Open AccessKnockdown of PSMB7 Induces Autophagy in Cardiomyocyte Cultures: Possible Role in Endoplasmic Reticulum Stress
Author(s) -
Victoria O. Kyrychenko,
Vasyl S. Nagibin,
Lesya V. Tumanovska,
Denis O. Pashevin,
Veronika L. Gurianova,
А. А. Мойбенко,
Victor Dosenko,
Daniel J. Klionsky
Publication year - 2013
Publication title -
pathobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.941
H-Index - 53
eISSN - 1423-0291
pISSN - 1015-2008
DOI - 10.1159/000350704
Subject(s) - endoplasmic reticulum , autophagy , gene knockdown , microbiology and biotechnology , unfolded protein response , biology , chemistry , cell culture , apoptosis , genetics
Proteasomal and autophagic pathways of protein degradation are two essential, endoplasmic reticulum (ER)-associated proteolytic systems involved in the ER stress response. The functional interaction between them has been shown by proteasome pharmacological inhibition. However, little data have been found concerning autophagy induction using an RNA interference approach due to the multisubunit composition of proteolytic systems. We suggested that silencing of single proteasome subunits can induce massive autophagy. Psmb7-specific small interference RNA added to isolated cardiomyocytes significantly affected mRNA expression of essential ER stress marker proteins, including DDIT3/CHOP and HSPA5/GRP78. mRNA expression of the key autophagy regulator MTOR was also increased. These findings were confirmed by single-cell reverse transcription real-time PCR on individual monodansylcadaverine (MDC)-labeled cardiomyocytes. RNA interference that decreased the levels of non-catalytic PSMB7 subunits of the proteasome had no influence on chymotrypsin- and trypsin-like activities, but significantly decreased peptidyl-glutamyl peptide-hydrolyzing activity. Immunohistochemical analysis showed increased levels of LC3-marked vacuoles in the cytoplasm of Psmb7-knockdown cells, and MDC staining showed significantly increased numbers of neonatal cardiomyocytes with autophagic vacuoles. After anoxia-reoxygenation, the number of cells with signs of autophagy after Psmb7 gene silencing was higher. Our results indicate that Psmb7 knockdown induces ER stress and autophagy in cardiomyocytes, which may be a useful approach to activate specific autophagy.