scholarly journals Functional characterization of a novel truncating mutation in Lamin A/C gene in a family with a severe cardiomyopathy with conduction defects

2018 ◽  
Vol 103-105 ◽  
pp. 57
Author(s):  
A. Gerbino ◽  
I. Bottillo ◽  
S. Milano ◽  
R. De Zio ◽  
G. Procino ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Lamin A ◽  
Truncating Mutation

scholarly journals Clinical Features of LMNA-Related Cardiomyopathy in 18 Patients and Characterization of Two Novel Variants

2021 ◽  
Vol 10 (21) ◽  
pp. 5075
Author(s):  
Valentina Ferradini ◽  
Joseph Cosma ◽  
Fabiana Romeo ◽  
Claudia De Masi ◽  
Michela Murdocca ◽  
...  
Keyword(s):  
Heart Disease ◽  
Functional Characterization ◽  
Clinical Manifestations ◽  
Structural Heart Disease ◽  
Left Ventricular ◽  
Dermal Fibroblasts ◽  
Lamin A ◽  
Lmna Gene

Dilated cardiomyopathy (DCM) refers to a spectrum of heterogeneous myocardial disorders characterized by ventricular dilation and depressed myocardial performance in the absence of hypertension, valvular, congenital, or ischemic heart disease. Mutations in LMNA gene, encoding for lamin A/C, account for 10% of familial DCM. LMNA-related cardiomyopathies are characterized by heterogeneous clinical manifestations that vary from a predominantly structural heart disease, mainly mild-to-moderate left ventricular (LV) dilatation associated or not with conduction system abnormalities, to highly pro-arrhythmic profiles where sudden cardiac death (SCD) occurs as the first manifestation of disease in an apparently normal heart. In the present study, we select, among 77 DCM families referred to our center for genetic counselling and molecular screening, 15 patient heterozygotes for LMNA variants. Segregation analysis in the relatives evidences other eight heterozygous patients. A genotype–phenotype correlation has been performed for symptomatic subjects. Lastly, we perform in vitro functional characterization of two novel LMNA variants using dermal fibroblasts obtained from three heterozygous patients, evidencing significant differences in terms of lamin expression and nuclear morphology. Due to the high risk of SCD that characterizes patients with lamin A/C cardiomyopathy, genetic testing for LMNA gene variants is highly recommended when there is suspicion of laminopathy.

scholarly journals Functional Characterization of a Novel Truncating Mutation in Lamin A/C Gene in a Family with a Severe Cardiomyopathy with Conduction Defects

2017 ◽  
Vol 44 (4) ◽  
pp. 1559-1577 ◽  
Author(s):  
Andrea Gerbino ◽  
Irene Bottillo ◽  
Serena Milano ◽  
Martina Lipari ◽  
Roberta De Zio ◽  
...  
Keyword(s):  
Connexin 43 ◽  
Cellular Localization ◽  
Laser Scanning ◽  
Molecular Mechanisms ◽  
Single Cells ◽  
Functional Characterization ◽  
Hek293 Cells ◽  
Lamin A ◽  
Cx43 Expression ◽  
Truncating Mutation

Background/Aims: Truncating LMNA gene mutations occur in many inherited cardiomyopathy cases, but the molecular mechanisms involved in the disease they cause have not yet been systematically investigated. Here, we studied a novel frameshift LMNA variant (p.D243Gfs*4) identified in three members of an Italian family co-segregating with a severe form of cardiomyopathy with conduction defects. Methods: HEK293 cells and HL-1 cardiomyocytes were transiently transfected with either Lamin A or D243Gfs*4 tagged with GFP (or mCherry). D243Gfs*4 expression, cellular localization and its effects on diverse cellular mechanisms were evaluated with western blotting, laser-scanning confocal microscopy and video-imaging analysis in single cells. Results: When expressed in HEK293 cells, GFP- (or mCherry)-tagged LMNA D243Gfs*4 colocalized with calnexin within the ER. ER mislocalization of LMNA D243Gfs*4 did not significantly induce ER stress response, abnormal Ca2+ handling and apoptosis when compared with HEK293 cells expressing another truncated mutant of LMNA (R321X) which similarly accumulates within the ER. Of note, HEK293-LMNA D243Gfs*4 cells showed a significant reduction of connexin 43 (CX43) expression level, which was completely rescued by activation of the WNT/β-catenin signaling pathway. When expressed in HL-1 cardiomyocytes, D243Gfs*4 significantly impaired the spontaneous Ca2+ oscillations recorded in these cells as result of propagation of the depolarizing waves through the gap junctions between non-transfected cells surrounding a cell harboring the mutation. Furthermore, mCh-D243Gfs*4 HL-1 cardiomyocytes showed reduced CX43-dependent Lucifer Yellow (LY) loading and propagation. Of note, activation of β-catenin rescued both LY loading and LMNA D243Gfs*4 -HL-1 cells spontaneous activity propagation. Conclusion: Overall, the present results clearly indicate the involvement of the aberrant CX43 expression/activity as a pathogenic mechanism for the conduction defects associated to this LMNA truncating alteration.

scholarly journals Clinical and Functional Characterization of a Novel Mutation in Lamin A/C Gene in a Multigenerational Family with Arrhythmogenic Cardiac Laminopathy

PLoS ONE ◽  
2015 ◽  
Vol 10 (4) ◽  
pp. e0121723 ◽  
Author(s):  
Cinzia Forleo ◽  
Monica Carmosino ◽  
Nicoletta Resta ◽  
Alessandra Rampazzo ◽  
Rosanna Valecce ◽  
...  
Keyword(s):  
Novel Mutation ◽  
Functional Characterization ◽  
Lamin A ◽  
Multigenerational Family

scholarly journals Functional Characterization of KCNMA1 mutation associated with dyskinesia, seizure, developmental delay, and cerebellar atrophy

2021 ◽  
Author(s):  
Emrah Yucesan ◽  
Beyza Goncu ◽  
Cemil Ozgul ◽  
Arda Kebapci ◽  
Ayca Dilruba Aslanger ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Cerebellar Atrophy ◽  
Bk Channels ◽  
Bk Channel ◽  
Functional Study ◽  
Loss Of Function ◽  
Gain Of Function ◽  
Α Subunit ◽  
Truncating Mutation

Abstract KCNMA1 located on chromosome 10q22.3, encodes the pore-forming α subunit of the “Big K+” (BK) large conductance calcium and voltage-activated K + channel. BK channels are widely distributed across tissues, including both excitable and non excitable cells. Numerous evidence suggests the functional BK channel alterations produced by different KCNMA1 alleles may associate with different symptoms, such as paroxysmal non kinesigenic dyskinesia with gain of function and ataxia with loss of function. Functional classifications revealed two major patterns, gain of function and loss of function effects on channel properties in different cell lines. In the literature, two mutations have been shown to confer gain of function properties to BK channels: D434G and N995S. On the other hand 10 mutations have been classified as loss of function (S351Y,G354S, G356R, G375R, C413Y/N449fs, I663V, P805L, and D984N) or putative loss of function (premature truncation mutations: Y676Lfs*7 and Arg458Ter). In this study, we report the functional characterization of a variant which was previously reported the whole exome sequencing revealed bi-allelic nonsense variation (NM_001161352.1 (ENST00000286628.8):c.1372C > T; Arg458*) of the cytoplasmic domain of calcium-activated potassium channel subunit alpha-1 protein. To detect functional consequences of the variation immunostaining and electrophysiological studies were conducted. In this study, we conducted patch-clamp recordings on WT and R458X mutant cells. We found the gain of function effect for the mutation. This is the first functional study observing an increased current in the KCNMA1 gene resulting from a truncating mutation

Functional characterization of human brown adipose tissue metabolism

2020 ◽  
Vol 477 (7) ◽  
pp. 1261-1286 ◽  
Author(s):  
Marie Anne Richard ◽  
Hannah Pallubinsky ◽  
Denis P. Blondin
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Functional Characterization ◽  
Human Infants ◽  
Positron Emission ◽  
Brown Adipose ◽  
Treatment Of Obesity ◽  
And Function

Brown adipose tissue (BAT) has long been described according to its histological features as a multilocular, lipid-containing tissue, light brown in color, that is also responsive to the cold and found especially in hibernating mammals and human infants. Its presence in both hibernators and human infants, combined with its function as a heat-generating organ, raised many questions about its role in humans. Early characterizations of the tissue in humans focused on its progressive atrophy with age and its apparent importance for cold-exposed workers. However, the use of positron emission tomography (PET) with the glucose tracer [18F]fluorodeoxyglucose ([18F]FDG) made it possible to begin characterizing the possible function of BAT in adult humans, and whether it could play a role in the prevention or treatment of obesity and type 2 diabetes (T2D). This review focuses on the in vivo functional characterization of human BAT, the methodological approaches applied to examine these features and addresses critical gaps that remain in moving the field forward. Specifically, we describe the anatomical and biomolecular features of human BAT, the modalities and applications of non-invasive tools such as PET and magnetic resonance imaging coupled with spectroscopy (MRI/MRS) to study BAT morphology and function in vivo, and finally describe the functional characteristics of human BAT that have only been possible through the development and application of such tools.

Functional Characterization of PM6/13, a β3-specific (GPIIIa/CD61) Monoclonal Antibody that Shows Preferential Inhibition of Fibrinogen Binding over Fibronectin Binding to Activated Human Platelets

1998 ◽  
Vol 79 (01) ◽  
pp. 177-185 ◽  
Author(s):  
Ashia Siddiqua ◽  
Michael Wilkinson ◽  
Vijay Kakkar ◽  
Yatin Patel ◽  
Salman Rahman ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Functional Characterization ◽  
Human Platelets ◽  
Western Blots ◽  
Activated Platelets ◽  
Reducing Conditions ◽  
Fibronectin Binding

SummaryWe report the characterization of a monoclonal antibody (MAb) PM6/13 which recognises glycoprotein IIIa (GPIIIa) on platelet membranes and in functional studies inhibits platelet aggregation induced by all agonists examined. In platelet-rich plasma, inhibition of aggregation induced by ADP or low concentrations of collagen was accompanied by inhibition of 5-hydroxytryptamine secretion. EC50 values were 10 and 9 [H9262]g/ml antibody against ADP and collagen induced responses respectively. In washed platelets treated with the cyclooxygenase inhibitor, indomethacin, PM6/13 inhibited platelet aggregation induced by thrombin (0.2 U/ml), collagen (10 [H9262]g/ml) and U46619 (3 [H9262]M) with EC50 = 4, 8 and 4 [H9262]g/ml respectively, without affecting [14C]5-hydroxytryptamine secretion or [3H]arachidonate release in appropriately labelled cells. Studies in Fura 2-labelled platelets revealed that elevation of intracellular calcium by ADP, thrombin or U46619 was unaffected by PM6/13 suggesting that the epitope recognised by the antibody did not influence Ca2+ regulation. In agreement with the results from the platelet aggregation studies, PM6/13 was found to potently inhibit binding of 125I-fibrinogen to ADP activated platelets. Binding of this ligand was also inhibited by two other MAbs tested, namely SZ-21 (also to GPIIIa) and PM6/248 (to the GPIIb-IIIa complex). However when tested against binding of 125I-fibronectin to thrombin stimulated platelets, PM6/13 was ineffective in contrast with SZ-21 and PM6/248, that were both potent inhibitors. This suggested that the epitopes recognised by PM6/13 and SZ-21 on GPIIIa were distinct. Studies employing proteolytic dissection of 125I-labelled GPIIIa by trypsin followed by immunoprecipitation with PM6/13 and analysis by SDS-PAGE, revealed the presence of four fragments at 70, 55, 30 and 28 kDa. PM6/13 did not recognize any protein bands on Western blots performed under reducing conditions. However Western blotting analysis with PM6/13 under non-reducing conditions revealed strong detection of the parent GP IIIa molecule, of trypsin treated samples revealed recognition of an 80 kDa fragment at 1 min, faint recognition of a 60 kDa fragment at 60 min and no recognition of any product at 18 h treatment. Under similar conditions, SZ-21 recognized fragments at 80, 75 and 55 kDa with the 55kDa species persisting even after 18 h trypsin treatment. These studies confirm the epitopes recognised by PM6/13 and SZ-21 to be distinct and that PM6/13 represents a useful tool to differentiate the characteristics of fibrinogen and fibronectin binding to the GPIIb-IIIa complex on activated platelets.

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