About GPNMB / Glycoprotein Nmb:
Glycoprotein Nmb, also known as Transmembrane glycoprotein NMB, is a protein found in humans. It is encoded by the GPNMB gene. In humans, two transcript variants are encoded; these are 550 and 572, respectively. These are the amino acid isoforms that have been characterized for the genes. The codes are known by other terms in the mouse and rat orthologues.
Glycoprotein Nmb has been identified in various cell types. These include melanocytes, osteoclasts, osteoblasts, dendritic cells. This type of protein shows homology to the precursor melanocyte-specific protein: it is also overexpressed in various cancer types. Also, the gene is transcriptionally regulated by the Microphthalmia-associated transcription factor.
It was thought that the GPNMB was expressed in poorly metastatic melanoma cells in humans. But recent studies have found this not to be the case. They identified a high presence of GPNMB expressions in aggressive melanoma, glioma and breast cancer specimens, giving rise to further inquiry.
Glycoprotein Nmb Interactions
The protein is important in the interaction with other cells, such as the osteoblast progenitor cells. In later stages of the matrix, osteoactivin works as a positive regulator of osteoblast differentiation contributing to maturation and mineralization. As seen in a rat fracture model, the process is crucial in repairing bone fracture.
Osteoactivin might be used as a therapy to treat general osteoporosis or fracture repair. It can effectively stimulate bone growth and bone regeneration. The osteoactivin is seen to increase during this process and is fully implicated by stimulating the osteoclast progenitor cells to grow.