Home Blog of Signal Transduction TGF-beta/Smad TGF-beta/Smad Hypoxia Upregulates Cxcl12 in Hepatocytes by a Complex Mechanism Involving Hypoxia-Inducible Factors and Transforming Growth Factor-β

Category

Archives

Popular Post

ESKM, a novel therapeutic agent for sensitive and resistant PH+ leukemias

The mechanism of resistance to JAK2 inhibitor in myeloproliferative neoplasms patients

Effects of PARP inhibitors in BRCA gene-mutated ovarian cancer

DASATINIB; An inhibitor of Receptor Tyrosine Kinase

GP130/JAK/STAT3 signaling pathway induces multiple myeloma

Hypoxia Upregulates Cxcl12 in Hepatocytes by a Complex Mechanism Involving Hypoxia-Inducible Factors and Transforming Growth Factor-β

Introduction: Cxcl12, or stromal-derived factor-1, is a chemokine produced by several hepatic cell types, including hepatocytes, after liver injury and surgical resection. Studies have revealed that Cxcl12 is important for regeneration of the liver after surgical resection and for development of liver fibrosis during chronic liver injury. While the function of Cxcl12 in the liver is well established, the mechanism by which Cxcl12 is upregulated is not fully understood. Because regions of hypoxia develop in the liver following injury, we tested the hypothesis that hypoxia upregulates Cxcl12 in hepatocytes by a hypoxia-inducible factor (HIF)-dependent mechanism.

Methods: To test this hypothesis, primary mouse hepatocytes were isolated from the livers of HIF-1α-deficient mice or HIF-1β-deficient mice and exposed to 1% oxygen. Cxcl12 expression was increased following exposure of primary mouse hepatocytes to 1% oxygen. Previously we have shown, that in addition to HIFs, transforming growth factor-β is required for upregulation of a subset of genes in hypoxic hepatocytes. To examine the role of TGF-β in regulation of Cxcl12 during hypoxia, hepatocytes were pretreated with the TGF-β receptor I inhibitor, SB431542.

Results: Upregulation of Cxcl12 by hypoxia was partially prevented in hepatocytes from HIF-1α-deficient mice and completely prevented in hepatocytes from HIF-1β-deficient hepatocytes. This suggests that under hypoxic conditions, both HIF-1α and HIF-2α regulate Cxcl12 in hepatocytes. Pretreatment of hepatocytes with SB431542 completely prevented upregulation Cxcl12 by hypoxia. Further, treatment of hepatocytes with recombinant TGF-β1 upregulated Cxcl12 in hepatocytes cultured in room air.

Conclusion: Collectively, these studies demonstrate that hypoxia upregulates Cxcl12 in primary mouse hepatocytes by a mechanism that involves HIFs and TGF-β.

 

Related Products

Cat.No. Product Name Information
S1067 SB431542 SB431542 is a potent and selective inhibitor of ALK5 with IC50 of 94 nM in a cell-free assay, 100-fold more selective for ALK5 than p38 MAPK and other kinases.

Related Targets

TGF-beta/Smad