Skip to main content

Advertisement

SpringerLink
Log in

Loss of pleckstrin homology domain and leucine-rich repeat protein phosphatase 2 has protective effects on high glucose-injured retinal ganglion cells via the effect on the Akt–GSK–3β–Nrf2 pathway

  • Original Research Paper
  • Published:
Inflammation Research Aims and scope Submit manuscript

Abstract

Objective

Pleckstrin homology domain and leucine-rich repeat protein phosphatase 2 (PHLPP2) is linked to various pathological states. However, whether PHLPP2 mediates diabetic retinopathy is unaddressed. This work explored the biological function of PHLPP2 in modulating high glucose (HG)-elicited damage of retinal ganglion cells (RGCs), an in vitro model for studying diabetic retinopathy.

Methods

Mouse RGCs were treated with HG to establish a cell model. PHLPP2 was silenced by transfecting specific shRNAs targeting PHLPP2. RT-qPCR, immunoblotting, CCK-8 assay, flow cytometry, TUNEL assay, and ELISA were carried out.

Results

Significant increases in PHLPP2 levels were observed in cultured RGCs exposed to HG. The severe damages evoked by HG to RGCs were remarkably weakened in PHLPP2-silenced RGCs, including improved cell survival, attenuated cell apoptosis, repressed oxidative stress, and prohibited proinflammatory response. The silencing of PHLPP2 strengthened the activation of Nrf2 in HG-treated RGCs via modulation of the Akt–GSK–3β axis. Interruption of the Akt–GSK–3β axis reversed PHLPP2-silencing-elicited Nrf2 activation. The protective effects of PHLPP2 silencing on HG-induced injury of RGCs were diminished by Nrf2 inhibition.

Conclusions

The loss of PHLPP2 was beneficial for HG-injured RGCs through the effect on the Akt–GSK–3β–Nrf2 pathway. This work suggests a possible role of PHLPP2 in diabetic retinopathy.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

Similar content being viewed by others

Data availability

The datasets used during the present study are available from the corresponding author on reasonable request.

Abbreviations

PHLPP2:

Pleckstrin homology domain and leucine-rich repeat protein phosphatase 2

HG:

High glucose

RGCs:

Retinal ganglion cells

Nrf2:

Nuclear factor erythroid 2-related factor 2

GSK-3β:

Glycogen synthase kinase-3β

ARE:

Anti-oxidant response elements

RT-qPCR:

Real-time quantitative polymerase chain reaction

MDA:

Malondialdehyde

SOD:

Superoxide dismutase

ELISA:

Enzyme-linked immunosorbent

IL:

Interleukin

TNF:

Tumor necrosis factor

References

  1. Wong TY, Cheung CM, Larsen M, Sharma S, Simo R. Diabetic retinopathy. Nat Rev Dis Primers. 2016;2:16012.

    Article  PubMed  Google Scholar 

  2. Simo R, Hernandez C, European Consortium for the Early Treatment of Diabetic R. Neurodegeneration in the diabetic eye: new insights and therapeutic perspectives. Trends Endocrinol Metab. 2014;25:23–33.

    Article  CAS  PubMed  Google Scholar 

  3. Baden T, Berens P, Franke K, Roman Roson M, Bethge M, Euler T. The functional diversity of retinal ganglion cells in the mouse. Nature. 2016;529:345–50.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  4. Jadeja RN, Martin PM. Oxidative stress and inflammation in retinal degeneration. Antioxidants (Basel). 2021;10:790.

    Article  CAS  PubMed  Google Scholar 

  5. Chalke SD, Kale PP. Combination approaches targeting neurodegeneration, oxidative stress and inflammation in the treatment of diabetic retinopathy. Curr Drug Targets. 2021;22:1810–24.

    Article  CAS  PubMed  Google Scholar 

  6. Gao T, Furnari F, Newton AC. PHLPP: a phosphatase that directly dephosphorylates Akt, promotes apoptosis, and suppresses tumor growth. Mol Cell. 2005;18:13–24.

    Article  CAS  PubMed  Google Scholar 

  7. O’Neill AK, Niederst MJ, Newton AC. Suppression of survival signalling pathways by the phosphatase PHLPP. FEBS J. 2013;280:572–83.

    Article  CAS  PubMed  Google Scholar 

  8. Brognard J, Newton AC. PHLiPPing the switch on Akt and protein kinase C signaling. Trends Endocrinol Metab. 2008;19:223–30.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Warfel NA, Newton AC. Pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP): a new player in cell signaling. J Biol Chem. 2012;287:3610–6.

    Article  CAS  PubMed  Google Scholar 

  10. Mathur A, Pandey VK, Kakkar P. PHLPP: a putative cellular target during insulin resistance and type 2 diabetes. J Endocrinol. 2017;233:R185–98.

    Article  CAS  PubMed  Google Scholar 

  11. Kim K, Kang JK, Jung YH, Lee SB, Rametta R, Dongiovanni P, et al. Adipocyte PHLPP2 inhibition prevents obesity-induced fatty liver. Nat Commun. 2021;12:1822.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  12. Yeh ST, Zambrano CM, Koch WJ, Purcell NH. PH domain leucine-rich repeat protein phosphatase 2 (PHLPP2) regulates G-protein-coupled receptor kinase 5 (GRK5)-induced cardiac hypertrophy in vitro. J Biol Chem. 2018;293:8056–64.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  13. Liu J, Weiss HL, Rychahou P, Jackson LN, Evers BM, Gao T. Loss of PHLPP expression in colon cancer: role in proliferation and tumorigenesis. Oncogene. 2009;28:994–1004.

    Article  CAS  PubMed  Google Scholar 

  14. Huang H, Pan X, Jin H, Li Y, Zhang L, Yang C, et al. PHLPP2 Downregulation contributes to lung carcinogenesis following B[a]P/B[a]PDE exposure. Clin Cancer Res. 2015;21:3783–93.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  15. Lemoine KA, Fassas JM, Ohannesian SH, Purcell NH. On the PHLPPside: emerging roles of PHLPP phosphatases in the heart. Cell Signal. 2021;86: 110097.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  16. Brognard J, Sierecki E, Gao T, Newton AC. PHLPP and a second isoform, PHLPP2, differentially attenuate the amplitude of Akt signaling by regulating distinct Akt isoforms. Mol Cell. 2007;25:917–31.

    Article  CAS  PubMed  Google Scholar 

  17. Wei XE, Zhang FY, Wang K, Zhang QX, Rong LQ. Assembly of the FKBP51-PHLPP2-AKT signaling complex in cerebral ischemia/reperfusion injury in rats. Brain Res. 2014;1566:60–8.

    Article  CAS  PubMed  Google Scholar 

  18. Jin A, Li B, Li W, Xiao D. PHLPP2 downregulation protects cardiomyocytes against hypoxia-induced injury through reinforcing Nrf2/ARE antioxidant signaling. Chem Biol Interact. 2019;314: 108848.

    Article  CAS  PubMed  Google Scholar 

  19. Wen YA, Li X, Goretsky T, Weiss HL, Barrett TA, Gao T. Loss of PHLPP protects against colitis by inhibiting intestinal epithelial cell apoptosis. Biochim Biophys Acta. 2015;1852:2013–23.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  20. Rizvi F, Mathur A, Kakkar P. Morin mitigates acetaminophen-induced liver injury by potentiating Nrf2 regulated survival mechanism through molecular intervention in PHLPP2-Akt-Gsk3beta axis. Apoptosis. 2015;20:1296–306.

    Article  CAS  PubMed  Google Scholar 

  21. Mathur A, Rizvi F, Kakkar P. PHLPP2 down regulation influences nuclear Nrf2 stability via Akt-1/Gsk3beta/Fyn kinase axis in acetaminophen induced oxidative renal toxicity: protection accorded by morin. Food Chem Toxicol. 2016;89:19–31.

    Article  CAS  PubMed  Google Scholar 

  22. Gan L, Johnson JA. Oxidative damage and the Nrf2-ARE pathway in neurodegenerative diseases. Biochim Biophys Acta. 2014;1842:1208–18.

    Article  CAS  PubMed  Google Scholar 

  23. Motohashi H, Katsuoka F, Engel JD, Yamamoto M. Small Maf proteins serve as transcriptional cofactors for keratinocyte differentiation in the Keap1-Nrf2 regulatory pathway. Proc Natl Acad Sci U S A. 2004;101:6379–84.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  24. Chen QM. Nrf2 for cardiac protection: pharmacological options against oxidative stress. Trends Pharmacol Sci. 2021;42:729–44.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Jimenez-Villegas J, Ferraiuolo L, Mead RJ, Shaw PJ, Cuadrado A, Rojo AI. NRF2 as a therapeutic opportunity to impact in the molecular roadmap of ALS. Free Radic Biol Med. 2021;173:125–41.

    Article  CAS  PubMed  Google Scholar 

  26. Stenvinkel P, Chertow GM, Devarajan P, Levin A, Andreoli SP, Bangalore S, et al. Chronic inflammation in chronic kidney disease progression: role of Nrf2. Kidney Int Rep. 2021;6:1775–87.

    Article  PubMed  PubMed Central  Google Scholar 

  27. Kowluru RA, Mishra M. Epigenetic regulation of redox signaling in diabetic retinopathy: role of Nrf2. Free Radic Biol Med. 2017;103:155–64.

    Article  CAS  PubMed  Google Scholar 

  28. Nabavi SF, Barber AJ, Spagnuolo C, Russo GL, Daglia M, Nabavi SM, et al. Nrf2 as molecular target for polyphenols: a novel therapeutic strategy in diabetic retinopathy. Crit Rev Clin Lab Sci. 2016;53:293–312.

    Article  CAS  PubMed  Google Scholar 

  29. Li CP, Wang SH, Wang WQ, Song SG, Liu XM. Long noncoding RNA-Sox2OT knockdown alleviates diabetes mellitus-induced retinal ganglion cell (RGC) injury. Cell Mol Neurobiol. 2017;37:361–9.

    Article  CAS  PubMed  Google Scholar 

  30. Lv P, Yu J, Xu X, Lu T, Xu F. Eriodictyol inhibits high glucose-induced oxidative stress and inflammation in retinal ganglial cells. J Cell Biochem. 2019;120:5644–51.

    Article  CAS  PubMed  Google Scholar 

  31. Sun W, Yu J, Kang Q. Upregulation of heme oxygenase-1 by Brahma-related gene 1 through Nrf2 signaling confers protective effect against high glucose-induced oxidative damage of retinal ganglion cells. Eur J Pharmacol. 2020;875: 173038.

    Article  CAS  PubMed  Google Scholar 

  32. Fao L, Mota SI, Rego AC. Shaping the Nrf2-ARE-related pathways in Alzheimer’s and Parkinson’s diseases. Ageing Res Rev. 2019;54: 100942.

    Article  CAS  PubMed  Google Scholar 

  33. Hayes JD, Chowdhry S, Dinkova-Kostova AT, Sutherland C. Dual regulation of transcription factor Nrf2 by Keap1 and by the combined actions of beta-TrCP and GSK-3. Biochem Soc Trans. 2015;43:611–20.

    Article  CAS  PubMed  Google Scholar 

  34. Chowdhry S, Zhang Y, McMahon M, Sutherland C, Cuadrado A, Hayes JD. Nrf2 is controlled by two distinct beta-TrCP recognition motifs in its Neh6 domain, one of which can be modulated by GSK-3 activity. Oncogene. 2013;32:3765–81.

    Article  CAS  PubMed  Google Scholar 

  35. Zhou Z, Li H, Bai S, Xu Z, Jiao Y. Loss of serine/threonine protein kinase 25 in retinal ganglion cells ameliorates high glucose-elicited damage through regulation of the AKT-GSK-3beta/Nrf2 pathway. Biochem Biophys Res Commun. 2022;600:87–93.

    Article  CAS  PubMed  Google Scholar 

  36. Rizvi F, Mathur A, Krishna S, Siddiqi MI, Kakkar P. Suppression in PHLPP2 induction by morin promotes Nrf2-regulated cellular defenses against oxidative injury to primary rat hepatocytes. Redox Biol. 2015;6:587–98.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  37. Xing H, Fu R, Cheng C, Cai Y, Wang X, Deng D, et al. Hyperoside protected against oxidative stress-induced liver injury via the PHLPP2-AKT-GSK-3beta signaling pathway in vivo and in vitro. Front Pharmacol. 2020;11:1065.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  38. Yan X, Li W, Yang L, Dong W, Chen W, Mao Y, et al. MiR-135a protects vascular endothelial cells against ventilator-induced lung injury by inhibiting PHLPP2 to activate PI3K/Akt pathway. Cell Physiol Biochem. 2018;48:1245–58.

    Article  CAS  PubMed  Google Scholar 

  39. Sun X, Lin J, Zhang Y, Kang S, Belkin N, Wara AK, et al. MicroRNA-181b improves glucose homeostasis and insulin sensitivity by regulating endothelial function in white adipose tissue. Circ Res. 2016;118:810–21.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  40. Rizvi F, Shukla S, Kakkar P. Essential role of PH domain and leucine-rich repeat protein phosphatase 2 in Nrf2 suppression via modulation of Akt/GSK3beta/Fyn kinase axis during oxidative hepatocellular toxicity. Cell Death Dis. 2014;5: e1153.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

Download references

Funding

This work was supported by the Natural Science Basic Research Program of Shaanxi, China (No. 2020JM-400) and the Key Research & Development Program of Shaanxi Province (No. 2020SF-268).

Author information

Authors and Affiliations

  1. Department of Ophthalmology, The First Affiliated Hospital of Xi’an Jiaotong University, No. 277 Yanta West Road, Xi’an, 710061, Shaanxi, China

    Xuan Liu, Li Chen, Lijun Cui & Ting Wei

  2. The Institute of Neurobiology, Xi’an Jiaotong University Health Science Center, No. 76 Yanta Road, Xi’an, 710061, Shaanxi, China

    Yong Liu & Zhichao Zhang

Authors
  1. Xuan Liu
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yong Liu
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Li Chen
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Zhichao Zhang
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Lijun Cui
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Ting Wei
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

XL and YL contributed to conceptualization and design. XL wrote the manuscript. YL reviewed the manuscript. XL and LC performed the experiments. ZZ, LC, and TW performed data analysis and provided technical support.

Corresponding authors

Correspondence to Xuan Liu or Yong Liu.

Ethics declarations

Conflict of interest

The authors have no competing interests to declare that are relevant to the content of this article.

Additional information

Responsible Editor: John Di Battista.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Liu, X., Liu, Y., Chen, L. et al. Loss of pleckstrin homology domain and leucine-rich repeat protein phosphatase 2 has protective effects on high glucose-injured retinal ganglion cells via the effect on the Akt–GSK–3β–Nrf2 pathway. Inflamm. Res. 72, 373–385 (2023). https://doi.org/10.1007/s00011-022-01680-1

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00011-022-01680-1

Keywords

Search

Navigation