A common genetic variant of the chromogranin A-derived peptide catestatin is associated with atherogenesis and hypertension in a Japanese population.

Chromogranin A (CHGA) is a major protein in the secretory granules of chromaffin cells. CHGA also gives rise to cardiovascular/metabolism regulatory peptides, such as catestatin (CST) and pancreastatin (PST). While CST is a potent inhibitor of catecholamine secretion, PST is a potent physiological inhibitor of glucose-induced insulin secretion. Recently, several SNPs were identified in the CST and PST domains of CHGA locus in different populations. Among the discovered SNPs, CST variant allele Ser-364 was associated with blood pressure alteration and PST variant allele Ser-297 was associated with significantly higher plasma glucose level. In this study, we examined whether these CST and PST variant alleles exist and influence cardiovascular and metabolic phenotypes in Japanese population. Our study comprised of 343 Japanese subjects aged 45-85 years (143 men and 200 women, mean age 66 ± 8 years). We determined the genotypes of CST and PST by PCR-direct sequencing method and carried out genotype-phenotype association analysis. In 343 participants, the minor allele frequency of CST variant Ser-364 was 6.10%. On the other hand, we did not detect the PST variant Ser-297 in this entire study population. The presence of Ser-364 allele was associated with increased in baPWV (an index of systemic arterial stiffness) that suggests an initiation and/or progression atherogenesis and hypertension. The Ser-364 allele was also associated with elevated systolic blood pressure and pulse pressure, consistent with increased baPWV. In conclusion, the CST Ser-364 allele may increase the risk for cardiovascular diseases in Japanese population.

Identical germline mutations in the TMEM127 gene in two unrelated Japanese patients with bilateral pheochromocytoma.

OBJECTIVE: Recently, TMEM127 was shown to be a new pheochromocytoma susceptibility gene; this is consistent with its function as a tumour suppressor gene (Journal of Clinical Endocrinology and Metabolism, 2009, 94, 2817). Most pheochromocytomas arise from the adrenal medulla, and in approximately half of the cases, the tumours are bilateral (Journal of Clinical Endocrinology and Metabolism, 2009, 94, 2817; Journal of the American Medical Association, 2004, 292, 943; Human Mutation, 2010, 31, 41; Science, 2009, 325, 1139). The aim of the present study was to determine whether TMEM127 mutations are involved in the pathogenesis of pheochromocytomas/paragangliomas in Japanese subjects. PATIENTS AND METHODS: For this study, 74 unrelated patients with pheochromocytoma/paraganglioma who tested negative for mutations and deletions in RET, VHL, SDHB and SDHD were recruited through a multi-institutional collaborative effort in Japan. The TMEM127 gene sequence was determined in their germline DNA, and tumour DNA was analysed for the loss of heterozygosity. In addition, their TMEM127 gene sequences were compared with sequences from 114 normal healthy, ethnically matched controls. RESULTS: Among the 74 eligible patients, two unrelated patients (2·7%) with bilateral adrenal pheochromocytoma were found to have an identical germline TMEM127 mutation (c.116_119delTGTC, p.Ile41ArgfsX39) associated with 2q deletion loss of heterozygosity, which was also previously described in a Brazilian case (Journal of the American Medical Association, 2004, 292, 943). We also determined that none of the 114 normal healthy controls had this deletion mutation. CONCLUSION: This is the first report showing that TMEM127 mutation plays a pathological role in pheochromocytoma in an Asian population. Although our surveillance is limited, the prevalence and the phenotype of this gene mutation appear to be similar to those reported in previous studies.

A large deletion in the succinate dehydrogenase B gene (SDHB) in a Japanese patient with abdominal paraganglioma and concomitant metastasis.

Recently, mutations in nuclear genes encoding two mitochondrial complex II subunit proteins, Succinate dehydrogenase D (SDHD) and SDHB, have been found to be associated with the development of familial pheochromocytomas and paragangliomas (hereditary pheochromocytoma/paraganglioma syndrome: HPPS). Growing evidence suggests that the mutation of SDHB is highly associated with abdominal paraganglioma and the following distant metastasis (malignant paraganglioma). In the present study, we used multiplex ligation dependent probe amplification (MLPA) analysis to identify a large heterozygous SDHB gene deletion encompassing sequences corresponding to the promoter region, in addition to exon 1 and exon 2 malignant paraganglioma patient in whom previously characterized SDHB mutations were undetectable. This is the first Japanese case report of malignant paraganglioma, with a large SDHB deletions. Our present findings strongly support the notion that large deletions in the SDHB gene should be considered in patients lacking characterized SDHB mutations.

R46Q mutation in the succinate dehydrogenase B gene (SDHB) in a Japanese family with both abdominal and thoracic paraganglioma following metastasis.

Recently, nuclear genes encoding two mitochondrial complex II subunit proteins, SDHD and SDHB, have been found to be associated with the development of familial pheochromocytomas and paragangliomas (hereditary pheochromocytoma/paraganglioma syndrome: HPPS). Growing evidence suggests that a mutation of SDHB is highly associated with abdominal (or thoracic) paraganglioma and the following distant metastasis (malignant paraganglioma). Previously, we identified a novel heterozygous G to A point mutation at the first base of intron 3 of the SDHB gene (IVS3+1G>A) in a malignant abdominal paraganglioma from a Japanese patient. In the present study, we report another case of SDHB mutation (R46Q) in a Japanese patient with both abdominal and thoracic paraganglioma following malignant metastasis. In addition, we identified an asymptomatic carrier of SDHB mutation in this family. Our report highlights the pathogenic role of the SDHB mutation (R46Q) in malignant paraganglioma. We also discuss the desired protocol that should be adopted to follow up an asymptomatic carrier of this mutation.

Novel germline mutations in the SDHB and SDHD genes in Japanese pheochromocytomas.

The SDHA, SDHB, SDHC, and SDHD genes code for subunits of succinate dehydrogenase (SDH), which forms part of the mitochondrial respiratory chain. Germline mutations in the genes encoding SDHB and SDHD have been reported in familial paragangliomas/pheochromocytomas and in apparently sporadic pheochromocytomas. SDHB and SDHD mutations are widely distributed along the genes with no apparent hot spots. SDHB mutations are often detected in malignant and extra-adrenal pheochromocytomas. SDHD mutations are also detected frequently in head and neck paragangliomas. We sequenced the entire coding regions of the SDHB and SDHD genes in 17 pheochromocytomas. We identified novel heterozygous G to A point mutations at the first base of intron 3 of the SDHB gene in a malignant extra-adrenal abdominal pheochromocytoma patient, and at the first base of codon 111 of the SDHD gene in an adrenal pheochromocytoma patient. Further, we confirmed the SDHD mutation by DHPLC. The prevalence of SDHB and SDHD mutations in pheochromocytomas we examined was 12% (2/17). Thus, we identified two novel SDH mutations in Japanese pheochromocytomas. Further studies will investigate the oncogenic potential of these mutations.

Expression of mRNAs for succinate dehydrogenase subunits and related genes in pheochromocytoma.

Mutations in the genes encoding succinate dehydrogenase (SDH) have been associated with susceptibility to pheochromocytoma. However, few reports have examined the level of SDH mRNAs expression. In this study, we examined the level of expression of mRNAs encoding SDHB, SDHC, and SDHD in pheochromocytoma, pheochromocytoma subgroups, and normal adrenal gland, and compared the expression of these genes to the level of expression of related genes in the same tissues. The mean relative level of expression of SDHB, SDHC, SDHD and VHL mRNA was 28.7+/-6.2%, 16.6+/-4.8%, 214+/-47.5% and 25.9+/-8.2%, respectively, in pheochromocytoma tissues compared to normal adrenal gland. Furthermore, the mean relative level of the RET proto-oncogene mRNA was 707+/-149% in pheochromocytoma compared to normal adrenal gland. The level of expression of the SDH genes was highly correlated in each individual sample (P<0.0001). The level of expression of the SDH mRNAs correlated with the level of VHL mRNA (P<0.0001), but not with the level of RET mRNA. The level of SDH mRNAs expression also correlated with the expression of phenylethanolamine N-methyl transferase (PNMT), an adrenaline synthesizing enzyme (P<0.01), which may explain the correlation between SDH expression and adrenaline content (P<0.05). The level of SDH mRNAs expression correlated strongly with the expression of VEGF mRNA (P<0.0001). In multiple endocrine neoplasia (MEN) 2a, the expression of the SDH genes and VHL mRNA was significantly higher than that observed in adrenal or extra-adrenal pheochromocytoma. The expression of the corticotropin-releasing hormone (CRH) mRNA was significantly higher in extra-adrenal pheochromocytoma than in adrenal pheochromocytoma or MEN2a. Thus, tumor-specific gene expression exists in pheochromocytoma, which may explain the characteristics of the tumor.

Long-term exercise stimulates adenosine monophosphate-activated protein kinase activity and subunit expression in rat visceral adipose tissue and liver.

Adenosine monophosphate-activated protein kinase (AMPK) is activated in response to adenosine triphosphate depletion caused by the metabolic and nutritional state. Mammalian AMPK is a heterotrimeric enzyme composed of a catalytic alpha subunit and 2 regulatory subunits (beta and gamma). Although much attention has been focused on exercise-induced AMPK activation in skeletal muscle, little information is available on the role of AMPK in adipose tissue and liver. Acetyl-coenzyme A carboxylase (ACC) is a well-known downstream target of AMPK. The ACC contains serine residues that are phosphorylated by AMPK. The present study was undertaken to determine whether long-term exercise of medium intensity (60% of Vo2max for 12 weeks) may influence AMPK enzyme activity, gene/protein expression, and subsequent ACC phosphorylation in rat adipose tissue (visceral and subcutaneous) and liver. We initially demonstrated that long-term exercise induced a significant increase in phosphorylation of Thr172 in the AMPK alpha1 subunit and of Ser79 in ACC in visceral adipose tissue rather than subcutaneous tissue. We also demonstrated that the AMPK alpha1-,alpha2-subunit messenger RNA (mRNA) level as well as the corresponding protein levels were increased in response to long-term exercise, whereas the other subunits were not altered significantly. In contrast to that of visceral adipose tissue, long-term exercise did not induce any significant effect on any of the AMPK subunit mRNA levels or alpha1-,alpha2-subunit protein levels in subcutaneous adipose tissue. In addition to adipose tissue, we demonstrated that long-term exercise induced an increase in both AMPK/ACC phosphorylation and alpha1-,alpha2-subunit mRNA/protein expression in the liver. Although the precise physiologic relevance of AMPK activation in these tissues remains unknown, it is possible that it might play an important role in long-term exercise-induced adaptation mechanisms and may lead to an improvement in certain metabolic abnormalities in metabolic diseases.

Expression of mRNAs for PACAP and its receptor in human neuroblastomas and their relationship to catecholamine synthesis.

PURPOSE: Pituitary adenylate cyclase-activating polypeptide (PACAP), a member of the secretin/glucagon/vasoactive intestinal peptide family, induces the expression of catecholamine-synthesizing enzymes in adrenal medullary cells. In addition, PACAP and its receptor have been detected in human neuroblastoma tissues and cell lines, though it is not yet known whether PACAP enhances the expression of genes encoding catecholamine-synthesizing enzymes. To address this question, we analyzed PACAP, PACAP receptor and tyrosine hydroxylase (TH) mRNAs in neuroblastomas. METHODS: The levels of mRNA for PACAP and vasoactive intestinal peptide (VIP), as well as their receptors and the mRNA for TH were measured by RT-PCR or real-time PCR analysis. RESULTS: VPAC1R mRNA was detected in all of 16 tissues and 3 cell lines that were examined, while VPAC2R mRNA was detected in 5 of 16 (31%) tissue and 2 of 3 cell lines. PAC1R mRNA was detected in 6 out of 16 (38%) tissues and none of 3 cell lines. mRNA expression of PACAP and TH were detected in many tissues (10/16 and 16/16, respectively). However, neither in tissues nor cell lines did PACAP mRNA expression correlate with TH mRNA expression. CONCLUSION: Our findings suggest that PACAP is not involved in the regulation of expression of TH in neuroblastomas.

Compound heterozygosity with two novel mutations in the HEXB gene produces adult Sandhoff disease presenting as a motor neuron disease phenotype.

Little information is available on molecular defects involved in adult Sandhoff disease presenting as motor neuron disease phenotype. We studied enzyme activities of beta-hexosaminidase (Hex) and the HEXB gene encoding the beta-subunit of Hex in a family of the Japanese case. Enzyme assay with 4-methylumbelliferyl-2-acetamido-2-deoxy-beta-D-glucopyranoside revealed a reduction in Hex A and B activity in proband's leukocytes. Although the activity of both in the mother were intermediate between those of controls and the proband, only Hex B reduction determined with heat inactivation was found in the father. Analysis of HEXB gene demonstrated two novel point mutations. The first mutation, IVS2-1G>A, was located at the 3'-splice acceptor site of intron 2 derived from the mother, causing exon 3 skipping. The resultant mRNA encoded a shorter beta-chain, which may not form an active enzyme. The second mutation was a G-to-A transition in exon 13 (c.1598G>A) derived from the father and resulted in arginine-to-histidine substitution at amino acid position 533 (R533H). Expression of R533H mutation in COS-1 cells demonstrated a lack of normal Hex activity, indicating that this mutation is pathological. Compound heterozygosity of these two mutations may trigger the development of adult Sandhoff disease with a motor neuron disease phenotype.

Adiponectin and adiponectin receptors in human pheochromocytoma.

AIM: Recent studies have demonstrated that serum adiponectin and its receptors in adipose and muscle tissues are suppressed in diabetic or obese individuals. Patients with pheochromocytoma are frequently diabetic. METHODS: Using real-time PCR, we examined mRNA expressions of adiponectin (Adp) and adiponectin receptor 1 (AdpR1) and AdpR2 in pheochromocytoma tissues from 49 patients. We also measured levels of serum total and high molecular weight (HMW) adiponectin levels in 10 pheochromocytomas and 33 normal volunteers. RESULTS: In pheochromocytoma tissue, AdpR1 mRNA expression was higher in adrenaline (A)-type tumors than in noradrenaline (NA)-type tumors. AdpR1 expression was significantly higher in A-type non-diabetics than in NA-type non-diabetics (p<0.05). AdpR1 mRNA expression was significantly associated with the tumor tissue adrenaline content (p<0.005) in linear regression analysis, which suggest that adrenaline positively regulates AdpR1 mRNA expression.Serum total and HMW Adp levels in patients with NA-type pheochromocytomas were approximately 3 times higher than those of healthy volunteers. After adrenalectomy, levels of adiponectin normalized. CONCLUSION: Our results indicate that serum total and HMW Adp, and AdpR1 gene expressions in pheochromocytoma tissue, are associated with the level of catecholamine produced in the tumor. It is tempting to speculate that catecholamine induces adiponectin production and signaling.