AbstractsBiology & Animal Science

Aicardi-Goutières Syndrome (AGS) is a rare encephalopathy which mimics a viral intrauterine infection and is characterized by calcifications of the basal ganglia, cerebral atrophy and IFN-a in the cerebrospinal fluid. AGS is a heterogenic disease associated with mutations in the gene of the exonuclease TREX1, in any of the genes codifying for the ribonuclease H2, in the phosphohydrolase SAMHD1, in the deaminase ADAR1 or in the cytoplasmic sensor MDA5. The knowledge of these functions is basic for the comprehension of the beginning of the pathogenesis of AGS. In this thesis we focused in the mechanism of Samhd1 transcription. We have seen that Samhd1 is induced by pro-inflammatory stimuli but neither by anti-inflammatory stimuli nor TNF-a, and that the induction of Samhd1 is through STAT1 pathway. We wanted to know a bit more about Samhd1 induction so we focused on the study of its promoter. We did a construct in a luciferase-reporter vector with 1500bp of Samhd1 promoter, and we saw that this region of the promoter is enough to induce luciferase expression. From this construct, we did new plasmids and when deleting a specific region, the luciferase expression was abolished, indicating that in Samhd1 promoter, 161bp are critical for Samhd1 induction. EMSA assays showed that Samhd1 expression is repressed in basal conditions by an unknown protein, and ChIP assays also showed that IRF1 is involved in Samhd1 induction by IFN-.. We hypothesized that the regulation mechanism is depending in an STAT1-depending pathway, through IRF1, and also in an STAT1-independing pathway, through an unknown mechanism up to date. We checked with proteomics analysis the protein which might be involved in Samhd1 repression but the results were not significant. We also constructed a conditional KO mouse for TREX1, and now we are crossing it with different CRE­Socs2 expressing strands. Homozygous KO expressing CRElitter, show a similar phenotype to TREX1 total KO. We are in the process to obtain homozygous KO expressing CRELysM, but due to problems with the penetrance of this CRE allele we have some difficulties. All together, the results of this thesis will shed light in the inner operation of AGS.; La síndrome d'Aicardi-Goutières (AGS), és una malaltia autoimmunitària recessiva que mimetitza una infecció vírica intrauterina, i la qual és caracteritzada per calcificacions intracranials, atròfia cerebral i augment d'IFN-alfa al líquid cefaloraquidi. L'AGS és una malaltia genètica heterogènia associada amb mutacions al gen que codifica per a l'exonucleasa TREX1, a qualsevol dels gens codificants per a les components de la ribonucleasa RNASE H2, a la fosfo­hidrolasa SAMHD1, a la deaminasa ADAR1 o al sensor citoplasmàtic MDA5. El coneixement d'aquestes funcions és fonamental per tal d'entendre la patogènesi de l'AGS. En aquesta tesi s'ha aprofundit en el coneixement del mecanisme regulador de la transcripció de Samhd1. Hem vist que Samhd1 es troba expressat en diferents òrgans sense necessitat de cap estímul previ, com el pàncrees, l’intestí prim…