MUC1/A and MUC1/B splice variants differentially regulate inflammatory cytokine expression

作者：Imbert Fernandez Yoannis; Radde Brandie N; Teng Yun; Young William W Jr; Hu Chuan; Klinge Carolyn M^*

来源：Experimental Eye Research, 2011, 93(5): 649-657.

DOI：10.1016/j.exer.2011.08.004

• dry eye disease
• IL-8
• INF alpha
• TGF beta
• miR-21

The frequency of a splice variant of mucin 1 (MUC1), MUC1/A was lower in dry eye disease patients compared to normal controls, suggesting a link between the absence of MUC1/A and the development of dry eye disease which is characterized by chronic inflammation. The objectives of the present study were to clone and characterize the phenotype of cells expressing solely MUC1/A versus MUC1/B or a variant lacking the extracellular domain (SEX) and to determine whether MUC1/A and MUC1/B differentially modulate inflammatory responses in transfected cells. The additional 27 bp and SNP present in the N-terminus of MUC1/A were cloned into a FLAG-MUC1/B expression vector. Transient transfection of MUC1/A and MUC1/B plasmids into MUCl-null COS-7 cells resulted in similar protein expression and plasma membrane localization. MUC1/B and MUC1/A differed in their ability to modulate tumor necrosis alpha (TNF alpha)-induced transcription of IL-1 beta and IL-8. MUC1/B and MUC1/A inhibited 1L-8 induction by TNF alpha at 4 h. However with 24 h TNF alpha, MUC1/A increased IL-1 beta and IL-8 whereas MUC1/B had no effect on cytokine expression. MUC1/B inhibited TNF alpha-induced luciferase activity from an NF-kappa B reporter whereas MUC1/A either inhibited or increased this luciferase activity depending on the time of TNF alpha treatment. MUC1/A, but not MUC1/B, increased the basal TGF beta expression. Both MUC1/B and MUC1/A blocked TNF alpha-induced miR-21 expression. These data demonstrate that MUC1/A and MUC1/B have different inflammatory activities and support the hypothesis that MUC1 genotypic differences may affect susceptibility to ocular surface damage in dry eye disease.