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

• Published in: 中国药理学报：英文版 2012, Vol.33 (6), p.743-751
• Main Author: Jun-chao WU Lin QI Yan WANG Kimberly B KEGEL Jennifer YODER Marian DIFIGLIA Zheng-hong QIN Fang LIN
• Format: Article
• Language: English
• Subjects: N-末端; PC12细胞; 积累; 组织蛋白酶B; 腺病毒感染; 蛋白酶体抑制剂; 蛋白酶抑制剂; 调控
• ISSN: 1671-4083; 1745-7254

Aim： Huntingtin protein （Htt） was a neuropathological hallmark in human Huntington＇s Disease. The study aimed to investigate whether the macroautophagy regulator, Beclinl, 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 pro- teins LC3 II and Beclinl, as well as the lysosome-associated enzymes Cathepsin B and L was evaluated using Western blotting. The locations of Beclinl and Htt were observed with immunofluorescence and confocal microscope. Results： Htt552 expression increased the expression of LC3 II, Beclinl, cathepsin B and L in autophagy/lysosomal degradation path- way. 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, Beclinl was redistributed from the nucleus to the cytoplasm. Htt siRNA prevented Beclinl redistribution in starvation conditions. Blockade of Beclinl nuclear export by leptomycin B or Beclinl deficiency caused by RNA interference induced the formation of mHtt552 aggregates. Conclusion Beclinl regulates the accumulation of Htt via macroautophagy.