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Expression of Sam68 Associates with Neuronal Apoptosis and Reactive Astrocytes After Spinal Cord Injury

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Abstract

Src-associated in mitosis (Sam68; 68 kDa) is a novel RNA-binding protein that belongs to the signal transduction and activation of RNA family involved in various biological processes. However, the expression and roles of Sam68 in the central nervous system remain unknown. In the present study, we performed a spinal cord injury (SCI) model in adult rats and found a significant increase of Sam68 protein levels in this model, which reached a peak at day 3 and then gradually returned to normal levels at day 14 after SCI. We use immunohistochemistry analysis revealing a widespread distribution of Sam68 in the spinal cord. In addition, double-immunofluorescence staining showed that Sam68 immunoreactivity was found predominantly in neurons and astrocytes. Moreover, colocalization of Sam68/active caspase-3 has been respectively detected in neuronal nuclei, and colocalization of Sam68/PCNA has been detected in glial fibrillary acidic protein. In vitro, we found that depletion of Sam68 by short interfering RNA inhibits neuronal apoptosis and astrocyte proliferation and decreases cyclin D1 protein levels. In conclusion, this is the first study to find the Sam68 expression in SCI. Our results suggest that Sam68 might be illustrated in the apoptosis of neurons and proliferation of astrocytes after SCI. This research will provide new drug targets for clinical treatment of SCI.

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Abbreviations

Sam68:

Src-associated in mitosis

SCI:

Spinal cord injury

NeuN:

Neuronal nuclear antigen

PCNA:

Proliferating cell nuclear antigen

GFAP:

Glial fibrillary acidic protein

GAPDH:

Glyceraldehyde-3-phosphate dehydrogenase

siRNA:

Short interfering RNA

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Acknowledgments

This work was supported by National Natural Science Foundation of China (Grant No. 81402220) and Nantong University Innovation Project (YKS14011).

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Authors and Affiliations

  1. Department of Orthopaedics, Affiliated Hospital of Nantong University, Jiangsu Province Key Laboratory for Information and Molecular Drug Target, Nantong University, 20. Xisi Road, Nantong, 226001, Jiangsu, China

    Xinlei Chen, Rong Qian, Jie Liu, Yu Yao & Feng Zhang

  2. Department of Orthopaedics, People’s Hospital of Yixing City, Yixing, 214200, Jiangsu, China

    Lei Liu & Zhenhuan Jiang

  3. Department of Rehabilitation, Nantong Second People’s Hospital, Nantong, 226001, Jiangsu, China

    Xinjian Song & Jianbing Ren

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  1. Xinlei Chen
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  2. Lei Liu
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  3. Rong Qian
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  4. Jie Liu
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  5. Yu Yao
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  9. Feng Zhang
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Correspondence to Feng Zhang.

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Chen, X., Liu, L., Qian, R. et al. Expression of Sam68 Associates with Neuronal Apoptosis and Reactive Astrocytes After Spinal Cord Injury. Cell Mol Neurobiol 37, 487–498 (2017). https://doi.org/10.1007/s10571-016-0384-x

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  • DOI: https://doi.org/10.1007/s10571-016-0384-x

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