THE PHYSIOLOGY OF PARATHYROID HORMONE-RELATED PROTEIN - AN EMERGING ROLE AS A DEVELOPMENTAL FACTOR

Parathyroid hormone-related protein (PTHrP) is the agent responsible f or humoral hypercalcemia of malignancy. Its pathogenic role in this sy ndrome is well established, and attention has focused in recent years on the elucidation of the roles played by PTHrP in normal developmenta l and adult physiology. This review focuses on studies of the past two years: (a) elucidation of the posttranslational processing pattern of PTHrP, the mechanisms of action of the various secretory forms of PTH rP, the role of PTHrP as an intracrine regulator of cell growth and ce ll death; (b) the emergence of PTHrP as a critical developmental facto r in the mammary gland, epidermis, and the skeleton; and (c) the advan ces in understanding of the roles of PTHrP in the regulation of pancre atic islet mass, vascular smooth muscle tone and proliferation, and ma terno-fetal calcium transfer across the placenta.