The peptidyl-prolyl isomerase Pin1 determines parathyroid hormone mRNA levels and stability in rat models of secondary hyperparathyroidism
Morris Nechama, … , Justin Silver, Tally Naveh-Many
Morris Nechama, … , Justin Silver, Tally Naveh-Many
Published September 21, 2009
Citation Information: J Clin Invest. 2009;119(10):3102-3114. https://doi.org/10.1172/JCI39522.
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Research Article

The peptidyl-prolyl isomerase Pin1 determines parathyroid hormone mRNA levels and stability in rat models of secondary hyperparathyroidism

Abstract

Secondary hyperparathyroidism is a major complication of chronic kidney disease (CKD). In experimental models of secondary hyperparathyroidism induced by hypocalcemia or CKD, parathyroid hormone (PTH) mRNA levels increase due to increased PTH mRNA stability. K-homology splicing regulator protein (KSRP) decreases the stability of PTH mRNA upon binding a cis-acting element in the PTH mRNA 3′ UTR region. As the peptidyl-prolyl isomerase (PPIase) Pin1 has recently been shown to regulate the turnover of multiple cytokine mRNAs, we investigated the role of Pin1 in regulating PTH mRNA stability in rat parathyroids and transfected cells. The data generated were consistent with Pin1 being a PTH mRNA destabilizing protein. Initial analysis indicated that Pin1 activity was decreased in parathyroid protein extracts from both hypocalcemic and CKD rats and that pharmacologic inhibition of Pin1 increased PTH mRNA levels posttranscriptionally in rat parathyroid and in transfected cells. Pin1 mediated its effects via interaction with KSRP, which led to KSRP dephosphorylation and activation. In the rat parathyroid, Pin1 inhibition decreased KSRP–PTH mRNA interactions, increasing PTH mRNA levels. Furthermore, Pin1–/– mice displayed increased serum PTH and PTH mRNA levels, suggesting that Pin1 determines basal PTH expression in vivo. These results demonstrate that Pin1 is a key mediator of PTH mRNA stability and indicate a role for Pin1 in the pathogenesis of secondary hyperparathyroidism in individuals with CKD.

Authors

Morris Nechama, Takafumi Uchida, Irit Mor Yosef-Levi, Justin Silver, Tally Naveh-Many

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Figure 4

Pin1 regulates PTH mRNA levels through the PTH mRNA ARE.

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Pin1 regulates PTH mRNA levels through the PTH mRNA ARE. (A) Schemat...
(A) Schematic representation of mRNAs for PTH, GH, and chimeric reporter GH containing the PTH mRNA ARE (GH63) used for transfections. (B and C) Pin1 overexpression. HEK293 cells were transiently cotransfected with expression plasmids for either GH or a chimeric GH63 (GH63) and GFP-Pin1 or pcDNA3 (control). (B) Northern blot analysis for PTH mRNA. (C) Quantification of 2 Northern blots as in B for GH (left) and GH63 (right); mean ± SEM; *P < 0.05 compared with GH63 without Pin1. (D–F) Effect of juglone on GH63. Cells were transiently transfected with expression plasmids for either GH or GH63 and incubated with juglone or vehicle (–). (D) Immunoblots for Pin1 in cell extracts after juglone or vehicle. (E) Northern blots for GH mRNA. (F) Quantification of Northern blots of 3 independent experiments as in E (*P < 0.05). The lanes in B and E were run on the same gel but were noncontiguous (white lines).