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Related Concept Videos

Osteoclasts in Bone Remodeling01:31

Osteoclasts 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...
Intracellular Signaling Affects Focal Adhesions01:17

Intracellular Signaling Affects Focal Adhesions

Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...
Tension Response at Adherens Junctions01:26

Tension Response at Adherens Junctions

The adherens junctions that anchor cells together are multi-protein complexes that dynamically adapt to mechanical stimuli such as tensile forces and shear stress. Mechanosensory proteins in these junctions can sense such mechanical stimuli and undergo a shift in their conformation, resulting in an altered function — a process called mechanotransduction.
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Cell Motility through Blebbing01:16

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Cell-matrix's Response to Mechanical Forces

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Related Experiment Video

Updated: May 20, 2026

Examining the Dynamics of Cellular Adhesion and Spreading of Epithelial Cells on Fibronectin During Oxidative Stress
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Examining the Dynamics of Cellular Adhesion and Spreading of Epithelial Cells on Fibronectin During Oxidative Stress

Published on: October 13, 2019

Paxillin contracts the osteoclast cytoskeleton.

Wei Zou1, Carl J Deselm, Thomas J Broekelmann

  • 1Department of Pathology and Immunology, School of Medicine, Washington University, St. Louis, MO 63110, USA.

Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research
|July 19, 2012
PubMed
Summary

Paxillin is crucial for osteoclast function in bone resorption. Its absence leads to "superspreading" but impairs bone degradation by disrupting cytoskeletal contraction via myosin IIA delivery.

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A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro
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Last Updated: May 20, 2026

Examining the Dynamics of Cellular Adhesion and Spreading of Epithelial Cells on Fibronectin During Oxidative Stress
10:57

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Published on: October 13, 2019

A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro
07:03

A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro

Published on: June 16, 2022

Area of Science:

  • Cell Biology
  • Biochemistry
  • Orthopedics

Background:

  • Osteoclastic bone resorption is vital for skeletal remodeling and relies on cytoskeletal organization.
  • The αvβ3 integrin and osteoclastogenic cytokines are key regulators of osteoclast function.
  • Paxillin's association with αvβ3 integrin suggests a potential role in bone degradation.

Purpose of the Study:

  • To investigate the role of paxillin in osteoclast cytoskeletal organization and bone resorption.
  • To determine how paxillin influences osteoclast spreading and actin dynamics in response to RANKL.
  • To elucidate the molecular mechanisms by which paxillin regulates osteoclast-mediated skeletal degradation.

Main Methods:

  • Generation of paxillin-deficient (Pax(-/-)) osteoclasts from embryonic stem cells.
  • Assessment of osteoclast spreading, actin band formation, and bone resorption pit depth.
  • Analysis of paxillin phosphorylation (serine and tyrosine) and its dependence on c-Src.
  • Rescue experiments using wild-type (WT) paxillin and paxillin mutants (lacking LD4 domain).
  • Investigation of myosin IIA delivery to the actin cytoskeleton.

Main Results:

  • Pax(-/-) osteoclasts exhibited "superspreading" and atypical actin bands but significantly reduced bone resorption.
  • RANKL stimulation induced paxillin serine and tyrosine phosphorylation, the latter via c-Src.
  • The abnormal phenotype of Pax(-/-) osteoclasts was rescued by WT paxillin but not by a mutant lacking the LD4 domain.
  • Paxillin's LD4 domain is essential for the RANKL-mediated delivery of myosin IIA to the actin cytoskeleton.
  • Paxillin-mediated cytoskeletal contraction, independent of tyrosine phosphorylation, is critical for bone degradation.

Conclusions:

  • Paxillin plays a critical role in regulating osteoclast cytoskeletal organization and bone resorption.
  • The paxillin LD4 domain is essential for mediating the delivery of myosin IIA, enabling cytoskeletal contraction required for bone degradation.
  • Paxillin acts as a crucial link between RANKL signaling and the mechanical forces necessary for osteoclast-mediated skeletal remodeling.