Endocytosis and Degradation of Pegvisomant and a Potential New Mechanism That Inhibits the Nuclear Translocation of GHR
Hainan Lan Wei Li Ruonan Li Xin Zheng Gan Luo
The Journal of Clinical Endocrinology & Metabolism, Volume 104, Issue 6, June 2019, Pages 1887–1899, https://doi.org/10.1210/jc.2018-02063
Published: 31 December 2018 Article history
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Abstract
Context
Pegvisomant, a growth hormone receptor (GHR) antagonist, is a well-known drug that was designed to treat acromegaly. However, recent studies have indicated that the GHR is a “moonlighting” protein that may exhibit dual functions based on its localization in the plasma membrane and nucleus. In light of this finding, we explored whether pegvisomant is a potential “moonlighting” GHR antagonist. In addition, the mechanisms of the endocytosis, postendocytic sorting, and degradation of pegvisomant are not fully understood.
Objective
This study investigated whether pegvisomant is a “moonlighting” antagonist and explored the mechanisms of the endocytosis, postendocytic sorting, and degradation of pegvisomant.
Methods
Indirect immunofluorescence and Western blot coupled with pharmacological inhibitors and gene silencing (small interfering RNA) were used to explore the mechanisms of the endocytosis, postendocytic sorting, and degradation of pegvisomant. Western blot, immunohistochemistry, and indirect immunofluorescence coupled with subcellular fractionation analysis were used to determine the effect of pegvisomant on GHR’s nuclear localization in vitro and in vivo.
Results
Here, we show that the endocytosis of pegvisomant is mainly mediated though the clathrin pathway. Further study of the postendocytic sorting of pegvisomant shows that pegvisomant enters into different types of endosomes under GHR mediation. In addition, GHR is slightly downregulated by pegvisomant; further study indicates that proteasomes and lysosomes may cooperate to regulate pegvisomant/GHR degradation. Most importantly, we show that pegvisomant inhibits the nuclear localization of GHR.
Conclusion
Our study showed that pegvisomant is a “moonlighting” antagonist. In addition, we revealed the mechanisms of the endocytosis, postendocytic sorting, and degradation of pegvisomant.
Issue Section: Growth, Growth Hormone, and Growth Factors
Copyright © 2019 Endocrine Society
Hainan Lan Wei Li Ruonan Li Xin Zheng Gan Luo
The Journal of Clinical Endocrinology & Metabolism, Volume 104, Issue 6, June 2019, Pages 1887–1899, https://doi.org/10.1210/jc.2018-02063
Published: 31 December 2018 Article history
Cite
Permissions Icon Permissions
Share
Abstract
Context
Pegvisomant, a growth hormone receptor (GHR) antagonist, is a well-known drug that was designed to treat acromegaly. However, recent studies have indicated that the GHR is a “moonlighting” protein that may exhibit dual functions based on its localization in the plasma membrane and nucleus. In light of this finding, we explored whether pegvisomant is a potential “moonlighting” GHR antagonist. In addition, the mechanisms of the endocytosis, postendocytic sorting, and degradation of pegvisomant are not fully understood.
Objective
This study investigated whether pegvisomant is a “moonlighting” antagonist and explored the mechanisms of the endocytosis, postendocytic sorting, and degradation of pegvisomant.
Methods
Indirect immunofluorescence and Western blot coupled with pharmacological inhibitors and gene silencing (small interfering RNA) were used to explore the mechanisms of the endocytosis, postendocytic sorting, and degradation of pegvisomant. Western blot, immunohistochemistry, and indirect immunofluorescence coupled with subcellular fractionation analysis were used to determine the effect of pegvisomant on GHR’s nuclear localization in vitro and in vivo.
Results
Here, we show that the endocytosis of pegvisomant is mainly mediated though the clathrin pathway. Further study of the postendocytic sorting of pegvisomant shows that pegvisomant enters into different types of endosomes under GHR mediation. In addition, GHR is slightly downregulated by pegvisomant; further study indicates that proteasomes and lysosomes may cooperate to regulate pegvisomant/GHR degradation. Most importantly, we show that pegvisomant inhibits the nuclear localization of GHR.
Conclusion
Our study showed that pegvisomant is a “moonlighting” antagonist. In addition, we revealed the mechanisms of the endocytosis, postendocytic sorting, and degradation of pegvisomant.
Issue Section: Growth, Growth Hormone, and Growth Factors
Copyright © 2019 Endocrine Society
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