Bone Resorption, the second volume of the series Topics in Bone Biology, is
centered on the osteoclast, the bone-resorbing cell. The volume thus complements
the first volume of the series, Bone Formation, which discussed
origin, function, and pathology of the bone-forming cell, the osteoblast.Both
volumes are addressed to scientists and clinicians who are active in or wish
to enter the field of skeletal function; this group encompasses a wide variety
of specialties, including orthopaedics, rheumatology, endocrinology,
nephrology, oncology, dentistry, nursing, and chiropractic medicine.
Rubin and Greenfield, in the first chapter, discuss the origin and differentiation
of the osteoclast. Recognized as a multinuclear cell about 150 years
ago, its origin was not uncovered until a century later when, as a result of
an experiment in which quail and chicken cells were co-cultured, it became
clear that osteoclasts arose from hematopoietic stem cells. The authors then
discuss the osteoclastogenic factor, now known as RANKL; the inhibitory
binding protein, osteoprotegerin (OPG); and the complex signaling pathway
that leads to differentiation and late differentiation of this complicated cell.
A section of the chapter is devoted to a concise discussion of regulators and
repressors of osteoclast differentiation, including sex steroids, calcitonin,
nitric oxide, and mechanical factors. The chapter concludes that the osteoclast
modulates bone development, bone growth, and bone disease.