Age-resolving osteopetrosis: A rat model implicating microphthalmia and the related transcription factor TFE3

Katherine N. Weilbaecher, Christine L. Hershey, Clifford M. Takemoto, Martin A. Horstmann, Timothy J. Hemesath, Armen H. Tashjian, David E. Fisher

Research output: Contribution to journalArticlepeer-review

82 Scopus citations


Microphthalmia (Mi) is a basic helix-loop-helix-leucine tipper (b-HLH- ZIP) transcription factor implicated in pigmentation, mast cells, and bone development. Two dominant-negative mi alleles (mi/mi and Mi(or)/Mi(or)) in mice cause osteopetrosis. In contrast, osteopetrosis has not been observed in a number of recessive mi alleles, suggesting the existence of Mi protein partners important in osteoclast function. An osteopetrotic rat of unknown genetic defect (mib) has been described whose skeletal sclerosis improves dramatically with age and that is associated with pigmentation defects reminiscent of mouse mi alleles. Here we report that this rat strain harbors a large genomic deletion encompassing the 3' half of mi including most of the b-HLH-ZIP region. Osteoclasts from these animals lack Mi protein in contrast to wild-type rat, mouse, and human osteoclasts. Mi is not detectable in primary osteoblasts. In addition TFE3, a b-HLH-ZIP transcription factor related to Mi, was found to be expressed in osteoclasts, but not osteoblasts, and to coimmunoprecipitate with Mi. These results demonstrate the existence of members of a family of biochemically related transcription factors that may cooperate to play a central role in osteoclast function and possibly in age related osteoclast homeostasis.

Original languageEnglish
Pages (from-to)775-785
Number of pages11
JournalJournal of Experimental Medicine
Issue number5
StatePublished - Mar 2 1998


Dive into the research topics of 'Age-resolving osteopetrosis: A rat model implicating microphthalmia and the related transcription factor TFE3'. Together they form a unique fingerprint.

Cite this