Identification and pharmacological induction of autophagy in the larval stages of Echinococcus granulosus: an active catabolic process in calcareous corpuscles.
Autophagy is a fundamental catabolic pathway conserved from yeast to mammals, but which remains unknown in parasite cestodes. In this work, the pharmacological induction of autophagy was cellularly and molecularly analysed in the larval stages of Echinococcus granulosus. Metacestode sensitivity to rapamycin and TORC1 expression in protoscoleces and metacestodes were shown. Ultrastructural studies showed that treated parasites had an isolation membrane, autophagosomes and autolysosomes, all of which evidenced the autophagic flux. Genes coding for key autophagy-related proteins were also identified in the Echinococcus genome. These genes were involved in autophagosome formation and transcriptional over-expression of Eg-atg5, Eg-atg6, Eg-atg8, Eg-atg12, Eg-atg16 and Eg-atg18 was shown in presence of rapamycin or arsenic trioxide. Thus, Echinococcus autophagy could be regulated by non-transcriptional inhibition through TOR and by transcription-dependent up-regulation via FoxO-like transcription factors and/or TFEB proteins. An increase in the punctate pattern and Eg-Atg8 polypeptide level in the tegument, parenchyma cells and excretory system of protoscoleces and in vesicularised parasites was detected after rapamycin treatment. This suggests the occurrence of basal autophagy in the larval stages and during vesicular development. In arsenic-treated protoscoleces, high Eg-Atg8 polypeptide levels within the free cytoplasmic matrix of calcareous corpuscles were observed, thus verifying the occurrence of autophagic events. These experiments also confirmed that the calcareous corpuscles are sites of arsenic trioxide accumulation. The detection of the autophagic machinery in this parasite represents a basic starting point to unravel the role of autophagy under both physiological and stress conditions which will allow identification of new strategies for drug discovery against neglected parasitic diseases caused by cestodes.
Laboratorio de Zoonosis Parasitarias, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata (UNMdP), Funes 3350, Nivel Cero, (7600) Mar del Plata, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
Julia A
JA
Loos
Laboratorio de Zoonosis Parasitarias, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata (UNMdP), Funes 3350, Nivel Cero, (7600) Mar del Plata, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
Pedro A
PA
Caparros
Laboratorio de Zoonosis Parasitarias, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata (UNMdP), Funes 3350, Nivel Cero, (7600) Mar del Plata, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
María Celeste
MC
Nicolao
Laboratorio de Zoonosis Parasitarias, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata (UNMdP), Funes 3350, Nivel Cero, (7600) Mar del Plata, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
Guillermo M
GM
Denegri
Laboratorio de Zoonosis Parasitarias, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata (UNMdP), Funes 3350, Nivel Cero, (7600) Mar del Plata, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina; Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata (UNMdP), Funes 3350, Nivel 2, (7600) Mar del Plata, Argentina. Electronic address: acumino@mdp.edu.ar.
Andrea C
AC
Cumino
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001343:Autophagy / Q000502:physiology*; D002119:Calcium Carbonate / Q000378:metabolism; D003001:Cloning, Molecular; D048209:Echinococcus granulosus / Q000187:drug effects* / Q000502:physiology* / Q000648:ultrastructure; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics / Q000502:physiology; D007814:Larva / Q000187:drug effects / Q000502:physiology; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism
D000900:Anti-Bacterial Agents; D051858:Forkhead Transcription Factors; D046912:Multiprotein Complexes; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D002119:Calcium Carbonate; D020123:Sirolimus
Arsenic trioxide; Autophagy; Calcareous corpuscles; Echinococcus; Eg-Atg8 expression; Rapamycin