KSHV MicroRNAs Repress Tropomyosin 1 and Increase Anchorage-Independent Growth and Endothelial Tube Formation

PLoS One. 2015 Aug 11;10(8):e0135560. doi: 10.1371/journal.pone.0135560. eCollection 2015.

Abstract

Kaposi's sarcoma (KS) is characterized by highly vascularized spindle-cell tumors induced after infection of endothelial cells by Kaposi's sarcoma-associated herpesvirus (KSHV). In KS tumors, KSHV expresses only a few latent proteins together with 12 pre-microRNAs. Previous microarray and proteomic studies predicted that multiple splice variants of the tumor suppressor protein tropomyosin 1 (TPM1) were targets of KSHV microRNAs. Here we show that at least two microRNAs of KSHV, miR-K2 and miR-K5, repress protein levels of specific isoforms of TPM1. We identified a functional miR-K5 binding site in the 3' untranslated region (UTR) of one TPM1 isoform. Furthermore, the inhibition or loss of miR-K2 or miR-K5 restores expression of TPM1 in KSHV-infected cells. TPM1 protein levels were also repressed in KSHV-infected clinical samples compared to uninfected samples. Functionally, miR-K2 increases viability of unanchored human umbilical vein endothelial cells (HUVEC) by inhibiting anoikis (apoptosis after cell detachment), enhances tube formation of HUVECs, and enhances VEGFA expression. Taken together, KSHV miR-K2 and miR-K5 may facilitate KSHV pathogenesis.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • 3' Untranslated Regions
  • Anoikis / genetics
  • Cell Line
  • Endothelial Cells / metabolism*
  • Endothelial Cells / virology
  • Gene Expression Regulation
  • Gene Order
  • Herpesvirus 8, Human / genetics*
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • MicroRNAs / genetics*
  • Molecular Weight
  • Protein Isoforms
  • RNA Interference*
  • RNA, Messenger / genetics
  • RNA, Viral*
  • Tropomyosin / chemistry
  • Tropomyosin / genetics*
  • Tropomyosin / metabolism

Substances

  • 3' Untranslated Regions
  • MicroRNAs
  • Protein Isoforms
  • RNA, Messenger
  • RNA, Viral
  • TPM1 protein, human
  • Tropomyosin