A mutation detection strategy for the human keratin 6A gene and novel missense mutations in two cases of pachyonychia congenita type 1

Pachyonychia congenita type 1 (PC-1) is an autosomal dominant ectodermal dysplasia characterized by hypertrophic nail dystrophy, focal non-epidermolytic palmoplantar keratoderma and variable features of oral leukokeratosis and follicular keratosis. Previously, we have shown that this disease can be caused by mutations in type I keratin K16 and one mutation has been reported in its type II keratin expression partner, K6a. Mutation analysis for K6a has been hampered by the presence of multiple copies of the K6 gene in the human genome, of which some are expressed and others are pseudogenes. Here, we describe a mutation detection strategy where the entire KRT6A gene, approximately 7 kb, is specifically amplified by long-range PCR. Using this technique, we have detected two novel mutations in the 1A domain of the K6a polypeptide, N171K and F174S. Mutations were confirmed in the affected individuals and were excluded from 50 unaffected unrelated individuals by restriction enzyme analysis of KRT6A PCR products. Additionally, mutation N171K was confirmed by RT-PCR in mRNA derived from lesional palmoplantar epidermis of an affected individual, confirming the specificity of the genomic PCR for the functional K6a gene. This, together with a similar strategy which we have developed for the K16 gene, provide a robust system for mutation detection and prenatal diagnosis for patients with PC-1.     

Identification of sporadic mutations in the helix initiation motif of keratin 6 in two pachyonychia congenita patients: further evidence for a mutational hot spot

Pachyonychia congenita (PC) is a rare, autosomal dominant, ectodermal dysplasia characterized most distinctly by the presence of symmetric nail hypertrophy. In the Jadassohn-Lewandowsky form, or PC-1, additional cutaneous manifestations may include palmoplantar hyperkeratosis, hyperhidrosis, follicular keratoses, and oral leukokeratosis. Mutations have previously been identified in the 1A helix initiation motif of either keratin 6 or keratin 16 in patients with PC-1. In the current study, we have identified 2 sporadic, heterozygous mutations in the 1A helix region of the K6 isoform (K6a). The first mutation identified was a 3 base pair deletion (K6adelta N171). The second mutation was a C-to-A transversion resulting in an amino acid substitution (K6a N171K). These data, in combination with previous reports, provide further evidence that this location is a mutational hot spot.     

Ontogeny and regional variability of keratin 2e (K2e) in developing human fetal skin: a unique spatial and temporal pattern of keratin expression in development

Keratin 2e (K2e) is expressed in the upper spinous and granular cells of adult epidermis. A highly specific polyclonal antibody was made against a C-terminal peptide of K2e and used to observe K2e expression at different developmental stages. At 12.5 weeks estimated gestational age (EGA) K2e was detected in trunk skin in scattered cells in the intermediate layer. At 13.5 weeks EGA, greater numbers of intermediate cells were stained with variable intensity, and staining in this pattern increased with age. Epidermal sheets from 14 weeks EGA showed that K2e + cells were excluded from developing hair follicles. At 135 days EGA, the following regional patterns were observed: in cheek, trunk, dorsal and ventral knee, elbow and dorsal hand there was moderate to intense staining of upper intermediate keratinocytes excluding cells of the hair canals and sweat ducts. The periumbilical region distinctly lacked K2e staining, while more distal areas showed increasing numbers of K2e + cells. The earliest expression of K2e was at 10 weeks EGA in the presumptive nail bed of developing digits. By 13.5 weeks EGA this pattern had shifted to the proximal nail fold, and K2e was absent in the nail bed. K2e was excluded from developing sweat glands and ducts and from developing hair follicles at the hair germ and early peg stages. By 15 weeks EGA in the fetal hair follicle small groups of cells were K2e + and by 19 weeks K2e + cells were seen at the level of the matrix. Some overlap in staining was detected for K2e with K10, and in palmar skin with K9; however, mostly the filamentous staining patterns for these keratins were distinctive. This study shows that the complex patterns of temporal and regional expression of K2e differ from known patterns for other epidermal keratins and suggest different regulation and function for this epidermal keratin.     

Distribution of an estrogen receptor-related protein (P29) in normal skin and in cultured human keratinocytes

A monoclonal antibody, ERD5, which recognizes a 29Kd phosphoprotein associated with human estrogen receptor of myometrium was used to study the expression of this protein in normal skin and in cultured human keratinocytes. By indirect immunofluorescence, both in vivo and in vitro keratinocytes showed a variable cytoplasmic staining which increased with cell differentiation. SDS gel electrophoresis of soluble extracts of cultured keratinocytes and normal epidermis showed that P29 was a minor protein. Immunoblot analysis demonstrated that ERD5 strongly reacted only with a 29Kd polypeptide band without any cross-reactivity. These data suggest that keratinocytes might be estrogen sensitive like other cells in which P29 has already been located. The exact role of this protein in the keratinocyte differentiation process and its relationship with estrogen receptors remain to be elucidated.     

Modulation of keratinocyte growth factor (KGF) mRNA expression in human dermal fibroblasts grown in monolayer or within a collagen matrix

Abstract In this study, we analysed the modulation of keratinocyte growth factor (KGF) mRNA expression in human dermal fibroblasts cultured either in monolayer or within a collagen matrix (dermal equivalent). In monolayer cultures, KGF expression by quiescent fibroblasts was stimulated by different growth substances such as serum, epidermal growth factor and basic fibroblast growth factor. Moreover, we demonstrated that the induction of this gene was mediated by at least 2 different signalling pathways involving protein kinase C (PKC) and cAMP. In dermal equivalents, we observed that the collagen matrix negatively modulated KGF mRNA expression. Indeed, among the growth substances used, only the serum slightly stimulated KGF expression. Nevertheless, as in monolayers, this induction involved at least PKC and cAMP signalling pathways. As the collagen matrix can modulate fibroblast growth, we also studied KGF expression in growing fibroblasts from either monolayer cultures or dermal equivalents. We then showed that this collagen matrix negatively influenced KGF expression independently of the proliferative state of fibroblasts. All these results underline the fact that KGF mRNA expression by human dermal fibroblasts is induced by different substances; however this expression can be modulated by fibroblast-matrix interactions.     

Effects of recombinant human tissue inhibitor of metalloproteinases-2 (rh-TIMP-2) on migration of epidermal keratinocytes in vitro and wound healing in vivo

Tissue inhibitors of metalloproteinases (TIMP), common inhibitors of matrix proteinases, have cell-promoting activity. We studied the effects of recombinant human tissue inhibitor of metalloproteinases-2 (rh-TIMP-2) on the migration of normal human epidermal keratinocytes (NHEK). An in vitro migration assay revealed that rh-TIMP-2 enhanced random migration (up to 170%, p<0.05) in a dose-dependent manner. When we applied rh-TIMP-2 solution (20 microg/20 microl/wound) daily to full-thickness wounds made with an 8-mm punch on the backs of healthy (n=8), aged (n=9), and diabetic (n=15) rodents, we observed faster wound closure (p<0.05) than in vehicle-treated controls. Accelerated wound closure was dose-dependent (0-20 microg/wound) in diabetic mice (n=6), and the optimal concentration was 10-20 microg of rh-TIMP-2/wound. Histological examinations performed on days 0, 5, 10, 15, and 20 in diabetic mice revealed faster migration of epidermal keratinocytes from wound edges. These results suggest that rh-TIMP-2 plays an important role in wound healing.     

Effects of thermal shocks on interleukin-1 levels and heat shock protein 72 (HSP72) expression in normal human keratinocytes

Interleukin-1 expression is reported to be modified under a number of cell conditions including physiological stress, injury and activation. We report the effects of the physiological stresses cold and heat shock on IL-1 levels in keratinocytes. Having observed that normal human skin obtained from plastic surgery, usually stored at 4C for a few hours, highly expressed HSP72, a constant feature of stressed human keratinocytes, we wondered whether this induction could be linked to a cold shock and to modification of IL-1 levels in keratinocytes. Cultured keratinocytes were incubated at 4, 37, 40 and 43C for 1.5, 4, 8 and 16 h in a defined medium. HSP72 expression was studied by immunohistochemistry and immunoblot and IL-1 was quantified using specific and sensitive radio-immunoassay. Our findings showed that intracellular IL-1 and IL-1 levels are not significantly modified by thermal shock. HSP72 is only induced after cell exposure to 43C and is not a cold-shock protein. These results demonstrate that thermal stress is not an inductive signal for IL-1 modification in keratinocytes.     

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.     

白芍总苷对角质形成细胞增殖及血管内皮生长因子和白介素-23表达的影响

目的 研究白芍总苷（TGP）对角质形成细胞增殖和分泌血管内皮生长因子（VEGF）和白介素（IL）-23的影响,探讨可能涉及的信号转导通路。方法 不同浓度TGP作用于体外培养的HaCaT细胞株,噻唑蓝（MTT）法观察TGP对HaCaT细胞增殖活性的影响。将HaCaT细胞分为三组,即对照组不加任何刺激因素,TGP组分别加入6种不同浓度的TGP,SB203580组在加入10 mol/L SB203580预处理2 h后加入125 mg/L TGP。实时定量PCR（RT-PCR）方法和ELISA方法检测TGP对HaCaT细胞VEGF和IL-23表达的影响;免疫印迹技术观察TGP作用于HaCaT细胞后p38的磷酸化及SB203580对p38磷酸化的影响。结果 TGP在低浓度（0.5、2.5 mg/L）时对HaCaT细胞增殖有促进作用,浓度≥12.5 mg/L时反而对细胞的增殖有抑制作用,至125 mg/L时抑制作用最强。TGP在低浓度（0.5、2.5 mg/L）时对HaCaT细胞VEGF和IL-23 mRNA和蛋白的表达有促进作用,12.5 ～ 125 mg/L时内可抑制HaCaT细胞VEGF mRNA和蛋白的表达,62.5 ～ 125 mg/L时可抑制IL-23 mRNA和蛋白的表达。TGP可时间依赖性地诱导HaCaT细胞p38的磷酸化,磷酸化p38 蛋白于125 mg/L TGP作用5 min后达到高峰,表达水平为0.3314 ± 0.0245,10 min后减弱至0.2173 ± 0.0189,但均高于对照组水平;30 min后表达水平降为0.1664 ± 0.0201;SB203580可减弱其作用,SB203580预处理组磷酸化p-p38 表达水平为0.1529 ± 0.0147。结论 TGP可抑制HaCaT细胞的增殖及VEGF和IL-23 mRNA和蛋白的表达,p38MAPK信号途径可能介导其抑制作用。