Objective To study the effect of amino acid site variation of HIV-1 Nef protein on its inhibition of neuronal autophagy and explore the mechanism of Nef protein-induced central nervous system injury.Methods HIV-1 nef genes were amplified and cloned from the temporal cortex (TC) of the central nervous system in 1 case of HIV-associated dementia (HAD) H and 1 case of non-HAD AIDS patient N.The amino acid sequences were aligned by NCBI BLAST tools and MEGA6.0 software to study the variation of amino acid sites.The eukaryotic expression vectors pEGFP-N1-nef derived from H-TC and N-TC were constructed and transfected into U87 cells to observe green fluorescence.At the same time,the expression of Nef protein,LC3-Ⅱ and p62 protein in U87 cells were detected by Western blot,and the effects of different sources of Nef on autophagy of U87 cells were analyzed.Results The nef genes were amplified by PCR and clone vectors pMD-19T-nef of H-TC and N-TC were successfully constructed.The sequencing confirmed that they were HIV-1B subtypes.The amino acid sequence analysis showed that there were differences between H-TC and N-TC key amino acid sites.The recombinant plasmid pEGFP-N1-nefwas successfully constructed and expressed Nef protein in U87 cells.Western blot analysis showed that the expression of LC3-Ⅱ protein was significantly different among groups (F =11.764,P =0.001).There was no significant difference in the expression of LC3-Ⅱ between cell control and plasmid control(P=0.169).The content of LC3-Ⅱ was low in the two groups of cells,which could not be detected by Western blot.The expression of LC3-Ⅱ in H-TC,N-TC and positive control CQ group increased,compared with blank control or blank vector.The difference was statistically significant (P=0.017,P=0.039,P=0.031),and the expression of LC3-Ⅱ in H-TC group was higher than that in N-TC group (P =0.023);the expression of p62 protein in H-TC,N-TC and positive control CQ group was higher than that in blank control or blank vector group,but there was no significant difference between groups (F=2.049,P =0.163).Conclusions HIV-1 Nef amino acid sites in the central nervous system of patients with HAD and non-HAD were different,and their effects on autophagy of U87 cells were different.The expression of LC3-Ⅱ,an autophagic marker protein,was more strongly induced by Nef from H-TC.

HIV-1 can cross the blood-brain barrier, infect the central nervous system, and cause a series of nervous system diseases. Oxidative stress (OS) plays an important role in the pathogenesis of different neurodegenerative diseases. When the body is subjected to various harmful stimulation, the regulation level of oxidation system and antioxidant system is out of balance, producing a large number of reactive oxygen species, which directly or indirectly leads to tissue damage. Tat protein, a trans-activator of transcription released after HIV-1 infection, plays an important role in brain injury. It can induce endothelial cells and nerve cells to produce living oxygen, make the body in a state of chronic oxidative stress, and aggravate the development of the disease. In this paper, the research progress in studies on the effect of HIV-1 Tat protein on oxidative stress of vascular endothelial cells and nerve cells was reviewed.

Objective:To study the amino acid site variation of HIV-1 Tat protein from different parts of AIDS patients with HAD and non HAD and its effect on oxidative stress of U87 cells.Methods:HIV-1 Tat amino acid sequences were analyzed by BLAST and MEGA6 software to study the variation of amino acid sites in four parts of central nervous tissue basal ganglia(BG) and peripheral spleen (SPL) of an HIV-associated dementia (HAD) patient(H) and a non-HAD patient(N), The HIV-1 tat genes were transfected into U87 cell. The green fluorescent protein was observed under microscope to determine the Tat protein expression. The expression of Tat protein in U87 cells was detected by Western blotting. CK-8 method , Western blotting and malondialdehyde (MDA) detection kit were used to study the effect of Tat protein on cell activity, oxidative stress index glutathione peroxidase (GPX), MDA level. Results:Amino acid sequence analysis showed that the key amino acid sites of HIV-1 Tat protein from N-BG, N-SPL, H-BG and H-SPL were different; Tat protein could inhibit the activity of U87 cells, which could be reversed by antioxidant N-acetyl-L-cysteine (NAC). Compared with the control group, the levels of MDA were increased and the expression of GPX protein was decreased in the four experimental groups ( P<0.05). And different sources of Tat protein had different ability to induce oxidative stress, the level of MDA in H-BG group was higher than that in N-BG group( P<0.05). The expression of GPX protein in BG group of both HAD and non-HAD patients was lower than that of SPL group( P<0.05). Conclusions:There are differences in the key amino acid sites of Tat protein in peripheral and central nervous system between HAD and non-HAD patients, and their effects on oxidative stress were also different.

Objective: To investigate the toxic effect of HIV-1 Vpr protein on neurons. Methods: HIV-1 vpr gene was amplified by nested PCR in four parts of peripheral spleen (SPL) and central nervous tissue meninges (MG) of HIV-associated dementia (HAD) patients and non-HAD patients. Eukaryotic expression vector pEGFP-N1-vpr was constructed. The gene sequence and key amino acid sites were analyzed by BLAST and MEGA6. The expression of Vpr protein in N2a cells was detected by Western-blotting. The effects of Vpr proteins from different sources on the activity and cell cycle of N2a cells were studied by flow cytometry. Results: HIV-1 vpr gene was successfully amplified by PCR. Sequence analysis showed that the vpr gene sequence belonged to HIV-1B subtype. There were amino acid mutations at C-terminal 84, 86 and 87 sites of central Vpr protein from HAD and non-HAD patients. Vpr protein could inhibit the activity of nerve cells, leading to G2 phase arrest. Different sources of Vpr had different intensity of action. Compared with other groups, Vpr protein from the meninges of HAD patients showed stronger inhibition of cell activity and G2 phase arrest ability. Conclusions Variations in key amino acid sites of Vpr protein could cause significant changes in its biological functions, and its significance in the pathogenesis of HAD remains to be further studied.