Polymerase-1 pathway activation in acute multiple sclerosis relapse

Background Increased expression of RNA polymerase 1 (POL1) molecular pathway was reported to be associated with increased disease activity in patients with multiple sclerosis (MS). However, the operating molecular mechanisms that characterize the pattern of acute MS relapse activity has not been thoroughly studied. Objective To assess POL1 pathway expression during acute MS relapse. Methods We studied POL1 pathway associated biomarkers during the first acute optic neuritis attack of MS, and in relapsing-remitting MS patients treated with disease-modifying drugs (DMDs) experiencing an acute MS relapse or a radiological relapse using gene expression microarrays and quantitative RT-PCR. Results In MS patients (N = 6) during the first acute optic neuritis attack POL1 pathway activation was evident by over-expression of POL1 related network including transcription factor UBTF and downstream components of Assembly of RNA POL1 complex (p=1.92E-03). POL1 related biomarkers RRN3, POLR1D and LRPPRC were over-expressed x1.6 (p = .002), ×1.7 (p = .01) and x2.0 (p = .001) times higher respectively, in MS patients (N = 30) during acute clinical relapse as compared with remission. Similarly, in MS patients (N = 21) that presented with a radiological relapse, we observed significant activation of POL1 related biomarkers including RRN3 (p = .01), POLR1D (p = .002), POLR1E (p = .0001) and LRPPRC (p = .006), as compared with remission, as well as overexpression of a large group of genes encoding ribosomal proteins like RPS6KA3 (p = 7.2E-6), RRP8 (p = .0002) and RPCS9 (p = .0008). Conclusions Our findings demonstrated increased POL1 pathway activity in acute MS relapse and suggest that targeted inactivation of POL1 pathway represent a novel strategy for a better treatment of acute MS relapse.