HIV Type 1<i>nef</i>Gene Inhibits Tumor Necrosis Factor α-Induced Apoptosis and Promotes Cell Proliferation through the Action of MAPK and JNK in Human Glial Cells

Robichaud, Gilles A.; Poulin, Louise

doi:10.1089/088922200750054684

Cited by 25 publications

(18 citation statements)

References 25 publications

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“…The most dramatic signaling abnormality induced by Nef results from its interaction with the Hck protein tyrosine kinase, resulting in oncogenic transformation of Rat-2 fibroblast (29). Nef induces resistance to tumor necrosis factor-␣-induced apoptosis in U251MG astrocyte cell line through interaction with MAPK and consequently promotes cell growth (30). In our study, the presence of Nef clearly triggers podocyte proliferation and dedifferentiation, growth in soft agar, and focus formation.…”

Section: Discussionsupporting

confidence: 48%

HIV-1 Nef Induces Proliferation and Anchorage-Independent Growth in Podocytes

Husain

Gusella²,

Klotman

et al. 2002

Journal of the American Society of Nephrology

141

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Abstract. HIV-associated nephropathy (HIVAN) is now the third leading cause of end-stage renal disease in the African American population. HIV-1 infects renal tubular and glomerular epithelial cells or podocytes, cells that are a critical part of the filtration barrier. HIV-1 infection induces the loss of podocyte differentiation markers and increases podocyte proliferation. It has been previously shown that HIV-infection induces loss of contact inhibition. Here, the HIV-1 gene responsible for proliferative changes is identified by using cultured podocytes in vitro. The HIV-1 proviral construct, pNL4-3 was rendered noninfectious by replacing the HIV-1 gag/pol sequences with an EGFP reporter gene (pNL4-3: ⌬G/P-EGFP). This construct was then pseudotyped with VSV.G envelope to infect podocytes that were conditionally immortalized with SV-40 T antigen. In addition, mutated constructs were engineered with premature stop codons in the HIV-1 env, vif, vpr, vpu, nef, or rev genes. The parental construct and all the other mutated constructs, with the exception of nef, induced proliferation under nonpermissive conditions and anchorage-independent growth (colony formation in soft agar) under permissive conditions. In contrast, deletion of nef markedly reduced proliferation and colony formation. Although tat alone, or tat plus rev induced marginal levels of anchorage-independent growth, coexpression with nef significantly increased colony formation. Finally, stable expression of Nef in a retroviral vector, pBabepuro, was sufficient to induce increased proliferation and colony formation. Moreover, nef induced saturation density and loss of contact inhibition. These data indicate that Nef induces multiple proliferative effects in podocytes in culture and that nef may therefore be an important gene in the pathogenesis of HIVAN in vivo.

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Section: Discussionsupporting

confidence: 48%

HIV-1 Nef Induces Proliferation and Anchorage-Independent Growth in Podocytes

Husain

Gusella²,

Klotman

et al. 2002

Journal of the American Society of Nephrology

141

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“…Calcium/calmodulin (Ca 2+ /CaM)-dependent protein kinases have been shown to regulate mitogen-activated protein kinases (MAPKs) (Enslen et al, 1996). Dysregulated MAPKs have been detected in the central nervous system of SIV-infected macaques (Barber et al, 2004), and it has been shown that Nef modulates MAPK activity in astrocytic U251MG cells (Robichaud and Poulin, 2000). Finally, activated p38 MAPK is necessary for CCL2/MCP-1 expression (Rovin et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

HIV-1 Nef upregulates CCL2/MCP-1 expression in astrocytes in a myristoylation- and calmodulin-dependent manner

Lehmann

Masanetz

Krämer

et al. 2006

Journal of Cell Science

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27 kDa accessory HIV and simian immunodeficiency virus (SIV) protein necessary for efficient virus replication and high viral load, has for several years been considered as a progression factor to AIDS (Greene and Peterlin, 2002). According to several excellent reviews, a variety of diverse functions including downregulation of cell-surface molecules have been assigned to the protein (Das and Jameel, 2005;Piguet and Trono, 1999;Roeth and Collins, 2006). Moreover, HIV-associated dementia (HAD) correlates with infiltration of monocytes into the brain. The accessory HIV-1 negative factor (Nef) protein, which modulates several signaling pathways, is constitutively present in persistently infected astroctyes. We demonstrated that monocytes responded with chemotaxis when subjected to cell culture supernatants of nef-expressing astrocytic U251MG cells. Using a protein array, we identified CC chemokine ligand 2/monocyte chemotactic protein-1 (CCL2/MCP-1) as a potential chemotactic factor mediating this phenomenon. CCL2/MCP-1 upregulation by Nef was further confirmed by ribonuclease protection assay, RT-PCR and ELISA. By applying neutralizing antibodies against CCL2/MCP-1 and using CCR2-deficient monocytes, we confirmed CCL2/MCP-1 as the exclusive factor secreted by nefexpressing astrocytes capable of attracting monocytes. Additionally, we showed that Nef-induced CCL2/MCP-1 expression depends on the myristoylation moiety of Nef and requires functional calmodulin. In summary, we suggest that Nef-induced CCL2/MCP-1 expression in astrocytes contributes to infiltration of monocytes into the brain, and thereby to progression of HAD.

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“…We have previously reported that sublines expressing wild-type Nef show morphological alterations, increased expression of activation markers (Kohleisen et al, 1999) and increased tumorigenicity in nude mice (Kramer-Hammerle et al, 2001). In addition Nef expression has been shown to protect U251MG cells from TNF-alpha induced apoptosis (Robichaud and Poulin, 2000). These observations suggest that stable expression of Nef alters cellular properties of astrocytes.…”

Section: Introductionmentioning

confidence: 88%