The regulation of N-terminal Huntingtin (Htt552) accumulation by Beclin1

Jun Chao Wu, Lin Qi, Yan Wang, Kimberly B. Kegel, Jennifer Yoder, Marian Difiglia, Zheng Hong Qin, Fang Lin*

*Corresponding author for this work

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Aim: Huntingtin protein (Htt) was a neuropathological hallmark in human Huntington's Disease. The study aimed to investigate whether the macroautophagy regulator, Beclin1, was involved in the degradation of Htt. Methods: PC12 cells and primary cultured brain neurons of rats were examined. pDC316 adenovirus shuttle plasmid was used to mediate the expression of wild-type Htt-18Q-552 or mutant Htt-100Q-552 in PC12 cells. The expression of the autophagy-related proteins LC3 II and Beclin1, as well as the lysosome-associated enzymes Cathepsin B and L was evaluated using Western blotting. The locations of Beclin1 and Htt were observed with immunofluorescence and confocal microscope. Results: Htt552 expression increased the expression of LC3 II, Beclin1, cathepsin B and L in autophagy/lysosomal degradation pathway. Treatment with the autophagy inhibitor 3-MA or the proteasome inhibitors lactacystin and MG-132 increased Htt552 levels in PC12 cells infected with Ad-Htt-18Q-552 or Ad-Htt-100Q-552. The proteasome inhibitor caused a higher accumulation of Htt552-18Q than Htt552-100Q, and the autophagy inhibitor resulted in a higher accumulation of Htt552-100Q than Htt552-18Q. Similar results were observed in primary cultured neurons infected with adenovirus. In Htt552-expressing cells, Beclin1 was redistributed from the nucleus to the cytoplasm. Htt siRNA prevented Beclin1 redistribution in starvation conditions. Blockade of Beclin1 nuclear export by leptomycin B or Beclin1 deficiency caused by RNA interference induced the formation of mHtt552 aggregates. Conclusion: Beclin1 regulates the accumulation of Htt via macroautophagy.

Original languageEnglish (US)
Pages (from-to)743-751
Number of pages9
JournalActa Pharmacologica Sinica
Volume33
Issue number6
DOIs
StatePublished - Jun 1 2012

Keywords

  • Beclin1
  • Huntingtin (Htt)
  • RNA interference
  • autophagy
  • autophagy/lysosome pathway
  • protein degradation
  • ubiquitin-proteasome system

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)

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    Wu, J. C., Qi, L., Wang, Y., Kegel, K. B., Yoder, J., Difiglia, M., Qin, Z. H., & Lin, F. (2012). The regulation of N-terminal Huntingtin (Htt552) accumulation by Beclin1. Acta Pharmacologica Sinica, 33(6), 743-751. https://doi.org/10.1038/aps.2012.14