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Hypermineralization of Hearing‐Related Bones by a Specific Osteoblast Subtype
Author(s) -
Kuroda Yukiko,
Kawaai Katsuhiro,
Hatano Naoya,
Wu Yanlin,
Takano Hidekazu,
Momose Atsushi,
Ishimoto Takuya,
Nakano Takayoshi,
Roschger Paul,
Blouin Stéphane,
Matsuo Koichi
Publication year - 2021
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.4320
Subject(s) - osteoblast , osteoid , osteocyte , microbiology and biotechnology , ossicles , anatomy , osteocalcin , type i collagen , bone canaliculus , chemistry , biology , endocrinology , middle ear , alkaline phosphatase , biochemistry , in vitro , enzyme
Auditory ossicles in the middle ear and bony labyrinth of the inner ear are highly mineralized in adult mammals. Cellular mechanisms underlying formation of dense bone during development are unknown. Here, we found that osteoblast‐like cells synthesizing highly mineralized hearing‐related bones produce both type I and type II collagens as the bone matrix, while conventional osteoblasts and chondrocytes primarily produce type I and type II collagens, respectively. Furthermore, these osteoblast‐like cells were not labeled in a “conventional osteoblast”‐specific green fluorescent protein (GFP) mouse line. Type II collagen‐producing osteoblast‐like cells were not chondrocytes as they express osteocalcin, localize along alizarin‐labeled osteoid, and form osteocyte lacunae and canaliculi, as do conventional osteoblasts. Auditory ossicles and the bony labyrinth exhibit not only higher bone matrix mineralization but also a higher degree of apatite orientation than do long bones. Therefore, we conclude that these type II collagen‐producing hypermineralizing osteoblasts (termed here auditory osteoblasts) represent a new osteoblast subtype. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).