Nup153 Unlocks the Nuclear Pore Complex for HIV-1 Nuclear Import in Non-Dividing Cells

2018 ◽  
Author(s):  
Silvana Opp ◽  
Alicia Martinez-Lopez ◽  
Thomas Fricke ◽  
Cindy Buffone ◽  
Marco Severgnini ◽  
...  
Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2242
Author(s):  
Qi Shen ◽  
Chunxiang Wu ◽  
Christian Freniere ◽  
Therese N. Tripler ◽  
Yong Xiong

The delivery of the HIV-1 genome into the nucleus is an indispensable step in retroviral infection of non-dividing cells, but the mechanism of HIV-1 nuclear import has been a longstanding debate due to controversial experimental evidence. It was commonly believed that the HIV-1 capsid would need to disassemble (uncoat) in the cytosol before nuclear import because the capsid is larger than the central channel of nuclear pore complexes (NPCs); however, increasing evidence demonstrates that intact, or nearly intact, HIV-1 capsid passes through the NPC to enter the nucleus. With the protection of the capsid, the HIV-1 core completes reverse transcription in the nucleus and is translocated to the integration site. Uncoating occurs while, or after, the viral genome is released near the integration site. These independent discoveries reveal a compelling new paradigm of this important step of the HIV-1 life cycle. In this review, we summarize the recent studies related to HIV-1 nuclear import, highlighting the spatial–temporal relationship between the nuclear entry of the virus core, reverse transcription, and capsid uncoating.


2018 ◽  
Author(s):  
David Alejandro Bejarano ◽  
Ke Peng ◽  
Vibor Laketa ◽  
Kathleen Börner ◽  
K Laurence Jost ◽  
...  

2020 ◽  
Author(s):  
Qi Shen ◽  
Chaoyi Xu ◽  
Sooin Jang ◽  
Qiancheng Xiong ◽  
Swapnil C. Devarkar ◽  
...  

SummaryThe capsid of human immunodeficiency virus 1 (HIV-1) plays a pivotal role in viral nuclear import, but the mechanism by which the viral core passages the nuclear pore complex (NPC) is poorly understood. Here, we use DNA-origami mimics of the NPC, termed NuPODs (NucleoPorins Organized by DNA), to reveal the mechanistic underpinnings of HIV-1 capsid nuclear entry. We found that trimeric interface formed via three capsid protein hexamers is targeted by a triple-arginine (RRR) motif but not the canonical phenylalanine-glycine (FG) motif of NUP153. As NUP153 is located on the nuclear face of the NPC, this result implies that the assembled capsid must cross the NPC in vivo. This hypothesis is corroborated by our observations of tubular capsid assemblies penetrating through NUP153 NuPODs. NUP153 prefers to bind highly curved capsid assemblies including those found at the tips of viral cores, thereby facilitating capsid insertion into the NPC. Furthermore, a balance of capsid stabilization by NUP153 and deformation by CPSF6, along with other cellular factors, may allow for the intact capsid to pass NPCs of various sizes. The NuPOD system serves as a unique tool for unraveling the previously elusive mechanisms of nuclear import of HIV-1 and other viruses.


2018 ◽  
Vol 92 (13) ◽  
pp. e00229-18 ◽  
Author(s):  
Xinlong Luo ◽  
Wei Yang ◽  
Guangxia Gao

ABSTRACTHuman immunodeficiency virus type 1 (HIV-1) can infect nondividing cells via passing through the nuclear pore complex. The nuclear membrane-imbedded protein SUN2 was recently reported to be involved in the nuclear import of HIV-1. Whether SUN1, which shares many functional similarities with SUN2, is involved in this process remained to be explored. Here we report that overexpression of SUN1 specifically inhibited infection by HIV-1 but not that by simian immunodeficiency virus (SIV) or murine leukemia virus (MLV). Overexpression of SUN1 did not affect reverse transcription but led to reduced accumulation of the 2-long-terminal-repeat (2-LTR) circular DNA and integrated viral DNA, suggesting a block in the process of nuclear import. HIV-1 CA was mapped as a determinant for viral sensitivity to SUN1. Treatment of SUN1-expressing cells with cyclosporine (CsA) significantly reduced the sensitivity of the virus to SUN1, and an HIV-1 mutant containing CA-G89A, which does not interact with cyclophilin A (CypA), was resistant to SUN1 overexpression. Downregulation of endogenous SUN1 inhibited the nuclear entry of the wild-type virus but not that of the G89A mutant. These results indicate that SUN1 participates in the HIV-1 nuclear entry process in a manner dependent on the interaction of CA with CypA.IMPORTANCEHIV-1 infects both dividing and nondividing cells. The viral preintegration complex (PIC) can enter the nucleus through the nuclear pore complex. It has been well known that the viral protein CA plays an important role in determining the pathways by which the PIC enters the nucleus. In addition, the interaction between CA and the cellular protein CypA has been reported to be important in the selection of nuclear entry pathways, though the underlying mechanisms are not very clear. Here we show that both SUN1 overexpression and downregulation inhibited HIV-1 nuclear entry. CA played an important role in determining the sensitivity of the virus to SUN1: the regulatory activity of SUN1 toward HIV-1 relied on the interaction between CA and CypA. These results help to explain how SUN1 is involved in the HIV-1 nuclear entry process.


Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1425
Author(s):  
Anabel Guedán ◽  
Eve R. Caroe ◽  
Genevieve C. R. Barr ◽  
Kate N. Bishop

HIV-1 can infect non-dividing cells. The nuclear envelope therefore represents a barrier that HIV-1 must traverse in order to gain access to the host cell chromatin for integration. Hence, nuclear entry is a critical step in the early stages of HIV-1 replication. Following membrane fusion, the viral capsid (CA) lattice, which forms the outer face of the retroviral core, makes numerous interactions with cellular proteins that orchestrate the progress of HIV-1 through the replication cycle. The ability of CA to interact with nuclear pore proteins and other host factors around the nuclear pore determines whether nuclear entry occurs. Uncoating, the process by which the CA lattice opens and/or disassembles, is another critical step that must occur prior to integration. Both early and delayed uncoating have detrimental effects on viral infectivity. How uncoating relates to nuclear entry is currently hotly debated. Recent technological advances have led to intense discussions about the timing, location, and requirements for uncoating and have prompted the field to consider alternative uncoating scenarios that presently focus on uncoating at the nuclear pore and within the nuclear compartment. This review describes recent advances in the study of HIV-1 nuclear entry, outlines the interactions of the retroviral CA protein, and discusses the challenges of investigating HIV-1 uncoating.


2020 ◽  
Vol 117 (45) ◽  
pp. 28344-28354 ◽  
Author(s):  
Lisa Miorin ◽  
Thomas Kehrer ◽  
Maria Teresa Sanchez-Aparicio ◽  
Ke Zhang ◽  
Phillip Cohen ◽  
...  

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic that is a serious global health problem. Evasion of IFN-mediated antiviral signaling is a common defense strategy that pathogenic viruses use to replicate and propagate in their host. In this study, we show that SARS-CoV-2 is able to efficiently block STAT1 and STAT2 nuclear translocation in order to impair transcriptional induction of IFN-stimulated genes (ISGs). Our results demonstrate that the viral accessory protein Orf6 exerts this anti-IFN activity. We found that SARS-CoV-2 Orf6 localizes at the nuclear pore complex (NPC) and directly interacts with Nup98-Rae1 via its C-terminal domain to impair docking of cargo-receptor (karyopherin/importin) complex and disrupt nuclear import. In addition, we show that a methionine-to-arginine substitution at residue 58 impairs Orf6 binding to the Nup98-Rae1 complex and abolishes its IFN antagonistic function. All together our data unravel a mechanism of viral antagonism in which a virus hijacks the Nup98-Rae1 complex to overcome the antiviral action of IFN.


2006 ◽  
Vol 84 (3-4) ◽  
pp. 279-286 ◽  
Author(s):  
Birthe Fahrenkrog

The nuclear pore complex (NPC) is the sole gateway between the nucleus and the cytoplasm of interphase eukaryotic cells, and it mediates all trafficking between these 2 cellular compartments. As such, the NPC and nuclear transport play central roles in translocating death signals from the cell membrane to the nucleus where they initiate biochemical and morphological changes occurring during apoptosis. Recent findings suggest that the correlation between the NPC, nuclear transport, and apoptosis goes beyond the simple fact that NPCs mediate nuclear transport of key players involved in the cell death program. In this context, the accessibility of key regulators of apoptosis appears to be highly modulated by nuclear transport (e.g., impaired nuclear import might be an apoptotic trigger). In this review, recent findings concerning the unexpected tight link between NPCs, nuclear transport, and apoptosis will be presented and critically discussed.


2011 ◽  
Vol 208 (6) ◽  
pp. i16-i16
Author(s):  
Anne Monette ◽  
Nelly Panté ◽  
Andrew J. Mouland

Sign in / Sign up

Export Citation Format

Share Document