Osteocalcin is Necessary for the Alignment of Apatite Crystallites, but Not Glucose Metabolism, Testosterone Synthesis, or Muscle Mass

Overview

Journal PLoS Genet

Specialty Genetics

Date 2020 May 29

PMID 32463816

Citations 83

Authors

Takeshi Moriishi

Ryosuke Ozasa

Takuya Ishimoto

Takayoshi Nakano

Tomoka Hasegawa

Toshihiro Miyazaki

Wenguang Liu

Ryo Fukuyama

Yuying Wang

Hisato Komori

Xin Qin

Norio Amizuka

Toshihisa Komori

Affiliations

Soon will be listed here.

Abstract

The strength of bone depends on bone quantity and quality. Osteocalcin (Ocn) is the most abundant noncollagenous protein in bone and is produced by osteoblasts. It has been previously claimed that Ocn inhibits bone formation and also functions as a hormone to regulate insulin secretion in the pancreas, testosterone synthesis in the testes, and muscle mass. We generated Ocn-deficient (Ocn-/-) mice by deleting Bglap and Bglap2. Analysis of Ocn-/-mice revealed that Ocn is not involved in the regulation of bone quantity, glucose metabolism, testosterone synthesis, or muscle mass. The orientation degree of collagen fibrils and size of biological apatite (BAp) crystallites in the c-axis were normal in the Ocn-/-bone. However, the crystallographic orientation of the BAp c-axis, which is normally parallel to collagen fibrils, was severely disrupted, resulting in reduced bone strength. These results demonstrate that Ocn is required for bone quality and strength by adjusting the alignment of BAp crystallites parallel to collagen fibrils; but it does not function as a hormone.

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