LAUSR

During the development of primary Sjögren's syndrome (pSS), aberrant expression of autoantigen is a hallmark event. To explore the regulation of autoantigen tripartite motif containing 21 (Ro/SSA, TRIM21), microRNA profiling was performed in our previous study. In which, two TRIM21‐targeting microRNAs were identified, namely miR‐1207‐5p and miR‐4695‐3p. To further pursue their roles in the development of pSS, assays were performed with cultured human submandibular gland (HSG) cells, and salivary gland tissues. Results showed that transfection of miR‐1207‐5p or miR‐4695‐3p mimics down‐regulated not only the expression of TRIM21, but also the levels of pro‐apoptotic genes B cell lymphoma 2 associated X (BAX), Caspase 9 (CASP‐9) and Caspase 8 (CASP‐8). This finally led to antiapoptotic phenotypes in HSG cells. Consistent with the antiapoptotic activity, transfection of microRNA inhibitors up‐regulated the expression of TRIM21 and led to a pro‐apoptotic phenotype. These therefore propose miR‐1207‐5p and miR‐4695‐3p as two antiapoptotic microRNAs functioning through apoptosis pathway. Supporting this speculation, assays performed with salivary gland tissues revealed down‐regulation of miR‐1207‐5p and miR‐4695‐3p, as well as up‐regulation of TRIM21 and pro‐apoptotic CASP‐8 gene in pSS samples.