ARMC5 mutations are associated with high levels of proliferating cell nuclear antigen and the presence of the serotonin receptor 5HT4R in PMAH nodules

ABSTRACT Objective To analyze the morphological and functional characteristics of primary macronodular adrenal hyperplasia (PMAH) nodules carrying or not carrying ARMC5 mutations and the consequences of the presence of mutations in terms of the pattern of macronodule composition and functional state. Subjects and methods The analyses were performed by hematoxylin-eosin staining, immunohistochemistry, microdissection of spongiocyte tissue and RT-qPCR of histological sections from 16 patients diagnosed with PMAH with germline (5) or germline/somatic mutations (5) and without mutations (6) in the ARMC5 gene. Results Hyperplastic nodules were predominantly composed of spongiocytes in mutated and nonmutated sections. ARMC5 mRNA expression in spongiocytes was higher in ARMC5-mutated nodules than in ARMC5-nonmutated nodules, and homogenous ARMC5 protein distribution was observed. The presence of arginine-vasopressin receptor (AVP1AR) and ectopic ACTH production were observed in both cell populations regardless of ARMC5 mutations; the numbers of serotonin receptor (5HT4R)- and proliferating cell nuclear antigen (PCNA)-positive cells were higher in macronodules carrying ARMC5 mutations than in those without mutations. Conclusions Our results suggest that the presence of ARMC5 mutations does not interfere with the pattern of distribution of spongiocytes and compact cells or with the presence of AVP1AR, gastric-inhibitory polypeptide receptor (GIPR) and ectopic ACTH. Nevertheless, the higher numbers of PCNA-positive cells in mutated nodules than in nonmutated nodules suggest that mutated ARMC5 can be related to higher proliferation rates in these cells. In conclusion, our results provide more information about the crosstalk among abnormal GPCRs, ectopic ACTH in steroidogenesis and the ARMC5 gene, which may be relevant in understanding the pathogenesis and diagnosis of patients with PMAH.

Cullin4B/E3-ubiquitin ligase negatively regulates beta-catenin.

Beta-catenin is the key transducer of Wingless-type MMTV integration site family member (Wnt) signalling, upregulation of which is the cause of cancer of the colon and other tissues. In the absence of Wnt signals, beta-catenin is targeted to ubiquitin-proteasome-mediated degradation. Here we present the functional characterization of E3-ubiquitin ligase encoded by cul4B. RNAi-mediated knock-down of Cul4B in a mouse cell line C3H T10 (1/2) results in an increase in beta-catenin levels. Loss-of-function mutation in Drosophila cul4 also shows increased beta-catenin/Armadillo levels in developing embryos and displays a characteristic naked-cuticle phenotype. Immunoprecipitation experiments suggest that Cul4B and beta-catenin are part of a signal complex in Drosophila, mouse and human. These preliminary results suggest a conserved role for Cul4B in the regulation of beta-catenin levels.

Searching for a schizophrenia susceptibility gene in the 22q11 region / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate a genetic association for schizophrenia within chromosome 22q11 in a Chinese Han population.</p><p><b>METHODS</b>The PCR-based restriction fragment length polymorphism (PCR-RFLP) analysis was used to detect three single nucleotide polymorphisms (SNPs), rs165655 (A/G base change) and rs165815 (C/T base change) present in the ARVCF (armadillo repeat gene deletion in velocardiofacial syndrome) locus, and rs756656 (A/C base change) in the LOC128979 (expressed sequence tags, EST) locus, among 100 Chinese family trios consisting of fathers, mothers and affected offspring with schizophrenia. Genotype data were analyzed by using linkage disequilibrium (LD) methods including haplotype relative risk (HRR) analysis, transmission disequilibrium test (TDT) and haplotype transmission analysis.</p><p><b>RESULTS</b>The genotype frequency distributions of three SNPs were all in Hardy-Weinberg equilibrium (P>0.05). Both the HRR and the TDT analysis showed that rs165815 was associated with schizophrenia (chi2=6.447, df=1, P=0.011 and chi2=6.313, df=1, P=0.012, respectively), whereas the other two SNPs did not show any allelic association. The haplotype transmission analysis showed a biased transmission for the rs165655-rs165815 haplotype system (chi2=17.224, df=3, P=0.0006) and for the rs756656-rs165655-rs165815 hapoltype system (chi2=20.965, df=7, P=0.0038).</p><p><b>CONCLUSION</b>Either the ARVCF gene itself or a nearby locus may confer susceptibility to schizophrenia in a Chinese Han population.</p>