Cytostatic Activity of Adenosine Triphosphate-Competitive Kinase Inhibitors in<i>BRAF</i>Mutant Thyroid Carcinoma Cells

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Coexistence of Ammonium Transporter and Channel Mechanisms in Amt-Mep-Rh Twin-His Variants Impairs the Filamentation Signaling Capacity of Fungal Mep2 Transceptors

Ammonium translocation through biological membranes, by the ubiquitous Amt-Mep-Rh family of transporters, plays a key role in all domains of life. Two highly conserved histidine residues protrude into the lumen of the pore of these transporters, forming the family's characteristic Twin-His motif. It has been hypothesized that the motif is essential to confer the selectivity of the transport mechanism. Here, using a combination of in vitro electrophysiology on Escherichia coli AmtB, in silico molecular dynamics simulations, and in vivo yeast functional complementation assays, we demonstrate that variations in the Twin- His motif trigger a mechanistic switch between a specific transporter, depending on ammonium deprotonation, to an unspecific ion channel activity. We therefore propose that there is no selective filter that governs specificity in Amt-Mep-Rh transporters, but the inherent mechanism of translocation, dependent on the fragmentation of the substrate, ensures the high specificity of the translocation. We show that coexistence of both mechanisms in single Twin-His variants of yeast Mep2 transceptors disrupts the signaling function and so impairs fungal filamentation. These data support a signaling process driven by the transport mechanism of the fungal Mep2 transceptors

A two-lane mechanism for selective biological ammonium transport

The transport of charged molecules across biological membranes faces the dual problem of accommodating charges in a highly hydrophobic environment while maintaining selective substrate translocation. This has been the subject of a particular controversy for the exchange of ammonium across cellular membranes, an essential process in all domains of life. Ammonium transport is mediated by the ubiquitous Amt/Mep/Rh transporters that includes the human Rhesus factors. Here, using a combination of electrophysiology, yeast functional complementation and extended molecular dynamics simulations, we reveal a unique two-lane pathway for electrogenic NH4+ transport in two archetypal members of the family, the transporters AmtB from Escherichia coli and Rh50 from Nitrosomonas europaea. The pathway underpins a mechanism by which charged H+ and neutral NH3 are carried separately across the membrane after NH4+ deprotonation. This mechanism defines a new principle of achieving transport selectivity against competing ions in a biological transport process

A Comparison of Methods to Harmonize Cortical Thickness Measurements Across Scanners and Sites

Results of neuroimaging datasets aggregated from multiple sites may be biased by site-specific profiles in participants’ demographic and clinical characteristics, as well as MRI acquisition protocols and scanning platforms. We compared the impact of four different harmonization methods on results obtained from analyses of cortical thickness data: (1) linear mixed-effects model (LME) that models site-specific random intercepts (LME INT), (2) LME that models both site-specific random intercepts and age-related random slopes (LME INT+SLP), (3) ComBat, and (4) ComBat with a generalized additive model (ComBat-GAM). Our test case for comparing harmonization methods was cortical thickness data aggregated from 29 sites, which included 1,340 cases with posttraumatic stress disorder (PTSD) (6.2–81.8 years old) and 2,057 trauma-exposed controls without PTSD (6.3–85.2 years old). We found that, compared to the other data harmonization methods, data processed with ComBat-GAM was more sensitive to the detection of significant case-control differences (Χ 2(3) = 63.704, p < 0.001) as well as case-control differences in age-related cortical thinning (Χ 2(3) = 12.082, p = 0.007). Both ComBat and ComBat-GAM outperformed LME methods in detecting sex differences (Χ 2(3) = 9.114, p = 0.028) in regional cortical thickness. ComBat-GAM also led to stronger estimates of age-related declines in cortical thickness (corrected p-values < 0.001), stronger estimates of case-related cortical thickness reduction (corrected p-values < 0.001), weaker estimates of age-related declines in cortical thickness in cases than controls (corrected p-values < 0.001), stronger estimates of cortical thickness reduction in females than males (corrected p-values < 0.001), and stronger estimates of cortical thickness reduction in females relative to males in cases than controls (corrected p-values < 0.001). Our results support the use of ComBat-GAM to minimize confounds and increase statistical power when harmonizing data with non-linear effects, and the use of either ComBat or ComBat-GAM for harmonizing data with linear effects

Global urban environmental change drives adaptation in white clover

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

RET-mediated CD44 proteolysis promotes autonomous proliferation of thyroid cells

This dissertation addresses signaling mechanisms involved in thyroid carcinoma formation, with a view of identifying novel levels for therapeutic intervention. In this frame, appended manuscripts II, III and IV focus on the functional characterization of a novel BRAF mutation and on molecular targeting of RET or BRAF pathways in thyroid cancer. The main body of the dissertation describes a novel signaling mechanism that we have identified in thyroid carcinomas harboring BRAF or RET/PTC oncogenes and that involves CD44. CD44, a cell surface adhesion molecule overexpressed in a wide range of cancer types, undergoes sequential proteolytic cleavage at the extracellular and intramembrane domains. This results in the shedding of the ectodomain (ectoCD44) and in the intracellular release of an intracellular fragment (CD44-ICD). CD44-ICD is translocated to the nucleus and activates gene transcription. Our group has previously demonstrated that CD44 is overexpressed in papillary thyroid carcinoma (PTC) tissue samples and in cell lines harboring RET/PTC or BRAF oncogenes. Here, we show that RET/PTC signaling induces γ-secretase-dependent CD44 proteolysis through the ERK pathway. Chemical blockade of either RET/PTC or MEK abrogates CD44 cleavage. Adoptive overexpression of CD44-ICD stimulates TSH-independent proliferation of thyroid follicular PC cells. CD44-ICD binds to CREB and stimulates CREB-mediated transcription in PC cells by potentiating CREB S133 phosphorylation. Through this mechanism, CD44-ICD up-regulates cyclin D1 expression and proliferation of thyroid cells. Taken together, these findings suggest that ERK kinase pathway-mediated CD44 cleavage sustains proliferation of thyrocytes harboring RET/PTC, RAS or BRAF oncogenes. This novel pathway may provide new molecular targets for therapeutic intervention in thyroid carcinoma

Road Map per un approccio integrato alla problematica ambientale del Porto di Napoli

Il presente documento ha lo scopo di fornire un approccio integrato allo sviluppo delle conoscenze di innovazioni di processi e di sviluppo tecnologico volti a definire il perimetro delle aree SIN a mare nell’ambito delle competenze dell’Autorità Portuale di Napoli, le modalità operative da adottare progressivamente per la risoluzione delle diverse problematiche legate all’escavo dei fondali, le soluzioni innovative in grado di ridurre costi e tempi di intervento nella piena compatibilità delle normative nazionali e comunitarie di riferimento in materia ambientale anche attraverso lo sviluppo di eventuali interventi e progetti pilota. Inoltre, obiettivo primario di questa relazione è l’identificazione dei più adeguati approcci al dragaggio dei sedimenti contaminati del porto di Napoli e alla loro gestione ambientale, nei termini, da un lato di un appropriato confinamento e stoccaggio in sicurezza degli stessi e dall’altro di un attenta gestione in relazione ad eventuali effetti sull’ecosistema marino e la salute della popolazione residente nelle aree limitrofe

Mechanisms of resistance to chemotherapeutic and anti-angiogenic drugs as novel targets for pancreatic cancer therapy

Pancreatic cancer remains one of the most lethal and poorly understood human malignancies and will continue to be a major unsolved health problem in the 21(st) century. Despite efforts over the past three decades to improve diagnosis and treatment, the prognosis for patients with pancreatic cancer is extremely poor with or without treatment, and incidence rates are virtually identical to mortality rates. Although advances have been made through the identification of relevant molecular pathways in pancreatic cancer, there is still a critical, unmet need for the translation of these findings into effective therapeutic strategies that could reduce the intrinsic drug resistance of this disease and for the integration of these molecularly targeted agents into established combination chemotherapy and radiotherapy regimens in order to improve patients' survival. Tumors are heterogeneous cellular entities whose growth and progression depend on reciprocal interactions between genetically altered neoplastic cells and a non-neoplastic microenvironment. To date, most of the mechanisms of resistance studied have been related to tumor cell-autonomous signaling pathways. However, recent data suggest a putative important role of tumor microenvironment in the development and maintenance of resistance to classic chemotherapeutic and targeted therapies. This present review is meant to describe and discuss some of the most important advances in the comprehension of the tumor cell-autonomous and tumor microenvironment-related molecular mechanisms responsible for the resistance of pancreatic cancer to the proapoptotic activity of the classic chemotherapeutic agents and to the most novel anti-angiogenic drugs. We present some of the emerging therapeutic targets for the modulation of this resistant phenotype

La ricerca universitaria in Medicina del Lavoro in Italia dal 1998 al 2007.

Studio statistico delle pubblicazioni su riviste peer review su temi di medicina del lavoro nell'ultimo decennio