Functional Characterization of Calcium Sensing Receptors (CaSR) Bearing Loss-of-Function or Gain-of Function Missense Mutations

2011 ◽  
pp. P1-173-P1-173
Author(s):  
Alicia Diaz-Thomas ◽  
Pallavi Iyer ◽  
Allen Root ◽  
John Cannon
Keyword(s):  
Functional Characterization ◽  
Missense Mutations ◽  
Loss Of Function ◽  
Gain Of Function ◽  
Calcium Sensing ◽  
Bearing Loss

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

scholarly journals Discovery and functional characterization of a neomorphic PTEN mutation

2015 ◽  
Vol 112 (45) ◽  
pp. 13976-13981 ◽  
Author(s):  
Helio A. Costa ◽  
Michael G. Leitner ◽  
Martin L. Sos ◽  
Angeliki Mavrantoni ◽  
Anna Rychkova ◽  
...  
Keyword(s):  
Cancer Biology ◽  
Functional Characterization ◽  
Genetic Alterations ◽  
Loss Of Function ◽  
Gain Of Function ◽  
Phosphatase And Tensin Homolog ◽  
Pten Loss ◽  
Tensin Homolog ◽  
Cancer Tumor

Although a variety of genetic alterations have been found across cancer types, the identification and functional characterization of candidate driver genetic lesions in an individual patient and their translation into clinically actionable strategies remain major hurdles. Here, we use whole genome sequencing of a prostate cancer tumor, computational analyses, and experimental validation to identify and predict novel oncogenic activity arising from a point mutation in the phosphatase and tensin homolog (PTEN) tumor suppressor protein. We demonstrate that this mutation (p.A126G) produces an enzymatic gain-of-function in PTEN, shifting its function from a phosphoinositide (PI) 3-phosphatase to a phosphoinositide (PI) 5-phosphatase. Using cellular assays, we demonstrate that this gain-of-function activity shifts cellular phosphoinositide levels, hyperactivates the PI3K/Akt cell proliferation pathway, and exhibits increased cell migration beyond canonical PTEN loss-of-function mutants. These findings suggest that mutationally modified PTEN can actively contribute to well-defined hallmarks of cancer. Lastly, we demonstrate that these effects can be substantially mitigated through chemical PI3K inhibitors. These results demonstrate a new dysfunction paradigm for PTEN cancer biology and suggest a potential framework for the translation of genomic data into actionable clinical strategies for targeted patient therapy.

scholarly journals Functional Characterization of the Adenylyl Cyclase Genesgs-1by Analysis of a Mutational Spectrum inCaenorhabditis elegans

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 133-142 ◽  
Author(s):  
Celine Moorman ◽  
Ronald H A Plasterk
Keyword(s):  
Life Span ◽  
Adenylyl Cyclase ◽  
Neuronal Degeneration ◽  
Functional Characterization ◽  
Adenylyl Cyclases ◽  
Loss Of Function ◽  
C Elegans ◽  
Larval Stages ◽  
Pharyngeal Pumping

AbstractThe sgs-1 (suppressor of activated Gαs) gene encodes one of the four adenylyl cyclases in the nematode C. elegans and is most similar to mammalian adenylyl cyclase type IX. We isolated a complete loss-of-function mutation in sgs-1 and found it to result in animals with retarded development that arrest in variable larval stages. sgs-1 mutant animals exhibit lethargic movement and pharyngeal pumping and (while not reaching adulthood) have a mean life span that is >50% extended compared to wild type. An extensive set of reduction-of-function mutations in sgs-1 was isolated in a screen for suppressors of a neuronal degeneration phenotype induced by the expression of a constitutively active version of the heterotrimeric Gαs subunit of C. elegans. Although most of these mutations change conserved residues within the catalytic domains of sgs-1, mutations in the less-conserved transmembrane domains are also found. The sgs-1 reduction-of-function mutants are viable and have reduced locomotion rates, but do not show defects in pharyngeal pumping or life span.

scholarly journals Genetic and Molecular Characterization of the Caenorhabditis elegans Gene, mel-26, a Postmeiotic Negative Regulator of MEI-1, a Meiotic-Specific Spindle Component

Genetics ◽  
1998 ◽  
Vol 150 (1) ◽  
pp. 119-128
Author(s):  
M Rhys Dow ◽  
Paul E Mains
Keyword(s):  
Caenorhabditis Elegans ◽  
Protein Interactions ◽  
Negative Regulator ◽  
Meiotic Spindle ◽  
Loss Of Function ◽  
Protein Protein Interactions ◽  
Gain Of Function ◽  
Recessive Mutations ◽  
Female Germline

Abstract We have previously described the gene mei-1, which encodes an essential component of the Caenorhabditis elegans meiotic spindle. When ectopically expressed after the completion of meiosis, mei-1 protein disrupts the function of the mitotic cleavage spindles. In this article, we describe the cloning and the further genetic characterization of mel-26, a postmeiotic negative regulator of mei-1. mel-26 was originally identified by a gain-of-function mutation. We have reverted this mutation to a loss-of-function allele, which has recessive phenotypes identical to the dominant defects of its gain-of-function parent. Both the dominant and recessive mutations of mel-26 result in mei-1 protein ectopically localized in mitotic spindles and centrosomes, leading to small and misoriented cleavage spindles. The loss-of-function mutation was used to clone mel-26 by transformation rescue. As suggested by genetic results indicating that mel-26 is required only maternally, mel-26 mRNA was expressed predominantly in the female germline. The gene encodes a protein that includes the BTB motif, which is thought to play a role in protein-protein interactions.

scholarly journals Identification and Functional Characterization of a Calcium-Sensing Receptor Mutation in an Infant with Familial Hypocalciuric Hypercalcemia

2016 ◽  
Vol 8 (3) ◽  
pp. 341-346 ◽  
Author(s):  
Anna Papadopoulou ◽  
Evangelia Gole ◽  
Katerina Melachroinou ◽  
Christos Meristoudis ◽  
Tania Siahanidou ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Familial Hypocalciuric Hypercalcemia ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing

scholarly journals Human xylosyltransferase I and N-terminal truncated forms: functional characterization of the core enzyme

2006 ◽  
Vol 394 (1) ◽  
pp. 163-171 ◽  
Author(s):  
Sandra Müller ◽  
Jennifer Disse ◽  
Manuela Schöttler ◽  
Sylvia Schön ◽  
Christian Prante ◽  
...  
Keyword(s):  
Amino Acids ◽  
Catalytic Activity ◽  
Binding Capacity ◽  
Functional Characterization ◽  
Terminal Region ◽  
Binding Motif ◽  
Heparin Binding ◽  
Loss Of Function ◽  
The Impact

Human XT-I (xylosyltransferase I; EC 2.4.2.26) initiates the biosynthesis of the glycosaminoglycan linkage region and is a diagnostic marker of an enhanced proteoglycan biosynthesis. In the present study, we have investigated mutant enzymes of human XT-I and assessed the impact of the N-terminal region on the enzymatic activity. Soluble mutant enzymes of human XT-I with deletions at the N-terminal domain were expressed in insect cells and analysed for catalytic activity. As many as 260 amino acids could be truncated at the N-terminal region of the enzyme without affecting its catalytic activity. However, truncation of 266, 272 and 273 amino acids resulted in a 70, 90 and >98% loss in catalytic activity. Interestingly, deletion of the single 12 amino acid motif G261KEAISALSRAK272 leads to a loss-of-function XT-I mutant. This is in agreement with our findings analysing the importance of the Cys residues where we have shown that C276A mutation resulted in a nearly inactive XT-I enzyme. Moreover, we investigated the location of the heparin-binding site of human XT-I using the truncated mutants. Heparin binding was observed to be slightly altered in mutants lacking 289 or 568 amino acids, but deletion of the potential heparin-binding motif P721KKVFKI727 did not lead to a loss of heparin binding capacity. The effect of heparin or UDP on the XT-I activity of all mutants was not significantly different from that of the wild-type. Our study demonstrates that over 80% of the nucleotide sequence of the XT-I-cDNA is necessary for expressing a recombinant enzyme with full catalytic activity.

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