15-Deoxy-Delta(12,14)-prostaglandin-J(2) reveals a new pVHL-independent, lysosomal-dependent mechanism of HIF-1alpha degradation.
Hypoxia-inducible factor-1alpha (HIF-1alpha) protein is degraded under normoxia by its association to von Hippel-Lindau protein (pVHL) and further proteasomal digestion. However, human renal cells HK-2 treated with 15-deoxy-Delta(12,14)-prostaglandin-J(2) (15d-PGJ(2)) accumulate HIF-1alpha in normoxic conditions. Thus, we aimed to investigate the mechanism involved in this accumulation. We found that 15d-PGJ(2) induced an over-accumulation of HIF-1alpha in RCC4 cells, which lack pVHL and in HK-2 cells treated with inhibitors of the pVHL-proteasome pathway. These results indicated that pVHL-proteasome-independent mechanisms are involved, and therefore we aimed to ascertain them. We have identified a new lysosomal-dependent mechanism of HIF-1alpha degradation as a target for 15d-PGJ(2) based on: (1) HIF-1alpha colocalized with the specific lysosomal marker Lamp-2a, (2) 15d-PGJ(2) inhibited the activity of cathepsin B, a lysosomal protease, and (3) inhibition of lysosomal activity did not result in over-accumulation of HIF-1alpha in 15d-PGJ(2)-treated cells. Therefore, expression of HIF-1alpha is also modulated by lysosomal degradation.
Olmos
Gemma
G
Departamento de Fisiología, Facultad de Medicina, Universidad de Alcalá, 28471, Alcalá de Henares, Madrid, Spain.
Arenas
María I
MI
Bienes
Raquel
R
Calzada
María Jose
MJ
Aragonés
Julián
J
Garcia-Bermejo
Maria Laura
ML
Landazuri
Manuel O
MO
Lucio-Cazaña
Javier
J
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000378:metabolism; D002401:Cathepsin B / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000166:cytology; D008247:Lysosomes / Q000378:metabolism*; D015230:Prostaglandin D2 / Q000031:analogs & derivatives* / Q000378:metabolism; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000235:genetics / Q000378:metabolism*
C097240:15-deoxy-delta(12,14)-prostaglandin J2; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D002154:Calpain; D002401:Cathepsin B; D015230:Prostaglandin D2; D002118:Calcium