The goal of this proposal is to elucidate the role of specific host proteins that interact with HIV-1 Gag in virus replication. We have identified the host proteins kindlin-3 and pacsin2 as binding partners for the NC and p6 domains of HIV-1 Gag, respectively. Knockdown and reconstitution experiments show that both proteins are critical for the spreading of HIV-1 among T cells. Based on our preliminary data, our hypothesis is that kindlin-3 and pacsin2 are involved in the cell-to- cell transmission of HIV-1. Kindlin-3 is required for the function of integrins such as LFA-1, which has been implicated in HIV transmission. However, our data demonstrate a striking requirement for kindlin-3 for HIV-1 replication even in T lymphoid cells lacking LFA-1. Our working model is that HIV-1 Gag mimics the kindlin-recruiting activity of integrins to induce donor cell polarization towards the virologial synapse and thereby promote virus transfer. We propose to investigate the mechanism by which kindlin-3 associates with HIV-1 virions, which step of the viral life cycle is promoted by kindlin-3, whether downstream partners of kindlin-3 are involved in HIV-1 replication, and whether the kindlin-3-dependent activity of integrins other than LFA-1 is important for HIV-1 replication. Pacsin2 can generate membrane curvature and nucleate filopodia formation. HIV-1 frequently buds from filopodia, and viral filopodia capped by Gag have been implicated in HIV-1 cell-cell transmission. Thus, pacsin2 may be important for HIV-1 transmission because it is involved in viral filopodia formation. We propose to investigate the role of Gag ubiquitination in the recruitment of pacsin2 into viral particles, the precise role of pacsin2 in HIV-1 replication, he role of the actin remodeling activity of pacsin2 in HIV-1 replication, and whether pacsin2 interaction partners on recycling endosomes are involved in HIV-1 replication. The transfer of HIV-1 from cell to cell is thought to be the predominant mode of transmission, but the molecular basis is poorly understood. An understanding of the roles of kindlin-3 and pacsin2 in HIV-1 replication may provide novel insights into this important mode of transmission.

Public Health Relevance

Our application proposes an in-depth investigation of the roles of specific host proteins that are taken up into virions in the spreading of HIV-1. The proposed studies are relevant to public health, because they may yield important new insights into how HIV-1 spreads from cell to cell, and may identify vulnerabilities that can be exploited to inhibit this important mode of transmission.

National Institute of Health (NIH)
Research Project (R01)
Project #
Application #
Study Section
AIDS Molecular and Cellular Biology Study Section (AMCB)
Program Officer
Sharma, Opendra K
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Massachusetts Medical School Worcester
Schools of Medicine
United States
Zip Code
Lata, Suman; Schoehn, Guy; Solomons, Julianna et al. (2009) Structure and function of ESCRT-III. Biochem Soc Trans 37:156-60
Usami, Yoshiko; Popov, Sergei; Popova, Elena et al. (2009) The ESCRT pathway and HIV-1 budding. Biochem Soc Trans 37:181-4
Pizzato, Massimo; Popova, Elena; Gottlinger, Heinrich G (2008) Nef can enhance the infectivity of receptor-pseudotyped human immunodeficiency virus type 1 particles. J Virol 82:10811-9
Ma, Yu May; Boucrot, Emmanuel; Villen, Judit et al. (2007) Targeting of AMSH to endosomes is required for epidermal growth factor receptor degradation. J Biol Chem 282:9805-12
Calistri, Arianna; Sette, Paola; Salata, Cristiano et al. (2007) Intracellular trafficking and maturation of herpes simplex virus type 1 gB and virus egress require functional biogenesis of multivesicular bodies. J Virol 81:11468-78
Usami, Yoshiko; Popov, Sergei; Gottlinger, Heinrich G (2007) Potent rescue of human immunodeficiency virus type 1 late domain mutants by ALIX/AIP1 depends on its CHMP4 binding site. J Virol 81:6614-22
Pizzato, Massimo; Helander, Anna; Popova, Elena et al. (2007) Dynamin 2 is required for the enhancement of HIV-1 infectivity by Nef. Proc Natl Acad Sci U S A 104:6812-7
Zamborlini, Alessia; Usami, Yoshiko; Radoshitzky, Sheli R et al. (2006) Release of autoinhibition converts ESCRT-III components into potent inhibitors of HIV-1 budding. Proc Natl Acad Sci U S A 103:19140-5
Muziol, Tadeusz; Pineda-Molina, Estela; Ravelli, Raimond B et al. (2006) Structural basis for budding by the ESCRT-III factor CHMP3. Dev Cell 10:821-30
Strack, Bettina; Calistri, Arianna; Craig, Stewart et al. (2003) AIP1/ALIX is a binding partner for HIV-1 p6 and EIAV p9 functioning in virus budding. Cell 114:689-99

Showing the most recent 10 out of 35 publications