Treatment with an inhibitor of fatty acid synthase attenuates bone loss in ovariectomized mice.

Bone and fat cells have an antagonistic relationship. Adipocytes exert a toxic effect on bone cells in vitro through the secretion of fatty acids, which are synthesized by fatty acid synthase (FAS). Inhibition of FAS in vitro rescues osteoblasts from fat-induced toxicity and cell death. In this study, we hypothesized that FAS inhibition would mitigate the loss of bone mass in ovariectomized (OVX) mice. We treated OVX C57BL/6 mice with cerulenin (a known inhibitor of FAS) for 6 weeks and compared their bone phenotype with vehicle-treated controls. Cerulenin-treated mice exhibited a significant decrease in body weight, triglycerides, leptin, and marrow and subcutaneous fat without changes in serum glucose or calciotropic hormones. These effects were associated with attenuation of bone loss and normalization of the bone phenotype in the cerulenin-treated OVX group compared to the vehicle-treated OVX group. Our results demonstrate that inhibition of FAS enhances bone formation, induces uncoupling between osteoblasts and osteoclasts, and favors mineralization, thus providing evidence that inhibition of FAS could constitute a new anabolic therapy for osteoporosis.

The Role of the Nuclear Envelope Protein MAN1 in Mesenchymal Stem Cell Differentiation.

Mutations in MAN1, a protein of the nuclear envelope, cause bone phenotypes characterized by hyperostosis. The mechanism of this pro-osteogenic phenotype remains unknown. We increased and decreased MAN1 expression in mesenchymal stem cells (MSC) upon which standard osteogenic and adipogenic differentiation were performed. MAN1 knockdown increased osteogenesis and mineralization. In contrast, osteogenesis remained stable upon MAN1 overexpression. Regarding a mechanism, we found that low levels of MAN1 facilitated the nuclear accumulation of regulatory smads and smads-related complexes, with a concurrently high expression of nuclear ß-Catenin. In addition, we found adipogenesis to be decreased in both conditions, although predominantly affected by MAN1 overexpression. Finally, lamin A, a protein of the nuclear envelope that regulates MSC differentiation, was unaffected by changes in MAN1. In conclusion, our studies demonstrated that lower levels of MAN1 in differentiating MSC are associated with higher osteogenesis and lower adipogenesis. High levels of MAN1 only affected adipogenesis. These effects could have an important role in the understanding of the role of the proteins of the nuclear envelope in bone formation. J. Cell. Biochem. 118: 4425-4435, 2017. © 2017 Wiley Periodicals, Inc.

Characterizing the molecular phenotype of an Atp7a(T985I) conditional knock in mouse model for X-linked distal hereditary motor neuropathy (dHMNX).

ATP7A is a P-type ATPase essential for cellular copper (Cu) transport and homeostasis. Loss-of-function ATP7A mutations causing systemic Cu deficiency are associated with severe Menkes disease or its milder allelic variant, occipital horn syndrome. We previously identified two rare ATP7A missense mutations (P1386S and T994I) leading to a non-fatal form of motor neuron disorder, X-linked distal hereditary motor neuropathy (dHMNX), without overt signs of systemic Cu deficiency. Recent investigations using a tissue specific Atp7a knock out model have demonstrated that Cu plays an essential role in motor neuron maintenance and function, however the underlying pathogenic mechanisms of ATP7A mutations causing axonal degeneration remain unknown. We have generated an Atp7a conditional knock in mouse model of dHMNX expressing Atp7a(T985I), the orthologue of the human ATP7A(T994I) identified in dHMNX patients. Although a degenerative motor phenotype is not observed, the knock in Atp7a(T985I/Y) mice show altered Cu levels within the peripheral and central nervous systems, an increased diameter of the muscle fibres and altered myogenin and myostatin gene expression. Atp7a(T985I/Y) mice have reduced Atp7a protein levels and recapitulate the defective trafficking and altered post-translational regulatory mechanisms observed in the human ATP7A(T994I) patient fibroblasts. Our model provides a unique opportunity to characterise the molecular phenotype of dHMNX and the time course of cellular events leading to the process of axonal degeneration in this disease.

Lamin A/C Acts as an Essential Factor in Mesenchymal Stem Cell Differentiation Through the Regulation of the Dynamics of the Wnt/ß-Catenin Pathway.

Changes in the expression of lamin A/C, a fibrilar protein of the nuclear envelope, are associated with the cellular features of age-related bone loss. Reduced expression of lamin A/C inhibits osteoblastogenesis while facilitating adipogenic differentiation of mesenchymal stem cells (MSC) in vitro and in vivo. In this study we investigated the regulatory role that lamin A/C plays on the essential elements of the Wnt/ß-catenin pathway, which are pivotal in MSC differentiation. Initially, we assessed the effect of lamin A/C gene (LMNA) overexpression on MSC differentiation while compared it to lamin A/C depleted MSC. Osteogenesis and gene expression of osteogenic factors were higher in LMNA-transfected MSC as compared to control. Conversely, adipogenesis and expression of adipogenic factors were significantly lower in LMNA transfected cells. Nuclear ß-catenin was significantly higher (∼two fold) in MSC expressing higher levels of LMNA as compared to control with nuclear ß-catenin levels being significantly lower (∼ -42%) in siRNA-treated MSC. Luciferase activity for ß-catenin-mediated transcriptional activation was significantly higher in cells overexpressing LMNA. These data indicate that MSC overexpressing LMNA have higher osteogenic and lower adipogenic differentiation potential. In conclusion, our studies demonstrate that lamin A/C plays a significant role in the differentiation of both osteoblasts and adipocytes by regulating some of the elements of Wnt/ß-catenin signaling during early MSC differentiation.

Fat and bone interactions.

Fat and bone have a complicated relationship. Although obesity has been associated with low fracture risk, there is increasing evidence that some of the factors that are released by peripheral fat into the circulation may also have a deleterious effect on bone mass, thus, predisposing to fractures. More importantly, the local interaction between fat and bone within the bone marrow seems to play a significant role in the pathogenesis of age-related bone loss and osteoporosis. This "local interaction" occurs inside the bone marrow and is associated with the autocrine and paracrine release of fatty acids and adipokines, which affect the cells in their vicinity including the osteoblasts, reducing their function and survival. In this review, we explore the particularities of the fat and bone cell interactions within the bone marrow, their significance in the pathogenesis of osteoporosis, and the potential therapeutic applications that regulating marrow fat may have in the near future as a novel pharmacologic treatment for osteoporosis.

Interferon gamma inhibits adipogenesis in vitro and prevents marrow fat infiltration in oophorectomized mice.

Interferon gamma (IFNγ) has been reported to induce osteoblastogenesis from mesenchymal stem cells (MSCs) both in vitro and in vivo. With ageing, adipocytes outnumber osteoblasts within the bone microenvironment leading to a decrease in bone formation. Since both osteoblasts and adipocytes are of mesenchymal origin, we hypothesized that IFNγ treatment might negatively affect adipogenesis while stimulating osteoblastogenesis in human MSC. To test this hypothesis, human MSCs were induced to differentiate into adipocytes in the presence or absence of osteogenic doses of IFNγ (1, 10, and 100 ng/ml). IFNγ-treated MSC showed a decrease in adipocyte differentiation and lipid deposition when compared with vehicle-treated controls. Additionally, adipogenic markers were significantly decreased by IFNγ treatment at the same doses that have been reported to have a strong osteogenic effect in vitro. Furthermore, DNA binding of peroxisome proliferator-activated receptor gamma was significantly lower in IFNγ-treated differentiating MSC. Subsequently, ovariectomized C57BL6 mice were treated with osteogenic doses of IFNγ three times a week for 6 weeks. In distal femur, treated mice showed significantly higher hematopoiesis concomitant with lower levels of fat volume/total volume, adipocyte number, and expression of adipogenic markers when compared with the vehicle-treated mice. Together, these findings demonstrate that, at osteogenic doses, IFNγ also acts as an inhibitor of adipogenesis in vitro and prevents marrow fat infiltration while favors hematopoiesis in ovariectomized mice.

Hemofilia: diagnóstico molecular y alternativas de tratamiento / Hemophilia: molecular diagnosis and alternatives of treatment

La hemofilia es una enfermedad recesiva ligada al cromosoma X que generalmente padecen los hombres. El diagnóstico genético preimplantación (DGP), el diagnóstico prenatal y el diagnóstico molecular de las mutaciones que causan hemofilia, se realizan en investigaciones aisladas con el fin de hacer prevención primaria, asesorar a las portadoras y a sus familias, lo que ha permitido traer al mundo niños libres de esta enfermedad y también mejorar la calidad de vida de los afectados. Los esperanzadores procedimientos en terapia génica (TG) han mostrado gran efectividad, se pretende con ella la producción normal de la proteína que está ausente o alterada en los afectados, pero en el momento los ensayos que se llevan a cabo en seres humanos están detenidos. Aquí se muestran otras terapias alternas que aunque están en fase de investigación, permitirían obtener una producción de proteína a largo término y que se han desarrollado gracias al entendimiento de la naturaleza molecular de los factores de la coagulación.

The haemophilia is a recessive disease tied to the X chromosome that generally men suffer. The genetic preimplantation diagnosis (GPD), the prenatal diagnosis and the molecular diagnosis of the mutations that cause haemophilia, are realized in isolated investigations (researches) in order to do primary prevention, provide advise to the carriers of the disease and their families, which has allowed to bring to the world children free of this disease and also to improve the quality of life of the affected ones. The hopeful procedures in gene therapy (GT) have shown great effectiveness. The intention is to achieve the normal production of the protein which is absent or it is altered in the affected ones, but at the moment the tests carried out in human beings are stopped. Here are other alternate therapies that although are in phase of investigation, would allow to obtain a production of protein to long term and which have been developed thanks to the understanding of the molecular nature of the coagulation factors.