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In this work we compared the mutated liver copper zinc-containing superoxide dismutase (SOD1) protein G93A of the transgenic rat model of familial amyotrophic lateral sclerosis (FALS), to wild-type (WT) rat SOD1. We examined their enzymatic activities and effects on isometric contractions of uteri of healthy virgin rats. G93A SOD1 showed a slightly higher activity than WT SOD1 and, in contrast to WT SOD1, G93A SOD1 did not induce smooth muscle relaxation. This result indicates that effects on smooth muscles are not related to SOD1 enzyme activity and suggest that heterodimers of G93A SOD1 form an ion-conducting pore that diminishes the relaxatory effects of SOD1. We propose that this type of pathogenic feedback affects neurons in FALS. [Projekat Ministarstva nauke Republike Srbije, br. 173014 i br. 175083]

Background: Mutated copper, zinc-containing superoxide dismutase (SOD1) may self-aggregate, an event that could also be an initial cause of motor neuron malfunction leading to disease onset. The effects of human mutated SOD1 protein from the blood of familial amyotrophic lateral sclerosis (FALS) patients bearing Leu144Phe (L144F) mutation were compared to wild-type (WT) human SOD1 derived from healthy examinees, for enzymatic activity and the effects on isometric contractions of non-vascular smooth muscle. Methods: We isolated WT and L144F SOD1 enzymes from eight patients with FALS, L144F mutation in exon 5 and eight healthy controls. We then investigated SOD1 activities in the obtained samples by the adrenaline method and profiled them electrophoretically. Finally, we applied WT and L144F SOD1 on the isolated rat uterus. Results: L144F SOD1 showed lower superoxide-dismutating activity compared to WT human SOD1. We found that, in contrast to WT human SOD1, mutated L144F does not induce smooth muscle relaxation. Conclusions: Our data suggest that the lack of relaxation of muscle tonus in the presence of mutated SOD1 may have pathogenic feedback effects in FALS. Uvod: Mutirana bakar, cink superoksid-dizmutaza (SOD1) može da pravi agregate, sto predstavlja početni uzrok oštećenja motornog neurona može da izazove nastanak bolesti. U ovom radu su pokazani efekti humane bakar, cink super-oksid dizmutaze iz krvi pacijenata obolelih od familijarne amiotrofične lateralne skleroze (FALS) sa Leu144Phe (L144F) mutacijom i normalne (wild-type - WT) humane SOD1, iz krvi zdravih kontrola, na glatkom mišiću. Metode: Izolovali smo WT i L144F SOD1 enzime kod osam odabranih FALS pacijenata sa L144F mutacijom na egzonu 5 i pet zdravih kontrola. Dalje smo ispitivali aktivnost SOD1 u dobijenim uzorcima adrenalinskom metodom i elektro-foretski ih profilisali. Konačno, izolovanu WT i L144F SOD1 aplicirali smo na izolovani uterus pacova. Rezultati: Aktivnost L144F SOD1 je statistički značajno manja (p