ReviewBone and muscle: Interactions beyond mechanical
Introduction
The topic of bone–muscle interactions has become of interest for basic, clinical, and translational scientists because of the realization of the implications of this emerging field of research [1]. The concept that bone and muscle cells communicate at the biochemical and molecular levels in ways beyond and complementary to those ways dictated by mechanical interactions is leading to new insight into how bone and muscles work together in health and disease. With life expectancy projected to surpass the centenary mark, the twin diseases osteoporosis–sarcopenia will exert additional, not yet fully understood, consequences on public health and the economy. In fact, humankind has never experienced a larger and broader demographic shift in its history with a projected 20% of the world population being 60 and older by 2050 and over 1/3 by 2150 [2], [3].
Section snippets
The mechanical coupling of bone and muscle is easier to appreciate and comprehend than biochemical cross-talk
The coupling of bones and skeletal muscles has been simplified and mainly viewed as mechanical in nature, where muscles are the load suppliers and bone simply provides the attachment sites. The musculoskeletal system is unquestionably much more complex than just bone and muscles. A broader comprehension of bone–muscle biochemical signaling could lead to unprecedented and previously unimagined therapies not only for these diseases, but likely for many other musculoskeletal diseases.
The close
Muscle as a secretory/endocrine organ
It was only during the last decade of research that skeletal muscles were recognized for their significant secretory capacity [7]. Myostatin, discovered in Se-Jin's laboratory in 1997 is arguably the most potent inhibitor of skeletal muscle cell proliferation and growth and is also considered one of the earliest muscle secreted factors [8], [9].
Pedersen and colleagues were the first research group to invent the term, ‘myokines,’ and since then, other muscle secreted factors have been documented
Bone as a secretory/endocrine organ
Bone is generally not thought of as an endocrine gland such as the pituitary or adrenals. However, the definition of an endocrine gland is that it must be highly vascularized and form a system that directly secretes hormones into the bloodstream to affect distant targets. Based on this definition, bone is an endocrine organ [15]. Osteoblasts have the capacity to release factors such as osteocalcin as do osteocytes. In addition, osteocytes produce circulating factors such as FGF23 and
Future directions
In summary, the mechanical and biochemical theories of bone–muscle crosstalk are not exclusive or one more important or relevant than the other theory. These theories are most likely complementary whereby mechanical force might prime bone and muscle for regulation and release of specific factors to exert their effects on the opposing tissue. Continued and progressive research aimed at merging these two theories will bring advances in knowledge that will translate into new therapies that could
Conflict of interest
The authors declare no conflicts of interest.
Human and animal rights and informed consent
This article does not contain any studies with human or animal subjects performed by any of the authors.
Acknowledgments
The research supported by the authors in muscle bone crosstalk is supported by NIAMS NIA PO1AG039355.
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2023, Journal of Advanced ResearchCitation Excerpt :Apart from being involved in the body's normal daily physiological activities, as a whole system, bones and muscles have a sophisticated and complex crosstalk [25,75]. This not only refers to mechanical conduction [76], but also through effective growth factors. Interactions between bones and muscles regulate various processes, including fluid circulation, cellular and molecular processes, as well as mechanical transmission [25,75].