Differential effects of hnRNP D/AUF1 isoforms on HIV-1 gene expression

• Published in: Nucleic acids research Vol. 40; no. 8; pp. 3663 - 3675
• Main Authors: Lund, Nicole, Milev, Miroslav P, Wong, Raymond, Sanmuganantham, Tharmila, Woolaway, Kathryn, Chabot, Benoit, Abou Elela, Sherif, Mouland, Andrew J, Cochrane, Alan
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.04.2012
• Subjects: Cytoplasm; env Gene Products, Human Immunodeficiency Virus - genetics; env Gene Products, Human Immunodeficiency Virus - metabolism; gag Gene Products, Human Immunodeficiency Virus - genetics; gag Gene Products, Human Immunodeficiency Virus - metabolism; Gag protein; Gene Expression; HeLa Cells; Heterogeneous-Nuclear Ribonucleoprotein D - antagonists & inhibitors; Heterogeneous-Nuclear Ribonucleoprotein D - genetics; Heterogeneous-Nuclear Ribonucleoprotein D - physiology; Heterogeneous-Nuclear Ribonucleoprotein Group A-B - antagonists & inhibitors; Heterogeneous-Nuclear Ribonucleoprotein Group A-B - genetics; Heterogeneous-Nuclear Ribonucleoprotein Group A-B - physiology; HIV-1 - genetics; HIV-1 - metabolism; Human immunodeficiency virus 1; Humans; Infection; Protein Isoforms - antagonists & inhibitors; Protein Isoforms - genetics; Protein Isoforms - physiology; RNA; RNA Interference; RNA processing; RNA, Viral - analysis; siRNA; Structural proteins
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/gkr1238

Control of RNA processing plays a major role in HIV-1 gene expression. To explore the role of several hnRNP proteins in this process, we carried out a siRNA screen to examine the effect of depletion of hnRNPs A1, A2, D, H, I and K on HIV-1 gene expression. While loss of hnRNPs H, I or K had little effect, depletion of A1 and A2 increased expression of viral structural proteins. In contrast, reduced hnRNP D expression decreased synthesis of HIV-1 Gag and Env. Loss of hnRNP D induced no changes in viral RNA abundance but reduced the accumulation of HIV-1 unspliced and singly spliced RNAs in the cytoplasm. Subsequent analyses determined that hnRNP D underwent relocalization to the cytoplasm upon HIV-1 infection and was associated with Gag protein. Screening of the four isoforms of hnRNP D determined that, upon overexpression, they had differential effects on HIV-1 Gag expression, p45 and p42 isoforms increased viral Gag synthesis while p40 and p37 suppressed it. The differential effect of hnRNP D isoforms on HIV-1 expression suggests that their relative abundance could contribute to the permissiveness of cell types to replicate the virus, a hypothesis subsequently confirmed by selective depletion of p45 and p42.