Effects of HIV-1 protease on cellular functions and their potential applications in antiretroviral therapy

Abstract

Human Immunodeficiency Virus Type 1 (HIV-1) protease inhibitors (PIs) are the most potent class of drugs in antiretroviral therapies. However, viral drug resistance to PIs could emerge rapidly thus reducing the effectiveness of those drugs. Of note, all current FDA-approved PIs are competitive inhibitors, i.e., inhibitors that compete with substrates for the active enzymatic site. This common inhibitory approach increases the likelihood of developing drug resistant HIV-1 strains that are resistant to many or all current PIs. Hence, new PIs that move away from the current target of the active enzymatic site are needed. Specifically, allosteric inhibitors, inhibitors that prohibit PR enzymatic activities through non-competitive binding to PR, should be sought. Another common feature of current PIs is they were all developed based on the structure-based design. Drugs derived from a structure-based strategy may generate target specific and potent inhibitors. However, this type of drug design can only target one site at a time and drugs discovered by this method are often associated with strong side effects such as cellular toxicity, limiting its number of target choices, efficacy, and applicability. In contrast, a cell-based system may provide a useful alternative strategy that can overcome many of the inherited shortcomings associated with structure-based drug designs. For example, allosteric PIs can be sought using a cell-based system without considering the site or mechanism of inhibition. In addition, a cell-based system can eliminate those PIs that have strong cytotoxic effect. Most importantly, a simple, economical, and easy-to-maintained eukaryotic cellular system such as yeast will allow us to search for potential PIs in a large-scaled high throughput screening (HTS) system, thus increasing the chances of success. Based on our many years of experience in using fission yeast as a model system to study HIV-1 Vpr, we propose the use of fission yeast as a possible surrogate system to study the effects of HIV-1 protease on cellular functions and to explore its utility as a HTS system to search for new PIs to battle HIV-1 resistant strains.

Cytotoxic, Cytostatic and HIV-1 PR Inhibitory Activities of the Soft Coral Litophyton arboreum

“…Thus, protease inhibitors are particularly useful, not only because they inhibit viral replication but also because they rescue host immune cells [37]. Potent PR inhibition were found in our bioassay for some of the tested compounds, compound 7 demonstrated activity at (IC 50 4.85 µM).…”

Drug‐resistant HIV‐1 protease regains functional dynamics through cleavage site coevolution

“…; Hornak and Simmerling ; Yang et al. ). On the other hand, in the second slowest mode, protease mutations lead a fluctuation orientation difference particularly at residue 39 in the unprimed monomer together with the active site and dimerization interface residues, which is recovered by the coevolving mutation on the substrate (Fig.…”

“…Therefore, the motion of residues 56, 69, and 78 is coupled to the motion of the flaps, which is known to be the significant functional motion of the protease (Nicholson et al 1995;Kurt et al 2003;Hornak and Simmerling 2007). The importance of such protease regions which interact with the flaps is implied in studies of developing allosteric inhibitors for HIV-1 protease that do not compete for the active site, where they are targeted as allosteric sites (Lebon and Ledecq 2000;Perryman et al 2004;Hornak and Simmerling 2007;Yang et al 2012). On the other hand, in the second slowest mode, protease mutations lead a fluctuation orientation difference particularly at residue 39 in the unprimed monomer together with the active site and dimerization interface residues, which is recovered by the coevolving mutation on the substrate (Fig.…”

Fission yeast cells overproducing HSET/KIFC1 provides a useful tool for identification and evaluation of human kinesin-14 inhibitors

“…those promoting lifespan extension (Sarnoski et al, 2017). Fission yeast has been used for several screenings, such as purification of specific compounds produced by Actinomycetes (Lewis et al, 2017) and a functional assay for Indinavir, an inhibitor against Human Immunodeficiency Virus Type-1 (Benko et al, 2016;Benko et al, 2017;Yang et al, 2012). Having seen toxicity derived from overproduced HSET in fission yeast cells (see Figure 1A), we exploited this lethal phenotype for the biological evaluation of known HSET inhibitors described earlier (AZ82, CW069 and SR31527) (Cosenza and Kramer, 2016;Xiao and Yang, 2016;Zhang et al, 2016).…”