Kaposi's Sarcoma-Associated Herpesvirus Suppression of DUSP1 Facilitates Cellular Pathogenesis following De Novo Infection

Abstract

Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma (KS), and KSHV activation of mitogen-activated protein kinases (MAPKs) initiates a number of key pathogenic determinants of KS. Direct inhibition of signal transduction as a therapeutic approach presents several challenges, and a better understanding of KSHV-induced mechanisms regulating MAPK activation may facilitate the development of new treatment or prevention strategies for KS. MAPK phosphatases, including dual-specificity phosphatase-1 (DUSP1), negatively regulate signal transduction and cytokine activation through MAPK dephosphorylation or interference with effector molecule binding to MAPKs, including the extracellular signal-regulated kinase (ERK). We found that ERK-dependent latent viral gene expression, the induction of promigratory factors, and cell invasiveness following de novo infection of primary human endothelial cells are in part dependent on KSHV suppression of DUSP1 expression during de novo infection. KSHV-encoded miR-K12-11 upregulates the expression of xCT (an amino acid transporter and KSHV fusion/entry receptor), and existing data indicate a role for xCT in the regulation of 14-3-3␤, a transcriptional repressor of DUSP1. We found that miR-K12-11 induces endothelial cell secretion of promigratory factors and cell invasiveness through upregulation of xCT-dependent, 14-3-3␤-mediated suppression of DUSP1. Finally, proof-of-principle experiments revealed that pharmacologic upregulation of DUSP1 inhibits the induction of promigratory factors and cell invasiveness during de novo KSHV infection. These data reveal an indirect role for miR-K12-11 in the regulation of DUSP1 and downstream pathogenesis.

KSHV

“…miR-K12-11 targets the host protein Jarid2 and both miR-155 and miR-K12-11 can induce expansion of splenic CD19+ B cells in vivo (Boss et al, 2011; Dahlke et al, 2012). Additionally, miR-K12-11 and -1 can induce MAPK signaling, promigration factors, and cell invasiveness through indirectly suppressing the MAPK phosphatase DUSP1 (Qin et al, 2013). …”

Kaposi's Sarcoma-Associated Herpesvirus Encodes a Mimic of Cellular miR-23

“…One major clue to the potential functions of the KSHV miRNAs is the identification of two of the KSHV miRNAs as viral analogs of the cellular miRNAs miR-155 and miR-142-3p (12,14,15). Several additional interactions and functions of the KSHV miRNAs have been identified (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35); however, the overall impact these miRNAs have on host gene expression and their phenotypic consequences remain largely unknown.…”

Induction of hyaluronan production by oncogenic KSHV and the contribution to viral pathogenesis in AIDS patients

“…Hyaluronan oligosaccharides (oHA) were prepared as described previously [13]. To obtain KSHV for infection experiments, BCBL-1 cells were incubated with 0.6 mM valproic acid for 6 days, purified virus concentrated from culture supernatants and infectious titers were determined as described previously [14]. …”

“…Transfection efficiency was determined through co-transfection of a lacZ reporter construct and quantified as described previously [14]. For RNA interference assays, Has1 or CD147 ON-TARGET plus SMART pool siRNA (Dharmacon), or negative control siRNA, were delivered using the DharmaFECT transfection reagent according to the manufacturer's instruction.…”