Related Experiment Video
Updated: Jun 14, 2026
09:37
A RANKL-based Osteoclast Culture Assay of Mouse Bone Marrow to Investigate the Role of mTORC1 in Osteoclast Formation
Published on: March 15, 2018
Mitf induction by RANKL is critical for osteoclastogenesis
Ssu-Yi Lu1, Mengtao Li, Yi-Ling Lin
1Section of Oral Pathology, Department of Diagnostic and Surgical Sciences, School of Dentistry, University of California, Los Angeles, CA 90095, USA.
Molecular Biology of the Cell
|April 2, 2010
Summary
Receptor activator for nuclear factor-kappaB ligand (RANKL) induces osteoclastogenesis through Microphthalmia-associated transcription factor isoform E (Mitf-E). Mitf-E is crucial for osteoclast development and distinct from Mitf-A and Tfe3.
Area of Science:
- Molecular Biology
- Cell Biology
- Developmental Biology
Background:
- Microphthalmia-associated transcription factor (Mitf) is vital for osteoclast development.
- Two main isoforms, Mitf-A and Mitf-E, exist in osteoclasts, with distinct expression patterns.
- The precise roles and regulation of Mitf isoforms in osteoclastogenesis are not fully understood.
Purpose of the Study:
- To elucidate the novel mechanism of osteoclastogenesis regulation by receptor activator for nuclear factor-kappaB ligand (RANKL) via Mitf.
- To compare the osteoclastogenic potential and cellular localization of Mitf-A and Mitf-E.
- To investigate the distinct roles of Mitf and Tfe3 in osteoclast differentiation.
Main Methods:
- Quantitative analysis of Mitf-A and Mitf-E expression in osteoclasts and macrophages.
- Assessment of osteoclastogenic activity of Mitf isoforms.
- Chromatin association studies of Mitf isoforms.
- RNA interference (RNAi) to evaluate Mitf and Tfe3 functional redundancy.
Main Results:
- RANKL significantly up-regulates Mitf-E expression during osteoclastogenesis, unlike the ubiquitous Mitf-A.
- Mitf-E exhibits stronger osteoclastogenic activity than Mitf-A and shows distinct chromatin association.
- Mitf plays a critical, non-redundant role in osteoclastogenesis, separate from Tfe3.
Conclusions:
- RANKL-induced Mitf-E is a key regulator of osteoclastogenesis.
- Mitf-E's chromatin association and potent activity highlight its specific function.
- Mitf has a distinct and essential role in osteoclast biology, not fully redundant with Tfe3.
Related Concept Videos
01:16TGF - β Signaling Pathway
The TGF-β signaling pathway regulates cell growth, differentiation, adhesion, motility, and development. TGF-β ligands that induce TGF-β signaling are synthesized in their latent form. Several proteases or cell surface receptors such as integrins act upon the latent form, releasing the active ligand. There are three types of mammalian TGF-βs: (TGF-β1, TGF-β2, and TGF-β3) that bind as homodimers or heterodimers to TGF-β receptors. The TGF-β receptors are of three kinds RI, RII, and RIII. The RI...
01:31Osteoclasts in Bone Remodeling
Osteoclasts are cells responsible for bone resorption and remodeling. They originate from hematopoietic progenitor cells present in the bone marrow. Numerous progenitor cells fuse to form multinucleated cells, each with 10-20 nuclei. A single osteoclast has a diameter of 150 to 200 µM. These cells have ruffled borders that break down the underlying bone tissue and release minerals such as calcium into the blood in bone resorption. Osteoclasts cling to bones with their ruffled edges during bone...
01:22PI3K/mTOR/AKT Signaling Pathway
The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast, mTORC2 consists of a rapamycin-insensitive companion...
01:07MAPK Signaling Cascades
Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
01:24Regulation of Angiogenesis and Blood Supply
Rapidly dividing tumors, embryos, and wounded tissues require more oxygen than usual, lowering the oxygen concentration in the blood. At low oxygen or hypoxic conditions, an oxygen-sensitive transcription factor called the hypoxia-inducible factor 1 or HIF1 is activated. HIF1 is a dimeric protein of alpha (ɑ) and beta (β) subunits. Under optimal oxygen conditions, HIF1β is present in the nucleus while HIF1ɑ remains in the cytosol. HIF1ɑ is hydroxylated by prolyl hydroxylase and factor...
03:03mTOR Signaling and Cancer Progression
The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
The mTOR pathway or the...