cAMP and EPAC are key players in the regulation of the signal transduction pathway involved in the α-hemolysin autophagic response.
Staphylococcus aureus is a microorganism that causes serious diseases in the human being. This microorganism is able to escape the phagolysosomal pathway, increasing intracellular bacterial survival and killing the eukaryotic host cell to spread the infection. One of the key features of S. aureus infection is the production of a series of virulence factors, including secreted enzymes and toxins. We have shown that the pore-forming toxin α-hemolysin (Hla) is the S. aureus-secreted factor responsible for the activation of the autophagic pathway and that this response occurs through a PI3K/Beclin1-independent form. In the present report we demonstrate that cAMP has a key role in the regulation of this autophagic response. Our results indicate that cAMP is able to inhibit the autophagy induced by Hla and that PKA, the classical cAMP effector, does not participate in this regulation. We present evidence that EPAC and Rap2b, through calpain activation, are the proteins involved in the regulation of Hla-induced autophagy. Similar results were obtained in cells infected with different S. aureus strains. Interestingly, in this report we show, for the first time to our knowledge, that both EPAC and Rap2b are recruited to the S. aureus-containing phagosome. We believe that our findings have important implications in understanding innate immune processes involved in intracellular pathogen invasion of the host cell.
Laboratorio de Biología Celular y Molecular - Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo-CONICET, Mendoza, Argentina.
María Belén
MB
Mestre
María Isabel
MI
Colombo
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy; D001427:Bacterial Toxins / Q000378:metabolism*; D000071186:Beclin-1; D016466:CHO Cells; D002154:Calpain / Q000096:biosynthesis / Q000378:metabolism; D002460:Cell Line; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006460:Hemolysin Proteins / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D015398:Signal Transduction; D013203:Staphylococcal Infections / Q000276:immunology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000276:immunology / Q000472:pathogenicity*; D037521:Virulence Factors / Q000378:metabolism; D020668:rap GTP-Binding Proteins / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D001427:Bacterial Toxins; D000071186:Beclin-1; D020662:Guanine Nucleotide Exchange Factors; D006460:Hemolysin Proteins; D008565:Membrane Proteins; C116122:RAPGEF3 protein, human; D037521:Virulence Factors; C021091:staphylococcal alpha-toxin; D000242:Cyclic AMP; D019869:Phosphatidylinositol 3-Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D002154:Calpain; C065562:RAP2B protein, human; D020668:rap GTP-Binding Proteins