Related Experiment Video
Updated: Aug 8, 2026
08:43
Calcification of Vascular Smooth Muscle Cells and Imaging of Aortic Calcification and Inflammation
Published on: May 31, 2016
Bone mineralization and osteoblast differentiation are negatively modulated by integrin alpha(v)beta3
S L Cheng1, C F Lai, S D Blystone
1Department of Internal Medicine, Washington University School of Medicine, Barnes-Jewish Hospital, St. Louis, Missouri 63110, USA.
Summary
Overexpressing alpha(v)beta3 integrin in osteoblasts boosts cell proliferation but hinders differentiation. This occurs through altered integrin-matrix interactions, signaling pathways, and matrix protein expression, impacting bone formation.
Area of Science:
- Cell Biology
- Biochemistry
- Integrin Signaling
Background:
- Bone matrix proteins interact with alpha(v)-containing integrins, including alpha(v)beta3.
- Understanding these interactions is crucial for osteoblast function and bone metabolism.
Purpose of the Study:
- To investigate the functional consequences of alpha(v)beta3 integrin overexpression on osteoblast proliferation and differentiation.
- To elucidate the underlying molecular mechanisms, including signaling pathways and matrix protein expression.
Main Methods:
- Developed a murine osteoblastic cell line overexpressing human alpha(v)beta3 integrin.
- Assessed cell adhesion, proliferation, matrix mineralization, and protein expression (alkaline phosphatase, osteocalcin, collagen I, BSP, osteopontin).
- Analyzed signaling pathway activation (AP-1, Erk, JNK, p38) and integrin levels (beta1-integrin).
Main Results:
- Human alpha(v)beta3 integrin expression was functional, increasing adhesion to osteopontin.
- Osteoblasts overexpressing alpha(v)beta3 showed increased proliferation but decreased matrix mineralization.
- Key differentiation markers (alkaline phosphatase, osteocalcin, collagen I, BSP) were downregulated, while osteopontin was upregulated transcriptionally.
- Signaling analysis revealed enhanced AP-1 and Erk activity, decreased JNK activity, and reduced beta1-integrin levels, impairing collagen I and fibronectin adhesion.
Conclusions:
- Overexpression of alpha(v)beta3 integrin in osteoblasts stimulates proliferation while inhibiting differentiation.
- These effects are mediated by altered integrin-matrix interactions, modified signal transduction pathways, and changes in matrix protein expression.
- Alpha(v)beta3 integrin plays a significant role in regulating osteoblast behavior and bone matrix formation.
More Related Videos
10:32Simple Establishment of a Vascularized Osteogenic Bone Marrow Niche Using Pre-Cast Poly(ethylene Glycol) (PEG) Hydrogels in an Imaging Microplate
Published on: May 19, 2023
05:25Using Inducible Osteoblastic Lineage-Specific Stat3 Knockout Mice to Study Alveolar Bone Remodeling During Orthodontic Tooth Movement
Published on: July 21, 2023
Related Concept Videos
01:40Bone Remodeling
Bone remodeling is a continuous and balanced process of bone resorption by osteoclasts and bone formation by osteoblasts. In adults, it helps maintain bone mass and calcium homeostasis. While mechanical stress can stimulate turnover as part of the normal maintenance and reparative process, several hormones also regulate bone remodeling.
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...
01:10Integrins
Animal and protozoan cells do not have cell walls to help maintain shape and provide structural stability. Instead, these eukaryotic cells secrete a sticky mass of carbohydrates and proteins into the spaces between adjacent cells. This network of proteins and molecules is called an extracellular matrix or ECM.
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...
01:15Activation of Integrins
Integrins bind ligands and transmit information from outside the cell to inside or vice-versa through an "outside-in signaling" or "inside-out signaling."
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
01:17Intracellular 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...
Some...
01:18The Bone Matrix
Bone contains a relatively small number of cells entrenched in a matrix of collagen fibers that provide an adherent surface for inorganic salt crystals. Both components of the matrix, organic and inorganic, contribute to the unusual properties of bone. Without collagen, bones would be brittle and shatter easily. Without mineral crystals, bones would flex and provide little support. This can be observed by an experiment: when the minerals of a bone are dissolved by soaking the bone in acid or...