Phlpp1 is associated with human intervertebral disc degeneration and its deficiency promotes healing after needle puncture injury in mice

Changli Zhang, Madeline P. Smith, George K. Zhou, Alon Lai, Robert C. Hoy, Victoria Mroz, Olivia M. Torre, Damien M. Laudier, Elizabeth W. Bradley, Jennifer J. Westendorf, James C. Iatridis, Svenja Illien-Jünger

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Back pain is a leading cause of global disability and is strongly associated with intervertebral disc (IVD) degeneration (IDD). Hallmarks of IDD include progressive cell loss and matrix degradation. The Akt signaling pathway regulates cellularity and matrix production in IVDs and its inactivation is known to contribute to a catabolic shift and increased cell loss via apoptosis. The PH domain leucine-rich repeat protein phosphatase (Phlpp1) directly regulates Akt signaling and therefore may play a role in regulating IDD, yet this has not been investigated. The aim of this study was to investigate if Phlpp1 has a role in Akt dysregulation during IDD. In human IVDs, Phlpp1 expression was positively correlated with IDD and the apoptosis marker cleaved Caspase-3, suggesting a key role of Phlpp1 in the progression of IDD. In mice, 3 days after IVD needle puncture injury, Phlpp1 knockout (KO) promoted Akt phosphorylation and cell proliferation, with less apoptosis. At 2 and 8 months after injury, Phlpp1 deficiency also had protective effects on IVD cellularity, matrix production, and collagen structure as measured with histological and immunohistochemical analyses. Specifically, Phlpp1-deletion resulted in enhanced nucleus pulposus matrix production and more chondrocytic cells at 2 months, and increased IVD height, nucleus pulposus cellularity, and extracellular matrix deposition 8 months after injury. In conclusion, Phlpp1 has a role in limiting cell survival and matrix degradation in IDD and research targeting its suppression could identify a potential therapeutic target for IDD.

Original languageEnglish (US)
Article number754
JournalCell Death and Disease
Volume10
Issue number10
DOIs
StatePublished - Oct 1 2019

ASJC Scopus subject areas

  • Immunology
  • Cellular and Molecular Neuroscience
  • Cell Biology
  • Cancer Research

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    Zhang, C., Smith, M. P., Zhou, G. K., Lai, A., Hoy, R. C., Mroz, V., Torre, O. M., Laudier, D. M., Bradley, E. W., Westendorf, J. J., Iatridis, J. C., & Illien-Jünger, S. (2019). Phlpp1 is associated with human intervertebral disc degeneration and its deficiency promotes healing after needle puncture injury in mice. Cell Death and Disease, 10(10), [754]. https://doi.org/10.1038/s41419-019-1985-3