RESUMEN
Objective To investigate the effect and mechanism of interfering the nicotinamide mononucleotide adenylyltransferase 1(NMNAT1)gene in Parkinson's disease(PD)mouse models. Methods Thirty mice were randomly assigned to three groups: the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)group, the small interfering nicotinamide mononucleotide adenylyltransferase 1 (siNMNAT1)+MPTP group, and the control group, with 10 mice in each group.After injecting siRNA-green fluorescent protein(GFP)lentivirals directly into substantia nigra(SN),mice received intraperitoneal injections of MPTP, which was the siNMNAT1 +MPTP group.While the MPTP group was only with injections of MPTP,and the control group was with neither siRNA nor MPTP.Then we assessed the motor coordination ability firstly.To observe the variation of nigrostriatal pathway, the counts of dopamanergic neurons in SN were measured by tyrosine hydroxylase(TH)immunofluorescence staining.And the expression of TH in striatum, which was used to estimate the dopaminergic neurons axonal variation, was analyzed by RT-PCR.Then the expression of TH, SOD1, Bcl2, Bax, Bcl2/Bax in SN was estimated through Western blotting.Results Compared with the control group,the siNMNAT1+MPTP group and the MPTP group decreased significantly in motor coordination ability(creep down time: siNMNAT1 +MPTP group(62.8 ±15.7)s,MPTP group(77.9 ±13.5)s, control group(122.0 ±25.2)s), dopamanergic neuron counts(siNMNAT1 +MPTP group 45.0 ±6.7, MPTP group 68.0 ±11.3, control group 93.0 ± 12.8)and the striatal TH expression(Creep down time: t=-6.291, P=0.000; t=-4.865, P=0.000.Dopamanergic neuron counts:t=-10.482,P=0.000;t=-4.624, P=0.000.TH expression:t=-9.117,P=0.000;t=-5.716, P=0.000).Although the siNMNAT1+MPTP group showed lower coordination ability than the MPTP group, there was no statistically significant difference.Whereas the counts of dopamanergic neurons in SN(t=-5.487, P=0.000), the expression of TH in striatum(t=-5.146,P=0.003),SOD1(t=-4.143, P=0.001)and Bcl2/Bax(t=-6.303, P=0.000)were obviously decreased in the siNMNAT1+MPTP group,in which Bax increased significantly(t=3.550,P=0.002).Conclusions Interfering the expression of NMNAT1 aggravated the neurodegeneration in PD, and the mechanism might be related to oxidative stress and programmed cell death.
RESUMEN
The intracellular parasite Trypanosomacruzi is the aetiological agent of Chagas disease, a public health concern with an increasing incidence rate. This increase is due, among other reasons, to the parasite’s drug resistance mechanisms, which require nicotinamide adenine dinucleotide (NAD+). Furthermore, this molecule is involved in metabolic and intracellular signalling processes necessary for the survival of T. cruzithroughout its life cycle. NAD+biosynthesis is performed by de novo and salvage pathways, which converge on the step that is catalysed by the enzyme nicotinamide mononucleotide adenylyltransferase (NMNAT) (enzyme commission number: 2.7.7.1). The identification of the NMNAT of T. cruziis important for the development of future therapeutic strategies to treat Chagas disease. In this study, a hypothetical open reading frame (ORF) for NMNAT was identified in the genome of T. cruzi.The corresponding putative protein was analysed by simulating structural models. The ORF was amplified from genomic DNA by polymerase chain reaction and was further used for the construction of a corresponding recombinant expression vector. The expressed recombinant protein was partially purified and its activity was evaluated using enzymatic assays. These results comprise the first identification of an NMNAT in T. cruziusing bioinformatics and experimental tools and hence represent the first step to understanding NAD+ metabolism in these parasites.