131 research outputs found
A Ras GTPase associated protein is involved in the phototropic and circadian photobiology responses in fungi
Light is an environmental signal perceived by most eukaryotic organisms and that can have major impacts on their growth and development. The MadC protein in the fungus Phycomyces blakesleeanus (Mucoromycotina) has been postulated to form part of the photosensory input for phototropism of the fruiting body sporangiophores, but the madC gene has remained unidentified since the 1960s when madC mutants were first isolated. In this study the madC gene was identified by positional cloning. All madC mutant strains contain loss-of-function point mutations within a gene predicted to encode a GTPase activating protein (GAP) for Ras. The madC gene complements the Saccharomyces cerevisiae Ras-GAP ira1 mutant and the encoded MadC protein interacts with P. blakesleeanus Ras homologs in yeast two-hybrid assays, indicating that MadC is a regulator of Ras signaling. Deletion of the homolog in the filamentous ascomycete Neurospora crassa affects the circadian clock output, yielding a pattern of asexual conidiation similar to a ras-1 mutant that is used in circadian studies in N. crassa. Thus, MadC is unlikely to be a photosensor, yet is a fundamental link in the photoresponses from blue light perceived by the conserved White Collar complex with Ras signaling in two distantly-related filamentous fungal species
E-cadherin expression is associated with somatostatin analogue response in acromegaly
Acromegaly is a rare disease resulting from hypersecretion of growth hormone (GH)
and insulin‐like growth factor 1 (IGF1) typically caused by pituitary adenomas, which
is associated with increased mortality and morbidity. Somatostatin analogues (SSAs)
represent the primary medical therapy for acromegaly and are currently used as
first‐line treatment or as second‐line therapy after unsuccessful pituitary surgery.
However, a considerable proportion of patients do not adequately respond to SSAs
treatment, and therefore, there is an urgent need to identify biomarkers predictors
of response to SSAs. The aim of this study was to examine E‐cadherin expression
by immunohistochemistry in fifty‐five GH‐producing pituitary tumours and determine
the potential association with response to SSAs as well as other clinical and
histopathological features. Acromegaly patients with tumours expressing low E‐cadherin
levels exhibit a worse response to SSAs. E‐cadherin levels are associated with
GH‐producing tumour histological subtypes. Our results indicate that the immunohistochemical
detection of E‐cadherin might be useful in categorizing acromegaly
patients based on the response to SSAs.ISCIII‐Subdirección General de Evaluación y Fomento de la Investigación PI13/02043 PI16/00175FEDER PI13/02043 PI16/00175Junta de Andalucía A‐0023‐2015 A‐0003‐2016 CTS‐1406 BIO‐0139Andalusian Ministry of Health C‐0015‐2014CIBERobn PI13/ 02043 PI16/0017
Binding site plasticity in viral PPxY Late domain recognition by the third WW domain of human NEDD4
The recognition of PPxY viral Late domains by the third WW domain of the HECT-E3 ubiquitin ligase
NEDD4 (hNEDD4-WW3) is essential for the completion of the budding process of numerous enveloped
viruses, including Ebola, Marburg, HTLV1 or Rabies. hNEDD4-WW3 has been validated as a promising
target for the development of novel host-oriented broad spectrum antivirals. Nonetheless, finding
inhibitors with good properties as therapeutic agents remains a challenge since the key determinants
of binding affinity and specificity are still poorly understood. We present here a detailed structural
and thermodynamic study of the interactions of hNEDD4-WW3 with viral Late domains combining
isothermal titration calorimetry, NMR structural determination and molecular dynamics simulations.
Structural and energetic differences in Late domain recognition reveal a highly plastic hNEDD4-WW3
binding site that can accommodate PPxY-containing ligands with varying orientations. These
orientations are mostly determined by specific conformations adopted by residues I859 and T866.
Our results suggest a conformational selection mechanism, extensive to other WW domains, and
highlight the functional relevance of hNEDD4-WW3 domain conformational flexibility at the binding
interface, which emerges as a key element to consider in the search for potent and selective inhibitors of
therapeutic interest.This research has been financed by grants BIO2009-13261-C02, BIO2012-39922-CO2 and
BIO2016-78746-C2-1-R from the Spanish Ministry of Education and Science (I.L.) including AEI/FEDER
EU funds, by CTQ2017-83810-R grant (F.J.B) and by BFU2014-53787-P, the IRB Barcelona and the BBVA
Foundation (M.J.M)
A Ras GTPase associated protein is involved in the phototropic and circadian photobiology responses in fungi
[EN] Light is an environmental signal perceived by most eukaryotic organisms and that can have major impacts on their growth and development. The MadC protein in the fungus Phycomyces blakesleeanus (Mucoromycotina) has been postulated to form part of the photosensory input for phototropism of the fruiting body sporangiophores, but the madC gene has remained unidentified since the 1960s when madC mutants were first isolated. In this study the madC gene was identified by positional cloning. All madC mutant strains contain loss-of-function point mutations within a gene predicted to encode a GTPase activating protein (GAP) for Ras. The madC gene complements the Saccharomyces cerevisiae Ras-GAP ira1 mutant and the encoded MadC protein interacts with P. blakesleeanus Ras homologs in yeast two-hybrid assays, indicating that MadC is a regulator of Ras signaling. Deletion of the homolog in the filamentous ascomycete Neurospora crassa affects the circadian clock output, yielding a pattern of asexual conidiation similar to a ras-1 mutant that is used in circadian studies in N. crassa. Thus, MadC is unlikely to be a photosensor, yet is a fundamental link in the photoresponses from blue light perceived by the conserved White Collar complex with Ras signaling in two distantly-related filamentous fungal species
Downregulation of epidermal growth factor receptor in hepatocellular carcinoma facilitates transforming growth factor-β-induced epithelial to amoeboid transition
The Epidermal Growth Factor Receptor (EGFR) and the Transforming Growth Factor-beta (TGF-β) are key regulators of hepatocarcinogenesis. Targeting EGFR was proposed as a promising therapy; however, poor success was obtained in human hepatocellular carcinoma (HCC) clinical trials. Here, we describe how EGFR is frequently downregulated in HCC patients while TGF-β is upregulated. Using 2D/3D cellular models, we show that after EGFR loss, TGF-β is more efficient in its pro-migratory and invasive effects, inducing epithelial to amoeboid transition. EGFR knock-down promotes loss of cell-cell and cell-to-matrix adhesion, favouring TGF-β-induced actomyosin contractility and acquisition of an amoeboid migratory phenotype. Moreover, TGF-β upregulates RHOC and CDC42 after EGFR silencing, promoting Myosin II in amoeboid cells. Importantly, low EGFR combined with high TGFB1 or RHOC/CDC42 levels confer poor patient prognosis. In conclusion, this work reveals a new tumour suppressor function for EGFR counteracting TGF-β-mediated epithelial to amoeboid transitions in HCC, supporting a rational for targeting the TGF-β pathway in patients with low EGFR expression. Our work also highlights the relevance of epithelial to amoeboid transition in human tumours and the need to better target this process in the clinic
XTEND: Extending the depth of field in cryo soft X-ray tomography
We have developed a new data collection method and processing framework in full field cryo soft X-ray tomography to computationally extend the depth of field (DOF) of a Fresnel zone plate lens. Structural features of 3D-reconstructed eukaryotic cells that are affected by DOF artifacts in standard reconstruction are now recovered. This approach, based on focal series projections, is easily applicable with closed expressions to select specific data acquisition parameters.This work was partially supported by MINECO grants BFU2014-54181 to JLC and AIC-A-2011-0638, BIO2013-44647-R and BIO2016-76400-R to JMC, Madrid. Regional government grants S2013/MIT-2850 to JLC and S2010/BMD-2305 to JMC, National Science Foundation grant DMS-1114901 to GTH, the European Union through BioStruct-X Project 283570 and Horizon 2020 through grant iNEXT (INFRAIA-1-2014-2015, Proposal: 653706).S
Progressive and Simultaneous Right and Left Atrial Remodeling Uncovered by a Comprehensive Magnetic Resonance Assessment in Atrial Fibrillation
Background Left atrial structural remodeling contributes to the arrhythmogenic substrate of atrial fibrillation (AF), but the role of the right atrium (RA) remains unknown. Our aims were to comprehensively characterize right atrial structural remodeling in AF and identify right atrial parameters predicting recurrences after ablation. Methods and Results A 3.0 T late gadolinium enhanced-cardiac magnetic resonance was obtained in 109 individuals (9 healthy volunteers, 100 patients with AF undergoing ablation). Right and left atrial volume, surface, and sphericity were quantified. Right atrial global and regional fibrosis burden was assessed with validated thresholds. Patients with AF were systematically followed after ablation for recurrences. Progressive right atrial dilation and an increase in sphericity were observed from healthy volunteers to patients with paroxysmal and persistent AF; fibrosis was similar among the groups. The correlation between parameters recapitulating right atrial remodeling was mild. Subsequently, remodeling in both atria was compared. The RA was larger than the left atrium (LA) in all groups. Fibrosis burden was higher in the LA than in the RA of patients with AF, whereas sphericity was higher in the LA of patients with persistent AF only. Fibrosis, volume, and surface of the RA and LA, but not sphericity, were strongly correlated. Tricuspid regurgitation predicted right atrial volume and shape, whereas diabetes was associated with right atrial fibrosis burden; sex and persistent AF also predicted right atrial volume. Fibrosis in the RA was mostly located in the inferior vena cava-RA junction. Only right atrial sphericity is significantly associated with AF recurrences after ablation (hazard ratio, 1.12 [95% CI, 1.01-1.25]). Conclusions AF progression associates with right atrial remodeling in parallel with the LA. Right atrial sphericity yields prognostic significance after ablation
Splicing Machinery is Dysregulated in Pituitary Neuroendocrine Tumors and is Associated with Aggressiveness Features
Pituitary neuroendocrine tumors (PitNETs) constitute approximately 15% of all brain tumors, and most have a sporadic origin. Recent studies suggest that altered alternative splicing and, consequently, appearance of aberrant splicing variants, is a common feature of most tumor pathologies. Moreover, spliceosome is considered an attractive therapeutic target in tumor pathologies, and the inhibition of SF3B1 (e.g., using pladienolide-B) has been shown to exert antitumor effects. Therefore, we aimed to analyze the expression levels of selected splicing-machinery components in 261 PitNETs (somatotropinomas/non-functioning PitNETS/corticotropinomas/prolactinomas) and evaluated the direct effects of pladienolide-B in cell proliferation/viability/hormone secretion in human PitNETs cell cultures and pituitary cell lines (AtT-20/GH3). Results revealed a severe dysregulation of splicing-machinery components in all the PitNET subtypes compared to normal pituitaries and a unique fingerprint of splicing-machinery components that accurately discriminate between normal and tumor tissue in each PitNET subtype. Moreover, expression of specific components was associated with key clinical parameters. Interestingly, certain components were commonly dysregulated throughout all PitNET subtypes. Finally, pladienolide-B reduced cell proliferation/viability/hormone secretion in PitNET cell cultures and cell lines. Altogether, our data demonstrate a drastic dysregulation of the splicing-machinery in PitNETs that might be associated to their tumorigenesis, paving the way to explore the use of specific splicing-machinery components as novel diagnostic/prognostic and therapeutic targets in PitNETs
In1-ghrelin splicing variant is overexpressed in pituitary adenomas and increases their aggressive features
Pituitary adenomas comprise a heterogeneous subset of pathologies causing serious comorbidities, which
would benefit from identification of novel, common molecular/cellular biomarkers and therapeutic targets.
The ghrelin system has been linked to development of certain endocrine-related cancers. Systematic analysis
of the presence and functional implications of some components of the ghrelin system, including native
ghrelin, receptors and the recently discovered splicing variant In1-ghrelin, in human normal pituitaries (n
5 11) and pituitary adenomas (n 5 169) revealed that expression pattern of ghrelin system suffers a clear
alteration in pituitary adenomasas comparedwith normal pituitary, where In1-ghrelin is markedly
overexpressed. Interestingly, in cultured pituitary adenoma cells In1-ghrelin treatment (acylated peptides at
100 nM; 24–72 h) increasedGHandACTHsecretion, Ca21 and ERK1/2 signaling and cell viability, whereas
In1-ghrelin silencing (using a specific siRNA; 100 nM) reduced cell viability. These results indicate that an
alteration of the ghrelin system, specially its In1-ghrelin variant, could contribute to pathogenesis of
different pituitary adenomas types, and suggest that this variant and its related ghrelin system could provide
new tools to identify novel, more general diagnostic, prognostic and potential therapeutic targets in
pituitary tumors
HLA-DRB1 association with Henoch-Schonlein purpura
Objective: Henoch-Schönlein purpura (HSP) is the most common vasculitis in children but it is not exceptional in adults. Increased familial occurrence supports a genetic predisposition for HSP. In this context, an association with the human leukocyte antigen-HLA-DRB1*01 phenotype has been suggested in Caucasian individuals with HSP. However, data on the potential association of HSP with HLA-DRB1*01 were based on small case series. To further investigate this issue, we performed HLA-DRB1 genotyping of the largest series of HSP patients ever assessed for genetic studies in Caucasians. Methods: 342 Spanish patients diagnosed with HSP fulfilling the American College of Rheumatology and the Michel et al classification criteria, and 303 sex and ethnically matched controls were assessed. HLA-DRB1 alleles were determined using a PCR-Sequence-Specific-Oligonucleotide Probe (PCR-SSOP) method. Results: A statistically significant increase of HLA-DRB1*01 in HSP patients when compared with controls was found (43% vs 7%, respectively; p<0.001; odds ratio-OR=2.03 [1.43-2.87]). It was due to the increased frequency of HLA-DRB1*0103 phenotype in HSP (14% vs 2%; p<0.001; OR=8.27 [3.46-23.9]). These results remained statistically significant after adjusting for Bonferroni correction. In contrast, a statistically significant decreased frequency of the HLA-DRB1*0301 phenotype was observed in patients compared to controls (5.6% vs 18.1%, respectively; p<0.001, OR=0.26 [0.14-0.47]), even after adjustment for Bonferroni correction. No HLA-DRB1 association with specific features of the disease was found. Conclusion: Our study confirms an association of HSP with HLA-DRB1*01 in Caucasians. Also, a protective effect against the development of HSP appears to exist in Caucasians carrying the HLA-DRB1*03 phenotype
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