The expression of neurofibromin in human osteoblasts and chondrocytes.

The goal of this study was to determine if neurofibromin is expressed in cultured human osteoblasts and chondrocytes that were isolated from ilia and ilial growth plate. Purity of the osteoblast and chondrocyte cultures was confirmed by alkaline phosphatase and toluidine blue staining, respectively. The reverse transcription-polymerase chain reaction (RT-PCR) was performed to detect neurofibromin mRNA. Indirect immunofluorescence and Western blot studies were done to delineate the cellular distribution and expression levels of neurofibromin. These experiments show that neurofibromin is expressed at low levels in human osteoblasts and chondrocytes and is located mainly in the cytoplasm. Only the type II isoform of neurofibromin is detected in these cells. These findings suggest that the type II isoform of neurofibromin plays a physiological role in human osteoblasts and chondrocytes. Whether functional deficiency of neurofibromin is responsible for skeletal abnormalities remains to be established.