4a) ICC improves specificity of colposcopy from 27.3% to 81.8% and PPV from 42.8% to 71.4%. Best performance is obtained with p16(INK4a) ICC and colposcopy: 83.3% SE, 81.8% SP, 71.4% PPV and 90.0% NPV. CONCLUSION p16(INK4a) is useful in sorting clinically relevant discrepant cases, and p16(INK4a) ICC significantly improves SP and PPV of colposcopy in management of ASCUS cytology.     

Combined analysis of HPV DNA and p16INK4a expression to predict prognosis in ASCUS and LSIL pap smears

Human papillomavirus (HPV) is known to play an important etiological role in the genesis of cervical cancer, but only a very small proportion of infected women develop invasive cervical cancer. The purpose of cervical cancer prevention is early diagnosis of its precursors. The molecular detection of HPV DNA as a diagnostic test to cervical carcinogenesis gave a low positive predictive value as compared to the use of biomarkers. p16INK4a has been proposed as putative surrogate biomarkers that would allow identification of dysplastic cervical epithelia. Serial consecutive cervical smears were test for high-risk HPV stained with immunocytochemistry for p16INK4a and followed-up for 36 months. The aim of the study was to evaluate the immunohistochemical expression of pl6INK4a as a marker of progression risk in low-grade dysplastic lesions of the cervix uteri. In the present series, significant pl6 overexpression was observed in the group that progressed from low to high-grade squamous intraepithelial lesion when compared with the group that did not progress. In conclusion, overexpression of p16INK4a acts as potential biomarkers for cervical cancer progression from premalignant lesions.     

p16INK4a Prevents Centrosome Dysfunction and Genomic Instability in Primary Cells

Aneuploidy, frequently observed in premalignant lesions, disrupts gene dosage and contributes to neoplastic progression. Theodor Boveri hypothesized nearly 100 years ago that aneuploidy was due to an increase in centrosome number (multipolar mitoses) and the resultant abnormal segregation of chromosomes. We performed immunocytochemistry, quantitative immunofluorescence, karyotypic analysis, and time-lapse microscopy on primary human diploid epithelial cells and fibroblasts to better understand the mechanism involved in the production of supernumerary centrosomes (more than two microtubule nucleating bodies) to directly demonstrate that the presence of supernumerary centrosomes in genomically intact cells generates aneuploid daughter cells. We show that loss of p16^INK4a generates supernumerary centrosomes through centriole pair splitting. Generation of supernumerary centrosomes in human diploid epithelial cells was shown to nucleate multipolar spindles and directly drive production of aneuploid daughter cells as a result of unequal segregation of the genomic material during mitosis. Finally, we demonstrate that p16^INK4a cooperates with p21 through regulation of cyclin-dependent kinase activity to prevent centriole pair splitting. Cells with loss of p16^INK4a activity have been found in vivo in histologically normal mammary tissue from a substantial fraction of healthy, disease-free women. Demonstration of centrosome dysfunction in cells due to loss of p16^INK4a suggests that, under the appropriate conditions, these cells can become aneuploid. Gain or loss of genomic material (aneuploidy) may provide the necessary proproliferation and antiapoptotic mechanisms needed for the earliest stages of tumorigenesis.     

p16INK4a Prevents Centrosome Dysfunction and Genomic Instability in Primary Cells

Aneuploidy, frequently observed in premalignant lesions, disrupts gene dosage and contributes to neoplastic progression. Theodor Boveri hypothesized nearly 100 years ago that aneuploidy was due to an increase in centrosome number (multipolar mitoses) and the resultant abnormal segregation of chromosomes. We performed immunocytochemistry, quantitative immunofluorescence, karyotypic analysis, and time-lapse microscopy on primary human diploid epithelial cells and fibroblasts to better understand the mechanism involved in the production of supernumerary centrosomes (more than two microtubule nucleating bodies) to directly demonstrate that the presence of supernumerary centrosomes in genomically intact cells generates aneuploid daughter cells. We show that loss of p16^INK4a generates supernumerary centrosomes through centriole pair splitting. Generation of supernumerary centrosomes in human diploid epithelial cells was shown to nucleate multipolar spindles and directly drive production of aneuploid daughter cells as a result of unequal segregation of the genomic material during mitosis. Finally, we demonstrate that p16^INK4a cooperates with p21 through regulation of cyclin-dependent kinase activity to prevent centriole pair splitting. Cells with loss of p16^INK4a activity have been found in vivo in histologically normal mammary tissue from a substantial fraction of healthy, disease-free women. Demonstration of centrosome dysfunction in cells due to loss of p16^INK4a suggests that, under the appropriate conditions, these cells can become aneuploid. Gain or loss of genomic material (aneuploidy) may provide the necessary proproliferation and antiapoptotic mechanisms needed for the earliest stages of tumorigenesis.     

Use of Human Papillomavirus DNA,E6/E7 mRNA,and p16 Immunocytochemistry to Detect and Predict anal High-Grade Squamous Intraepithelial Lesions in HIV-Positive and HIV-Negative Men Who Have Sex with Men

Background

Men who have sex with men (MSM) are at high risk of having anal cancer. Anal high-grade squamous intraepithelial lesion (HSIL) is the precursor of anal cancer. We explored the use of different biomarkers associated with human papillomavirus (HPV) infection and HPV-mediated cell transformation to detect and predict HSIL among HIV-positive and HIV-negative MSM.

Methodology/Principal Findings

A total of 123 HIV-positive and 123 HIV-negative MSM were enrolled and followed for 12 months. High-resolution anoscopy (HRA) with biopsies were performed at every visit along with anal sample collection for cytology, high-risk HPV DNA genotyping, HPV E6/E7 mRNA, and p16 immunocytochemistry. Performance characteristics and area under the receiver operator characteristics curve were calculated for these biomarkers at baseline, and Cox regression compared the usefulness of these biomarkers in predicting incident HSIL. High-risk HPV DNA, E6/E7 mRNA, and p16 immunocytochemistry each identified 43–46% of MSM whose baseline test positivity would trigger HRA referral. E6/E7 mRNA had the highest sensitivity (64.7%) and correctly classified the highest number of prevalent HSIL cases. With the exception of p16 immunochemistry, most tests showed significant increases in sensitivity but decreases specificity versus anal cytology, while the overall number of correctly classified cases was not significantly different. Baseline or persistent type 16 and/or 18 HPV DNA was the only test significantly predicting incident histologic HSIL within 12 months in models adjusted for HIV status and low-grade squamous intraepithelial lesions at baseline.

Conclusions/Significance

Countries with a high HIV prevalence among MSM and limited HRA resources may consider using biomarkers to identify individuals at high risk of HSIL. E6/E7 mRNA had the highest sensitivity for prevalent HSIL detection regardless of HIV status, whereas type 16 and/or 18 HPV DNA performed best in predicting development of incident HSIL within 12 months.     

p53 is not necessary for nuclear translocation of GAPDH during NO-induced apoptosis

Aberrant GAPDH expression following S-nitrosoglutathione (GSNO) treatment was compared in HepG2 cells, which express functional p53, and Hep3B cells, which lack functional p53. The results of Western blotting and fluorescent immunocytochemistry revealed that nuclear translocation and accumulation of GAPDH occur in both HepG2 and Hep3B cells. This finding suggests that p53 may not be necessary for the GSNO-induced translocation of GAPDH to the nucleus during apoptotic cell death in hepatoma cells.     

Fos in the suprachiasmatic nucleus of house mouse lines that reveal a different phase-delay response to the same light pulse

Increased light intensity of a 5-min light pulse is positively correlated with Fos mRNA and Fos protein levels in the suprachiasmatic nucleus (SCN) of hamsters. These findings suggest that the level of Fos activation is proportional to the light intensity and that the magnitude of the phase-shift response depends on the level of Fos activation. However, to what extent different phase-delay responses to the same light pulse are mediated by differential Fos activation is unknown. To elucidate this, the authors used selected house mouse lines that reveal an almost threefold difference in phase-delay responses in constant darkness (DD) between circadian time (CT) 16 and CT 20 to the same light pulse. The authors measured wheel-running activity and subjected male mice of these lines to a 15-min light pulse at CT 16 after 2 weeks in DD. The behavioral response was measured and 10 to 12 days later the animals were again subjected to the same light pulse at CT 16. One hour after the start of the second light pulse, the animals were sacrificed for Fos immunocytochemistry. Results indicate a significant difference between the lines in the phase-delay response (F2,26 = 5.112, p < 0.017) and the level of Fos activation (F2,26 = 27.15, p < 0.0001) after a 15-min light pulse at CT 16. These findings support the hypothesis that the magnitude of the phase-delay response is proportional to the number of cells in the SCN that exhibit Fos induction after the same 15-min light pulse at CT 16 in DD. It also indicates a possible difference in the input pathways among the lines.     

Dextran sulfate sodium enhances interleukin-1 beta release via activation of p38 MAPK and ERK1/2 pathways in murine peritoneal macrophages

Interleukin (IL)-1 beta is a pro-inflammatory cytokine that has been shown to play a pivotal role in the onset of inflammatory bowel disease (IBD), however, the molecular mechanisms underlying the production of IL-1 beta in IBD are not fully understood. We investigated dextran sulfate sodium (DSS)-induced IL-1 beta production and caspase-1 activities in murine peritoneal macrophages (pM phi). Further, the activation status of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun NH(2)-terminal kinase (JNK1/2), as well as their upstream target kinases, were examined by Western blotting. In addition, mRNA expression was assessed by RT-PCR and CXC chemokine ligand 16 (CXCL16) protein was detected by immunocytochemistry. DSS-treated pM phi released IL-1 beta protein in a time-dependent manner without affecting mRNA levels during 3-24 h, and caspase-1 activity peaked at 5 min (29-fold). IL-1 beta release and caspase-1 activity induced by DSS were significantly inhibited by a MAPK kinase 1/2 inhibitor, a p38 MAPK inhibitor, and NAC, however, not by JNK1/2 or a protein kinase C inhibitor. In addition, DSS strikingly induced the phosphorylation of p38 MAPK and ERK1/2 within 2 and 10 min, respectively. DSS also induced intracellular generation of reactive oxygen species (ROS). Pre-treatment with anti-CXCL16 for 24 h, but not anti-scavenger receptor-A, anti-CD36, or anti-CD68 antibodies, significantly suppressed DSS-induced IL-1 beta production. Our results suggest that DSS triggers the release of IL-1 beta protein from murine pM phi at a post-translational level through binding with CXCL16, ROS generation, and resultant activation of both p38 MAPK and ERK1/2 pathways, and finally caspase-1 activation.     

Naris occlusion alters transductory protein immunoreactivity in olfactory epithelium

We have recently shown that unilateral naris occlusion (UNO) causes an increase in olfactory marker protein (OMP) immunoreactivity (IR) in mouse olfactory sensory neurons (OSN) from the occluded side of the nasal cavity and a decrease in OMP-IR on the non-occluded side, relative to controls. Given OMP's demonstrated role in olfactory modulation, these OMP-IR changes have been interpreted as a compensatory response by OSNs to odor deprivation on the occluded side and to supernormal exposure to odor on the non-occluded side of the nasal cavity. In the current study, we examined the developmental timing and the regional distribution of this process throughout the nasal cavity using immunocytochemistry. Results demonstrate that OMP-IR diverges in OSNs from the occluded side relative to the non-occluded side of the nasal cavity within eleven days after UNO, with statistically significant differences measurable after 17 days (n=16). We also measured relative levels of the Type 4 phosphodiesterase (PDE4A), another potential olfactory modulator, in nasal cavity tissue from UNO (n=8) and untreated mice (n=9) using western blots and immunocytochemistry. Like OMP, PDE4A-IR increased on the occluded side of the nasal cavity after UNO. Finally, we used immunocytochemistry to assess relative levels of olfactory-specific adenylyl cyclase (ACIII, n=4) and G-protein (Golf, n=2) in OSNs from the occluded and non-occluded sides of the nasal cavity of UNO mice. Following UNO, ACIII but not Golf -IR levels diverged comparing the occluded to the non-occluded sides of the nasal cavity. Taken together, our findings provide support for the previously unknown phenomenon of compensatory responses by OSNs to odor environment.     

Induction of apoptosis in p16INK4A mutant cell lines by adenovirus-mediated overexpression of p16INK4A protein

The tumor suppressor gene p16INK4A is a cyclin-dependent kinase inhibitor (CDKI) and an important cell cycle regulator. We have previously constructed a recombinant adenovirus which expresses p16 (Adp16) and shown that infection in a variety of human tumor cell lines with this recombinant virus results in high levels of p16INK4A protein expression resulting in cell cycle arrest and loss of cyclin-cdk activity. Furthermore, adenoviral-mediated overexpression of wild-type p16INK4A is more toxic in cancer cells which express mutant forms of p16INK4A compared to cancer cell lines containing endogenous wild-type p16. TUNEL assay and DAPI staining following infection of MDA-MB 231 breast cancer cells with Adp16 indicate that p16INK4A-mediated cytotoxicity was associated with apoptosis. This is supported by studies demonstrating a decrease in cpp32 and cyclinB1 protein levels and induction of poly (ADP-ribose) polymerase (PARP) cleavage following infection of MDA-MB-231 cells with Adp16. These results suggest that gene therapy using Adp16 may be a promising treatment option for human cancers containing alterations in p16 expression.     

Association between the nucleolus and the coiled body

By means of light and electron microscopic immunocytochemistry, we have localized p80-coilin, a specific protein marker for coiled bodies, in mammalian cell lines as well as in primary rat neuron cultures. p80-coilin-stained nuclear bodies, which also contained fibrillarin, could be subsequently silver stained by a method specific for the visualization of nucleolar organizer regions. In cycling cells, most coiled bodies were not associated with nucleoli, whereas in rat neurons such as association was frequent. The treatment of cycling cells with actinomycin D or 5,6-dichloro-1-beta-D-ribo furanosyl-benzimidazole led to nucleolar segregation and/or disintegration, and to an association of p80-coilin staining structures with nucleoli. p80-coilin-positive structures contained fibrillarin in both untreated and treated cells. These results support the opinion that there might be a special association between coiled bodies and nucleoli, particularly in neuronal cells.     

Nuclear translocation of Skp2 facilitates its destruction in response to TGFβ signaling

Skp2, a F-box protein that determines the substrate specificity for SCF ubiquitin ligase, has recently been demonstrated to be degraded by Cdh1/APC in response to TGFβ signaling. The TGFβ-induced Skp2 proteolysis results in the stabilization of p27 that is necessary to facilitate TGFβ cytostatic effect. Previous observation from immunocytochemistry indicates that Cdh1 principally localizes in the nucleus while Skp2 mainly localizes in the cytosol, which leaves us a puzzle on how Skp2 is recognized and then ubiquitylated by Cdh1/APC in response to TGFβ stimulation. Here, we report that Skp2 is rapidly translocated from the cytosol to the nucleus upon the cellular stimulation with TGFβ. Using a combinatorial approach of immunocytochemistry, biochemical-fraction-coupled immunoprecipitation, mutagenesis as well as protein degradation assay, we have demonstrated that the TGFβ-induced Skp2 nucleus translocation is critical for TGFβ cytostatic effect that allows physical interaction between Cdh1 and Skp2 and in turn facilitates the Skp2 ubquitylation by Cdh1/APC. Disruption of nuclear localization motifs on Skp2 stabilizes Skp2 in the presence of TGF-β signaling, which attenuates TGFβ-induced p27 accumulation and antagonizes TGFβ-induced growth inhibition. Our finding reveals a cellular mechanism that facilitates Skp2 ubiquitylation by Cdh1/APC in response to TGFβ.     

Codon optimization of MTS1 and its expression in Escherichia coli

MTS1, which encodes a protein named p16, is an important gene involved in tumorigenesis. To increase the expression of p16 in Escherichia coli, MTS1 was synthesized de novo by recursive PCR, with codons optimized towards E. coli. Studies indicate that N-terminal amino acids of p16 had negative impact on its expression in E. coli. The function of p16DeltaN8 is not affected by the absence of N-terminal eight amino acids, compared with p16. p16DeltaN8 was expressed in E. coli, which reached 22% of total cell proteins. Purified p16DeltaN8 (purity was 98%) was delivered into A875 (melanoma), MCF7 (breast cancer), and HeLa (cervical cancer) cells by lipofectin. Results show purified p16DeltaN8 remarkably inhibited the growth of A875 and MCF7 cells, whereas it had little effect on HeLa cells.     

Immunocytochemical detection of p21ras expression in fresh human leukaemic cells and cell lines

The expression of p21ras proteins was investigated by immunocytochemistry in permanent cell lines and in fresh human leukaemic cells. While high and low levels of p21ras could be detected in most of the cell lines, no significant p21ras immunoreactivity was noted in cells of ten human acute and chronic leukaemias. Thus, notwithstanding its possible role in the initial transformation process in human leukaemias, p21ras expression appears not to be an irrevocable requirement for the maintenance of the transformed state.     

A pea nuclear protein that is induced by dehydration belongs to the vicilin superfamily.

The purification to homogeneity of p16, a protein with an electrophoretic mobility compatible with an apparent molecular mass of 16 kDa, from nuclei of ungerminated pea embryonic axes is described. A cDNA clone of its gene, which was designated psp54, was also isolated. The psp54 cDNA contains an open reading frame coding for a 54.4-kDa polypeptide (p54). p16 corresponds to the C-terminal third of p54, although the mechanisms by which the primary polypeptide could be processed are not yet known. The sequence of p54 is 60% identical with that of the precursor of a sucrose-binding soybean protein, and, to a lesser extent (31-34%), it shares homology with some storage proteins. p16 is also 30% homologous with Nhp2p, a yeast nuclear protein. The psp54 gene, present in a single copy in pea genome, starts being expressed during seed desiccation. Soon after rehydration in seed germination, p54 mRNA disappears and is no longer detectable in vegetative tissues, except in response to hydric stress (exposure to abscisic acid, osmolites or desiccation). p16 can be recovered from nuclei cross-linked to histone H3, when the disulfide bridges that occur in vivo are preserved. On the other hand, p16 shares some properties with dehydrins, which are thought to protect cellular structures against desiccation. We propose that the possible precursor polypeptide p54 belongs to the vicilin superfamily, members of which play a variety of roles. The function of p16 may be related to the protection of chromatin structure against desiccation during seed development.