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- Title
A novel role for protein tyrosine phosphatase 1B as a positive regulator of neuroinflammation.
- Authors
Gyun Jee Song; Myungsu Jung; Jong-Heon Kim; Hana Park; Rahman, Md Habibur; Sheng Zhang; Zhong-Yin Zhang; Dong Ho Park; Hyun Kook; In-Kyu Lee; Kyoungho Suk; Song, Gyun Jee; Jung, Myungsu; Kim, Jong-Heon; Park, Hana; Zhang, Sheng; Zhang, Zhong-Yin; Park, Dong Ho; Kook, Hyun; Lee, In-Kyu
- Abstract
<bold>Background: </bold>Protein tyrosine phosphatase 1B (PTP1B) is a member of the non-transmembrane phosphotyrosine phosphatase family. Recently, PTP1B has been proposed to be a novel target of anti-cancer and anti-diabetic drugs. However, the role of PTP1B in the central nervous system is not clearly understood. Therefore, in this study, we sought to define PTP1B's role in brain inflammation.<bold>Methods: </bold>PTP1B messenger RNA (mRNA) and protein expression levels were examined in mouse brain and microglial cells after LPS treatment using RT-PCR and western blotting. Pharmacological inhibitors of PTP1B, NF-κB, and Src kinase were used to analyze these signal transduction pathways in microglia. A Griess reaction protocol was used to determine nitric oxide (NO) concentrations in primary microglia cultures and microglial cell lines. Proinflammatory cytokine production was measured by RT-PCR. Western blotting was used to assess Src phosphorylation levels. Immunostaining for Iba-1 was used to determine microglial activation in the mouse brain.<bold>Results: </bold>PTP1B expression levels were significantly increased in the brain 24 h after LPS injection, suggesting a functional role for PTP1B in brain inflammation. Microglial cells overexpressing PTP1B exhibited an enhanced production of NO and gene expression levels of TNF-α, iNOS, and IL-6 following LPS exposure, suggesting that PTP1B potentiates the microglial proinflammatory response. To confirm the role of PTP1B in neuroinflammation, we employed a highly potent and selective inhibitor of PTP1B (PTP1Bi). In LPS- or TNF-α-stimulated microglial cells, in vitro blockade of PTP1B activity using PTP1Bi markedly attenuated NO production. PTP1Bi also suppressed the expression levels of iNOS, COX-2, TNF-α, and IL-1β. PTP1B activated Src by dephosphorylating the Src protein at a negative regulatory site. PTP1B-mediated Src activation led to an enhanced proinflammatory response in the microglial cells. An intracerebroventricular injection of PTP1Bi significantly attenuated microglial activation in the hippocampus and cortex of LPS-injected mice compared to vehicle-injected mice. The gene expression levels of proinflammatory cytokines were also significantly suppressed in the brain by a PTP1Bi injection. Together, these data suggest that PTP1Bi has an anti-inflammatory effect in a mouse model of neuroinflammation.<bold>Conclusions: </bold>This study demonstrates that PTP1B is an important positive regulator of neuroinflammation and is a promising therapeutic target for neuroinflammatory and neurodegenerative diseases.
- Subjects
PROTEIN-tyrosine kinases; CYTOKINES; LIPOPOLYSACCHARIDES; MICROGLIA; CENTRAL nervous system
- Publication
Journal of Neuroinflammation, 2016, Vol 13, p1
- ISSN
1742-2094
- Publication type
journal article
- DOI
10.1186/s12974-016-0545-3