Pharmacological Inhibition of Protein Kinase C Reduces West Nile Virus Replication

Abstract

Flaviviruses are relevant animal and human pathogens that include West Nile virus (WNV), Japanese encephalitis virus, dengue virus, or Zika virus, among others. Currently, no licensed therapy is available to fight flaviviral infections. Protein kinases C (PKCs) constitute a family of multifunctional lipid-dependent isoenzymes that regulate a wide variety of cellular processes (apoptosis, differentiation, proliferation, cellular transformation, motility, adhesion, etc.) being currently considered at the front line of drug development for the treatment of diverse human disorders. PKCs have also been implicated in different steps during viral replication; however, nowadays, results regarding their role in flavivirus replication are controversial. Here we demonstrate that calphostin C and chelerythrine, two broad-PKC inhibitors that target conventional, novel and atypical PKCs, significantly inhibit WNV multiplication in cell culture without affecting cell viability. A reduction of viral yields was observed in treated cells when compared with mock-treated cells. Likewise, immunofluorescence detection of viral enveloped E protein was reduced in treated cells, as was the amount of viral RNA released to the supernatant, mainly in those treated with chelerythrine. On the other hand, two PKC inhibitors specific for conventional and novel isoforms (staurosporine and enzastaurine) did not show any significant effect in WNV multiplication. These results suggested that PKCs, more probably atypical PKCs, are likely involved in WNV multiplication, although both broad-spectrum tested drugs seem to act through different mechanisms, and point to them as potential antiviral candidates for WNV, as well as for other related flaviviruses.

Atypical Protein Kinase Cs in Melanoma Progression

“…Calphostin C and chelerythrine two wide range PKC inhibitors that target all three PKC classes. Results indicate that atypical PKCs are involved in WNV multiplication process which can be effectively retard using said inhibitors [88].…”

A New Advanced In Silico Drug Discovery Method for Novel Coronavirus (SARS-CoV-2) with Tensor Decomposition-Based Unsupervised Feature Extraction

“…Chelerythrine chloride Chelerythrine chloride exhibited the third and fifth smallest (significant) -value in "LINCS L1000 Chem Pert up" and had multiple hits (Table S2). It is known to exhibit pharmacological inhibition of protein kinase C reduces West Nile virus replication (See Fig,1 [3]).…”

Potential for Protein Kinase Pharmacological Regulation in Flaviviridae Infections

“…The PKG inhibitor Rp-8-pCPT-cGMPS drastically decreases DENV replication in human HEK293T cell culture, while the PKG activator 8-Br-PET-cGMP produces an increase in DENV yield [20]. Similarly, WNV has been reported to upregulate PKCs during infection [91], and the PKC inhibitors calphostin C and chelerythrine have been reported to reduce WNV multiplication [92]. In contrast, in vitro number of DENV viral copies increased upon treatment with the PKC inhibitor bisindolylmaleimide I, whilst the opposite effect was observed in baby hamster kidney (BHK-21) cells treated with the PKC activator phorbol 12-myristate 13-acetate, thus indicating that inhibition of PKC activity promotes DENV replication [72].…”