Phlpp1 is induced by estrogen in osteoclasts and its loss in Ctsk-expressing cells does not protect against ovariectomy-induced bone loss.
Phlpp1 is induced by estrogen in osteoclasts and its loss in Ctsk-expressing cells does not protect against ovariectomy-induced bone loss.
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DOI：
10.1371/journal.pone.0251732
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发表时间：
2021
期刊：
影响因子：
3.7
通讯作者：
Bradley EW
中科院分区：
文献类型：
--
作者：
Hanson MK;Karkache IY;Molstad DHH;Norton AA;Mansky KC;Bradley EW
先前的研究表明，Ctsk-Cre表达细胞中蛋白磷酸酶Phlpp 1的缺失增强了骨量，其特征在于破骨细胞活性降低和与骨形成的偶联增加。由于Ctsk-Cre的非特异性表达，该观察结果的确切机制尚不清楚。为了进一步确定骨吸收破骨细胞的作用，我们对Phlpp 1 cKOCtsk和WT小鼠进行了卵巢切除术（Ovx）和假手术。Micro-CT分析证实Phlpp 1 cKOCtsk假手术组雌性动物的骨量增加。相比之下，Ovx在两组中均诱导骨丢失，Phlpp 1 cKOCtsk和WT小鼠之间无差异。组织形态计量学表明，Ovx小鼠每个骨表面的破骨细胞缺乏差异，这表明雌二醇（E2）是Phlpp 1缺乏症产生影响所必需的。我们进行了高通量无偏转录分析Phlpp 1 cKOCtsk破骨细胞，并确定了290个差异表达的基因。通过交叉引用这些差异表达的基因与所有雌激素反应元件（ERE）的基因，我们确定IGFBP 4作为潜在的雌激素依赖性目标的Phlpp 1。E2诱导PHLPP 1表达，但降低IGFBP 4水平。此外，Phlpp 1的遗传缺失或化学抑制与IGFBP 4水平相关。然后，我们评估了IGFBP 4表达的破骨细胞在体内完整的12周龄的女性。在WT雌性动物中观察到TRAP+破骨细胞的中度IGFBP 4免疫组织化学染色。相反，完整的Phlpp 1 cKOCtsk雌性中的TRAP+骨衬里细胞强烈表达IGFBP 4，但在卵巢切除后TRAP+骨衬里细胞中的水平降低。这些结果表明，Phlpp 1条件性缺陷的影响在Ovx后丢失，可能是由于IGFBP 4的雌激素依赖性调节。
Prior studies demonstrated that deletion of the protein phosphatase Phlpp1 in Ctsk-Cre expressing cells enhances bone mass, characterized by diminished osteoclast activity and increased coupling to bone formation. Due to non-specific expression of Ctsk-Cre, the definitive mechanism for this observation was unclear. To further define the role of bone resorbing osteoclasts, we performed ovariectomy (Ovx) and Sham surgeries on Phlpp1 cKOCtsk and WT mice. Micro-CT analyses confirmed enhanced bone mass of Phlpp1 cKOCtsk Sham females. In contrast, Ovx induced bone loss in both groups, with no difference between Phlpp1 cKOCtsk and WT mice. Histomorphometry demonstrated that Ovx mice lacked differences in osteoclasts per bone surface, suggesting that estradiol (E2) is required for Phlpp1 deficiency to have an effect. We performed high throughput unbiased transcriptional profiling of Phlpp1 cKOCtsk osteoclasts and identified 290 differentially expressed genes. By cross-referencing these differentially expressed genes with all estrogen response element (ERE) containing genes, we identified IGFBP4 as potential estrogen-dependent target of Phlpp1. E2 induced PHLPP1 expression, but reduced IGFBP4 levels. Moreover, genetic deletion or chemical inhibition of Phlpp1 was correlated with IGFBP4 levels. We then assessed IGFBP4 expression by osteoclasts in vivo within intact 12-week-old females. Modest IGFBP4 immunohistochemical staining of TRAP+ osteoclasts within WT females was observed. In contrast, TRAP+ bone lining cells within intact Phlpp1 cKOCtsk females robustly expressed IGFBP4, but levels were diminished within TRAP+ bone lining cells following Ovx. These results demonstrate that effects of Phlpp1 conditional deficiency are lost following Ovx, potentially due to estrogen-dependent regulation of IGFBP4.
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影响因子：
5.2
作者：
Beattie J;Al-Khafaji H;Noer PR;Alkharobi HE;Alhodhodi A;Meade J;El-Gendy R;Oxvig C
通讯作者：
Oxvig C
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影响因子：
3.9
作者：
Grzechnik AT;Newton AC
通讯作者：
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影响因子：
3.7
作者：
Razidlo DF;Whitney TJ;Casper ME;McGee-Lawrence ME;Stensgard BA;Li X;Secreto FJ;Knutson SK;Hiebert SW;Westendorf JJ
通讯作者：
Westendorf JJ
影响因子：
4.8
作者：
Bradley, Elizabeth W.;Carpio, Lomeli R.;Westendorf, Jennifer J.
通讯作者：
Westendorf, Jennifer J.
影响因子：
5.8
作者：
Wang, Liguo;Wang, Shengqin;Li, Wei
通讯作者：
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