Expression Of Parathyroid Hormone Research Articles

Circadian regulation of calcium and phosphorus homeostasis during the oviposition cycle in laying hens

Maintenance of calcium and phosphorus homeostasis in laying hens is crucial for preservation of skeletal integrity and eggshell quality, though physiological regulation of these systems is incompletely defined. To investigate changes in mineral and vitamin D3 homeostasis during the 24-h egg formation cycle, 32-wk-old commercial laying hens were sampled at 1, 3, 4, 6, 7, 8, 12, 15, 18, 21, 23, and 24 h post-oviposition (HPOP; n ≥ 4). Ovum location and egg calcification stage were recorded, and blood chemistry, plasma vitamin D3 metabolites, circulating parathyroid hormone (PTH), and expression of genes mediating uptake and utilization of calcium and phosphorus were evaluated. Elevated levels of renal 25-hydroxylase from 12 to 23 HPOP suggest this tissue might play a role in vitamin D3 25-hydroxylation during eggshell calcification. In shell gland, retinoid-x-receptor gamma upregulation between 6 and 8 HPOP followed by subsequently increased vitamin D receptor indicate that vitamin D3 signaling is important for eggshell calcification. Increased expression of PTH, calcitonin, and fibroblast growth factor 23 (FGF23) receptors in the shell gland between 18 and 24 HPOP suggest elevated sensitivity to these hormones toward the end of eggshell calcification. Shell gland sodium-calcium exchanger 1 was upregulated between 4 and 7 HPOP and plasma membrane calcium ATPase 1 increased throughout eggshell calcification, suggesting the primary calcium transporter may differ according to eggshell calcification stage. Expression in shell gland further indicated that bicarbonate synthesis precedes transport, where genes peaked at 6 to 7 and 12 to 18 HPOP, respectively. Inorganic phosphorus transporter 1 (PiT-1) expression peaked in kidney between 12 and 15 HPOP, likely to excrete excess circulating phosphorus, and in shell gland between 18 and 21 HPOP. Upregulation of FGF23 receptors and PiT-1 during late eggshell calcification suggest shell gland phosphorus uptake is important at this time. Together, these findings identified potentially novel hormonal pathways involved in calcium and phosphorus homeostasis along with associated circadian patterns in gene expression that can be used to devise strategies aimed at improving eggshell and skeletal strength in laying hens.

Immunohistochemical characterization of a steroid secreting oncocytic adrenal carcinoma responsible for paraneoplastic hyperparathyroidism.

We report a unique case of a 44-year-old man with paraneoplastic hyperparathyroidism due to an oncocytic adrenocortical carcinoma (stage pT3N0R0M0, ENSAT 2 with a 4% Ki-67). Paraneoplastic hyperparathyroidism was associated with mild ACTH-independent hypercortisolism and increased estradiol secretion responsible for gynecomastia and hypogonadism. Biological investigations performed in blood samples from peripheral and adrenal veins revealed that the tumor secreted PTH and estradiol. Ectopic PTH secretion was confirmed by abnormally high expression of PTH mRNA and clusters of PTH immunoreactive cells in the tumor tissue. Double-immunochemistry studies and analysis of contiguous slides for the expression of PTH and steroidogenic markers (SRB-1, 3β-HSD and aromatase) were performed. The results suggested the presence of two tumor cells subtypes with large cells with voluminous nuclei producing only PTH and that were distinct from steroid producing cells.

Kidney Failure Alters Parathyroid Pin1 Phosphorylation and Parathyroid Hormone mRNA-Binding Proteins, Leading to Secondary Hyperparathyroidism.

Secondary hyperparathyroidism (SHP) is a common complication of CKD that increases morbidity and mortality. In experimental SHP, increased parathyroid hormone (PTH) expression is due to enhanced PTH mRNA stability, mediated by changes in its interaction with stabilizing AUF1 and destabilizing KSRP. The isomerase Pin1 leads to KSRP dephosphorylation, but in SHP parathyroid Pin1 activity is decreased and hence phosphorylated KSRP fails to bind PTH mRNA, resulting in high PTH mRNA stability and levels. The up- and downstream mechanisms by which CKD stimulates the parathyroid glands remain elusive. Adenine-rich high-phosphate diets induced CKD in rats and mice. Parathyroid organ cultures and transfected cells were incubated with Pin1 inhibitors for their effect on PTH expression. Mass spectrometry was performed on both parathyroid and PTH mRNA pulled-down proteins. CKD led to changes in rat parathyroid proteome and phosphoproteome profiles, including KSRP phosphorylation at Pin1 target sites. Furthermore, both acute and chronic kidney failure led to parathyroid-specific Pin1 Ser16 and Ser71 phosphorylation, which disrupts Pin1 activity. Pharmacologic Pin1 inhibition, which mimics the decreased Pin1 activity in SHP, increased PTH expression ex vivo in parathyroid glands in culture and in transfected cells through the PTH mRNA-protein interaction element and KSRP phosphorylation. Kidney failure leads to loss of parathyroid Pin1 activity by inducing Pin1 phosphorylation. This predisposes parathyroids to increase PTH production through impaired PTH mRNA decay that is dependent on KSRP phosphorylation at Pin1-target motifs. Pin1 and KSRP phosphorylation and the Pin1-KSRP-PTH mRNA axis thus drive SHP.

Integrated transcriptomic and proteomic analyses for the characterization of parathyroid oxyphil cells in uremic patients.

Chief cells are the predominant cells in parathyroid glands of healthy adults; however, parathyroid oxyphil cells, whose function is unknown, increase dramatically in patients with secondary hyperparathyroidism (SHPT). Calcitriol and calcimimetics are the most powerful treatments for SHPT, while the mechanisms leading to calcitriol or calcimimetic resistance in oxyphil cell-predominant SHPT are unknown. Here we used transcriptomic and proteomic techniques to characterize oxyphil cells by comparing the differences between chief and oxyphil cell nodules of parathyroid glands in uremic patients. Compared to chief cell nodules, the most marked expression increases in oxyphil cell nodules were for mitochondrion-associated proteins. The mitochondria number and mitochondrial DNA content were also significantly increased in oxyphil cell nodules. Moreover, oxyphil cell nodules expressed parathyroid-specific factors, and exhibited lower levels of proliferation-related proteins but higher synthesis and secretion level of parathyroid hormone (PTH). The protein expression of SHPT-regulating factors, including vitamin-D receptor, calcium-sensing receptor and Klotho, were significantly downregulated in oxyphil cell nodules. Therefore, oxyphil cells characterized by enrich mitochondria in uremic patients showed higher synthesis and secretion of PTH but lower expression of SHPT regulators than chief cells, which may contribute to the pathophysiology of SHPT and the treatment resistance to calcitriol and calcimimetics.

Cultivation and characterization of primary human parathyroid cells from patients with severe secondary hyperparathyroidism

To establish an cell model of hyperparathyroidism by isolation, in vitro culture, and identification of parathyroid cells from patients with secondary hyperparathyroidism (SHPT). The parathyroid gland tissues obtained from 10 patients with SHPT were dissociated by collagenase digestion for primary culture of the parathyroid cells. Morphological changes and growth characteristics of the cells were assessed by microscopic imaging and cell counting. The mRNA and protein expression levels of parathyroid hormone (PTH), calcium-sensing receptor (CaSR), and glial cells missing 2 (GCM2) in the primary and passaged cells were determined by immunofluorescence, qRT-PCR, and Western blotting. Primary cultures of parathyroid cells were successfully obtained. The cells exhibited a high expression of PTH shown by immunofluorescence assay and had a population doubling time of approximately 71.61 h. PTH secretion in the second-passage (P2) cells was significantly lower than that in the primary (P0) and first-passage (P1) cells (P < 0.001). Despite a significant downregulation of CaSR mRNA (P=0.017) and protein (P=0.006) in P1 cells as compared with P0 cells, no significant differences were found in mRNA and protein expressions of PTH or GCM2 between the two cell generations. Primary cultures of parathyroid cells isolated from SHPT patients by collagenase digestion show similar biological properties to the cells in vivo.

Vitamin D receptor gene polymorphisms in chronic kidney disease Egyptian children: effect on biochemical markers of bone mineral disorders.

The aim of this study was to assess the association between four vitamin D receptor (VDR) single nucleotide polymorphisms BsmI (rs1544410), ApaI (rs7975232), FokI (rs2228570) and TaqI (rs731236) and the susceptibility to chronic kidney disease (CKD) in Egyptian children and to evaluate their association with mineral status in these patients. The current study included 305 patients with CKD and 100 apparently healthy children. We measured the serum vitamin D (VD), para-thyroid hormone (PTH) level and fibroblast growth factor 23 (FGF-23) levels by ELISA method. The genotyping of the four VDR gene variants was carried out by PCR-RFLP technique. The TaqI AG &amp; the BsmI TT genotypes were associated with a significantly higher risk of CKD. The expression of 25-OH D serum level was decreased in patients with TaqI GG &amp; AG genotypes groups and in patients with BsmI TT genotype group The expression of PTH serum level was increased in patients with BsmI CT genotype group. The expression of FGF-23 serum level was increased in patients with Taq1 AG genotype group. We found 3 specific haplotypes; AGCA, AGCC and GGCA for healthy controls. Our study showed an association between VDR TaqI, BsmI polymorphisms and the susceptibility to CKD. The existence of VDR vari-ants affected the protein expression of VD, FGF-23 and PTH. The AGCA, AGCC and GGCA haplotypes were considered as protec-tive factors against the development of renal nephropathy in our population.

Parathyroid Hormone Secretion and Receptor Expression Determine the Age-Related Degree of Osteogenic Differentiation in Dental Pulp Stem Cells.

Objective: To demonstrate the levels of parathyroid hormone secretion and genetic expressions of parathyroid hormone (PTH) and PTH1 receptor (PTH1R) genes in the dental pulp stem cells (DPSCs) from different age groups before and after induction of osteogenic differentiation. In addition, we also wanted to check their correlation with the degree of osteogenic differentiation. Methods: Human primary DPSCs from three age groups (milk tooth (SHEDs), 7–12 years old; young DPSCs (yDPSCs), 20–40 years old; old DPSCs (oDPSCs), 60+ years old) were characterized for mesenchymal stem cell (MSC) markers. DPSCs were subjected to osteogenic differentiation and functional staining. Gene expression levels were analyzed by qRT-PCR. Surface receptor analysis was done by flow cytometry. Comparative protein levels were evaluated by ELISA. Results: All SHEDs, yDPSCs, and oDPSCs were found to be expressing mesenchymal stem cell markers. SHEDs showed more mineralization than yDPSCs and oDPSCs after osteogenic induction. SHEDs exhibited higher expression of PTH and PTH1R before and after osteogenic induction, and after osteogenic induction, SHEDs showed more expression for RUNX2, ALPL, and OCN. Higher levels of PTH were observed in SHEDs and yDPSCs, and the number of PTH1R positive cells was relatively lower in yDPSCs and oDPSCs than in SHEDs. After osteogenic induction, SHEDs were superior in the secretion of OPG, and the secretions of ALPL and PTH and the number of PTH1R positive cells were relatively low in the oDPSCs. Conclusions: The therapeutic quality of dental pulp stem cells is largely based on their ability to retain their stemness characteristics. This study emphasizes the criterion of aging, which affects the secretion of PTH by these cells, which in turn attenuates their osteogenic potential.

MRNA Profiles of Porcine Parathyroid Glands Following Variable Phosphorus Supplies throughout Fetal and Postnatal Life.

Knowledge of gene expression profiles reflecting functional features and specific responsiveness of parathyroid glands (PTGs) contributes to understanding mineral homeostasis and parathyroid function in healthy and diseased conditions. The study aims to reveal effector molecules driving the maintenance of phosphorus (P) homeostasis and parathyroid hormone (PTH) responsiveness to variable P supply throughout fetal and postnatal life. In this study, a long-term dietary intervention was performed by keeping pig offspring on distinct mineral P levels throughout fetal and postnatal life. Respective adaptation processes of P homeostasis were assessed in mRNA profiles of PTGs and serum minerals. RNA sequencing data and resulting molecular pathways of PTGs showed that the PTH abundance is very strictly controlled via e.g., PIN1, CaSR, MAfB, PLC and PKA signaling to regulate PTH expression, stability, and secretion. Additionally, the observed dietary effects on collagen expression indicate shifts in the ratio between connective tissue and parenchyma, thereby affecting cell-cell contacts as another line of PTH regulation. Taken together, the mRNA profiles of porcine PTGs reflect physiological responses in-vivo following variable dietary P supplies during fetal and postnatal life. The results serve to evaluate a long-term nutrition strategy with implications for improving the mineral balance in individuals with pathological disorders.

Dietary phosphorus restriction affects bone metabolism, vitamin D metabolism and rumen fermentation traits in sheep.

Homeostasis of calcium (Ca) and phosphate (Pi ) is maintained by a concerted interplay of absorption and reabsorption via the gastrointestinal tract and the kidney and by storage and mobilization from the bone regulated mainly by parathyroid hormone (PTH), 1,25-dihydroxycholecalciferol and calcitonin. The present study aimed at characterizing the effects of dietary P restriction on bone, vitamin D metabolism and rumen fermentation traits reflecting the endogenous P cycle maintaining the ruminal P supply for microbial metabolism. The experiments were done in eleven female, non-pregnant, non-lactating four- to nine-year-old Black Headed Mutton sheep allotted to two feeding groups: "P-restricted" (0.11% P/kg DM and 0.88% Ca/kg DM) and "Control" (0.38% P/kg DM and 0.88% Ca/kg DM). Dietary P restriction did not lead to hypophosphataemia, probably due to a compensation by bone mobilization, demonstrated by increased serum concentrations of a resorption marker and altered gene expression in bone tissue. In addition, the RNA expression of fibroblast growth factor 23, a bone-derived factor involved in the regulation of vitamin D metabolism, was significantly reduced with dietary P restriction. Furthermore, several genes related to vitamin D metabolism and plasma concentrations of 1,25-(OH)2 D were associated with serum concentrations of phosphate (Pi ). In the parotid gland, the expression of the Pi transporter NaPi2b was negatively associated with serum Pi and positively with parathyroid PTH expression. Although Pi concentrations in saliva and the gastrointestinal tract were significantly reduced, we found no adverse effects of the P-restricted ration on the production of short chain fatty acids, but slight differences in the production of butyrate as well as its relationship to rumen Pi and ammonia concentrations that might indicate an impact on ruminal fermentation.

Physical Activity-Dependent Regulation of Parathyroid Hormone and Calcium-Phosphorous Metabolism.

Exercise perturbs homeostasis, alters the levels of circulating mediators and hormones, and increases the demand by skeletal muscles and other vital organs for energy substrates. Exercise also affects bone and mineral metabolism, particularly calcium and phosphate, both of which are essential for muscle contraction, neuromuscular signaling, biosynthesis of adenosine triphosphate (ATP), and other energy substrates. Parathyroid hormone (PTH) is involved in the regulation of calcium and phosphate homeostasis. Understanding the effects of exercise on PTH secretion is fundamental for appreciating how the body adapts to exercise. Altered PTH metabolism underlies hyperparathyroidism and hypoparathyroidism, the complications of which affect the organs involved in calcium and phosphorous metabolism (bone and kidney) and other body systems as well. Exercise affects PTH expression and secretion by altering the circulating levels of calcium and phosphate. In turn, PTH responds directly to exercise and exercise-induced myokines. Here, we review the main concepts of the regulation of PTH expression and secretion under physiological conditions, in acute and chronic exercise, and in relation to PTH-related disorders.

Older Age Is Associated with Decreased Levels of VDR, CYP27B1, and CYP24A1 and Increased Levels of PTH in Human Parathyroid Glands.

Parathyroid glands contain the vitamin D receptor (VDR) and 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) and 24-hydroxylase (CYP24A1), which catalyze the production and degradation of 1,25-dihydroxyvitamin D [1,25(OH)2D], respectively. Previous studies have shown that the serum level of intact parathyroid hormone (iPTH) increases with age. We hypothesized that the expression of CYP27B1 or VDR in parathyroid glands decreases with age, which might account for the increased serum levels of iPTH due to decreased suppression of parathyroid hormone (PTH) secretion by 1,25(OH)2D in older people. To test this hypothesis, we examined relative expression levels of VDR, CYP27B1, CYP24A1, and PTH in specimens from parathyroid glands unintentionally removed during thyroidectomy for 70 patients varying in age from 10 to 70 years. The results showed that there was an inverse correlation between age and VDR, CYP27B1, and CYP24A1 expression (p < 0.05). A significant positive correlation between PTH expression levels and age was also observed (p < 0.05). These data indicate that older age is associated with decreased levels of VDR, CYP27B1, and CYP24A1 and increased levels of PTH in human parathyroid glands.

Dietary protein and calcium modulate parathyroid vitamin D receptor expression in young ruminants

For economic reasons and in order to minimize nitrogen excretion and thus pollution, the crude protein content in the diet of livestock animals should be as low as possible without negatively affecting the animals´ health and performance. As ruminants can efficiently use dietary protein because of the ruminohepatic circulation of urea, they are considered to cope more easily with such a feeding regime than monogastric animals. However, despite unaltered daily weight gain, massive changes in mineral homeostasis and vitamin D metabolism were observed with dietary protein reduction (N-) in young, growing goats. Serum concentrations of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) were decreased with a low N intake, even if calcium (Ca) was also restricted (Ca-). Interestingly, concentrations of cyclic adenosine monophosphate (cAMP) measured as an indirect assessment for the parathyroid hormone (PTH) activity were not affected by low protein. Therefore, it was hypothesized that the sensitivity of the parathyroid gland is modulated during these dietary interventions. Four groups of male German colored goats received a control (N+/Ca+), a reduced protein (N-/Ca+), a reduced Ca (N+/Ca-) or a reduced protein and Ca (N-/Ca-) diet. After six weeks we determined the expression of PTH, PTH receptor, Ca sensing receptor (CASR), vitamin D receptor (VDR), retinoid X receptor (RXRα), Klotho, fibroblast growth factor receptor 1c-splicing form, and the sodium-dependent Pi transporter (PiT1) in the parathyroid glands. Concentrations of cAMP were not affected, while those of Ca and 1,25-(OH)2D3were diminished and that of 25-hydroxyvitamin D3 was increased with N- feeding. The expression patterns of the described target genes were not altered. In contrast, animals fed the Ca- rations showed enhanced serum 1,25-(OH)2D3 and cAMP levels with no changes in blood Ca concentrations demonstrating an efficient adaptation. The mRNA expression of expression of VDR and CASR in the parathyroid gland was significantly diminished and RXRα, PTHR and PiT1 expression was elevated. Instead of the assumed desensitization of the parathyroid gland with N-, our results indicate elevated responsiveness to decreased blood Ca with feeding Ca-.

Effect of parathyroid hormone on cardiac function in rats with cardiomyopathy.

The present study investigated the role of parathyroid hormone (PTH) in non-ischemic cardiomyopathy (CM) and its underlying mechanism. A total of 30 Sprague-Dawley male rats were randomly divided into a control group (n=6) and an experimental group (n=24). To induce CM in the rats of the experimental group, 2 mg/kg Adriamycin (ADR) was administered intraperitoneally with 5 equal injections every third day followed by 5 weekly injections resulting in a cumulative dose of 20 mg/kg. Following establishment of the model, rats in the experimental group were subdivided into a PTH-untreated CM group that received daily normal saline subcutaneous injections for 7 days and three treated CM groups that received daily subcutaneous injections of 5, 10, or 20 µg/kg of recombinant PTH for 7 days. Rats in the control group accordingly received intraperitoneal and subcutaneous injections of normal saline. Blood sample analysis revealed that B-type natriuretic peptide (BNP), troponin T, C-reactive protein (CRP), creatinine and phosphorus concentrations were increased in the PTH-untreated CM group compared with that in the control group, whereas PTH and calcium concentrations were decreased. Administration of PTH dose-dependently decreased BNP, CRP, creatinine and phosphorus levels, and increased PTH and calcium levels. Notably, there were significant differences in PTH, BNP, troponin T, CRP, creatinine, calcium, and phosphorus levels among the rats in the five groups (P<0.01). Cardiac ultrasonography results indicated that the left ventricular ejection fraction (LVEF) was significantly decreased in rats treated with ADR compared with the rats from the control group (P<0.01). However, the LVEF gradually recovered with elevated PTH treatment doses. The overall differences of LVEF and left ventricular end-systolic volume in the five experimental groups were statistically significant (P<0.01). Furthermore, there were dose-dependent increases in LV mass and left ventricular end-diastolic volume in PTH-treated rats; however, the differences between any two groups did not reach statistical significance (P>0.05). Immunohistochemical staining and western blot analysis using an anti-PTH polyclonal antibody was performed to evaluate the protein expression levels of PTH in myocardial tissues. The mRNA expression levels of PTH and BNP were measured using reverse transcription-quantitative polymerase chain reaction. The results demonstrated that the mRNA and protein expression levels of PTH in myocardial tissues were significantly decreased in ADR-treated rats compared with the levels in the control group rats. Injection of recombinant PTH significantly increased PTH expression and reduced BNP expression in dose-dependent manners (P<0.05). These findings demonstrated that PTH can improve cardiac function in rats with ADR-induced CM, suggesting a potential therapeutic application for PTH in non-ischemic CM.

Effects of FGF-23-mediated ERK/MAPK signaling pathway on parathyroid hormone secretion of parathyroid cells in rats with secondary hyperparathyroidism.

This study is supposed to investigate the effect of FGF-23 on parathyroid hormone (PTH) secretion through ERK/MAPK signaling pathway in secondary hyperparathyroidism (SHPT) rat model. Thirty rats were equally served as the normal and SHPT groups. After transfection, parathyroid cells was assigned into blank, NC, pcDNA3.1-FGF-23, siRNA-FGF-23, U0126, and siRNA-FGF-23 + U0126 groups. The serum levels of Calcium (Ca), Phosphorus (P), alkaline phosphatase (ALP), and PTH were detected. HE and immunohistochemical (IHC) staining were used for the histopathological changes and the FGF-23, EKR1/2, and pEKR1/2 expressions. qRT-PCR and Western blotting were performed to determine the mRNA and protein expression of FGF-23, PTH, MAPK, EKR1/2, and Klotho. The proliferation, apoptosis, and cell cycle were all measured for parathyroid cells by CCK-8 assay, TUNEL staining and Flow cytometry. Compared with the normal group, the SHPT group showed increased serum levels PTH, P, ALP, and FGF-23 and mRNA and protein expressions of FGF-23 and PTH, whereas declined Ca and p-ERK1/2 expression, mRNA and protein expression of Klotho, cell apoptosis rate was reduced. Furthermore, compared to the blank and NC groups, the pcDNA3.1-FGF-23 and U0126 groups had a decreased mRNA expression of Klotho, protein expression of EKR1/2 and Klotho, and cell apoptosis rate was down-regulated, whereas the RNA and protein expressions of FGF-23 and PTH were up-regulated, and cell proliferation was elevated. The opposite results were observed in the siRNA-FGF-23 group. Our study demonstrated that FGF-23 could inhibit signaling transduction of ERK/MAPK pathway and accelerate the secretion of PTH in rats with SHPT.

Decreased expression of PTH1R is a poor prognosis in hepatocellular carcinoma.

Hypercalcemia is a potentially fatal and not rare complication of hepatocellular carcinoma (HCC), and its underlying mechanism remains unclear. Parathyroid hormone (PTH) is the most important regulator of the concentrations of calcium and phosphate in blood; parathyroid hormone-related protein (PTHrP) was the most frequent cause of humoral hypercalcemia of malignancy; parathyroid hormone 1 receptor (PTH1R) is the common receptor for PTH and PTHrP. The aim of this study is to investigate the expression of PTH, PTHrP, and PTH1R in HCC tissues, and their relationship with clinical pathological characters in HCC. First, a meta-analysis based on online Oncomine Expression Array database was conducted to compare the different mRNA expression of PTH1R, PTH and PTHrP between hepatocellular carcinoma and normal tissues. Then, the protein expression level of differentially expressed gene was examined by immunohistochemistry staining in 223 HCC tissues and 102 non-tumorous liver tissues controls. The relationship between the protein expression and clinicopathological parameters was analyzed by χ2 test, and overall survival analysis was performed using Kaplan-Meier survival analysis. PTH1R mRNA expression was significantly lower in HCC tissues compared with normal tissues, while the expression of PTH and PTHrP showed no significant difference between HCC tissues and normal tissues. High PTH1R protein expression was found in 90/102 cases of adjacent non-tumorous liver tissues, and in 91 of 223 cases of HCC tissues. PTH1R expression was significantly related to tumor size, Edmondson Grade, AFP, and overall survival. PTH1R may be the major cause of hypercalcemia in HCC, and the decreased PTH1R expression was a poor prognosis in HCC.

The association between parathyroid hormone 1‑34 and the Wnt/β‑catenin signaling pathway in a rat model of osteoarthritis.

The aim of the current study was to determine the effect of parathyroid hormone (PTH) 1–34 on cartilage degeneration, and the association between PTH 1–34 and factors associated with the Wnt/β-catenin pathway following anterior cruciate ligament and medial meniscectomy-induced osteoarthritis (OA) in rats. A total of 64 Sprague-Dawley rats were randomly divided into the following four groups: Sham-operated rats with normal saline (NS)-treatment (n=16); anterior cruciate ligament transection with partial medial meniscectomy (ACLT + MMx) rats with NS-treatment (n=16); sham-operated rats treated with PTH 1–34 (n=16); and ACLT + MMx rats treated with PTH 1–34 (n=16). PTH (15 µg/kg/day) was administered via subcutaneous injection 5 days per week from the first postoperative day for 2 or 6 weeks. Staining with hematoxylin and eosin and safranin O, and a scoring system modified by Mankin were used to assess the histopathological features of cartilage. The present study detected the expression of PTH 1 receptor (PTH1R), sclerostin, dickkopf Wnt signaling pathway inhibitor 1 (DKK1), β-catenin and runt-related transcription factor 2 (RUNX2) in cartilage by immunohistochemical analysis to determine the association between PTH 1–34 and factors associated with the Wnt/β-catenin pathway. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to detect the mRNA expression levels of PTH1R and β-catenin in cartilage. Histological analysis demonstrated that cartilage degeneration was present post-surgery and gradually increased over time. PTH 1–34 reduced the Mankin scores in ACLT + MMx rats compared with the NS-treated ACLT + MMx rats. Immunohistochemistry and RT-qPCR analysis demonstrated that, in cartilage, PTH 1–34 treatment increased the mRNA expression and protein levels of PTH1R and β-catenin, and decreased protein levels of sclerostin, DKK1 and RUNX2 in ACLT + MMx rats compared with the NS-treated ACLT + MMx group. The present study demonstrated that PTH 1–34 upregulated the Wnt/β-catenin signaling pathway and that PTH1-34 downregulated RUNX2 through an alternative pathway to the Wnt/β-catenin signaling pathway, in a rat model of OA.

An Excess of CYP24A1, Lack of CaSR, and a Novel lncRNA Near the PTH Gene Characterize an Ectopic PTH-Producing Tumor.

Thus far, only 23 cases of the ectopic production of parathyroid hormone (PTH) have been reported. We have characterized the genome-wide transcription profile of an ectopic PTH-producing tumor originating from a retroperitoneal histiocytoma. We found that the calcium-sensing receptor (CaSR) was barely expressed in the tumor. Lack of CaSR, a crucial braking apparatus in the presence of both intraparathyroid and, probably, serendipitous PTH expression, might contribute strongly to the establishment and maintenance of the ectopic transcriptional activation of the PTH gene in nonparathyroid cells. Along with candidate drivers with a crucial frameshift mutation or copy number variation at specific chromosomal areas obtained from whole exome sequencing, we identified robust tumor-specific cytochrome P450 family 24 subfamily A member 1 (CYP24A1) overproduction, which was not observed in other non–PTH-expressing retroperitoneal histiocytoma and parathyroid adenoma samples. We then found a 2.5-kb noncoding RNA in the PTH 3′-downstream region that was exclusively present in the parathyroid adenoma and our tumor. Such a co-occurrence might act as another driver of ectopic PTH-producing tumorigenesis; both might release the control of PTH gene expression by shutting down the other branches of the safety system (e.g., CaSR and the vitamin D3–vitamin D receptor axis).

Let-7 and MicroRNA-148 Regulate Parathyroid Hormone Levels in Secondary Hyperparathyroidism.

Secondary hyperparathyroidism commonly complicates CKD and associates with morbidity and mortality. We profiled microRNA (miRNA) in parathyroid glands from experimental hyperparathyroidism models and patients receiving dialysis and studied the function of specific miRNAs. miRNA deep-sequencing showed that human and rodent parathyroids share similar profiles. Parathyroids from uremic and normal rats segregated on the basis of their miRNA expression profiles, and a similar finding was observed in humans. We identified parathyroid miRNAs that were dysregulated in experimental hyperparathyroidism, including miR-29, miR-21, miR-148, miR-30, and miR-141 (upregulated); and miR-10, miR-125, and miR-25 (downregulated). Inhibition of the abundant let-7 family increased parathyroid hormone (PTH) secretion in normal and uremic rats, as well as in mouse parathyroid organ cultures. Conversely, inhibition of the upregulated miR-148 family prevented the increase in serum PTH level in uremic rats and decreased levels of secreted PTH in parathyroid cultures. The evolutionary conservation of abundant miRNAs in normal parathyroid glands and the regulation of these miRNAs in secondary hyperparathyroidism indicates their importance for parathyroid function and the development of hyperparathyroidism. Specifically, let-7 and miR-148 antagonism modified PTH secretion in vivo and in vitro, implying roles for these specific miRNAs. These findings may be utilized for therapeutic interventions aimed at altering PTH expression in diseases such as osteoporosis and secondary hyperparathyroidism.

FGF23 Neutralizing Antibody Ameliorates Hypophosphatemia and Impaired FGF Receptor Signaling in Kidneys of HMWFGF2 Transgenic Mice.

High molecular weight FGF2 transgenic mice (HMWTg) phenocopy the Hyp mouse, homolog of human X-linked hypophosphatemic rickets with phosphate wasting and abnormal fibroblast growth factor (FGF23), fibroblast growth factor receptor (FGFR), Klotho and mitogen activated protein kinases (MAPK) signaling in kidney. In this study, we assessed whether short-term (24 h) in vivo administration of FGF23 neutralizing antibody (FGF23Ab) could rescue hypophosphatemia and impaired FGFR signaling in kidneys of HMWTg male mice. Bone mineral density and bone mineral content in 1-month-old HMWTg mice were significantly reduced compared with Control/VectorTg mice. Serum FGF23 was significantly increased in HMWTg compared with VectorTg. Serum phosphate was significantly reduced in HMWTg and was rescued by FGF23Ab. Serum parathyroid hormone (PTH) was significantly increased in HMWTg but was not reduced by FGF23Ab. 1, 25(OH)2 D was inappropriately normal in serum of HMWTg and was significantly increased in both Vector and HMWTg by FGF23Ab. Analysis of HMWTg kidneys revealed significantly increased mRNA expression of the FGF23 co-receptor Klotho, transcription factor mRNAs for early growth response-1 transcription factor (Egr-1), and c-fos were all significantly decreased by FGF23Ab. A significant reduction in the phosphate transporter Npt2a mRNA was also observed in HMWTg kidneys, which was increased by FGF23Ab. FGF23Ab reduced p-FGFR1, p-FGFR3, KLOTHO, p-ERK1/2, C-FOS, and increased NPT2A protein in HMWTg kidneys. We conclude that FGF23 blockade rescued hypophosphatemia by regulating FGF23/FGFR downstream signaling in HMWTg kidneys. Furthermore, HMWFGF2 isoforms regulate PTH expression independent of FGF23/FGFR signaling. J. Cell. Physiol. 232: 610-616, 2017. © 2016 Wiley Periodicals, Inc.

Risk factors associated with secondary hyperparathyroidism in patients with chronic kidney disease.

Secondary hyperparathyroidism (SHPT) is common in patients with chronic kidney disease (CKD), and its development and progression are affected by various factors. The aim of the present study was to identify the risk factors for SHPT in patients with CKD. A retrospective study was performed in 498 patients (305 males and 193 females) with CKD, observed in the The First Hospital of Jilin University between January 2008 and December 2012. The demographic, clinical and laboratory data were collected. Patients were divided into the SHPT group (n=424) with elevated serum parathyroid hormone (PTH) expression levels and the control group (n=74) with normal serum PTH expression levels. Univariate and multivariate regression analyses were employed to explore the risk factors for SHPT. Serum PTH expression levels in women with CKD were significantly higher than in men (P=0.047). Serum PTH expression levels were positively correlated with the expression levels of serum creatinine (P<0.01), phosphorus (P<0.01), C-reactive protein (P<0.05), triglyceride (P<0.05), cholesterol (P<0.05) and low-density lipoprotein cholesterol (P<0.05), but were negatively correlated with the expression levels of hemoglobin (P<0.05), calcium (P<0.01) and CO2 combining power (P<0.01) in patients with CKD. Multivariate analysis showed that the serum expression levels of creatinine [µmol/l; odds radio (OR), 1.003; 95% confidence interval (CI), 1.002-1.004; P=0.001] and phosphorus (mmol/l; OR, 2.19; 95% CI, 1.254-3.826; P=0.006) in patients with CKD significantly influenced serum PTH expression levels. The SHPT risk factors include female gender, low calcium, high phosphorus, acidosis, anemia, hypertension, hyperlipidemia and micro-inflammation, with blood phosphorus and creatinine being independent risk factors.