Annexin A1 and A2: roles in retrograde trafficking of Shiga toxin.
Annexins constitute a family of calcium and membrane binding proteins. As annexin A1 and A2 have previously been linked to various membrane trafficking events, we initiated this study to investigate the role of these annexins in the uptake and intracellular transport of the bacterial Shiga toxin (Stx) and the plant toxin ricin. Once endocytosed, both toxins are retrogradely transported from endosomes to the Golgi apparatus and the endoplasmic reticulum before being targeted to the cytosol where they inhibit protein synthesis. This study was performed to obtain new information both about toxin transport and the function of annexin A1 and annexin A2. Our data show that depletion of annexin A1 or A2 alters the retrograde transport of Stx but not ricin, without affecting toxin binding or internalization. Knockdown of annexin A1 increases Golgi transport of Stx, whereas knockdown of annexin A2 slightly decreases the same transport step. Interestingly, annexin A1 was found in proximity to cytoplasmic phospholipase A2 (cPLA(2)), and the basal as well as the increased Golgi transport of Stx upon annexin A1 knockdown is dependent on cPLA(2) activity. In conclusion, annexin A1 and A2 have different roles in Stx transport to the trans-Golgi network. The most prominent role is played by annexin A1 which normally works as a negative regulator of retrograde transport from the endosomes to the Golgi network, most likely by complex formation and inhibition of cPLA(2).
Department of Biochemistry, Centre for Cancer Biomedicine, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo, Norway.
Lionel
L
Tcatchoff
Sofia
S
Andersson
Audrun
A
Utskarpen
Tove Irene
TI
Klokk
Sigrid S
SS
Skånland
Sascha
S
Pust
Volker
V
Gerke
Kirsten
K
Sandvig
D000098:Acetophenones / Q000494:pharmacology; D017305:Annexin A1 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D017306:Annexin A2 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D001578:Benzopyrans / Q000494:pharmacology; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D064801:Phospholipase A2 Inhibitors; D054467:Phospholipases A2 / Q000378:metabolism; D011485:Protein Binding; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000378:metabolism; D021381:Protein Transport; D011725:Pyridines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D012276:Ricin / Q000378:metabolism; D022621:Shiga Toxin / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism
C472822:ANXA2 protein, human; D000098:Acetophenones; D017305:Annexin A1; D017306:Annexin A2; D001578:Benzopyrans; D007093:Imidazoles; D064801:Phospholipase A2 Inhibitors; D011725:Pyridines; D034741:RNA, Small Interfering; D017527:Receptor, IGF Type 2; C034304:cation-dependent mannose-6-phosphate receptor; D022621:Shiga Toxin; D012276:Ricin; C085746:rottlerin; D051745:Protein Kinase C-delta; D048051:p38 Mitogen-Activated Protein Kinases; D054467:Phospholipases A2; C093642:SB 203580