Androgens, estrogens, and bone loss in males

男性雄激素、雌激素和骨质流失

• 批准号: 10254219
• 负责人: STAVROS C. MANOLAGAS
• 金额: --
• 依托单位: CENTRAL ARKANSAS VETERANS HLTHCARE SYS
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2021-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10254219
• 关键词: Adult; Androgen Receptor; Androgens; Apoptosis; Apoptotic; Applications Grants; Attenuated; B-Lymphocytes; Bone Marrow; Bone Marrow Cells; Bone remodeling; CD19 gene; CXCL12 gene; CXCR4 gene; Calvaria; Cell Culture Techniques; Cells; Coculture Techniques; Dendrimers; Development; Down-Regulation; Estradiol; Estrogen Receptor alpha; Estrogens; Family; Female; Funding; Generations; Hematopoietic; Homing; Hormones; Hydrogen Peroxide; In Vitro; Life; Longevity; Maintenance; Malignant neoplasm of prostate; Mediating; Mesenchymal; Mesenchymal Stem Cells; Messenger RNA; Mitochondria; Molecular; Mus; Nuclear; Null Lymphocytes; Orchiectomy; Osteoblasts; Osteoclasts; Osteocytes; Osteoporosis; Pharmaceutical Preparations; Plasma; Production; Proteins; Receptor Signaling; Research; Role; Signal Transduction; Surface; TNFSF11 gene; Testing; Testosterone; Veterans; Woman; Work; attenuation; base; bone; bone loss; bone mass; cell type; chemokine; cortical bone; dentin matrix protein 1; gonad function; insight; macrophage; male; malignant breast neoplasm; men; mouse model; novel; novel therapeutics; osteoclastogenesis; osteoporosis with pathological fracture; prevent; progenitor; protective effect; receptor; reproductive organ; sex; substantia spongiosa

Both androgens and estrogens contribute to the maintenance of bone mass during adult life in men, but the cell targets and molecular mechanisms of these effects remain poorly understood. During the preceding funding period, we found that the effects of androgens on cancellous bone result from AR signaling in cells of the mesenchymal lineage leading to a decrease in osteoclasts; and orchidectomy (ORX) increases soluble RANKL levels as well as the number of B-lymphocytes in the murine bone marrow. RANKL derived from osteocytes is critical for cancellous bone remodeling and B-lymphocyte-derived RANKL contributes to the loss of cancellous bone mass in ovariectomized (OVX) mice. In cortical bone, however, the effects of androgens do not require AR signaling in any cell type of the mesenchymal lineage, nor do they require ERα signaling downstream of committed osteoblast progenitors targeted by Osx1-Cre, or AR or ERα signaling in the osteoclast lineage. Estrogens, nonetheless, attenuate endocortical resorption in females by ERα signaling in uncommitted mesenchymal progenitors targeted by Prx1-Cre. In addition, the mRNA and secreted protein levels of SDF1 – a chemotactic cytokine of the CXC family that is abundantly expressed in Prx1-Cre targeted cells and promotes osteoclast generation – are higher in GFP-tagged ERα null cells as well as bone marrow cell cultures from female ERαf/f;Prx1-Cre mice as compared to identical cultures from littermate controls; and so is osteoclastogenesis in co-cultures of ERα null BM stromal or calvaria cells with macrophages. Furthermore, both OVX and ORX increase SDF1 in the bone marrow plasma, administration of E2 to ORX mice prevents this increase, and E2, but not DHT, prevents cortical bone loss in ORX mice. Finally, we found that the OVX- or ORX-induced cortical bone loss is prevented by restraining H2O2 generation in osteoclast mitochondria; and the loss of cortical bone mass in OVX mice is prevented by a 17β-E2 dendrimer conjugate (EDC), incapable of stimulating nuclear- initiated actions of ERα. Based on these advances, we will test the interrelated hypotheses that: in males, the protective effects of androgens on cancellous bone result from AR signaling in osteocytes, B-lymphocytes, or both. These actions result in the attenuation of RANKL and thereby attenuation of the number of cancellous osteoclasts. The protective effects of androgens against endocortical resorption result, at least in part, from ERα- mediated actions (upon aromatization of androgens to estrogens) on Prx1-Cre targeted uncommitted mesenchymal progenitors. These actions repress SDF1 production, thereby attenuating osteoclast formation and homing at the endosteal surfaces. The suppressive effect of estrogens on SDF1 production ultimately leads to the restraining of H2O2 accumulation in osteoclasts and results from non-nuclear-initiated signaling of the ERα. To advance these hypotheses we will try to elucidate the mechanism of the protective effects of androgens on cancellous bone by determining the role of osteocyte- and B-lymphocyte-derived RANKL as well as the role of the B lymphocyte AR in these effects. To do this we will study: i) mice in which RANKL is deleted from mature osteoblasts/osteocytes (RANKLf/f;Dmp1-Cre), ii) mice in which both AR and RANKL are deleted from osteoblasts/osteocytes (RANKLf/f;ARf/y;Dmp1-Cre), iii) mice in which RANKL is deleted from B-lymphocytes (RANKLf/f;CD19-Cre), and iv) mice in which AR is deleted from B-lymphocytes (ARf/y;CD19-Cre). In addition, we will elucidate the mechanism of the protective effects of androgens on cortical bone by investigating: a) whether down-regulation of SDF1 in uncommited mesenchymal progenitors is responsible for some of these effects using: i) mice in which SDF1 is deleted in Prx1-Cre targeted cells, and ii) mice in which the SDF1 receptor, CXCR4, is deleted in LysM-Cre targeted cells; and b) whether the effect of androgens results from ERα-mediated actions upon androgen aromatization to estrogens using ERαf/f;Prx1-Cre mice. Using co-cultures of stromal and hematopoietic cells, we will also examine whether SDF1 promotes osteoclastogenesis via H2O2; and whether the effect of estrogens on SDF1 results from non-nuclear-initiated signaling of the ERα.

雄激素和雌激素在成年男性的成年生活期间都有助于维持骨骼质量，但是细胞 这些作用的靶标和分子机制仍然很少了解。在上前的资金期间 时期，我们发现雄激素对取消骨骼的影响是由于细胞中AR信号传导而导致的 间充质谱系导致破骨细胞的减少；兰花切除术（ORX）增加了固体rankl 鼠骨髓中的B淋巴细胞的水平以及B-淋巴细胞的数量。从骨细胞得出的RANKL是 取消骨骼重塑和B淋巴细胞衍生的RANKL至关重要 卵巢切除（OVX）小鼠中的骨量。然而，在皮质骨中，雄激素的作用不需要AR 在间充质谱系的任何细胞类型中的信号传导，也不需要下游的ERα信号传导 由OSX1-CRE靶向的成骨细胞祖细胞或破骨细胞谱系中的AR或ERα信号传导。 雌激素，尽管如此，通过未承诺的ERα信号传导在女性中衰减的内皮分辨率 由Prx1-cre靶向的间充质祖细胞。另外，mRNA和分泌的SDF1蛋白水平 - a CXC家族的趋化细胞因子在PRX1-CRE靶向细胞中绝对表达并促进 破骨细胞的产生 - 在GFP标记的ERα无效细胞以及女性的骨髓细胞培养物中较高 与窝窝对照组的相同培养物相比，ERαf/f; prx1-cre小鼠；破骨细胞生成也是如此 ERαNULLBM基质或钙钙细胞与巨噬细胞的共培养。此外，OVX和ORX都 增加骨髓等离子体中的SDF1，给予E2至ORX小鼠可防止这种增加，E2，E2， 但不是DHT，可以防止Orx小鼠的皮质骨质流失。最后，我们发现OVX-或ORX诱导的皮质 通过限制破骨细胞线粒体中的H2O2产生来阻止骨质流失；和皮质骨的损失 OVX小鼠中的质量是通过17β-E2树枝状聚合物共轭（EDC）预防的，无法刺激核核。 启动ERα的作用。基于这些进步，我们将测试相互关联的假设：在男性中， 雄激素对骨细胞，B淋巴细胞中AR信号传导的取消骨骼的保护作用 两个都。这些动作导致RANKL的衰减，从而衰减取消的数量 破骨细胞。雄激素对内皮分辨率的受保护作用至少部分地来自ERα- 对PRX1-CRE的无针对性的介导的作用（雄激素芳香化以逃脱） 间充质祖细胞。这些动作反映了SDF1的产生，从而减弱了破骨细胞的形成 并在内骨表面归巢。进化对SDF1生产的抑制作用最终导致 在破骨细胞中H2O2积累的限制，并由无核发起的信号传导产生 ERα。为了推进这些假设，我们将尝试阐明雄激素受保护作用的机制 通过确定骨细胞和B淋巴细胞衍生的RANKL的作用以及角色 这些作用中B淋巴细胞的AR。为此，我们将研究：i）RANKL从成熟中删除的小鼠 成骨细胞/骨细胞（RANKLF/F; DMP1-CRE），II）AR和RANKL从中删除的小鼠 成骨细胞/骨细胞（RANKLF/F; ARF/Y; DMP1-CRE），III）小鼠，其中RankL从B- lymphocytes中删除 （RANKLF/F; CD19-CRE）和IV）AR从B淋巴细胞中删除的小鼠（ARF/Y; CD19-CRE）。另外，我们 将通过研究雄激素对皮质骨的受保护作用的机理：a）是否是否 在未承诺的间充质祖细胞中SDF1的下调负责其中一些影响 使用：i）在PRX1-CRE靶向细胞中删除SDF1的小鼠，以及II）SDF1受体的小鼠，其中SDF1受体， CXCR4在Lysm-Cre靶向细胞中删除； b）雄激素的作用是否是由ERα介导的 使用ERαF/F; PRX1-CRE小鼠对雌激素芳香化的作用。使用基质和 造血细胞，我们还将检查SDF1是否通过H2O2促进了骨质质发生。是否 进化对SDF1的影响是由于ERα的非核发起信号传导而产生的。