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.

雄激素和雌激素都有助于维持男性成年期间的骨量，但细胞 在之前的资助期间，人们对这些效应的目标和分子机制仍知之甚少。 在此期间，我们发现雄激素对松质骨的影响是由松质骨细胞中的AR信号传导引起的 间充质谱系导致破骨细胞减少；睾丸切除术 (ORX) 增加可溶性 RANKL 小鼠骨髓中源自骨细胞的 RANKL 水平以及 B 淋巴细胞数量。 对于松质骨重塑至关重要，B 淋巴细胞衍生的 RANKL 有助于松质骨的丧失 然而，在皮质骨中，雄激素的作用不需要 AR。 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 破骨细胞谱系中 Osx1-Cre、AR 或 ERα 信号传导靶向的定型成骨细胞祖细胞。 然而，雌激素通过 ERα 信号传导减弱女性的皮质内吸收。 Prx1-Cre 靶向的间充质祖细胞此外，SDF1 的 mRNA 和分泌蛋白水平。 CXC 家族的趋化细胞因子在 Prx1-Cre 靶细胞中大量表达并促进 破骨细胞生成 - GFP 标记的 ERα 无效细胞以及女性骨髓细胞培养物中的破骨细胞生成量较高 ERαf/f；Prx1-Cre 小鼠与同窝对照的相同培养物相比，破骨细胞生成也是如此； ERα 缺失的 BM 基质细胞或颅盖细胞与巨噬细胞的共培养物。 增加骨髓血浆中的 SDF1，给 ORX 小鼠施用 E2 可防止这种增加，并且 E2， 但 DHT 却不能防止 ORX 小鼠的皮质骨丢失。最后，我们发现 OVX 或 ORX 诱导的皮质骨丢失。 通过抑制破骨细胞线粒体中 H2O2 的产生和皮质骨的损失来防止骨损失； OVX 小鼠中的质量被 17β-E2 树枝状聚合物缀合物 (EDC) 阻止，该缀合物无法刺激核 基于这些进展，我们将测试以下相关假设：在男性中， 雄激素对松质骨的保护作用是由骨细胞、B 淋巴细胞或骨细胞中的 AR 信号传导引起的 这些行为都会导致 RANKL 的衰减，从而导致取消数量的衰减。 雄激素对内皮质吸收的保护作用至少部分来自 ERα-。 对 Prx1-Cre 的介导作用（雄激素芳香化为雌激素后） 这些作用抑制 SDF1 的产生，从而减弱破骨细胞的形成。 雌激素对 SDF1 产生的抑制作用最终导致骨内膜表面归巢。 抑制破骨细胞中 H2O2 积累，是非核启动信号传导的结果 为了推进这些假设，我们将尝试阐明雄激素的保护作用机制。 通过确定骨细胞和 B 淋巴细胞衍生的 RANKL 的作用以及 为了做到这一点，我们将研究： i) 成熟小鼠中 RANKL 被删除的小鼠。 成骨细胞/骨细胞 (RANKLf/f;Dmp1-Cre), ii) AR 和 RANKL 均被删除的小鼠 成骨细胞/骨细胞 (RANKLf/f;ARf/y;Dmp1-Cre), iii) B 淋巴细胞中删除 RANKL 的小鼠 (RANKLf/f;CD19-Cre) 和 iv) B 淋巴细胞中删除了 AR 的小鼠 (ARf/y;CD19-Cre)。 将通过研究以下内容来阐明雄激素对皮质骨的保护作用的机制：a) 是否 未定型间充质祖细胞中 SDF1 的下调是造成其中一些影响的原因 使用：i) Prx1-Cre 靶细胞中 SDF1 被删除的小鼠，以及 ii) SDF1 受体被删除的小鼠， CXCR4 在 LysM-Cre 靶细胞中被删除；b) 雄激素的作用是否是由 ERα 介导的结果； 使用 ERαf/f;Prx1-Cre 小鼠使用基质和雌激素的共培养物对雄激素芳香化为雌激素的作用。 造血细胞，我们还将检查SDF1是否通过H2O2促进破骨细胞生成； 雌激素对 SDF1 的影响是由 ERα 的非核启动信号传导引起的。