Divide and conquer: a viral bifunctional RNA utilizes both RNA and protein to modulate pro-tumourigenic pathways

Kaposi’s sarcoma-associated herpesvirus kaposin RNA and KapB protein exert distinct, sometimes opposing effects on cellular growth and inflammatory signalling in infected endothelial cells.

• Why it matters: Prior overexpression studies could not separate functions of the kaposin transcript from those of the encoded KapB protein, obscuring which biomolecule drives pro-tumourigenic pathway modulation.
• What they did: The authors built reductionist overexpression constructs: a latency-mimicking {Delta}Starts that forms kaposin nuclear speckles without translating Kap proteins, and a lytic-mimicking AltB that exports and translates abundant KapB.
• The result: KapB increased actin stress fibres, cell enlargement, total YAP, and YAP-target pro-growth and pro-inflammatory transcription, while kaposin RNA caused p-body disassembly and reduced pro-growth and pro-inflammatory transcripts.