Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Neurotoxicity induces cleavage of p35 to p25 by calpain


Cyclin-dependent kinase 5 (cdk5) and its neuron-specific activator p35 are required for neurite outgrowth and cortical lamination1,2,3. Proteolytic cleavage of p35 produces p25, which accumulates in the brains of patients with Alzheimer's disease4. Conversion of p35 to p25 causes prolonged activation and mislocalization of cdk5. Consequently, the p25/cdk5 kinase hyperphosphorylates tau, disrupts the cytoskeleton and promotes the death (apoptosis) of primary neurons. Here we describe the mechanism of conversion of p35 to p25. In cultured primary cortical neurons, excitotoxins, hypoxic stress and calcium influx induce the production of p25. In fresh brain lysates, addition of calcium can stimulate cleavage of p35 to p25. Specific inhibitors of calpain, a calcium-dependent cysteine protease, effectively inhibit the calcium-induced cleavage of p35. In vitro, calpain directly cleaves p35 to release a fragment with relative molecular mass 25,000. The sequence of the calpain cleavage product corresponds precisely to that of p25. Application of the amyloid β-peptide Aβ(1–42) induces the conversion of p35 to p25 in primary cortical neurons. Furthermore, inhibition of cdk5 or calpain activity reduces cell death in Aβ-treated cortical neurons. These observations indicate that cleavage of p35 to p25 by calpain may be involved in the pathogenesis of Alzheimer's disease.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Neurotoxicity induces cleavage of p35 to p25.
Figure 2: Ca2+ is necessary for p35 cleavage in vitro.
Figure 3: Calpain directly cleaves p35 to p25.
Figure 4: Conversion of p35 to p25 in primary cortical neurons is mediated by calpain and requires Ca2+.
Figure 5: Aβ(1–42) induces conversion of p35 to p25; inhibition of cdk5 or calpain reduces Aβ(1–42)-induced cell death.

Similar content being viewed by others


  1. Ohshima, T. et al. Targeted disruption of the cyclin-dependent kinase 5 gene results in abnormal corticogenesis, neuronal pathology and perinatal death. Proc. Natl Acad. Sci. USA 93, 11173– 11178 (1996).

    Article  ADS  CAS  Google Scholar 

  2. Chae, T. et al. Mice lacking p35, a neuronal specific activator of Cdk5, display cortical lamination defects, seizures, and adult lethality. Neuron 18, 29–42 ( 1997).

    Article  CAS  Google Scholar 

  3. Nikolic, M., Dudek, H., Kwon, Y. T., Ramos, Y. F. & Tsai, L. H. The cdk5/p35 kinase is essential for neurite outgrowth during neuronal differentiation. Genes Dev. 10, 816–825 (1996).

    Article  CAS  Google Scholar 

  4. Patrick, G. N. et al. Conversion of p35 to p25 de-regulates cdk5 activity and promotes neurodegeneration. Nature 402, 615– 622 (1999).

    Article  ADS  CAS  Google Scholar 

  5. Wang, K. K. W. in Calpain: Pharmacology and Toxicology of Calcium-Dependent Protease (eds Wang, K. K. W. & Yuen, P.-W.) 77–102 (Taylor & Francis, Philadelphia, 1999).

    Google Scholar 

  6. Sorimachi, H., Ishiura, S. & Suzuki, K. Structure and physiological function of calpains. Biochem. J. 328, 721–732 (1997).

    Article  CAS  Google Scholar 

  7. Lew, J. et al. A brain-specific activator of cyclin-dependent kinase 5. Nature 371, 423–426 ( 1994).

    Article  ADS  CAS  Google Scholar 

  8. Yankner, B. A. Mechanisms of neuronal degeneration in Alzheimer's disease. Neuron 16, 921–932 ( 1996).

    Article  CAS  Google Scholar 

  9. Alvarez, A., Toro, R., Caceres, A. & Maccioni, R. B. Inhibition of tau phosphorylating protein kinase cdk5 prevents β-amyloid-induced neuronal death. FEBS Lett. 459, 421– 426 (1999).

    Article  CAS  Google Scholar 

  10. Arispe, N., Pollard, H. B. & Rojas, E. Giant multilevel cation channels formed by Alzheimer disease amyloid beta protein [A beta P-(1-40)] in bilayer membranes. Proc. Natl Acad. Sci. USA 90, 10573– 10577 (1993).

    Article  ADS  CAS  Google Scholar 

  11. Hartmann, H., Eckert, A. & Muller, W. E. β-Amyloid protein amplifies calcium signalling in central neurons from the adult mouse. Biochem. Biophys. Res. Commun. 194, 1216–1220 ( 1993).

    Article  CAS  Google Scholar 

  12. Mattson, M. P. et al. β-Amyloid peptides destabilize calcium homeostasis and render human cortical neurons vulnerable to excitotoxicity. J. Neurosci. 12, 376–389 ( 1992).

    Article  CAS  Google Scholar 

  13. Pascale, A. & Etcheberrigaray, R. Calcium alterations in Alzheimer's disease: pathophysiology, models and therapeutic opportunities. Pharmacol. Res. 39, 81–88 (1999).

    Article  CAS  Google Scholar 

  14. Grynspan, R., Griffin, W. R., Cataldo, A., Katayama, S. & Nixon, R. A. Active site-directed antibodies identify calpain II as an early-appearing and pervasive component of neurofibrillary pathology in Alzheimer's disease. Brain Res. 763, 145–158 (1997).

    Article  CAS  Google Scholar 

  15. Nixon, R. A. et al. Calcium-activated neutral proteinase (calpain) system in aging and Alzheimer's disease. Ann. NY Acad. Sci. 747, 77–91 (1994).

    Article  ADS  CAS  Google Scholar 

  16. Saito, K., Elce, J. S., Hamos, J. E. & Nixon, R. A. Widespread activation of calcium-activated neutral proteinase (calpain) in the brain in Alzheimer disease: a potential molecular basis for neuronal degeneration. Proc. Natl Acad. Sci. USA 90, 2628– 2632 (1993).

    Article  ADS  CAS  Google Scholar 

  17. Iwamoto, N., Thangnipon, W., Crawford, C. & Emson, P. C. Localization of calpain immunoreactivity in senile plaques and in neurones undergoing neurofibrillary degeneration in Alzheimer's disease. Brain Res. 561, 177–180 (1991).

    Article  CAS  Google Scholar 

  18. Selkoe, D. J. Translating cell biology into therapeutic advances in Alzheimer's disease. Nature 399, A23–A31 (1999).

    Article  ADS  CAS  Google Scholar 

  19. Seisjo, B. K. in Brain Energy Metabolism 454 (Wiley, New York, 1978).

    Google Scholar 

  20. Nikolic, M., Chou, M. M., Lu, W., Mayer, B. J. & Tsai, L. H. The p35/Cdk5 kinase is a neuron-specific Rac effector that inhibits Pak1 activity. Nature 395, 194–198 (1998).

    Article  ADS  CAS  Google Scholar 

Download references


We thank J. Elce for the m-calpain antibody; A. Bonni and V. Tannoch for reading this manuscript; M. Ahlijanian, B. Yankner, E. Wang, K. Kosik and members of the Tsai lab for discussions. This work was partially supported by NIH grants to L.-H.T. L.-H.T. is an assistant investigator of the Howard Hughes Medical Institute, a Rita Allen Foundation scholar and a recipient of an Ester A. and Joseph Kligenstein Fund grant.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Li-Huei Tsai.

Supplementary Information

Rights and permissions

Reprints and permissions

About this article

Cite this article

Lee, Ms., Kwon, Y., Li, M. et al. Neurotoxicity induces cleavage of p35 to p25 by calpain. Nature 405, 360–364 (2000).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing