The HIV-1 capsid-binding host factor CPSF6 is post-transcriptionally regulated by the cellular microRNA miR-125b

Abstract

Cleavage and polyadenylation specificity factor 6 (CPSF6) is a cellular protein involved in mRNA processing. Emerging evidence suggests that CPSF6 also plays key roles in HIV-1 infection, specifically during nuclear import and integration targeting. However, the cellular and molecular mechanisms that regulate CPSF6 expression are largely unknown. In this study, we report a post-transcriptional mechanism that regulates CPSF6 via the cellular microRNA miR-125b. An in silico analysis revealed that the 3′UTR of CPSF6 contains a miR-125b–binding site that is conserved across several mammalian species. Because miRNAs repress protein expression, we tested the effects of miR-125b expression on CPSF6 levels in miR-125b knockdown and over-expression experiments, revealing that miR-125b and CPSF6 levels are inversely correlated. To determine whether miR-125b post-transcriptionally regulates CPSF6, we introduced the 3′UTR of CPSF6 mRNA into a luciferase reporter and found that miR-125b negatively regulates CPSF6 3′UTR-driven luciferase activity. Accordingly, mutations in the miR-125b seed sequence abrogated the regulatory effect of the miRNA on the CPSF6 3′UTR. Finally, pulldown experiments demonstrated that miR-125b physically interacts with CPSF6 3′UTR. Interestingly, HIV-1 infection down-regulated miR-125b expression concurrent with up-regulation of CPSF6. Notably, miR-125b down-regulation in infected cells was not due to reduced pri-miRNA or pre-miRNA levels. However, miR-125b down-regulation depended on HIV-1 reverse transcription but not viral DNA integration. These findings establish a post-transcriptional mechanism that controls CPSF6 expression and highlight a novel function of miR-125b during HIV-host interaction.

HIV-induced membraneless organelles orchestrate post-nuclear entry steps

“…To investigate whether LLPS aids the virus to navigate into the nuclear space through CPSF6, we performed a series of experiments. First, we observed an increase in CPSF6 intensity exclusively in the nucleus of infected cells ( Figure 2A ), in line with a recent observation that HIV-1 induces an increase of CPSF6 proteins ( Chaudhuri et al., 2020 ). This observation suggests that CPSF6 during viral infection undergoes LLPS, known as a concentration-dependent phenomenon ( Alberti et al., 2019 ).…”

“…Indeed, viruses carrying the capsid mutation N74D, unable to bind to CPSF6, do not prompt CPSF6 clustering formation ( Supplementary Figure S1A ; Selyutina et al., 2020 ). On the other hand, this phenomenon could also be prompted by the overexpression of CPSF6 ( Chaudhuri et al., 2020 ) due to the viral infection.…”

SIV Infection Regulates Compartmentalization of Circulating Blood Plasma miRNAs within Extracellular Vesicles (EVs) and Extracellular Condensates (ECs) and Decreases EV-Associated miRNA-128

“…These observations are remarkable because miRNA pathways have been shown to regulate HIV replication and contribute to latency [ 73 ]. Several miRNAs, including miRNAs-28, -29, -125b, -150, -223, and -382, negatively affect HIV by directly targeting the viral RNA genome and/or by repressing virus-dependent cellular cofactors [ 74 , 75 , 76 ]. For example, the Let-7 family of miRNAs was shown to be significantly lower in patients with chronic HIV infection compared to healthy controls [ 77 ] and several let-7 family members (let-7d-5p, let-7a, let-7c) decreased over time in progressive liver fibrosis in hepatitis C-infected patients [ 78 ].…”

WGCNA Analysis Identifies Polycystic Ovary Syndrome-Associated Circular RNAs That Interact with RNA-Binding Proteins and Sponge miRNAs

“… 34 CPSF6 was revealed to be upregulated after HIV-1 infection. 35 These findings indicate that our identified circRNAs may be involved in PCOS by changing inflammation, apoptosis and steroidogenesis of cumulus cells.…”