Bone Abstracts

Osteoporosis in men causes significant morbidity and mortality. Considerable progress has been made in understanding the pathophysiology and management of osteoporosis, though it remains under-diagnosed and under-treated, particularly in men. Osteoporosis is widely considered to be more prevalent in women, even though at least one-third of all osteoporotic fractures occur in men. A major difference between the male and the female skeleton is the larger bone dimensions in the m...

The gut microbiota (GM), the commensal bacteria living in our intestine, performs numerous useful functions, including modulating host metabolism and immune status. Our recent studies demonstrate that the GM is also a regulator of bone mass and we propose that the effect of the GM on bone mass is mediated via effects on the immune system, which in turn regulates osteoclastogenesis. A role of the GM in bone metabolism is further supported by studies demonstrating that antibioti...

Estradiol (E2) signaling via estrogen receptor alpha (ERα) is important for the male skeleton as demonstrated by ERα inactivation in both mice and man. ERα mediates estrogenic effects by translocating to the nucleus and there affects gene transcription, but some effects can also be mediated via extra-nuclear actions of the receptor by, e.g., triggering cytoplasmic signaling cascades. ERα contains various domains and the role of activation functio...

Introduction: Fibroblast growth factor (FGF23) is a hormone derived from osteoblasts and osteocytes being involved in calcium and phosphate homeostasis, where serum iron (S-Fe) has been suggested as a potential mediator of FGF23 regulation. The aim was to determine whether iron status is a determinant of FGF23 in elderly men.Methods: The MrOS (osteoporotic fractures in men is a population based study of elderly men, in the Gothenburg part, (median age of...

Excess vitamin A has been associated with decreased cortical bone thickness and increased fracture risk. While most studies in rodents have been done using very high doses of vitamin A for a few days, we here investigate how clinically relevant doses of vitamin A, calculated from the Recommended Daily Allowance (RDA) in humans, affects the bone phenotype in mice after longer exposure.C57BL/6 mice were fed either a control diet (15 IU/g retinyl acetate), ...

Estrogens are important regulators of bone mass and exert their physiological effects on bone mainly via estrogen receptor α (ERα). Central ERα has been reported to exert an inhibitory role on bone mass. ERα is widely distributed in the brain with a high expression in the arcuate nucleus (ARC) and the ventral medial nucleus (VMN) in the hypothalamus. Here, we tested the hypothesis that ERα in hypothalamic pro-opiomelanocortin (POMC) neurons, located in...

see P490....

It is well established that estrogen, mainly via estrogen receptor alpha (ERα), has positive effects on bone, but estrogen is not considered as a treatment option against osteoporosis due to negative side-effects in other tissues. ERα is widely subjected to posttranslational modifications (PTMs), which can affect cellular responses to estrogen in a tissue specific manner by influencing the function of ERα and its interactions with other proteins. The in vivo...

see PP279....

Hip and forearm fractures are the two clinically most important non-vertebral fractures. Twin studies have demonstrated a high heritability of these fractures and the heritable component of fracture risk is largely independent of BMD.To identify common genetic variants associated with hip and forearm fractures, we performed a genome-wide association study (GWAS ~ 2.5 million SNPs) meta-analysis of two large fracture data sets within the well-characterize...