title: Autophagy-related proteins are functionally active in human spermatozoa and may be involved in the regulation of cell survival and motility.
abstract: Macroautophagy (hereafter autophagy) is an evolutionarily highly conserved cellular process that participates in the maintenance of intracellular homeostasis through the degradation of most long-lived proteins and entire organelles. Autophagy participates in some reproductive events; however, there are not reports regarding the role of autophagy in the regulation of sperm physiology. Hence, the aim of this study was to investigate whether autophagy-related proteins are present and functionally active in human spermatozoa. Proteins related to autophagy/mitophagy process (LC3, Atg5, Atg16, Beclin 1, p62, m-TOR, AMPKα 1/2, and PINK1) were present in human spermatozoa. LC3 colocalized with p62 in the middle piece of the spermatozoa. Autophagy activation induced a significant increase in motility and a decrease in PINK1, TOM20 expression and caspase 3/7 activation. In contrast, autophagy inhibition resulted in decreased motility, viability, ATP and intracellular calcium concentration whereas PINK1, TOM20 expression, AMPK phosphorylation and caspase 3/7 activation were significantly increased. In conclusion our results show that autophagy related proteins and upstream regulators are present and functional in human spermatozoa. Modification of mitochondrial proteins expression after autophagy activation/inhibition may be indicating that a specialized form of autophagy named mitophagy may be regulating sperm function such as motility and viability and may be cooperating with apoptosis.
authors.affiliation: Cell Physiology Research Group, Department of Physiology, University of Extremadura, Caceres, Spain.
authors.forename: I M
authors.initials: IM
authors.lastname: Aparicio
authors.affiliation: Neuroimmunophysiology and Chrononutrition Research Group, Department of Physiology, University of Extremadura, Badajoz, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Espino
authors.affiliation: Neuroimmunophysiology and Chrononutrition Research Group, Department of Physiology, University of Extremadura, Badajoz, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Bejarano
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Extremadura, Caceres, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Gallardo-Soler
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Extremadura, Caceres, Spain.
authors.forename: M L
authors.initials: ML
authors.lastname: Campo
authors.affiliation: Cell Physiology Research Group, Department of Physiology, University of Extremadura, Caceres, Spain.
authors.forename: G M
authors.initials: GM
authors.lastname: Salido
authors.affiliation: Neuroimmunophysiology and Chrononutrition Research Group, Department of Physiology, University of Extremadura, Badajoz, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Pariente
authors.affiliation: Laboratory of Spermatology, Department of Animal Medicine, University of Extremadura, Caceres, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Peña
authors.affiliation: Cell Physiology Research Group, Department of Physiology, University of Extremadura, Caceres, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Tapia
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D001343:Autophagy / Q000187:drug effects; D000071183:Autophagy-Related Proteins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002738:Chloroquine / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D012661:Semen / Q000378:metabolism; D000071456:Sequestosome-1 Protein / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D013094:Spermatozoa / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D000099202:PTEN-Induced Putative Kinase
chemical_list: D055372:AMP-Activated Protein Kinases; D000255:Adenosine Triphosphate; D000071183:Autophagy-Related Proteins; D002118:Calcium; D020169:Caspases; D002738:Chloroquine; D018942:Macrolides; D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011494:Protein Kinases; D011956:Receptors, Cell Surface; D000071456:Sequestosome-1 Protein; D020123:Sirolimus; D000099202:PTEN-Induced Putative Kinase; C084008:TOMM20 protein, human; C040929:bafilomycin A1