High-affinity renal lead-binding proteins in environmentally-exposed humans

Area of Science:

• Toxicology
• Molecular Biology
• Environmental Health

Background:

• Chronic low-level lead (Pb) exposure is linked to reduced kidney function in humans.
• The precise molecular mechanisms driving lead toxicity remain largely unknown.

Purpose of the Study:

• To identify specific cytosolic lead-binding proteins (PbBPs) in the kidneys of environmentally exposed humans.
• To elucidate the molecular targets of lead and understand its toxicity mechanisms in renal tissue.

Main Methods:

• Investigated cytosolic PbBPs in kidney cortex tissue from environmentally exposed humans.
• Localized PbBPs based on physiologically bound lead in vivo.
• Identified and characterized lead-binding polypeptides using biochemical methods.

Main Results:

• Identified two high-affinity lead-binding polypeptides: thymosin beta 4 (Tβ4) and acyl-CoA binding protein (ACBP/DBI).
• These proteins bind lead with high affinity (Kd ≈ 14 nM) and constitute over 35% of total kidney cortex lead.
• Tβ4 and ACBP/DBI are conserved across species and tissues, involved in diverse cellular functions.

Conclusions:

• Provides the first evidence of specific molecular targets for lead in human kidney tissue.
• Suggests that low-level lead toxicity may result from altered functions of Tβ4 and ACBP/DBI in renal and other tissues, including the central nervous system.