ABSTRACT
Objective To measure expressions of nicastrin and its downstream Notch-HES signaling pathwayassociated proteins in skin lesions of patients with acne inversa harbouring nicastrin gene mutations.Methods An immunohistochemical study was performed to measure the expressions of nicastrin and Notch-HES signaling pathwayassociated proteins in paraffin-embeded skin samples from lesions of 4 patients with acne inversa and confirmed nicastrin mutations and from normal skin of 6 human controls.Spearman correlation analysis was carried out to assess the relationship between the expressions of nicastrin and Notch-HES signaling pathway-associated proteins.Results In normal control skin samples,nicastrin was widely distributed in the full-thickness epidermis and skin appendages such as pilosebaceous units,apocrine glands and eccrine glands.However,the expressions of nicastrin and Notch-HES signaling pathway-associated proteins were markedly decreased in the epidermis and hair follicle infundibulum in lesions of patients harbouring nicastrin gene mutations compared with normal control skin.Furthermore,nicastrin expression was positively correlated with Notchl,Notch3 and HES-1 expressions (r =0.831,0.748 and 0.807,P ＜ 0.01,0.05 and 0.01 respectively),but not significantly correlated with Notch2 or HES-5 expressions (r =0.597,0.591 respectively,both P ＞0.05).Conclusion Nicastrin expression markedly decreases in lesions of patients with acne inversa harbouring nicastrin gene mutations,and is positively correlated with the expressions of several Notch-HES signaling pathway-associated proteins,suggesting that the decrease in nicastrin expression may take part in the pathogenesis of acne inversa by influencing the expression of the downstream Notch-HES signaling pathway.
ABSTRACT
The gamma-secretase complex mediates the final cleavage of APP to generate the principal component of amyloid plaques in the brains of Alzheimer's disease patients.Four integral membrane proteins (PS,NCT,PEN-2 and APH-1) are essential and sufficient for gamma-secretase activity.To identify the promoter of human nicastrin gene (NCT),its 5' -flanking region has been characterized and a 270 bp fragment containing the TSS (transcription start site) for the promoter activity has been identified.EMSA assays confirmed that all four AP-1 binding sites and two NFAT sites in the NCT promoter region were able to bind relative transcription factors in vitro.Mutations,as well as treatment with PDTC,which adjust the regulatory effect of AP-1 and NFAT,altered NCT promoter activity in both HeLa cells and rat cortical neurons.The results demonstrated that AP-1 and NFAT are involved in the regulation of hNCT transcription and suggest that balanced activation of AP-1 and NFAT ensures a strict temporal and tissue-specific control of NCT transcription.
ABSTRACT
AIM: To explore the possibility that proteasome is involved in nicastrin(NCT) degradation and NCT is ubiquitinated before degradation.METHODS: Following the generation of NCT stable cell lines,the methods of Western blotting,pulse-chase metabolic labeling technique,double immunofluorescent staining,combined with proteasomal inhibition were used to investigate the NCT expression in NCT stable cell line.RESULTS: Treatment of the cells with proteasomal inhibitors significantly increased both endogenous NCT(produced by the cell itself) and exogenous NCT(produced by the gene transfection) in SH-SY5Y cells.The effect of specific proteasomal inhibitor lactacystin on NCT expression was in time-and dose-dependent manners.Pulse-chase metabolic labeling experiment showed that the turnover of newly-synthesized radio-labeled nicastrin protein was blocked by lactacystin.The results of double immunofluorescent staining showed that NCT and ubiquitin were co-located in the cells.CONCLUSION: The proteasome is involved in the degradation of NCT in neuronal cells,and NCT is ubiquitinated before degradation.