p53蛋白在UVB诱导凋亡的富集表皮干细胞的角质形成细胞中的表达

目的研究p53蛋白在中波紫外线(ultraviolet lightB,UVB)诱导凋亡的富集表皮干细胞的角质形成细胞群中的表达情况。方法分离富集人表皮干细胞的角质形成细胞群和正常角质形成细胞群,使用UVB诱导两种细胞群凋亡,蛋白印迹法比较不同剂量UVB诱导前后两组细胞的p53蛋白表达的差异。结果两种细胞在不同剂量的UVB照射后p53蛋白表达均比照射前显著增加,在20mJ/cm2与40mJ/cm2照射剂量时,富集人表皮干细胞的角质形成细胞群p53蛋白表达高于正常角质形成的细胞群,差异有统计学意义(P<0.05)。结论富集人表皮干细胞的角质形成细胞p53蛋白表达比其它角质形成细胞对中波紫外线的照射易感。     

过表达p53基因和中波紫外线照射对人皮肤成纤维细胞衰老的影响

目的建立稳定过表达野生型p53基因(wtp53)的人皮肤成纤维细胞系,探讨过表达p53基因及中波紫外线(UVB)照射对人皮肤成纤维细胞(HSF)衰老的影响。方法在脂质体lipofectamine TM 2000介导下,将含有wtp53的真核表达质粒pCMV-p53导入HSF中,经G418筛选抗性克隆,扩大培养,建立转染克隆细胞系。用RT-PCR,实时荧光定量PCR和蛋白印迹法分析目的基因及其蛋白表达。亚毒性剂量UVB照射细胞,以染色法检测SAβ-gal活性,MTT法检测细胞增殖能力。结果成功构建过表达p53的HSF细胞系,转染细胞中存在p53基因及蛋白的稳定过表达。过表达p53的细胞株不论UVB照射与否SAβ-gal活性均未见增高,过表达p53可使HSF的增殖能力减弱,但对UVB诱导的细胞生长停滞的影响并不显著。结论过表达p53不能促进HSF的复制衰老和UVB诱导的早期衰老,过表达p53引起的HSF增殖减弱可能与细胞凋亡有关而非衰老。     

Growth advantage by overexpression of normal Harvey ras proto-oncogene in cultured rat epidermal keratinocytes

Summary The ras proto-oncogene is frequently amplified and overexpressed in the hyperproliferative conditions of epidermal keratinocytes. To investigate the effects of its overexpression on the growth of keratinocytes in a model system, we constructed expression vectors for normal human Ha-ras and introduced them into FRSK cells, a fetal rat epidermal keratinocyte cell line. Several clones containing the transfected Ha-ras were isolated, and two of them overexpressed this gene. In these clones DNA synthesis and cell growth were greater than in other clones expressing this gene at low levels. Thus we suggest that overexpression of normal ras gene may provide growth advantage to epidermal keratinocytes.     

Nucleofection: a new, highly efficient transfection method for primary human keratinocytes*

Transfection is an essential tool for numerous in vitro applications including studies of gene expression, promoter analysis, and intracellular signaling pathways and also for therapeutic strategies such as tissue engineering and gene therapy. However, transfection of primary cells including keratinocytes with common methods such as calcium phosphate, DEAE-dextran, liposome-mediated transfer, electroporation or viral vectors is problematic because of low transfection efficiency and the induction of terminal differentiation. Here we analyzed the use of nucleofection, a new, electroporation-based transfection method that enables the DNA to enter directly the nucleus, for the transfection of keratinocytes. Several different conditions were tested and optimized, resulting in a final transfection efficiency of 56% in primary human epidermal keratinocytes. This efficiency is superior to all non-viral transfection methods reported so far. The number of non-viable keratinocytes after nucleofection was low, varying between 14 and 16%. In contrast to other transfection protocols, nucleofection did not induce terminal differentiation in the transfected keratinocytes. In addition, nucleofection is a fast method, because the results can be analyzed within 7 h. In summary, nucleofection is a fast, easy and highly effective alternative for the transfection of primary human keratinocytes, which offers new opportunities for various research applications.     

Co-expression of p16INK4A and laminin 5 by keratinocytes: a wound-healing response coupling hypermotility with growth arrest that goes awry during epithelial neoplastic progression

The replicative lifespan of human keratinocytes in culture is restricted by a telomere-unrelated induction of p16INK4A (p16) and p14ARF. We have found that, in vivo, p16 is expressed by epidermal and oral keratinocytes at the migrating fronts of healing wounds and at the stromal interface of severely dysplastic and early invasive lesions and that such cells also invariably display increased expression of Laminin 5 (Lam5). In culture, p16 and Lam5 are coexpressed in keratinocytes at senescence, at the edges of wounds made in confluent cultures, and when cells are plated on dishes coated with the gamma2 precursor form of Lam5 (Lam5gamma2pre). Lam5/p16 coexpression in all three in vitro settings is associated with directional hypermotility and growth arrest. Hypermotility and growth arrest are uncoupled in p16- and p14ARF/p53-deficient keratinocytes and squamous cell carcinoma (SCC) cells; such cells become hypermotile is response to Lam5gamma2pre but do not growth arrest. Thus, the Lam5/p16 response is activated in normal wound healing, causing growth arrest of migratory keratinocytes that lead wound reepithelialization. This response also becomes activated at a critical stage of neoplastic progression, acting as a tumor suppressor mechanism. Rare premalignant cells that lose p16 remain motile and proliferative, thereby resulting in invasive growth as SCC.     

人乳头瘤病毒6bL1双顺反子载体的构建及其在哺乳动物细胞内的表达

目的 构建尖锐湿疣患者人乳头瘤病毒6b型晚期基因（HPV6b L1）的双顺反子表达载体,并使其在哺乳动物细胞内表达,以期建立含有HPV6b L1的细胞模型。方法 表达质粒pEGFP-HPV6bL1经双酶切纯化后与经过相同双酶切的真核表达质粒pIRES2-EGFP连接,酶切鉴定,挑选阳性克隆进行测序。重组质粒pIRES2-HPV6bL1-EGFP转染进小鼠成纤维细胞（NIH3T3）,荧光显微镜下观察EGFP蛋白的表达,RT-PCR检测HPV6b L1 mRNA的生成。结果 成功构建含HPV6b L1的重组质粒pIRES2-HPV6bL1-EGFP。重组体成功转染进NIH3T3细胞,并用G418筛选。同时荧光倒置显微镜下可观察到细胞内有绿色荧光蛋白的表达。进一步进行RT-PCR,检测到HPV6b L1 mRNA的生成。结论 成功构建携带HPV6b L1的重组体pIRES2-HPV6bL1-EGFP并转染入NIH3T3细胞。经荧光倒置显微镜观察及RT-PCR方法检测证明HPV6b L1在NIH3T3细胞内成功表达。     

人乳头瘤病毒6bL1双顺反子载体的构建及其在哺乳动物细胞内的表达

目的构建尖锐湿疣患者人乳头瘤病毒6b型晚期基因(HPV6b L1)的双顺反子表达载体,并使其在哺乳动物细胞内表达,以期建立含有HPV6b L1的细胞模型.方法表达质粒pEGFP-HPV6bL1经双酶切纯化后与经过相同双酶切的真核表达质粒pIRES2-EGFP连接,酶切鉴定,挑选阳性克隆进行测序.重组质粒pIRES2-HPV6bL1-EGFP转染进小鼠成纤维细胞(NIH3T3),荧光显微镜下观察EGFP蛋白的表达.RT-PCR检测HPV6b L1 mRNA的生成.结果成功构建含HPV6b L1的重组质粒pIRES2-HPV6bL1-EGFP.重组体成功转染进NIH3T3细胞,并用G418筛选.同时荧光倒置显微镜下可观察到细胞内有绿色荧光蛋白的表达.进一步进行RT-PCR,检测到HPV6b L1 mRNA的生成.结论成功构建携带HPV6b L1的重组体pIRES2-HPV6bL1-EGFP并转染入NIH3T3细胞.经荧光倒置显微镜观察及RT-PCR方法检测证明HPV6b L1在NIH3T3细胞内成功表达.     

人乳头瘤病毒6bL1双顺反子载体的构建及其在哺乳动物细胞内的表达

目的构建尖锐湿疣患者人乳头瘤病毒6b型晚期基因(HPV6b L1)的双顺反子表达载体,并使其在哺乳动物细胞内表达,以期建立含有HPV6b L1的细胞模型.方法表达质粒pEGFP-HPV6bL1经双酶切纯化后与经过相同双酶切的真核表达质粒pIRES2-EGFP连接,酶切鉴定,挑选阳性克隆进行测序.重组质粒pIRES2-HPV6bL1-EGFP转染进小鼠成纤维细胞(NIH3T3),荧光显微镜下观察EGFP蛋白的表达.RT-PCR检测HPV6b L1 mRNA的生成.结果成功构建含HPV6b L1的重组质粒pIRES2-HPV6bL1-EGFP.重组体成功转染进NIH3T3细胞,并用G418筛选.同时荧光倒置显微镜下可观察到细胞内有绿色荧光蛋白的表达.进一步进行RT-PCR,检测到HPV6b L1 mRNA的生成.结论成功构建携带HPV6b L1的重组体pIRES2-HPV6bL1-EGFP并转染入NIH3T3细胞.经荧光倒置显微镜观察及RT-PCR方法检测证明HPV6b L1在NIH3T3细胞内成功表达.     

人乳头瘤病毒6bL1双顺反子载体的构建及其在哺乳动物细胞内的表达

目的构建尖锐湿疣患者人乳头瘤病毒6b型晚期基因(HPV6b L1)的双顺反子表达载体,并使其在哺乳动物细胞内表达,以期建立含有HPV6b L1的细胞模型.方法表达质粒pEGFP-HPV6bL1经双酶切纯化后与经过相同双酶切的真核表达质粒pIRES2-EGFP连接,酶切鉴定,挑选阳性克隆进行测序.重组质粒pIRES2-HPV6bL1-EGFP转染进小鼠成纤维细胞(NIH3T3),荧光显微镜下观察EGFP蛋白的表达.RT-PCR检测HPV6b L1 mRNA的生成.结果成功构建含HPV6b L1的重组质粒pIRES2-HPV6bL1-EGFP.重组体成功转染进NIH3T3细胞,并用G418筛选.同时荧光倒置显微镜下可观察到细胞内有绿色荧光蛋白的表达.进一步进行RT-PCR,检测到HPV6b L1 mRNA的生成.结论成功构建携带HPV6b L1的重组体pIRES2-HPV6bL1-EGFP并转染入NIH3T3细胞.经荧光倒置显微镜观察及RT-PCR方法检测证明HPV6b L1在NIH3T3细胞内成功表达.     

Apoptosis regulators and responses in human melanocytic and keratinocytic cells

Apoptosis in keratinocytes is required for epidermal turnover, stratum corneum formation, and removal of ultraviolet-damaged premalignant cells. Its role in melanocyte homeostasis and transformation, on the other hand, has not been defined, although apoptosis resistance is a commonly recognized feature of melanoma. We examined the expression of apoptosis regulators in melanocytes, keratinocytes, melanoma, and HaCat cells. Melanocytic cells expressed relatively high levels of Bcl-2, Bcl-X(L), Mcl-1, C-IAP-1, C-IAP-2, XIAP, Livin, and Apaf-1. The only apoptotic regulator that was differentially expressed in melanoma cells and not melanocytes was Survivin, whereas Bax was expressed in melanocytes but not in most melanoma lines. Keratinocytic cells, on the other hand, expressed high levels of FLIP and were relatively deficient in Bcl-2 family proteins. Levels of p53 were highest in HaCat cells and some of the melanoma lines, and barely detectable in melanocytes and keratinocytes. Next, susceptibility of these cells types to apoptosis induced by ultraviolet B, the tyrosine analog 4-tert-butylphenol, and cytotoxic drugs was examined. Melanocytes were relatively resistant to ultraviolet B, whereas keratinocytes were unresponsive to 4-tert-butylphenol. Melanocytes and keratinocytes were generally less susceptible than melanoma lines and HaCat cells to etoposide, cisplatin, and staurosporine. Induction of apoptosis in these cell types was generally associated with decreased levels of Mcl-1, XIAP, and Livin, and increased levels of p53, whereas levels of other apoptotic regulators were unaltered. These results provide insights into the potential roles of apoptosis in the function and transformation of epidermal melanocytes and keratinocytes.     

The effect of ultra violet B (TL-01) phototherapy on epidermal expression of p53 protein in psoriatic plaques

BACKGROUND: Psoriasis is a genetically determined inflammatory skin disease. It is now recognized that narrow band TL-01 phototherapy is an effective treatment for psoriasis. However, ultraviolet (UV) exposure induces p53 mutations in keratinocytes and repeated exposure of skin to UV radiation results in clonal expansion of these initiated p53-mutant cells within the epidermis. AIM: The present study aims to examine epidermal p53 expression in the skin of psoriatic patients at different time points following TL-01 phototherapy. METHODS: Skin samples from patients suffering from plaque-type psoriasis, collected before, during and at the final stages of TL-01 phototherapy were examined for p53 expression by immunohistochemistry. RESULTS/CONCLUSION: Our results showed an increase in p53 expressing keratinocytes following TL-01 phototherapy. Some of these cells were arranged spatially, as conical clones arising from putative stem cell compartments, suggesting that the chronic TL-01 treatment might have triggered cell growth and clonal expansion, an important step in initiating skin carcinogenesis.     

HINT1对人黑素瘤细胞A375增殖和凋亡的影响

目的 探讨HINTl基因对人黑素瘤细胞A375增殖、凋亡的影响及其作用机制.方法 应用构建的peDNA.3.1/mye-His(-)A-HINTl真核表达载体,建立稳定转染且能高表达HINTI的A375细胞模型.用M1rr法检测细胞增殖活性变化,流式细胞仪检测细胞周期及细胞凋亡率,TUNEL法检测细胞凋亡.分光光度法检测Caspase 3,Caspase 8及Caspase 9的相对活性.Western印迹法检测bcl-2、bax、细胞色素C及p53的表达.结果 与空载体-A375及未转染A375细胞相比,HINT1-A375细胞生长速度明显减慢(P<0.05);Gl期细胞增多(73.17%±3.99%,F=25.65,P<0.05),S期细胞减少(16.75%±1.62%.F=75.48,P<0.01),细胞出现明显的晚期凋亡(23.57%±9.58%,F=11.71,P<0.01). TUNEL法显示凋亡阳性细胞百分比(12%±1%)显著增高(F=358.02,P<0.01);Caspase 9(0.45±0.03,F=135.62,P<0.01)和Caspase 3表达(0.46±0.04,F=90.28,P<0.01)升高.凋亡相关蛋白bax、细胞色素C及p53表达增加,bel-2表达降低.结论 高表达H1NT1可抑制A375细胞的增殖,促进其凋亡,细胞周期出现G_1期阻滞,提示HINT1可能是人黑素瘤的抑癌基因.     

MIA基因-RNAi对人黑素瘤A375细胞增殖的影响

目的探讨RNA干扰技术抑制恶性黑素瘤细胞株A375MIA基因表达后,对A375细胞增殖的影响。方法构建针对人黑素瘤A375细胞(MIA)基因3个不同靶序列的RNAi真核表达载体pLTE-hMIA-RNAi,用磷酸钙细胞转染法把构建的载体分别转染HEK293细胞,采用Western技术和RT-PCR技术分别检测MIA基因蛋白的表达和mRNA水平。选择对MIA基因表达抑制作用最强的RNAi载体转染A375细胞后,用细胞计数检测细胞增殖的变化。结果构建的3个RNAi质粒和对照组相比,pLTE-hMIA-RNAi352质粒对MIA的表达减少量>80%,hMIA的mRNA水平下降约83%,与对照组比较差异有显著性意义。而pLTE-hMIA-RNAi203、pLTE-hMIA-RNAi343质粒对MIA的表达及mRNA水平的影响,与对照组比较差异无显著性意义。转染pLTE-hMIA-RNAi352质粒的A375细胞增殖能力较对照组显著下降。结论构建的针对人MIA基因352位靶序列的RNAi质粒pLTE-hMIA-RNAi352可显著抑制MIA的表达及A375细胞增殖。     

Role of p21(Waf-1) in regulating the G1 and G2/M checkpoints in ultraviolet-irradiated keratinocytes

This study examines the role of p21(Waf-1) , a p53-dependent protein, in regulating mechanisms that protect keratinocytes against ultraviolet-B-induced cellular damage. Keratinocytes from p21(Waf-1) or p53-deficient mice were irradiated with ultraviolet B, and examined for DNA repair, cell cycle progression, and cell death. Both p21(Waf-1) -deficient and p53-deficient cells failed to maintain G2 arrest, and p21(Waf-1) -deficient cells, and to a lesser extent p53-deficient cells, also failed to undergo G1 arrest. After exposure to ultraviolet B, p53-deficient cells were more susceptible to cell death than wild-type cells. p21(Waf-1) -deficient cells did not undergo apoptotic cell death more often, however, but did have an increased frequency of nuclear abnormalities, suggesting mitotic catastrophe. TUNEL assay showed DNA fragmentation in the p53 +/+, p21(Waf-1) +/+, and p53 -/- cells, but not in p21(Waf-1) -/- cells. This result is consistent with the suggestion that p21(Waf-1) -deficient keratinocytes undergo mitotic cell death (catastrophe) after exposure to ultraviolet B irradiation in the system. Western analysis demonstrated that p21(Waf-1) expression was upregulated in p53-proficient and -deficient keratinocytes, supporting the notion that a p53-independent mechanism contributes to the response to ultraviolet B in keratinocytes. Finally, p21(Waf-1) -deficient cells had slightly less efficient nucleotide excision repair. In summary, this study suggests that p21(Waf-1) regulates the ultraviolet-B-induced G2/M checkpoint through p53, and the G1 checkpoint partially through p53. p21(Waf-1) does not significantly regulate DNA repair in ultraviolet-irradiated keratinocytes, however.     

Recombinant adeno-associated virus type 2-mediated gene transfer into human keratinocytes is influenced by both the ubiquitin/proteasome pathway and epidermal growth factor receptor tyrosine kinase

Efficient gene delivery into keratinocytes is a prerequisite for successful skin gene therapy. Vectors based on recombinant adeno-associated virus type 2 (rAAV-2) offer several promising features that make them attractive for cutaneous applications. However, highly efficient gene delivery may be hampered by different cellular factors, including lack of viral receptors, impairment of cytoplasmic trafficking or limitations in viral second-strand synthesis. This study was undertaken to find factors that influence rAAV-2-mediated in vitro gene transfer into human keratinocytes and, consequently, ways to optimize gene delivery. Transduction experiments using rAAV-2 vectors expressing green fluorescent protein (GFP) demonstrated that impaired cellular trafficking of vector particles and high levels of autophosphorylation at epidermal growth factor receptor tyrosine kinase (EGF-R TK) have a negative influence on gene transfer into keratinocytes. Treatment of keratinocytes with proteasome inhibitor MG132 resulted in a transient augmentation of GFP expression in up to 37% of cells. Treatment with EGF-R TK inhibitors (quinazoline type) enhanced transgene expression in 10–14.5% of the cells. Gene expression was stable for more than 10 weeks and persisted until proliferative senescence occurred. This stable gene expression allows speculation that keratinocyte stem cells have initially been transduced. These findings might have relevance for the use of rAAV-2 vectors in skin gene therapy: transient enhancement of rAAV-2 transduction with proteasome inhibitors might be useful for genetic promotion of wound healing or skin-directed vaccination. Treatment with quinazolines may increase rAAV-2 transduction of keratinocyte stem cells, which is important for gene therapy approaches to inherited diseases.     

TGM1基因RNA干扰表达载体pLVX-siTGM1的构建与鉴定

目的:构建针对转谷氨酰胺酶1基因(transglutaminase 1,TGM1)的shRNA表达载体,通过脂质体进行HaCaT细胞内转染,筛选出最显著抑制TGM1的shRNA干扰载体。方法:构建三个针对TGM1基因的RNA干扰质粒:pLVX-543shRNAi、pLVX-1265shRNAi和pLVX-1649shRNAi。通过双酶切、PCR鉴定及基因片段测序分析验证构建效果。脂质体介导质粒转染HaCaT细胞。实时定量RT-PCR检测TGM1 mRNA的表达,Western blot检测TGM1蛋白的表达。结果:重组构建的三个干扰载体经PCR分析及插入基因片段序列分析,三对碱基成功插入到预计位点,序列完全一致。转染三个重组干扰表达载体72小时后,RT-PCR检测TGM1基因沉默的效率,pLVX-543shRNAi、pLVX-1265shRNAi和pLVX-1649shRNAi分别为62.4%、73.5%和91.3%;Western blot检测TGM1蛋白的表达水平均明显降低,其中pLVX-1649shRNAi干扰载体降低最明显。结论:成功构建了TGM1 shRNA重组慢病毒载体,并且筛选出最有效抑制TGM1表达的干扰载体pLVX-1649shRNA,为进一步研究TGM1基因在鱼鳞病发病中的功能奠定基础。     

Enhanced epidermal ultraviolet responses in chronically sun-exposed skin are dependent on previous sun exposure

The p53 protein plays a key role in protecting cells from acquiring manifest mutations by inducing cell cycle arrest or apoptosis. The mechanisms for differences in epidermal responses to ultraviolet irradiation are unclear, although they have been shown to be related to both genetic events and environmental factors. In this study, we compared epidermal ultraviolet responses in chronically sun-exposed and non-sun-exposed skin using immunohistochemistry with antibodies recognizing thymine dimers and p53 protein. Six healthy volunteers were subjected to both artificial ultraviolet irradiation and natural sunlight, with and without photoprotection. A smaller number of thymine dimer-positive keratinocytes were detected 24 h after ultraviolet exposure in chronically sun-exposed skin compared to non-sun-exposed skin. Further, the p53 response was more variable in chronically sun-exposed skin. A significant correlation between total ultraviolet dose and number of p53-immunoreactive keratinocytes was found after natural sun exposure. Our findings suggest that repair of DNA damage is more efficient in chronically sun-exposed skin than in non-sun-exposed skin.     

A low UVB dose, with the potential to trigger a protective p53-dependent gene program, increases the resilience of keratinocytes against future UVB insults

One protein central in the response of human keratinocytes to ultraviolet B damage is p53. By transactivating genes involved in either cell cycle arrest or DNA repair, p53 has a leading role in the recovery from this damage. Considering this role, we wished to investigate whether the triggering of a p53-dependent gene program by repetitive ultraviolet B (UVB) exposure can induce an adaptive response in human skin cells. In particular, we examined two p53-target genes, p21/WAF1 and p53R2, with a crucial role in p53-induced cell cycle arrest and p53-induced DNA repair respectively. Exposure to a mild UVB dose was able to induce an adaptive response in human keratinocytes, leading to increased survival of cells that maintain their capacity to repair DNA damage upon exposure to apoptotic doses of UVB. Our study indicates that this adaptation response is only achieved if the interval between subsequent UVB insults allows sufficient time for the p53-induced protective gene program to be induced. Our results also demonstrate that small but quickly recurring UVB exposures are as harmful as one intense, continual exposure to UVB irradiation. Future research will be oriented toward investigating alternative ways to induce an adaptive response without pre-exposing the cells to UV.