Hypoxia induces connective tissue growth factor mRNA expression

Area of Science:

• Cell Biology
• Molecular Biology
• Renal Physiology

Background:

• Connective tissue growth factor (CTGF) is a key profibrotic factor involved in cell proliferation and matrix production.
• CTGF induction by hypoxia has been observed in various cell types.
• Renal tubular cells play a crucial role in kidney function and disease pathogenesis.

Purpose of the Study:

• To investigate the effect of hypoxia on CTGF gene expression in cultured mouse renal tubular cells (MTC).
• To elucidate the roles of mitogen-activated protein kinase (MAPK) signaling pathways and transforming growth factor-beta (TGF-β) in hypoxia-induced CTGF expression.

Main Methods:

• Cultured mouse renal tubular cells (MTC) were exposed to hypoxia (1% O2) or normoxia.
• CTGF mRNA expression was quantified using Northern blot and real-time PCR.
• Specific inhibitors for JNK, ERK, p38 MAPK, and neutralizing anti-TGF-β1 antibodies were used to assess pathway involvement.

Main Results:

• Hypoxia significantly increased CTGF mRNA expression in MTC.
• Inhibition of p38 MAPK reduced hypoxia-induced CTGF expression, while JNK and ERK inhibitors had no effect.
• Hypoxia stimulated TGF-β production, but anti-TGF-β1 antibodies did not abolish CTGF mRNA induction.

Conclusions:

• Hypoxia up-regulates CTGF gene expression in mouse renal tubular cells.
• The p38 MAPK pathway is involved in the hypoxic stimulation of CTGF.
• Hypoxia induces CTGF mRNA expression via a TGF-β1-independent mechanism.