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- Andersson, Elin, 1975, et al.
(författare)
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Glycine-amide is an active metabolite of the antiretroviral tripeptide glycyl-prolyl-glycine-amide.
- 2005
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Ingår i: Antimicrobial agents and chemotherapy. - 0066-4804. ; 49:1, s. 40-4
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Tidskriftsartikel (refereegranskat)abstract
- The chemically modified tripeptide glycyl-prolyl-glycine-amide (GPG-NH(2)) inhibits replication of human immunodeficiency virus (HIV) type 1 (HIV-1) in vitro, probably by interfering with capsid formation. The aim of the present study was to determine whether the metabolites glycyl-proline (GP-OH), glycine (G-OH), prolyl-glycine-amide (PG-NH(2)), proline (P-OH), and glycine-amide (G-NH(2)) from proteolytic cleavage may inhibit the replication of HIV-1 in vitro. PG-NH(2) has previously been shown to have a modest effect on HIV-1 replication. In the present study we show that G-NH(2) exhibits a pronounced inhibitory effect on HIV-1. This effect was not due to a decrease in cell proliferation or viability and could not be shown for herpes simplex virus type 1. The G-NH(2) concentration that inhibited virus replication by 50% (IC(50)) was equimolar to that of GPG-NH(2) and ranged from 3 to 41 microM. Transmission electron microscopy revealed that the effect of G-NH(2) on HIV-1 morphology was equivalent to that of GPG-NH(2) and showed disarranged capsid structures, indicating interference with capsid formation. Serial passage of HIV-infected cells with G-NH(2) for more than 20 subcultivations did not decrease the susceptibility to the compound. The results from this study suggest that GPG-NH(2) might act as a prodrug and that G-NH(2) is an active antiretroviral metabolite.
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| 2. |
- Jaremo, Petter, et al.
(författare)
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Alzheimers Disease: Erythrocyte 2,3-diphosphoglycerate Content and Circulating Erythropoietin
- 2019
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Ingår i: Current Alzheimer Research. - : BENTHAM SCIENCE PUBL LTD. - 1567-2050 .- 1875-5828. ; 16:9, s. 834-835
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Tidskriftsartikel (refereegranskat)abstract
- Background: Alzheimers Disease (AD) features the accumulation of beta-amyloid in erythrocytes. The subsequent red cell damage may well affect their oxygen-carrying capabilities. 2,3-diphosphoglycerate (2,3-DPG) binds to the hemoglobin thereby promoting oxygen release. It is theorized that 2,3-DPG is reduced in AD and that the resulting hypoxia triggers erythropoietin (EPO) release. Methods amp; Objective: To explore this theory, we analyzed red cell 2,3-DPG content and EPO in AD, mild cognitive impairment, and the control group, subjective cognitive impairment. Results: We studied (i) 2,3-DPG in red cells, and (ii) circulating EPO in AD, and both markers were unaffected by dementia. Disturbances of these oxygen-regulatory pathways do not appear to participate in brain hypoxia in AD.
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| 3. |
- Jaremo, Petter, et al.
(författare)
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Erythrocyte Amyloid Beta Peptide Isoform Distributions in Alzheimer and Mild Cognitive Impairment
- 2019
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Ingår i: Current Alzheimer Research. - : BENTHAM SCIENCE PUBL LTD. - 1567-2050 .- 1875-5828. ; 16:11, s. 1050-1054
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: We recently showed that Amyloid Beta (A beta)(40) accumulates in erythrocytes and possibly causes cell damage as evidenced by an increased number of assumed injured low-density (kg/L) erythrocytes. Furthermore, we have suggested a separation technique to isolate and concentrate such damaged red blood cells for subsequent analysis. Objectives: We isolated high- and low-density erythrocytes and investigated the accumulation patterns of the A beta peptides (A beta(40), A beta(42), and A beta(43) ) in Alzheimer (AD), mild cognitive impairment (MCI), and Subjective Cognitive Impairment (SCI). Methods: Whole blood was fractionated through a density gradient, resulting in two concentrated high-and presumed injured low-density erythrocyte fractions. After cell lysis, intracellular A beta(40) , A beta 4(2), and A beta (43) were quantified by ELISA. Results: In both high- and low-density erythrocytes, A beta(40) displayed the lowest concentration in MCI, while it was equal and higher in AD and SCI. A beta(40) was detected at a 10-fold higher level than A beta(42), and in injured low-density erythrocytes, the lowest quantity of A beta(42) was found in AD and MCI. A beta(40) exhibited a 100-fold greater amount than A beta(43). and lighter erythrocytes of MCI subjects displayed less intracellular A beta(43) than SCI. Conclusion: Red blood cell accumulation patterns of A beta(40), A beta(42), and A beta(43) differ significantly between AD, MCI, and SCI. The data must be verified through larger clinical trials. It is, however, tenable that AP peptide distributions in erythrocyte subpopulations have the potential to be used for diagnostic purposes.
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| 4. |
- Jejcic, Alenka
(författare)
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Altering HIV-1 envelope glycoprotein maturation and its effects on viral infectivity
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- HIV-1 is dependent on its envelope glycoprotein (Env) to initiate infection. Env binds to cellular receptors and mediate the following fusion of the viral envelope with the cell plasma membrane. In an attempt to inhibit these events the tri-peptide glycyl-prolyl-glycine amide (GPG-NH2) was designed to block the interaction of Env with its secondary co-receptor. Although the GPG-NH2 was shown to have antiviral properties, its mode of action was found to be other than the intended. It was observed that GPG-NH2 acted late in the viral replication cycle and that it affected the cellular expression of Env, but its antiviral mechanism remained unclear. Therefore, the main objectives of this thesis were: 1) To elucidate the effect of GPG-NH2 on Env and determine if this affected virus infectivity; 2) To examine if the antiviral mechanism and the specific effect on Env was owing to GPG-NH2 or its metabolites G-NH2 or αHGA; 3) To examine the regulatory importance of the native Env signal sequence for cellular Env expression, viral particle incorporation of Env and viral replication. In this thesis it is shown that treatment of HIV-1 infected cells with GPG-NH2 results in production of viral particles with dramatically reduced infectivity. This is in part a consequence of reduced viral incorporation of Env, which disables the viral entry into cells. The mechanism was uncovered by examining Env expression in GPG-NH2 treated cells, which revealed a significant reduction in Env steady-state levels and its processing to gp120/gp41 but also a decrease in its molecular mass as a result of glycan removal. Taken together the results show that GPG-NH2 impairs Env maturation, which targets it for endoplasmic reticulum-associated protein degradation (ERAD), where Env is deglycosylated en route to its destruction. This effect of GPG-NH2 was further shown to be a result of its metabolizing via the intermediate G-NH2 into the active metabolite αHGA, by enzymes in the fetal bovine serum (FBS) added to the cell culture medium. It was further shown that in the presence of human serum or in the absence of any serum only the final metabolite αHGA was capable of directing Env for destruction. These observed effects were all found to be dependent on the native Env signal sequence and the proteasome. The 30 residue long Env signal sequence of the precursor Env, gp160, targets it for co-translational translocation into the endoplasmic reticulum (ER). We found that the ER targeting function of the signal sequence was remarkably tolerant to large N-terminal truncations. Its first 8 N-terminal residues were entirely dispensable for adequate gp160 expression levels. However, they provide the signal sequence with regulatory functions detected first when examining the viral particles. The wild type virus incorporated ~80 % more of the precursor gp160 and 20 % less of its processed form, gp120/gp41, compared to the 8 residue truncated signal sequence virus. By promoting viral incorporation of the inactive precursor gp160 over the fusogenic gp120/gp41 the wt signal sequence down regulate the viral particle infectivity by ~40 %. This indicates that the signal sequence may have post ER targeting functions that permit significant amounts of gp160 trafficking through Golgi without being processed and become incorporated into the viral particles. Interestingly, the intra cellular capsid protein levels were initially lower and the viral particle release was initiated later in the presence of the native Env signal sequence than in its absence or in the presence of truncated Env signal sequences. In conclusion these data illustrate that changes in the viral particle Env content and composition has a profound effect on the HIV-1 infectivity, which can be achieved by targeting selective steps in its biosynthesis and that small molecules may be utilized therapeutically to target unwanted pathogenic proteins for degradation by the existing cellular machinery.
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| 5. |
- Jejcic, Alenka, et al.
(författare)
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GPG-NH2 acts via the metabolite alpha HGA to target HIV-1 Env to the ER-associated protein degradation pathway
- 2010
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Ingår i: Retrovirology. - : Springer Science and Business Media LLC. - 1742-4690. ; 7, s. 20-
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Tidskriftsartikel (refereegranskat)abstract
- Background: The synthetic peptide glycyl-prolyl-glycine amide (GPG-NH2) was previously shown to abolish the ability of HIV-1 particles to fuse with the target cells, by reducing the content of the viral envelope glycoprotein (Env) in progeny HIV-1 particles. The loss of Env was found to result from GPG-NH2 targeting the Env precursor protein gp160 to the ER-associated protein degradation (ERAD) pathway during its maturation. However, the antiviral effect of GPG-NH2 has been shown to be mediated by its metabolite alpha-hydroxy-glycineamide (alpha HGA), which is produced in the presence of fetal bovine serum, but not human serum. In accordance, we wanted to investigate whether the targeting of gp160 to the ERAD pathway by GPG-NH2 was attributed to its metabolite alpha HGA. Results: In the presence of fetal bovine serum, GPG-NH2, its intermediary metabolite glycine amide (G-NH2), and final metabolite alpha HGA all induced the degradation of gp160 through the ERAD pathway. However, when fetal bovine serum was replaced with human serum only aHGA showed an effect on gp160, and this activity was further shown to be completely independent of serum. This indicated that GPG-NH2 acts as a pro-drug, which was supported by the observation that it had to be added earlier to the cell cultures than alpha HGA to induce the degradation of gp160. Furthermore, the substantial reduction of Env incorporation into HIV-1 particles that occurs during GPG-NH2 treatment was also achieved by treating HIV-1 infected cells with alpha HGA. Conclusions: The previously observed specificity of GPG-NH2 towards gp160 in HIV-1 infected cells, resulting in the production of Env (gp120/gp41) deficient fusion incompetent HIV-1 particles, was most probably due to the action of the GPG-NH2 metabolite alpha HGA.
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