Patent ID: 7453021

Claim:
A transgenic rodent whose genome comprises: (a) a nucleotide sequence encoding a constitutively enzymatically active matrix metalloproteinase (MMP) that cleaves Type II collagen selected from the group consisting of a constitutively enzymatically active human matrix metalloproteinase (hMMP) and a constitutively enzymatically active mammalian matrix metalloproteinase-13 (MMP-13), wherein the nucleotide sequence encoding the MMP is operatively linked to a regulatable promoter; and (b) a nucleotide sequence encoding a repressor-activator fusion polypeptide that binds to the regulatable promoter in the absence of a repressor-activator fusion polypeptide-binding compound and does not bind to the regulatable promoter in the presence of the compound, which nucleotide sequence encoding the repressor-activator fusion polypeptide is operatively linked to a chondrocyte-specific promoter, wherein expression of the MMP is capable of being repressed in the rodent until adulthood, and wherein the MMP is capable of being expressed in the rodent during adulthood to a level sufficient to cause Type II collagen degradation in the joints of the rodent.