Conclusions
We conclude that TACI activation can upregulate c-maf expression which, in turn, controls cyclin D2, and integrin beta7 gene expression.
Methods
Using gene expression profiling, we investigated whether these patterns are kept in TACI+ or TACI- HMCL.
Results
Eighty genes/EST interrogated by Affymetrix microarrays were differentially expressed between TACI+ and TACI- HMCL, particularly c-maf, cyclin D2, and integrin beta7. Triggered by the finding that TACI and c-maf expressions correlate in TACI+ HMCL, we demonstrated that TACI activation influences c-maf expression: (i) activation of TACI by BAFF or APRIL increases c-maf, cyclin D2, and integrin beta7 gene expressions in TACI+ HMCL, (ii) blocking of autocrine BAFF/APRIL stimulation in some TACI+ HMCL by the TACI-Fc fusion protein reduces c-maf, cyclin D2, and integrin beta7 gene expression, (iii) nucleofection of siRNA to c-maf decreases c-maf mRNA levels and reduces the expression of cyclin D2 and integrin beta7 gene expressions, without affecting TACI expression Interpretation and conclusions: We conclude that TACI activation can upregulate c-maf expression which, in turn, controls cyclin D2, and integrin beta7 gene expression.