CRANIOFACIAL DEVELOPMENT: METABOLIC CONTROL OF APOPTOSIS

描述(改编自申请者摘要)：负责 骨形成是成骨细胞。最近的研究表明，成骨细胞是 通过一种进化上保守的生理过程从骨骼中删除 细胞凋亡。细胞凋亡程序的激活对维持生命周期至关重要 组织的大小、形状和功能；对细胞凋亡的干扰是紧密的 与颅面、四肢和脊柱畸形有关。令人惊讶的是，几乎没有 已知骨中细胞凋亡程序的调节。整体而言 目前赠款提案的假设是PO2和/或 PI可以通过改变细胞的氧化作用来触发成骨细胞的凋亡 新陈代谢(导致膜电位损失和诱导 ‘通透性转变’状态)，激活bc l-2，增强caspase 活动。首席调查员认为，这些变化将改变 氧化还原敏感转录因子NF-kB和AP-1的表达。评估 在这一假设下，概述了四个具体目标。在具体目标1中， 申请人提议确定PI和PO2变化如何调节成骨细胞 细胞培养和颅骨中的细胞凋亡。在具体目标2中，他建议 确定诱导的细胞凋亡是否是通过改变细胞内 Bcl超家族成员的表达和/或活性，特别是与 关于Bcl一2、Bclxl和Bcl一XL间同源二聚体和杂二聚体的形成 BCL-XS，以及Bcl2定位的变化。在具体目标3中， 首席研究员试图确定线粒体功能的变化 促进成骨细胞凋亡和诱导caspase活性，a 半胱氨酸天冬氨酸蛋白酶家族，被认为具有 在细胞凋亡中。最后，在具体目标4中，申请人打算研究 等电点和低氧对两种酶表达和功能的影响 氧化还原敏感的转录因子，即核因子-kB和AP-1。加在一起， 这些研究应该突出骨细胞凋亡的分子基础，a 现在被认为对骨骼生长和骨骼至关重要的现象 改建。

DESCRIPTION (Adapted from the Applicant's Abstract): The cell responsible for bone formation is the osteoblast. Recent work indicates that osteoblasts are deleted from bone by an evolutionarily conserved physiological process called apoptosis. Activation of the apoptotic program is critical for the maintenance of tissue size, shape and function; interference with apoptosis is tightly linked to craniofacial, limb and spine malformations. Surprisingly, little is known of the regulation of the apoptotic program in bone. The overall hypothesis of the present grant proposal is that a local change in pO2 and/or Pi can trigger osteoblastic apoptosis, by altering the cell's oxidative metabolism (resulting in a loss of membrane potential and the induction of 'permeability transition' state), activating Bcl-2 and enhancing caspase activity. These changes, the principal investigator believes, will alter the expression of redox-sensitive transcription factors, NF-kB and AP-1. To assess this postulation, four Specific Aims are outlined. In Specific Aim 1, the applicant proposes to determine how Pi and pO2 changes regulate osteoblast apoptosis in cell cultures and calvaria. In Specific Aim 2, he proposes to ascertain whether the induced apoptosis is mediated by alterations in the expression and/or activity of members of the Bcl superfamily, specifically with respect to homodimer and heterodimer formation between Bcl-2, Bcl-XL and Bcl-XS, as well as changes in Bcl-2 localization. In Specific Aim 3, the principal investigator seeks to determine if changes in mitochondrial function promote osteoblastic apoptosis and an induction in the activity of caspases, a family of cysteinyl aspartate proteinases that are acknowledged to have a role in apoptosis. Finally, in Specific Aim 4, the applicant intends to study the effect of Pi and a low PO2 on the expression and function of two redox-sensitive transcription factors, namely, NF-kB and AP-1. Taken together, these studies should highlight the molecular basis of bone cell apoptosis, a phenomenon that is now considered critical for bone growth and skeletal remodeling.