First-in-class humanized FSH blocking antibody targets bone and fat

Blocking the action of FSH genetically or pharmacologically in mice reduces body fat, lowers serum cholesterol, and increases bone mass, making an anti-FSH agent a potential therapeutic for three global epidemics: obesity, osteoporosis, and hypercholesterolemia. Here, we report the generation, structure, and function of a first-in-class, fully humanized, epitope-specific FSH blocking antibody with a KD of 7 nM. Protein thermal shift, molecular dynamics, and fine mapping of the FSH-FSH receptor interface confirm stable binding of the Fab domain to two of five receptor-interacting residues of the FSHβ subunit, which is sufficient to block its interaction with the FSH receptor. In doing so, the humanized antibody profoundly inhibited FSH action in cell-based assays, a prelude to further preclinical and clinical testing

Blocking FSH induces thermogenic adipose tissue and reduces body fat

Functional Genomics of Systemic Disorder

DGAT Activity is Dispensable for Myeloma Cell Proliferation

Multiple myeloma (MM) is the third most common blood cancer and is defined by the clonal expansion of malignant plasma cells in the bone marrow (BM). MM remains incurable due to the development of resistance to current chemotherapies; therefore, it is paramount to investigate novel treatments and the mechanisms of drug resistance in multiple myeloma cells. Recently, changes in both catabolic and anabolic lipid metabolism have been shown to support the proliferation, migration and the development of drug resistance in breast, prostate, and ovarian cancer. However, the role of lipid metabolism in myeloma cells has been understudied. Given the data in other cancers, we hypothesized that lipid metabolism contributes to myeloma cell proliferation and drug resistance. In order to test the role of global lipid metabolism in MM cell proliferation, we treated human and mouse myeloma cell lines with an inhibitor (Triacsin C, TriC) of acyl CoA synthetase (ACSL), an enzyme critical for both catabolic and anabolic lipid metabolism. Interestingly, TriC treatment severely decreased MM cell proliferation and increased apoptosis in a dose-dependent manner. Motivated to understand the specific mechanism of TriC’s toxicity, we explored the individual contributions of catabolic and anabolic lipid metabolism to myeloma cell proliferation. Here, we report that myeloma cells accumulate lipid droplets, express lipid droplet-related transcripts and can utilize lipid droplets as an energy source. We hypothesized that inhibition of lipid droplet formation would increase cytosolic free fatty acids that could be used to fuel proliferation in myeloma cells. Surprisingly, treatment with inhibitors against the rate-limiting enzymes that are responsible for the formation of lipid droplets did not alter the proliferation of both human and mouse myeloma cell lines. Taken together, our data suggests that global lipid metabolism is critical for myeloma cell proliferation but lipid droplet formation is dispensable in this process. Future directions will explore the role of de novo fatty acid synthesis and catabolic lipid metabolism with respect to myeloma cell proliferation, migration and drug resistance

Gender-specific changes in bone turnover and skeletal architecture in igfbp-2-null mice.

IGF-binding protein-2 (IGFBP-2) is a 36-kDa protein that binds to the IGFs with high affinity. To determine its role in bone turnover, we compared Igfbp2(-/-) mice with Igfbp2(+/+) colony controls. Igfbp2(-/-) males had shorter femurs and were heavier than controls but were not insulin resistant. Serum IGF-I levels in Igfbp2(-/-) mice were 10% higher than Igfbp2(+/+) controls at 8 wk of age; in males, this was accompanied by a 3-fold increase in hepatic Igfbp3 and Igfbp5 mRNA transcripts compared with Igfbp2(+/+) controls. The skeletal phenotype of the Igfbp2(-/-) mice was gender and compartment specific; Igfbp2(-/-) females had increased cortical thickness with a greater periosteal circumference compared with controls, whereas male Igfbp2(-/-) males had reduced cortical bone area and a 20% reduction in the trabecular bone volume fraction due to thinner trabeculae than Igfbp2(+/+) controls. Serum osteocalcin levels were reduced by nearly 40% in Igfbp2(-/-) males, and in vitro, both CFU-ALP(+) preosteoblasts, and tartrate-resistant acid phosphatase-positive osteoclasts were significantly less abundant than in Igfbp2(+/+) male mice. Histomorphometry confirmed fewer osteoblasts and osteoclasts per bone perimeter and reduced bone formation in the Igfbp2(-/-) males. Lysates from both osteoblasts and osteoclasts in the Igfbp2(-/-) males had phosphatase and tensin homolog (PTEN) levels that were significantly higher than Igfbp2(+/+) controls and were suppressed by addition of exogenous IGFBP-2. In summary, there are gender- and compartment-specific changes in Igfbp2(-/-) mice. IGFBP-2 may regulate bone turnover in both an IGF-I-dependent and -independent manner

A novel spontaneous mutation of Irs1 in mice results in hyperinsulinemia, reduced growth, low bone mass and impaired adipogenesis.

A spontaneous mouse mutant, designated \u27small\u27 (sml), was recognized by reduced body size suggesting a defect in the IGF1/GH axis. The mutation was mapped to the chromosome 1 region containing Irs1, a viable candidate gene whose sequence revealed a single nucleotide deletion resulting in a premature stop codon. Despite normal mRNA levels in mutant and control littermate livers, western blot analysis revealed no detectable protein in mutant liver lysates. When compared with the control littermates, Irs1(sml)/Irs1(sml) (Irs1(sml/sml)) mice were small, lean, hearing impaired; had 20% less serum IGF1; were hyperinsulinemic; and were mildly insulin resistant. Irs1(sml/sml) mice had low bone mineral density, reduced trabecular and cortical thicknesses, and low bone formation rates, while osteoblast and osteoclast numbers were increased in the females but not different in the males compared with the Irs1(+/+) controls. In vitro, Irs1(sml/sml) bone marrow stromal cell cultures showed decreased alkaline phosphatase-positive colony forming units (pre-osteoblasts; CFU-AP+) and normal numbers of tartrate-resistant acid phosphatase-positive osteoclasts. Irs1(sml/sml) stromal cells treated with IGF1 exhibited a 50% decrease in AKT phosphorylation, indicative of defective downstream signaling. Similarities between engineered knockouts and the spontaneous mutation of Irs1(sml) were identified as well as significant differences with respect to heterozygosity and gender. In sum, we have identified a spontaneous mutation in the Irs1 gene associated with a major skeletal phenotype. Changes in the heterozygous Irs1(+)(/sml) mice raise the possibility that similar mutations in humans are associated with short stature or osteoporosis

Room temperature housing results in premature cancellous bone loss in growing female mice: implications for the mouse as a preclinical model for age-related bone loss.

UNLABELLED: Room temperature housing (22 °C) results in premature cancellous bone loss in female mice. The bone loss was prevented by housing mice at thermoneutral temperature (32 °C). Thermogenesis differs markedly between mice and humans and mild cold stress induced by standard room temperature housing may introduce an unrecognized confounding variable into preclinical studies. INTRODUCTION: Female mice are often used as preclinical models for osteoporosis but, in contrast to humans, mice exhibit cancellous bone loss during growth. Mice are routinely housed at room temperature (18-23 °C), a strategy that exaggerates physiological differences in thermoregulation between mice (obligatory daily heterotherms) and humans (homeotherms). The purpose of this investigation was to assess whether housing female mice at thermoneutral (temperature range where the basal rate of energy production is at equilibrium with heat loss) alters bone growth, turnover and microarchitecture. METHODS: Growing (4-week-old) female C57BL/6J and C3H/HeJ mice were housed at either 22 or 32 °C for up to 18 weeks. RESULTS: C57BL/6J mice housed at 22 °C experienced a 62 % cancellous bone loss from the distal femur metaphysis during the interval from 8 to 18 weeks of age and lesser bone loss from the distal femur epiphysis, whereas cancellous and cortical bone mass in 32 °C-housed mice were unchanged or increased. The impact of thermoneutral housing on cancellous bone was not limited to C57BL/6J mice as C3H/HeJ mice exhibited a similar skeletal response. The beneficial effects of thermoneutral housing on cancellous bone were associated with decreased Ucp1 gene expression in brown adipose tissue, increased bone marrow adiposity, higher rates of bone formation, higher expression levels of osteogenic genes and locally decreased bone resorption. CONCLUSIONS: Housing female mice at 22 °C resulted in premature cancellous bone loss. Failure to account for species differences in thermoregulation may seriously confound interpretation of studies utilizing mice as preclinical models for osteoporosis

Gender-Specific Changes in Bone Turnover and Skeletal Architecture in Igfbp-2-Null Mice

IGF-binding protein-2 (IGFBP-2) is a 36-kDa protein that binds to the IGFs with high affinity. To determine its role in bone turnover, we compared Igfbp2−/− mice with Igfbp2+/+ colony controls. Igfbp2−/− males had shorter femurs and were heavier than controls but were not insulin resistant. Serum IGF-I levels in Igfbp2−/− mice were 10% higher than Igfbp2+/+ controls at 8 wk of age; in males, this was accompanied by a 3-fold increase in hepatic Igfbp3 and Igfbp5 mRNA transcripts compared with Igfbp2+/+ controls. The skeletal phenotype of the Igfbp2−/− mice was gender and compartment specific; Igfbp2−/− females had increased cortical thickness with a greater periosteal circumference compared with controls, whereas male Igfbp2−/− males had reduced cortical bone area and a 20% reduction in the trabecular bone volume fraction due to thinner trabeculae than Igfbp2+/+ controls. Serum osteocalcin levels were reduced by nearly 40% in Igfbp2−/− males, and in vitro, both CFU-ALP+ preosteoblasts, and tartrate-resistant acid phosphatase-positive osteoclasts were significantly less abundant than in Igfbp2+/+ male mice. Histomorphometry confirmed fewer osteoblasts and osteoclasts per bone perimeter and reduced bone formation in the Igfbp2−/− males. Lysates from both osteoblasts and osteoclasts in the Igfbp2−/− males had phosphatase and tensin homolog (PTEN) levels that were significantly higher than Igfbp2+/+ controls and were suppressed by addition of exogenous IGFBP-2. In summary, there are gender- and compartment-specific changes in Igfbp2−/− mice. IGFBP-2 may regulate bone turnover in both an IGF-I-dependent and -independent manner