Low-dose cadmium activates the JNK signaling pathway in human renal podocytes

Area of Science:

• Nephrology
• Environmental Toxicology
• Cell Biology

Background:

• Cadmium (Cd) is a known environmental toxin.
• Previous research indicated low-dose Cd damages the glomerular filtration barrier (GFB).
• The precise mechanisms by which Cd affects podocytes, key components of the GFB, remain unclear.

Purpose of the Study:

• To investigate the effects of low-dose cadmium exposure on human renal podocytes (HRPs).
• To determine if Cd activates the c-Jun N-terminal kinase (JNK) signaling pathway in HRPs.
• To assess the impact of Cd on HRP proliferation, viability, apoptosis, and differentiation markers.

Main Methods:

• Human renal podocytes (HRPs) were treated with 4 µM Cadmium (Cd).
• Western blot analysis was used to examine JNK pathway activation and expression of c-Jun and c-Fos.
• MTT assay, trypan blue exclusion assay, and flow cytometry assessed proliferation, viability, and apoptosis.
• Immunofluorescence staining and Phalloidin-labeling evaluated cytoskeletal structure and differentiation markers (CD2-associated protein, synaptopodin).

Main Results:

• Cadmium (Cd) treatment activated the JNK pathway, increasing c-Jun and c-Fos protein levels.
• No significant changes were observed in HRP proliferation, viability, or apoptosis following Cd exposure.
• Cd did not affect the F-actin cytoskeleton alignment or the expression of podocyte differentiation markers.

Conclusions:

• Low-dose cadmium exposure activates the JNK signaling pathway in human renal podocytes.
• Despite JNK pathway activation, essential podocyte functions and structural integrity remain unaffected by low-dose Cd.
• These findings suggest a dissociation between JNK pathway activation and functional impairment in podocytes exposed to low-dose cadmium.