Human Immunodeficiency Virus Type 1 Protease Cleaves Procaspase 8 In Vivo

Abstract

Human immunodeficiency virus type 1 (HIV-1) infection causes apoptosis of infected CD4 T cells as well as uninfected (bystander) CD4 and CD8 T cells. It remains unknown what signals cause infected cells to die.We demonstrate that HIV-1 protease specifically cleaves procaspase 8 to create a novel fragment termed casp8p41, which independently induces apoptosis. casp8p41 is specific to HIV-1 protease-induced death but not other caspase 8-dependent death stimuli. In HIV-1-infected patients, casp8p41 is detected only in CD4 ؉ T cells, predominantly in the CD27 ؉ memory subset, its presence increases with increasing viral load, and it colocalizes with both infected and apoptotic cells. These data indicate that casp8p41 independently induces apoptosis and is a specific product of HIV-1 protease which may contribute to death of HIV-1-infected cells.

The HIV-1-Specific Protein Casp8p41 Induces Death of Infected Cells through Bax/Bak

“…Casp8p41 in pEGFP and pcDNA3 were previously described (3,44). The Casp8p41⌬DED constructs were made by PCR using primers 5Ј-CGGATCCATGGAAAGGGACTT-3Ј and 5Ј-CTAGATTAAAAC ACTTTGGGTTTTCCAGCAAGG-3Ј, cut with BamHI and XbaI, and inserted into the designated sites in vectors.…”

“…Mutations in HIV-1 protease that selectively alter the ability of the protease to cleave caspase 8 also reduce HIV-1-induced cell death compared to wild-type (WT) protease (42). Since Casp8p41 is unique to HIV-1-infected cells (44) and is a host cellular protein, which would not be subject to mutational escape, it is an attractive candidate for therapeutic targeting.…”

“…Indeed, the effects of enhanced immune activation (2), bacterial translocation (56), and the heightened production of proapoptotic ligands (57) are seen in a variety of other disease states. A recently described pathway of CD4 death that is unique to HIV-1 is one whereby HIV-1 protease, which is active within the cytosolic compartment of HIV-1-infected T cells (24)(25)(26), cleaves the host protein caspase 8, creating a novel cleavage fragment termed Casp8p41 (44). This fragment is missing the catalytic cysteine at position 360 that is responsible for the catalytic activity of caspase 8.…”

Production of Retroviral and Lentiviral Gene Therapy Vectors: Challenges in the Manufacturing of Lipid Enveloped Virus

“…It is well established that numerous HIV-1-encoded proteins are capable of causing cell death, including tat, nef, env, vpr and the protease (PR) (Gougeon 2003); from those, only the protease is still required in the current packaging systems. HIV protease mediates its toxicity in vitro and in vivo, by cleaving and activating procaspase 8, leading to mitochondrial release of cytochrome c, activation of the downstream caspases 9 and 3 and lastly, nuclear fragmentation (Nie et al 2007;Nie et al 2002). Ikeda and coworkers have reported the development of a 293T derived cell line, STAR, stable and continuously producing LV using an HIV-1 codon optimized gag-pol (Ikeda et al 2003).…”

The importance of physicochemical characteristics and nonlinear classifiers in determining HIV-1 protease specificity

“…746: 746 exemplars (401 cleaved, 345 noncleaved) 14 1625: 1,625 exemplars (374 cleaved, 1251 noncleaved) 8 Schilling: 3,272 exemplars (434 cleaved, 2,838 noncleaved) 15 Impens: 947 exemplars (149 cleaved, 798 noncleaved)collected from 4 publications [16][17][18][19] This corresponds to a total of 6,590 exemplars, of which 1,358 represent HIV-1 protease cleavages. These 4 data sets contain 740 repeated exemplars, and 10 octamers with different classifications in different sets.…”