Research article

LRP1 shedding in human brain: roles of ADAM10 and ADAM17

Qiang Liu¹ , Juan Zhang¹ , Hien Tran² , Marcel M Verbeek³ , Karina Reiss⁴ , Steven Estus⁵ and Guojun Bu^1,2

¹  Department of Pediatrics, Washington University School of Medicine, St Louis, MO 63110, USA

²  Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO 63110, USA

³  Department of Neurology, Radboud University Nijmegen Medical Centre, Donders Centre for Neuroscience, the Netherlands

⁴  Department of Dermatology, Christian-Albrecht University Kiel, Kiel, Germany

⁵  Department of Physiology and Sanders-Brown Center on Aging, University of Kentucky, USA

author email corresponding author email

Molecular Neurodegeneration 2009, 4:17doi:10.1186/1750-1326-4-17

Published:	16 April 2009

Abstract

Background

The low-density lipoprotein receptor-related protein 1 (LRP1) plays critical roles in lipid metabolism, cell survival, and the clearance of amyloid-β (Aβ) peptide. Functional soluble LRP1 (sLRP1) has been detected in circulating human placenta; however, whether sLRP1 is also present in the central nervous system is unclear.

Results

Here we show that abundant sLRP1 capable of binding its ligands is present in human brain tissue and cerebral spinal fluid (CSF). Interestingly, the levels of sLRP1 in CSF are significantly increased in older individuals, suggesting that either LRP1 shedding is increased or sLRP1 clearance is decreased during aging. To examine potential effects of pathological ligands on LRP1 shedding, we treated MEF cells with Aβ peptide and found that LRP1 shedding was increased. ADAM10 and ADAM17 are key members of the ADAM family that process membrane-associated proteins including amyloid precursor protein and Notch. We found that LRP1 shedding was significantly decreased in MEF cells lacking ADAM10 and/or ADAM17. Furthermore, forced expression of ADAM10 increased LRP1 shedding, which was inhibited by ADAM-specific inhibitor TIMP-3.

Conclusion

Our results demonstrate that LRP1 is shed by ADAM10 and ADAM17 and functional sLRP1 is abundantly present in human brain and CSF. Dysregulated LRP1 shedding during aging could alter its function and may contribute to the pathogenesis of AD.