CD154 Induces Interleukin-6 Secretion by Kidney Tubular Epithelial Cells under Hypoxic Conditions: Inhibition by Chloroquine

Figure 4

Induction of HIF-1α and HIF-2α and endoplasmic reticulum stress in HK-2 cells grown under hypoxic conditions; (a) HIF-1α and HIF-2α are induced in response to hypoxic stress. Top panel: HK-2 cells were grown under hypoxic conditions for the indicated times and immunoblotting with anti-HIF-1α or anti-HIF-2α antibodies performed on cell lysates (β-tubulin was used as loading controls); bottom panels: cells were grown under hypoxic conditions for the indicated times in the presence or not of 100 ng/mL rsCD154 and immunoblotting with anti-HIF-1α antibody performed on cell lysates (calnexin (CNX) was used as loading controls). (b) VEGF concentration increases in HK-2 cell supernatants in response to hypoxic stress. VEGF was quantified by ELISA in supernatants of HK-2 cells grown under hypoxic or normoxic conditions (, significant relatively to normoxic control; UD: undetectable levels). (c) Hypoxia induces time-dependent endoplasmic reticulum stress features in HK-2 cells. HK-2 cells were grown under hypoxic conditions for the indicated times and immunoblotting with antibodies against BiP, eIF2α, and Phospho-eIF2α (P-eIF2α) performed on cell lysates (calnexin (CNX) was used as a loading control). (d) Fold induction of the spliced/unspliced ratio of XBP-1 (XBP1 s/u) mRNA in HK-2 cells grown under hypoxic conditions for the indicated times in the presence or absence of rsCD154 (, significant relatively to time 0).

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