Context: Follistatin is a plasma protein recently reported to increase under conditions with negative energy balance, such as exercise and fasting in humans. Currently, the perception is that circulating follistatin is a result of para/autocrine actions from various tissues. The large and acute increase in circulating follistatin in response to exercise suggests that it may function as an endocrine signal.
Objective: We assessed origin and regulation of circulating follistatin in humans.
Design/interventions: First, we assessed arterial-to-venous difference of follistatin over the splanchnic bed at rest and during exercise in healthy humans. To evaluate the regulation of plasma follistatin we manipulated glucagon-to-insulin ratio in humans at rest as well as in cultured hepatocytes. Finally, the impact of follistatin on human islets of Langerhans was assessed.
Results: We demonstrate that in humans the liver is a major contributor to circulating follistatin both at rest and during exercise. Glucagon increases and insulin inhibits follistatin secretion both in vivo and in vitro, mediated via the secondary messenger cAMP in the hepatocyte. Short-term follistatin treatment reduced glucagon secretion from islets of Langerhans, whereas long-term follistatin treatment prevented apoptosis and induced proliferation of rat β cells.
Conclusions: In conclusion, in humans, the liver secretes follistatin at rest and during exercise, and the glucagon-to-insulin ratio is a key determinant of circulating follistatin levels. Circulating follistatin may be a marker of the glucagon-to-insulin tone on the liver.
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http://dx.doi.org/10.1210/jc.2015-3668 | DOI Listing |
Biomolecules
November 2024
Department of Morphological Sciences, Adelson School of Medicine, Ariel University, Ariel 40700, Israel.
Commun Biol
October 2024
Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, Lausanne, Switzerland.
The Activin-A precursor dimer can be cleaved by furin, but how this proteolytic maturation is regulated in vivo and how it facilitates access to signaling receptors is unclear. Here, analysis in a syngeneic melanoma grafting model shows that without furin coexpression, Activin-A failed to accelerate tumor growth, correlating with failure of one or both subunits to undergo cleavage in signal-sending cells, even though compensatory processing by host cells nonetheless sustained elevated circulating Activin-A levels. In reporter assays, furin-independent cleavage of one subunit enabled juxtacrine Activin-A signaling, whereas completion of proteolytic maturation by coexpressed furin or by recipient cells stimulated contact-independent activity, crosstalk with BMP receptors, and signal inhibition by follistatin.
View Article and Find Full Text PDFFront Endocrinol (Lausanne)
October 2024
First Department of Surgery, Jagiellonian University Medical College, Krakow, Poland.
Background: Some experimental data suggest that myokines may play an important role in developing cancer-associated cachexia (CAC), but their relevance in humans remains poorly explored. In our study, we tested the hypothesis that circulating myokines are associated with the pathogenesis of CAC in a model population of gastric cancer.
Methods: A group of 171 treatment naïve patients with adenocarcinoma of the stomach were prospectively examined.
Eur Heart J
November 2024
Unit of Medical Epidemiology, Department of Surgical Sciences, Uppsala University, Dag Hammarskjölds väg 14 B, 75185, Uppsala, Sweden.
Background And Aims: Few population-based cohort studies, including both men and women, have explored circulating proteins associated with incident myocardial infarction (MI). This study investigated the relationships between circulating cardiometabolic-related proteins and MI risk using cohort-based and Mendelian randomization (MR) analyses and explored potential sex-specific differences.
Methods: The discovery cohort included 11 751 Swedish adults (55-93 years).
Front Endocrinol (Lausanne)
September 2024
Division of Endocrinology Diabetes and Metabolism at Baylor College of Medicine, Houston, TX, United States.
Background: Testosterone (T) therapy increases lean mass and reduces total body and truncal fat mass in hypogonadal men. However, the underlying molecular mechanisms for the reciprocal changes in fat and lean mass in humans are not entirely clear.
Methods: Secondary analysis of specimens obtained from a single-arm, open-label clinical trial on pharmacogenetics of response to T therapy in men with late-onset hypogonadism, conducted between 2011 and 2016 involving 105 men (40-74 years old), who were given intramuscular T cypionate 200 mg every 2 weeks for 18 months.
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