Deciphering the physiological function(s) of Panx3, a gene displaying specific expression in bone-forming osteoblasts

破译 Panx3 的生理功能，Panx3 是一种在骨形成成骨细胞中显示特异性表达的基因

• 批准号: 492686146
• 负责人: Professor Dr. Johannes Keller, Ph.D.
• 金额: --
• 依托单位: Institut für Osteologie und Biomechanik (IOBM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/492686146?language=en
• 关键词: Deciphering; physiological; function; Panx3; gene

Bone formation mediated by osteoblasts is essential for development, growth, remodeling and regeneration of the skeleton. This process depends on the provision of large amounts of energy, and osteoblasts were recently found to rely mostly on glucose availability. Moreover, genetic evidence obtained in the last two decades has clearly demonstrated that bone is also an endocrine organ, and that osteoblast lineage cells release hormonal regulators of serum phosphate and glucose homeostasis. The relevance of energy metabolism regulation by osteoblast-derived molecules is however still debated, and the underlying complexities are still not fully understood.We have previously identified a potential role of Pannexin-3 (Panx3), a transmembrane protein predominantly expressed by osteoblasts, in linking bone formation to energy metabolism. In particular, we could demonstrate that Panx3 deficiency in neonatal mice not only results in impaired skeletal development, but also in hypoglycemia. Additional experiments revealed that Panx3-deficient osteoblasts display higher intracellular ATP levels, potentially mimicking energy excess and reducing expression of metabolically relevant genes. Another key finding was that Panx3-deficient neonates displayed a higher hepatic glycogen content despite absence of Panx3 expression in the liver. Finally, we could identify Panx3 to be relevant for bone regeneration, a process found associated with alterations in blood glucose levels and metabolic marker expression in liver and adipose tissue.Collectively, our findings strongly suggest that Panx3 deficiency impairs osteoblast activity in states of excessive bone formation, i.e. during skeletal development/growth and fracture healing and that Panx3 deficiency additionally impacts glucose homeostasis by altering metabolic functions of the liver. Since our previous data also raise several questions, we now intend to perform additional analyses to define the molecular functions of Panx3 in skeletal development and energy metabolism. First, we will perform in depth-phenotyping of mice lacking Panx3, ubiquitously or only in specific cell types, during skeletal development and growth. Second, since we did not detect major abnormalities in adult Panx3-deficient mice, we will challenge them by different means, which includes genetic activation of bone formation, but also induction of bone regeneration. Third, in order to understand the molecular bases of the observed phenotypes we will analyze primary wildtype and Panx3-deficient cells, which includes unbiased transcriptomic approaches.

成骨细胞介导的骨形成对于骨骼的发育、生长、重塑和再生至关重要。这个过程依赖于大量能量的提供，最近发现成骨细胞主要依赖于葡萄糖的可用性。此外，在过去的二十年中获得的遗传证据已经清楚地表明，骨也是一种内分泌器官，成骨细胞谱系细胞释放血清磷酸盐和葡萄糖稳态的激素调节剂。然而，成骨细胞衍生的分子的能量代谢调节的相关性仍有争议，和潜在的复杂性仍然没有完全understood.We以前已经确定了Pannexin-3（Panx 3），主要由成骨细胞表达的跨膜蛋白的潜在作用，在连接骨形成的能量代谢。特别是，我们可以证明新生小鼠的Panx 3缺乏不仅会导致骨骼发育受损，还会导致低血糖。其他实验表明，Panx 3缺陷型成骨细胞显示出更高的细胞内ATP水平，可能模拟能量过剩并减少代谢相关基因的表达。另一个关键发现是，尽管肝脏中缺乏Panx 3表达，但Panx 3缺陷的新生儿显示出更高的肝糖原含量。最后，我们可以确定Panx 3与骨再生有关，这一过程与血糖水平和肝脏和脂肪组织中代谢标志物表达的改变有关。总的来说，我们的研究结果强烈表明，Panx 3缺乏会损害过度骨形成状态下的成骨细胞活性，即在骨骼发育/生长和骨折愈合期间，并且Panx 3缺乏通过改变肝脏的代谢功能另外影响葡萄糖稳态。由于我们之前的数据也提出了一些问题，我们现在打算进行额外的分析，以确定Panx 3在骨骼发育和能量代谢中的分子功能。首先，我们将在骨骼发育和生长过程中对缺乏Panx 3的小鼠进行深入的表型分析，这些小鼠普遍存在或仅存在于特定的细胞类型中。第二，由于我们没有在成年Panx 3缺陷小鼠中检测到主要异常，我们将通过不同的方式挑战它们，包括骨形成的遗传激活，以及骨再生的诱导。第三，为了理解观察到的表型的分子基础，我们将分析原代野生型和Panx 3缺陷细胞，其中包括无偏转录组学方法。