The mammalian CHORD-containing protein melusin is a stress response protein interacting with Hsp90 and Sgt1

Melusin is a mammalian muscle specific CHORD containing protein capable of activating signal transduction pathways leading to cardiomyocytes hypertrophy in response to mechanical stress. To define melusin function we searched for molecular partners possibly involved in melusin dependent signal transduction. Here we show that melusin and heat shock proteins are co-regulated. Moreover, melusin directly binds to Hsp90, a ubiquitous chaperone involved in regulating several signaling pathways. In addition, melusin interacts with Sgt1, an Hsp90 binding molecule. Melusin does not behave as an Hsp90 substrate but rather as a chaperone capable to protect citrate synthase from heat induced aggregation. These results describe melusin as a new component of the Hsp90 chaperone machinery.     

Association between copy-number variation on metabolic phenotypes and HDL-C levels in patients with polycystic ovary syndrome

Polygenic diseases with a broad phenotypic spectrum, such as polycystic ovary syndrome (PCOS), present a particular challenge in terms of identifying the underlying genetic mechanisms, nevertheless genetic variants have impact on the individual phenotype. We aimed to determine if next to genetic variations like SNPs further mechanisms might play a role in the pathogenesis of PCOS. We examined the effect of copy-number variations (CNVs) on metabolic phenotypes in PCOS. The intragenic rs1244979, rs2815752 in NEGR1 gene, and rs780094 in GCKR gene were genotyped and CNVs were determined by droplet digital polymerase chain reaction (ddPCR) in PCOS patients (n?=?153) and controls without metabolic syndrome (n?=?142). The study indicated that SNPs are not associated with the pathogenesis of PCOS but affect metabolic phenotypes. The CNVs investigated show a lower variability in PCOS than in CON. Furthermore, we provided direct evidence that the copy number, but not the genotype of the CNV in the genomic regions of rs780094(GCKR) is associated with low level of high-density lipoprotein cholesterol in PCOS. This study supports the hypothesis that not only genetic variants, but also CNVs in metabolically relevant genes, have an effect on metabolic phenotypes in our group of PCOS patients.     

Overexpression of prothymosin alpha predicts poor disease outcome in head and neck cancer

Background

In our recent study, tissue proteomic analysis of oral pre-malignant lesions (OPLs) and normal oral mucosa led to the identification of a panel of biomarkers, including prothymosin alpha (PTMA), to distinguish OPLs from histologically normal oral tissues. This study aimed to determine the clinical significance of PTMA overexpression in oral squamous cell hyperplasia, dysplasia and head and neck squamous cell carcinoma (HNSCC).

Methodology

Immunohistochemistry of PTMA protein was performed in HNSCCs (n = 100), squamous cell hyperplasia (n = 116), dysplasia (n = 50) and histologically normal oral tissues (n = 100). Statistical analysis was carried out to determine the association of PTMA overexpression with clinicopathological parameters and disease prognosis over 7 years for HNSCC patients.

Results

Our immunohistochemical analysis demonstrated significant overexpression of nuclear PTMA in squamous cell hyperplasia (63.8%), dysplasia (50%) and HNSCC (61%) in comparison with oral normal mucosa (p_trend<0.001). Chi-square analysis showed significant association of nuclear PTMA with advanced tumor stages (III+IV). Kaplan Meier survival analysis indicated reduced disease free survival (DFS) in HNSCC patients (p<0.001; median survival 11 months). Notably, Cox-multivariate analysis revealed nuclear PTMA as an independent predictor of poor prognosis of HNSCC patients (p<0.001, Hazard''s ratio, HR = 5.2, 95% CI = 2.3–11.8) in comparison with the histological grade, T-stage, nodal status and tumor stage.

Conclusions

Nuclear PTMA may serve as prognostic marker in HNSCC to determine the subset of patients that are likely to show recurrence of the disease.     

Variability of organ-specific gene expression in transgenic tobacco plants

Variability of expression of introduced marker genes was analysed in a large number of tobacco regenerants from anAgrobacterium-mediated transformation. In spite of standardization of sampling, considerable variation of GUS and NPTII expression was observed between individual transformants at different times of analysis and in different parts of the same plant. Organ-specificity of root versus leaf expression conferred by the par promoter from the haemoglobin gene ofParasponia andersonii in front of thegus gene showed a continuous spectrum. GUS expression in roots was found in 128 out of 140 plants; expression in leaves was found in 46 plants, and was always lower than in the corresponding roots. NPTII expression regulated by the nos promoter also showed a continuous spectrum. Expression levels were generally higher in roots than in leaves. Plants with high GUS expression in leaves showed high NPTII activity as well. A positive correlation between the level of NPTII expression and the numbers of integrated gene copies was noted. Chromosomal position effects and physiological determination are suggested as triggers for the variations. The transformed regenerated tobacco plants were largely comparable to clonal variants.     

Spectrophotometric and Molecular Properties of Mutated Rice Phytochrome A

A cDNA (PHYA) for the phytochrome A apoprotein (PHYA) of riceand three mutated sequences (phyA S/A, the first ten serineresidues in the N-terminal domain of PHYA were changed to alanineresidues; phyA ND, the first 80 N-terminal amino acids weredeleted; phyA CD, the amino acids of the C-terminal domain from689 to 1,128 were deleted) were expressed in yeast, and thewild-type and mutant apophytochromes were allowed to combinein vitro with the chromophore phycocyanobilin (PCB). The PCB-attachedproduct of phyA S/A gave very similar spectrophotometric peaksto the PhA_fr and PhyA_fr forms of wild-type product. By contrast,the peak of the product of phyA CD in the P_fr form was significantlyshifted towards a shorter wavelength, an indication that, whereasthe C-terminal domain is not crucial for the PCB attachment,it greatly influences the absorption maximum of PhyA_fr. Therate of 50% reversion from PhyA_fr to PhA_r in darkness was 3h at 27°C with all of the samples, showing that the S/Aand CD mutations did not affect this property. No photoreversibilitywas detected with the product of phyA ND. Gel-filtration analysisof the wild-type PHYA and the product of phyA S/A showed thatthe apparent molecular mass of each was 330 kDa, suggestingthat both exists as dimers in solution. ⁴Present address: Institut für Entwicklungs- und Molekularbiologieder Pflanzen, Heinrich-Heine-Universität-Düsseldorf,Universitätsstr. 1, 40225 Düsseldorf, Germany