TNF-α mediates SDF-1α–induced NF-κB activation and cytotoxic effects in primary astrocytes
Yulong Han, … , Carlos A. Pardo, Richard M. Ransohoff
Yulong Han, … , Carlos A. Pardo, Richard M. Ransohoff
Published August 1, 2001
Citation Information: J Clin Invest. 2001;108(3):425-435. https://doi.org/10.1172/JCI12629.
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Article

TNF-α mediates SDF-1α–induced NF-κB activation and cytotoxic effects in primary astrocytes

Abstract

Stromal-derived cell factor-1α (SDF-1α; CXCL12) and its receptor, CXCR4, are constitutively expressed on neuroepithelial cells and are believed to be involved in both development and pathological processes, such as AIDS-associated neurologic disorders. Here, we demonstrate that SDF-1α activates NF-κB, stimulates production of chemokines and cytokines, and induces cell death in primary astrocytes, effects that depend on ongoing secretion of TNF-α. SDF-1α upregulated TNF-α mRNA and protein secretion, as well as TNF receptor 2 expression. TNF-α treatment mimicked SDF-1α induction of NF-κB, IL-1α/β, and RANTES, as well as cell death; neutralizing antibodies against TNF-α opposed these responses. We also found that SDF-1α activated Erk1 and Erk2 (Erk1/2) MAPK in a biphasic fashion. Early Erk1/2 activation was stimulated directly by SDF-1α and late activation was mediated by TNF-α. PD98059 suppression of early Erk1/2 activation correlated with reduction of SDF-1α–induced TNF-α expression. Late Erk1/2 activation was involved in TNF-α–stimulated NF-κB activation and cytokine induction. SDF-1α was induced in reactive CXCR4-positive astrocytes near axotomized spinal cord motor neurons, consistent with autocrine SDF-1/CXCR4 signaling in these cells. We propose that these novel effects of SDF-1α are relevant to the pathogenic and developmental roles of SDF-1α in the CNS.

Authors

Yulong Han, Tao He, DeRen Huang, Carlos A. Pardo, Richard M. Ransohoff

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Figure 1

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SDF-1α activates NF-κB in primary astrocytes. (a–f) Immunofluorescence s...
SDF-1α activates NF-κB in primary astrocytes. (a–f) Immunofluorescence staining of ventral lumbar spinal cord section: anti-GFAP (a and d, red), anti–SDF-1α (b, green), and anti-CXCR4 (e, green). Colocalization of GFAP and SDF-1α (c) or CXCR4 (f) within astrocytes (arrowheads). (g–i) SDF-1α induces NF-κB DNA binding activity. Primary astrocytes were incubated with medium alone or SDF-1α (2 hours) or IFN-γ (250 U/ml; 15 minutes) or TNF-α (30 minutes). Shown are results of EMSA with Fcγ-GAS (g) and IP-10 κB2 probes (g–h). SDF-1α selectively induces NF-κB DNAbinding complex (g) competed by wild-type but not mutant κB elements (h) or supershifted by anti-p50 and anti-p65 antibodies (i). (j) SDF-1α stimulates NF-κB reporter in luciferase activity assay. Primary astrocytes were cotransfected with p6κB-luc and pRL-TK constructs and treated with SDF-1α for 6 hours in the presence or absence of pertussis toxin (PTX) or PD98059 (PD). Shown are mean ± SD(Student’s t test:*PTX + SDF-1α vs. SDF-1α, P = 0.5689; **PD + SDF-1α vs. SDF-1α , P < 0.001). (k) PTX does not suppress SDF-1α- or TNF-α–stimulated activation. Primary astrocytes were treated with SDF-1α for 2 hours or TNF-α for 30 minutes in the presence or absence of PTX. Shown are results of EMSA with IP-10 κB2 probes. Data represent three or more than three experiments (g–k).