Clinical Research Centre, UCD School of Medicine & Medical Science, Mater Misericordiae University Hospital, Dublin, Ireland.
J Orthop Res. 2013 Feb;31(2):218-26. doi: 10.1002/jor.22196. Epub 2012 Jul 31.
HIV infection is associated with metabolic bone disease resulting in bone demineralization and reduced bone mass. The molecular mechanisms driving this disease process have yet to be elucidated. Wnt/β-catenin signaling plays a key role in bone development and remodeling. We attempted to determine the effects of the HIV-1 protein, gp120, on Wnt/β-catenin signaling at an intracellular and transcriptional level in primary human osteoblasts (HOBs). This work, inclusive of experimental controls, was part of a greater project assessing the effects of a variety of different agents on Wnt/β-catenin signaling (BMC Musculoskelet Disord 2010;11:210).We examined the phenotypic effects of silencing and overexpressing the Wnt antagonist, Dickkopf-1 (Dkk1) in HOBs treated with gp120. HOBs exposed to gp120 displayed a significant reduction in alkaline phosphatase activity (ALP) activity and cell proliferation and increased cellular apoptosis over a 48 h time course. Immunocytochemistry demonstrated a significant reduction in intracytosolic and intranuclear β-catenin in response to HIV-1 protein exposure. These changes were associated with a reduction of TCF/LEF-mediated transcription, the transcriptional outcome of canonical Wnt β-catenin signaling. Silencing Dkk1 expression in HOBs exposed to gp120 resulted in increased ALP activity and cell proliferation, and decreased cellular apoptosis relative to scrambled control. Dkk1 overexpression exacerbated the inhibitory effect of gp120 on HOB function, with decreases in ALP activity and cell proliferation and increased cellular apoptosis relative to vector control. Wnt/β-catenin signaling plays a key regulatory role in HIV-associated bone loss, with Dkk1, aputative central mediator in this degenerative process.
HIV 感染与代谢性骨病相关，导致骨质脱矿和骨量减少。导致这种疾病过程的分子机制尚未阐明。Wnt/β-catenin 信号通路在骨发育和重塑中起着关键作用。我们试图确定 HIV-1 蛋白 gp120 在原代人成骨细胞（HOB）中在细胞内和转录水平上对 Wnt/β-catenin 信号通路的影响。这项工作，包括实验对照，是评估各种不同的药物对 Wnt/β-catenin 信号通路的影响的更大项目的一部分（BMC Musculoskelet Disord 2010；11:210）。我们研究了沉默和过表达 Wnt 拮抗剂 Dickkopf-1（Dkk1）对 gp120 处理的 HOB 的表型影响。暴露于 gp120 的 HOB 在 48 小时的时间过程中显示碱性磷酸酶（ALP）活性和细胞增殖减少，细胞凋亡增加。免疫细胞化学显示，HIV-1 蛋白暴露后，细胞内和核内β-catenin 明显减少。这些变化与 TCF/LEF 介导的转录减少有关，这是经典 Wnt β-catenin 信号通路的转录结果。在暴露于 gp120 的 HOB 中沉默 Dkk1 表达导致 ALP 活性和细胞增殖增加，细胞凋亡减少与 scrambled 对照相比。Dkk1 过表达加剧了 gp120 对 HOB 功能的抑制作用，与载体对照相比，ALP 活性和细胞增殖减少，细胞凋亡增加。Wnt/β-catenin 信号通路在 HIV 相关的骨丢失中起着关键的调节作用，Dkk1 是这个退行性过程中的一个潜在的中央介质。
