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Find video protocols related to scientific articles indexed in Pubmed.
Somatic mutations of the catalytic subunit of cyclic AMP-dependent protein kinase (PRKACA) gene in Japanese patients with several adrenal adenomas secreting cortisol [Rapid Communication].
Endocr. J.
PUBLISHED: 07-25-2014
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Somatic mutations of the catalytic subunit of the cyclic AMP-dependent protein kinase (PRKACA) gene have recently been identified in about 35% of cortisol-producing adenomas (CPAs), with the affected patients showing overt Cushing's syndrome. Since we recently reported higher prevalence of mutations of the KCNJ5 gene and associations with autonomous cortisol secretion in Japanese aldosterone-producing adenomas than in Western countries, there might be different features of CPAs between Japan and the West. We therefore investigated mutations of the PRKACA gene in Japanese patients with several adrenal tumors secreting cortisol, including overt Cushing's syndrome, subclinical Cushing's syndrome, and aldosterone-producing adenomas (APAs) co-secreting cortisol operated on at Gunma University Hospital. Of the 13 patients with CPA who showed overt Cushing's syndrome, 3 (23%) had recurrent somatic mutations of the PRKACA gene, p.L206R (c.617 T>G), and there were no mutations in subclinical Cushing's syndrome. Among 33 APAs, 24 had somatic mutations of the KCNJ5 gene, either G151R or L168R, 11 (33%) had autonomous cortisol secretion, but there were no mutations of the PRKACA gene. We established a PCR-restriction fragment length polymorphism assay and revealed that the mutated allele was expressed at a similar level to the wild-type allele. These findings demonstrated that 1) the prevalence of Japanese patients with CPA who showed overt Cushing's syndrome and whose somatic mutations in the PRKACA gene was similar to that in Western countries, 2) the mutation might be specific for CPAs causing overt Cushing's syndrome, and 3) the mutant PRKACA allele was expressed appropriately in CPAs.
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Coordinated regulation of transcription and alternative splicing by the thyroid hormone receptor and its associating coregulators.
Biochem. Biophys. Res. Commun.
PUBLISHED: 07-01-2014
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Emerging evidence has indicated that the transcription and processing of precursor mRNA (pre-mRNA) are functionally coupled to modulate gene expression. In collaboration with coregulators, several steroid hormone receptors have previously been shown to directly affect alternative pre-mRNA splicing coupled to hormone-induced gene transcription; however, the roles of the thyroid hormone receptor (TR) and its coregulators in alternative splicing coordinated with transcription remain unknown. In the present study, we constructed a luciferase reporter and CD44 alternative splicing (AS) minigene driven by a minimal promoter carrying 2 copies of the palindromic thyroid hormone-response element. We then examined whether TR could modulate pre-mRNA processing coupled to triiodothyronine (T3)-induced gene transcription using luciferase reporter and splicing minigene assays in HeLa cells. In the presence of cotransfected TR?1, T3 increased luciferase activities along with the inclusion of the CD44 variable exons 4 and 5 in a dose- and time-dependent manner. In contrast, cotransfected TR?1 did not affect the exon-inclusion of the CD44 minigene driven by the cytomegalovirus promoter. T3-induced two-exon inclusion was significantly increased by the cotransfection of the TR-associated protein, 150-kDa, a subunit of the TRAP/Mediator complex that has recently been shown to function as a splicing factor. In contrast, T3-induced two-exon inclusion was significantly decreased by cotransfection of the polypyrimidine tract-binding protein-associated splicing factor, which was previously shown to function as a corepressor of TR. These results demonstrated that liganded TR in cooperation with its associating cofactors could modulate alternative pre-mRNA splicing coupled to gene transcription.
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Haploinsufficient and predominant expression of multiple endocrine neoplasia type 1 (MEN1)-related genes, MLL, p27Kip1 and p18Ink4C in endocrine organs.
Biochem. Biophys. Res. Commun.
PUBLISHED: 10-01-2011
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Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominantly inherited syndrome characterized by parathyroid, gastro-entero-pancreatic and anterior pituitary tumors. Although the tissue selectivity of tumors in specific endocrine organs is the very essence of MEN1, the mechanisms underlying the tissue-selectivity of tumors remain unknown. The product of the Men1 gene, menin, and mixed lineage leukemia (MLL) have been found to cooperatively regulate p27(Kip1)/CDKN1B (p27) and p18(Ink4C)/CDKN2C (p18) genes. However, there are no reports on the tissue distribution of these MEN1-related genes. We investigated the expression of these genes in the endocrine and non-endocrine organs of wild-type, Men1 knockout and MLL knockout mice. Men1 mRNA was expressed at a similar level in endocrine and non-endocrine organs. However, MLL, p27 and p18 mRNAs were predominantly expressed in the endocrine organs. Notably, p27 and MLL mRNAs were expressed in the pituitary gland at levels approximately 12- and 17-fold higher than those in the liver. The heterozygotes of Men1 knockout mice the levels of MLL, p27 and p18 mRNAs did not differ from those in the wild-type mice. In contrast, heterozygotes of MLL knockout mice showed significant reductions in p27 mRNA as well as protein levels in the pituitary and p27 and p18 in the pancreatic islets, but not in the liver. This study demonstrated for the first time the predominant expression MEN1-related genes, particularly MLL and p27, in the endocrine organs, and a tissue-specific haploinsuffiency of MLL, but not menin, may lead to a decrease in levels of p27 and p18 mRNAs in endocrine organs. These findings may provide basic information for understanding the mechanisms of tissue selectivity of the tumorigenesis in patients with MEN1.
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Attenuated expression of menin and p27 (Kip1) in an aggressive case of multiple endocrine neoplasia type 1 (MEN1) associated with an atypical prolactinoma and a malignant pancreatic endocrine tumor.
Endocr. J.
PUBLISHED: 03-25-2011
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Tumors in multiple endocrine neoplasia type 1 (MEN1) are generally benign. Since information on the pathogenesis of MEN1 in malignant cases is limited, we conducted genetic analysis and compared the expression of menin, p27(Kip1)(p27)/CDKN1B and p18(Ink4C)(p18)/CDKN2C with levels in benign cases. We describe the case of a 56 year-old male with an atypical prolactinoma and malignant pancreatic neuroenocrine tumor. At age 50, he had undergone transsphenoidal surgery to remove a prolactinoma. However, the tumor relapsed twice. Histological analysis of the recurrent prolactinoma revealed the presence of prolactin, a high MIB-1 index (32.1 %), p53-positive cells (0.2%), and an unusual association with FSH-positive cells. A few years later, he was also found to have a non-functioning pancreatic tumor with probable metastasis to the extradullar region. The metastatic region tested positive for chromogranin and CD56, and negative for prolactin, with 1.2 % of cells p53-positive. Although genetic analyses of the MEN1, p27, and p18 genes demonstrated no mutation, numbers of menin, p27 and p18 immuno-positive cells were significantly down-regulated in the recurrent prolactinoma, but that of p18 was intact in the metastatic region. Furthermore, MEN1 and p27 mRNA levels of the recurrent prolactinoma were down-regulated, particularly the MEN1 mRNA level, compared to levels in 10 cases of benign prolactinoma, while the p18 mRNA level was similar to that of normal pituitary. The tumor in this case may be a subtype of MEN1 showing more aggressive and malignant features probably induced by low levels of menin and p27.
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Liver X receptor-?/? expression ratio is increased in ACTH-secreting pituitary adenomas.
Neurosci. Lett.
PUBLISHED: 02-05-2011
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The liver X receptors (LXR-? and -?) are nuclear oxysterol receptors that play pivotal roles in regulating the expression of genes involved in cholesterol transport and metabolism. Recently, several groups have reported that the LXRs also regulate adrenal steroidogenesis. In the previous report, we demonstrated that LXR-? is dominantly expressed in the pituitary and that LXR-? positively regulates the proopiomelanocortin (POMC) gene promoter at the transcriptional level. In this report, we evaluated the expression levels of LXR-? and -? gene in the human pituitary tumor. Even though LXR-? mRNA levels are not significantly increased in ACTH-secreting adenomas, LXR-?/? expression ratio is significantly higher than other pituitary tumors including normal pituitaries. Furthermore, in At-T20 cells, which express POMC gene, overexpression of LXR-? decreased POMC gene promoter activities. Thus, we concluded that LXR-?/? gene expression ratio is a critical factor to activate POMC gene expression in ACTH-secreting pituitary adenomas.
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Primary bilateral adrenal diffuse large B-cell lymphoma demonstrating adrenal failure.
Intern. Med.
PUBLISHED: 10-15-2010
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Primary adrenal lymphoma (PAL) is extremely rare although involvement of malignant lymphoma into adrenals is common. We report a case of a 58-year-old man with bilateral PAL who demonstrated adrenal insufficiency. Primary large B-cell lymphoma was proven by a computed tomography-guided needle biopsy of the adrenal tumor. Although a complete remission was once achieved by combination chemotherapy plus rituximab, a recurrence occurred with brain metastasis leading to his death. We concluded that PAL should be considered as a possible cause of bilateral adrenal incidentalomas with progressive adrenal insufficiency.
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Resistance to thyroid hormone due to a novel thyroid hormone receptor mutant in a patient with hypothyroidism secondary to lingual thyroid and functional characterization of the mutant receptor.
Thyroid
PUBLISHED: 07-10-2010
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We describe a rare case of congenital hypothyroidism and an extremely high serum thyrotropin (TSH) level caused by a combination of resistance to thyroid hormone (RTH) and a lingual thyroid. As the RTH mutant, R316C, was new, the optimum dose of levothyroxine was unclear. To aid in assessment of the therapy, we characterized the mutant R316C thyroid hormone receptor (TR) and compared it with a common mutant, R316H, using in vitro studies.
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Troglitazone, a ligand of peroxisome proliferator-activated receptor-{gamma}, stabilizes NUCB2 (Nesfatin) mRNA by activating the ERK1/2 pathway: isolation and characterization of the human NUCB2 gene.
Endocrinology
PUBLISHED: 04-28-2010
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We recently identified a novel satiety peptide, nesfatin-1, containing 82 amino acids derived from the precursor peptide, nucleobindin 2 (NUCB2), from a troglitazone (TZ)-induced cDNA library. We examined the molecular mechanism underlying TZ-induced NUCB2 mRNA expression. Although TZ induced the mRNA expression in HTB185 cells, a nuclear run-on assay revealed no significant change in the transcription of the gene. Surprisingly, HTB185 cells possessed no functional peroxisome proliferator-activated receptor-gamma. We therefore examined the effect of TZ on the mRNAs stability. The half-life of NUCB2 mRNA was approximately 6 h, and incubation with TZ increased this to 27 h. Furthermore, this increase was completely inhibited by an ERK inhibitor, PD98059, and phosphorylated ERK1/2 was significantly increased after 30 min incubation with TZ. In addition, we cloned the entire NUCB2 gene and identified four adenylate/uridylate-rich elements (AREs) in the 3 untranslated region (UTR), to which several proteins of HTB185 extracts treated with TZ bound. The reporter assay fused with 3UTR showed that the second and third AREs were crucial. Furthermore, the human NUCB2 gene spanned 55 kb and contained 14 exons and 13 introns. The transcriptional start site formed clusters around 246 bp upstream from the translational start site. We confirmed that a construct containing 5889 bp of the promoter region was very active in neuron-derived cell lines but not stimulated by TZ. These findings demonstrated a novel action of derivatives of thiazolidinediones, oral insulin-sensitizing antidiabetic agents, to stabilize the mRNA of NUCB2 through AREs in the 3UTR by activating the ERK1/2 pathway independently of peroxisome proliferator-activated receptor-gamma.
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Epigenetic inactivation of the thyroid hormone receptor beta1 gene at 3p24.2 in lung cancer.
Ann. Surg. Oncol.
PUBLISHED: 02-13-2010
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Frequent allelic loss on chromosome 3p in various human cancers suggests the presence of tumor suppressor genes in this region. The thyroid hormone receptor beta1 (TRbeta1) gene is located at 3p24.2, where allelic loss frequently occurs in lung cancer, and aberrant TRbeta1 methylation was observed in several human cancers.
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Transcriptional activation of the mixed lineage leukemia-p27Kip1 pathway by a somatostatin analogue.
Clin. Cancer Res.
PUBLISHED: 03-24-2009
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Mixed lineage leukemia (MLL) is a histone methyltransferase that activates gene transcription and associates with menin. In multiple endocrine neoplasia type 1 (Men1), a mutation of menin caused decreased expression of the p27(Kip1) and p18(Ink4C) genes and deregulated cell growth. We hypothesized that the same pathway might be involved in sporadic pituitary adenomas.
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Aberrant histone modifications at the thyrotropin-releasing hormone gene in resistance to thyroid hormone: analysis of F455S mutant thyroid hormone receptor.
Endocrinology
PUBLISHED: 03-19-2009
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We reported a novel mutation of thyroid hormone receptor (TR)-beta, F455S, in a patient with pituitary resistance to thyroid hormone (RTH), who showed impaired release of nuclear receptor corepressor and abnormal histone deacetylation. In the present study, we further analyzed the histone modifications and the dynamics of TR and RNA polymerase II on the TRH gene. The lysine residues 9 (H3K9) and 14 (K14) of the histone H3 were acetylated in the absence of thyroid hormone (TH), and addition of TH caused a temporary deacetylation of both residues. Although H3K4 was di- and trimethylated in the absence of T(3), no methylation of H3K9 or K27 was detected. Long-term incubation with T(3) decreased the level of trimethylated H3K4, the amount of TR, and the level of phosphorylated RNA polymerase II but not dimethylated H3K4. Treatment with an inhibitor for H3K4 methyltransferase, 5-deoxy-5-methylthioadenosine, decreased basal promoter activity but did not affect the repression by TH. Conversely, overexpression of MLL, an H3K4-specific methyltransferase, caused an increase in basal activity. In the presence of F455S, methylation of H3K4 and the dynamics of TR were intact, but both H3K9 and H3K14 were hyperacetylated, and T(3)-induced deacetylation was impaired, resulting in a high transcriptional level. These findings demonstrated that 1) negative regulation of the TRH gene by TH involves both the acetylation and methylation of specific residues of histone tails and changing the amount of TR, and 2) the major impairment to histone modifications in F455S was hyperacetylation of the specific histone tails.
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