Parathyroid hormone-related protein in lower vertebrates

Area of Science:

• Comparative physiology
• Evolutionary biology
• Endocrinology

Background:

• Parathyroid hormone-related protein (PTHrP) is a key mediator of hypercalcemia in human cancers.
• Elevated PTHrP levels are observed in some fish species, suggesting a potential hormonal role in aquatic vertebrates.
• The evolutionary origins and conserved functions of PTHrP remain largely unexplored in lower vertebrates.

Purpose of the Study:

• To investigate the evolutionary history and tissue distribution of parathyroid hormone-related protein (PTHrP) in diverse vertebrate species.
• To determine if PTHrP plays a conserved role in non-mammalian vertebrates.
• To explore the ancient functions of PTHrP beyond its role in human malignancy.

Main Methods:

• Immunohistochemistry was employed to localize PTHrP expression in various tissues.
• In situ hybridization was utilized to examine PTHrP gene expression patterns.
• Tissues from lungfish, lamprey, bony fish, and cartilaginous fish were analyzed.

Main Results:

• PTHrP was consistently localized to the skin and kidney tubules across all studied vertebrate species.
• In developing lungfish, PTHrP was detected in the notochord, developing brain, and skeletal muscle.
• These findings indicate a widespread presence of PTHrP in lower vertebrates.

Conclusions:

• Parathyroid hormone-related protein (PTHrP) is of ancient evolutionary origin.
• PTHrP appears to have a fundamental and conserved function in vertebrates, extending beyond its role in human disease.
• The localization in skin and kidney suggests roles in ion transport or homeostasis across diverse vertebrate lineages.