Purpose: Biglycan is a proteoglycan of the small leucine-rich repeat family. It is present in all connective tissues and plays key structural and signaling roles. This review aimed to compile available evidence in the characteristics and distribution of biglycan and its glycosylated and non-glycosylated forms in connective tissues with a specific focus on the contribution to homeostasis of bone and changes of biglycan structure with aging.Methods: The Pubmed database was searched and included the terms "biglycan", "proteoglycans", "glycosaminoglycans", "bone", "osteoblast", "osteocyte", "osteoclast", "aging", "inflammation", "cartilage". Abstracts were appraised and a series of original articles and reviews studied to generate this narrative review.Results: Based on the search, biglycan significantly affects bone development and homeostasis and can be significantly changed by the aging process in several connective tissues, which in turn affects the behavior of tissue and cell responses in aged networks. Further, as the understanding of the various forms of biglycan in vivo is expanded and the function of its components in vitro is dissected, this proteoglycan can potentially serve as a therapeutic or biomarker molecule to detect tissue destruction.Conclusions: Biglycan is a key player in skeletal bone homeostasis, and overall, there is more evidence on the role of biglycan in development and less in the adult physiological or diseased young and aged systems. Further understanding of its conformation, degradation peptides and post-translational modifications will be required to understand the role of biglycan in bone maintenance and to support the development of treatments for age-related bone dysfunctions.

中文翻译：

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双糖链蛋白聚糖结构功能在骨稳态和衰老中的证据。

目的：Biglycan 是富含亮氨酸的小重复家族的蛋白聚糖。它存在于所有结缔组织中，并起着关键的结构和信号作用。本综述旨在收集关于双糖链蛋白聚糖及其糖基化和非糖基化形式在结缔组织中的特征和分布的现有证据，特别关注对骨骼稳态的贡献和双糖链蛋白聚糖结构随年龄的变化。方法：Pubmed 数据库是搜索并包括了术语“双糖链”、“蛋白聚糖”、“糖胺聚糖”、“骨”、“成骨细胞”、“骨细胞”、“破骨细胞”、“衰老”、“炎症”、“软骨”。对摘要进行了评估，并研究了一系列原创文章和评论，以生成这种叙述性评论。结果：基于搜索，双糖蛋白聚糖显着影响骨骼发育和体内平衡，并且可以通过多种结缔组织的衰老过程显着改变，进而影响衰老网络中组织和细胞反应的行为。此外，随着对体内各种形式的双糖链蛋白聚糖的理解不断扩大，并对其体外成分的功能进行了剖析，这种蛋白多糖有可能作为检测组织破坏的治疗剂或生物标志物分子。结论：双糖链蛋白聚糖是检测组织破坏的关键因素。骨骼体内平衡，总的来说，有更多证据表明双糖链蛋白聚糖在发育中的作用，而在成人生理或患病的年轻和老年系统中的作用则较少。进一步了解其构象，