Human immunodeficiency virus reactivation by phorbol esters or T-cell receptor Ligation requires both PKCα and PKCθ

Latently human immunodeficiency virus (HIV-infected memory CD4(+) T cells represent the major obstacle to eradicating HIV from infected patients. Antigens, T-cell receptor (TCR) ligation, and phorbol esters can reactivate HIV from latency in a protein kinase C (PKC)-dependent manner; however, it is unknown which specific PKC isoforms are required for this effect. We demonstrate that constitutively active (CA) forms of both PKC theta, PKC theta A148E, and PKC alpha, PKC alpha A25E, induce HIV long terminal repeat (LTR)-dependent transcription in Jurkat and primary human CD4(+) T cells and that both PKC theta A148E and PKCctA25E cause HIV reactivation in J1.1 T cells. Suppression of both PKC alpha and PKC theta with short hairpinned (sh) RNA inhibited CD3/CD28-induced HIV LTR-dependent transcription and HIV reactivation in J1.1 T cells. Both prostratin and phorbol myristate 13-acetate induced HIV LTR-dependent transcription and HIV reactivation in J1.1 T cells that was blocked by shRNA against either PKC alpha or PKC theta. Since suppression of PKC alpha and PKC theta together has no greater inhibitory effect on HIV reactivation than inhibition of PKC alpha alone, our data confirm that PKC alpha and PKC theta act in sequence. The requirement for PKC alpha and PKC theta for prostratin-induced HIV reactivation and the ability of selective PKC alpha or PKC theta agonists to induce HIV transcription indicate that these PKC isoforms are important targets for therapeutic drug design.