The “soft” side of the bone: unveiling its endocrine functions

Author(s):  
Alfredo Cappariello ◽  
Marco Ponzetti ◽  
Nadia Rucci

AbstractBone has always been regarded as a merely structural tissue, a “hard” scaffold protecting all of its “soft” fellows, while they did the rest of the work. In the last few decades this concept has totally changed, and new findings are starting to portray bone as a very talkative tissue that is capable not only of being regulated, but also of regulating other organs. In this review we aim to discuss the endocrine regulation that bone has over whole-body homeostasis, with emphasis on energy metabolism, male fertility, cognitive functions and phosphate (Pi) metabolism. These delicate tasks are mainly carried out by two known hormones, osteocalcin (Ocn) and fibroblast growth factor 23 (FGF23) and possibly other hormones that are yet to be found. The extreme plasticity and dynamicity of bone allows a very fine tuning over the actions these hormones exert, portraying this tissue as a full-fledged endocrine organ, in addition to its classical roles. In conclusion, our findings suggest that bone also has a “soft side”, and is daily taking care of our entire organism in ways that were unknown until the last few years.

Bone Research ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Nikolai Jaschke ◽  
Wolfgang Sipos ◽  
Lorenz C. Hofbauer ◽  
Tilman D. Rachner ◽  
Martina Rauner

AbstractThe regulation of whole-body homeostasis by the skeleton is mediated by its capacity to secrete endocrine signaling molecules. Although bone-derived hormones confer several adaptive benefits, their physiological functions also involve trade-offs, thus eventually contributing to disease. In this manuscript, we discuss the origins and functions of two of the best-studied skeletal mediators, fibroblast growth factor 23 and osteocalcin, in an evolutionary context. Moreover, we provide a theoretical framework seeking to explain the broad involvement of these two hormones in amniote physiology as well as their potential to fuel the development and progression of diseases. Vice versa, we outline which perturbations might be amenable to manipulation of these systems and discuss limitations and ongoing challenges in skeletal endocrine research. Finally, we summarize unresolved questions and potential future studies in this thriving field.


2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 368-368
Author(s):  
Jianguo Wang ◽  
Xiaoyan Zhu ◽  
Baoyu Zhao

Abstract Background: Fibroblast growth factor 21 (FGF21) plays essential roles in the regulation of whole body energy metabolism. However, it is not entirely clear for dairy cows whether FGF21 activates AMPK signaling pathway and what will be affected for lipid metabolism in bovine hepatocytes. Methods: Bovine hepatocytes were isolated from caudate lobes by using three-step of perfusion and collagenase digestion method. The accumulation of TG and the secretion of VLDL were examined in hepatocytes and supernatant, respectively. The expressions of the metabolic key factors were detected by Real-time PCR and Western Blot.Results: The 4th hour is the optimal time that FGF21 activates AMPK. FGF21 has significant dose-dependent inhibition of TG in bovine hepatocytes; and high concentration (1800 pg/mL) significantly promoted VLDL secretion at 4 h. The protein expression of APOB 100, APOE and MTTP, which are components of VLDL, were stimulated by FGF21, and all the mRNA expression reached the peak point (P < 0.01) at medium concentration (900 pg/mL). Interestingly, the proteins associated with lipid transportation were promoted too, such as LDLR, CD36, L-FABP. To some extent, meanwhile, it could be observed that some genes regulating lipid oxidation were strengthened following FGF21 treatment. In detail, ACOX1 and SIRT1 were very sensitive to the concentration of FGF21, showing remarkable difference at low concentration (P < 0.01); PGC-α, PPAR-α and CPT-1 showed significant changes at 900 pg/mL (P < 0.01); CPT-2 required a higher concentration to achieve significant enhancement. However, the results had a negative impact on lipogenesis. SREBP1c, ACC, FASN and ACLY were inhibited after treatment with low or medium doses of FGF21 (P < 0.01). Conclusion: FGF21 can promote lipid oxidation and transport, while inhibit lipid synthesis via activating AMPK signalling pathway in primary hepatocytes of dairy cows, thereby participation in the adaptive regulation of energy metabolism.


2017 ◽  
Author(s):  
Elisa Holmlund-Suila ◽  
Maria Enlund-Cerullo ◽  
Saara Valkama ◽  
Helena Hauta-alus ◽  
Jenni Rosendahl ◽  
...  

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