title: Transient receptor potential vanilloid 1 activation induces autophagy in thymocytes through ROS-regulated AMPK and Atg4C pathways.
abstract: Autophagy is a highly conserved process involved in lymphocyte development and differentiation. Herein, we demonstrated for the first time that triggering of TRPV1 by the specific agonist CPS induces autophagy in mouse thymocytes. TRPV1-dependent autophagy required [Ca(2+)](i) and ROS generation, resulting in AMPK activation. CPS specifically increased Atg4C mRNA expression and induced oxidation of Atg4C protein by ROS generation. TRPV1-triggered autophagy was Atg6/Beclin-1-dependent, as demonstrated by the use of Beclin-1(+/-) transgenic mice, and involved ROS- and AMPK-mediated up-regulation of Beclin-1 expression. Autophagy is activated as a prosurvival process, as its inhibition triggered apoptosis of thymocytes: this effect was accompanied by down-regulation of Atg4C, Bcl-X(L), and Irgm1 mRNA expression, decreased Bcl-X(L) and Beclin-1 protein levels, and caspase-3 activation, suggesting the existence of a molecular interplay between autophagic and apoptotic programs. TRPV1 activation by CPS altered the expression of CD4 and CD8α antigens, inducing the development of DP(dull). Interestingly, we found that CPS induces autophagy of DP(dull) cells, and inhibition of CPS-induced autophagy by the 3-MA autophagic inhibitor induces apoptosis of DP(dull) cells, suggesting the presence of an interplay between autophagic survival and apoptotic cell death. Overall, our findings suggest that DP(dull) cells constitute a distinct thymocyte subpopulation involved in the homeostatic control of cellularity and in the responses to chemical stress signals during thymocyte maturation, via regulating autophagy and apoptosis in a TRPV1-dependent manner.
authors: School of Pharmacy, Section of Experimental Medicine, University of Camerino, Camerino (MC), Italy.
authors: Valerio
authors: V
authors: Farfariello
authors: Consuelo
authors: C
authors: Amantini
authors: Giorgio
authors: G
authors: Santoni
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D000818:Animals; D001343:Autophagy / Q000276:immunology*; D000071183:Autophagy-Related Proteins; D015153:Blotting, Western; D003546:Cysteine Endopeptidases / Q000276:immunology / Q000378:metabolism*; D053938:DNA Fragmentation; D004789:Enzyme Activation / Q000276:immunology; D005434:Flow Cytometry; D047468:Immunoprecipitation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011494:Protein Kinases / Q000276:immunology / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology; D050916:TRPV Cation Channels / Q000276:immunology / Q000378:metabolism*; D060168:Thymocytes / Q000276:immunology / Q000378:metabolism*
chemical_list: D000071183:Autophagy-Related Proteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; D011494:Protein Kinases; D000091162:AMP-Activated Protein Kinase Kinases; C522187:Atg4C protein, mouse; D003546:Cysteine Endopeptidases