scholarly journals Intrafamilial Phenotypic Variability of Collagen VI-Related Myopathy Due to a New Mutation in the COL6A1 Gene

2020 ◽  
pp. 1-12
Author(s):  
Sergey N. Bardakov ◽  
Roman V. Deev ◽  
Raisat M. Magomedova ◽  
Zoya R. Umakhanova ◽  
Valérie Allamand ◽  
...  
Keyword(s):  
Phenotypic Variability ◽  
Donor Site ◽  
Clinical Manifestations ◽  
Dermal Fibroblasts ◽  
Intermediate Phenotype ◽  
Splice Donor Site ◽  
Vertical Posture ◽  
Collagen Vi ◽  
Exon 2 ◽  
Bethlem Myopathy

A family of five male siblings (three survivors at 48, 53 and 58 years old; two deceased at 8 months old and 2.5 years old) demonstrating significant phenotypic variability ranging from intermediate to the myosclerotic like Bethlem myopathy is presented. Whole-exome sequencing (WES) identified a new homozygous missense mutation chr21:47402679 T >  C in the canonical splice donor site of the second intron (c.227 + 2T>C) in the COL6A1 gene. mRNA analysis confirmed skipping of exon 2 encoding 925 amino-acids in 94–95% of resulting transcripts. Three sibs presented with intermediate phenotype of collagen VI-related dystrophies (48, 53 and 2.5 years old) while the fourth sibling (58 years old) was classified as Bethlem myopathy with spine rigidity. The two older siblings with the moderate progressive phenotype (48 and 53 years old) lost their ability to maintain a vertical posture caused by pronounced contractures of large joints, but continued to ambulated throughout life on fully bent legs without auxiliary means of support. Immunofluorescence analysis of dermal fibroblasts demonstrated that no type VI collagen was secreted in any of the siblings’ cells, regardless of clinical manifestations severity while fibroblast proliferation and colony formation ability was decreased. The detailed genetic and long term clinical data contribute to broadening the genotypic and phenotypic spectrum of COL6A1 related disease.

scholarly journals Case Report: Two Novel Frameshift Mutations in SLC20A2 and One Novel Splice Donor Mutation in PDGFB Associated With Primary Familial Brain Calcification

2021 ◽  
Vol 12 ◽  
Author(s):  
Yuqi Shen ◽  
Shi Shu ◽  
Yaqiong Ren ◽  
Weibo Xia ◽  
Jianhua Chen ◽  
...  
Keyword(s):  
Donor Site ◽  
Clinical Manifestations ◽  
Dominant Negative ◽  
Mutation Spectrum ◽  
Splice Donor Site ◽  
Dominant Negative Effect ◽  
Splice Donor ◽  
Frameshift Mutations ◽  
Primary Familial Brain Calcification ◽  
Brain Calcification

Primary familial brain calcification (PFBC, OMIM#213600), also known as Fahr's disease, is characterized by bilateral and symmetric brain calcification in the basal ganglia (globus pallidus, caudate nucleus, and putamen), thalamus, subcortical white matter, and cerebellum. PFBC can be caused by loss-of-function mutations in any of the six known causative genes. The most common clinical manifestations include movement disorders, cognitive impairment, and neuropsychiatric signs that gradually emerge in middle-aged patients. To broaden the PFBC mutation spectrum, we examined nine members of a family with PFBC and two sporadic cases from clinical departments, and sequenced all PFBC-causative genes in the index case. Two novel frameshift mutations in SLC20A2 [NM_001257180.2; c.806delC, p.(Pro269Glnfs*49) and c.1154delG, p.(Ser385Ilefs*70)] and one novel splice donor site mutation (NM_002608.4, c.456+1G>C, r.436_456del) in PDGFB were identified in the patient cohort. c.806delC co-segregated with brain calcification and led to SLC20A2 haploinsufficiency among the affected family members. The c.456+1G>C mutation in PDGFB resulted in aberrant mRNA splicing, thereby forming mature transcripts containing an in-frame 21 base pair (bp) deletion, which might create a stably truncated protein [p.(Val146_Gln152del)] and exert a dominant negative effect on wild-type PDGFB. All three mutations were located in highly conserved regions among multiple species and predicted to be pathogenic, as evaluated by at least eight common genetic variation scoring systems. This study identified three novel mutations in SLC20A2 and PDGFB, which broadened and enriched the PFBC mutation spectrum.

scholarly journals A novel pathway for alternative splicing: identification of an RNA intermediate that generates an alternative 5' splice donor site not present in the primary transcript of AMPD1.

1990 ◽  
Vol 10 (10) ◽  
pp. 5271-5278 ◽  
Author(s):  
I Mineo ◽  
P R Clarke ◽  
R L Sabina ◽  
E W Holmes
Keyword(s):  
Alternative Splicing ◽  
Donor Site ◽  
Specific Pattern ◽  
Splice Donor Site ◽  
Splice Donor ◽  
Primary Transcript ◽  
Exon 2 ◽  
Tissue Specific ◽  
Exon 1 ◽  
Alternatively Spliced

AMP deaminase (AMPD) is a central enzyme in eucaryotic energy metabolism, and tissue-specific as well as stage-specific isoforms are found in many vertebrates. This study demonstrates the AMPD1 gene product in rat is alternatively spliced. The second exon, a 12-base miniexon, was found to be excluded or included in a tissue-specific and stage-specific pattern. This example of cassette splicing utilizes a unique pathway through an RNA intermediate that generates an alternative 5' splice donor site at the point where exon 2 is ligated to exon 1. In the analogous intermediate of human AMPD1, the potential 5' splice donor site created at the boundary of exon 1 and exon 2 was a poor substrate for splicing because of differences in exon 2 sequences, and human AMPD1 was not alternatively spliced. These results demonstrate that in some cases alternative splicing may proceed through an RNA intermediate that generates an alternative splice donor site not present in the primary transcript. Discrimination between alternative 5' splice donor sites in the RNA intermediate of AMPD1 is apparently controlled by tissue-specific and stage-specific signals.

scholarly journals Multiple transcripts of the CYP21 gene are generated by the mutation of the splicing donor site in intron 2 from GT to AT in 21-hydroxylase deficiency

2001 ◽  
Vol 171 (3) ◽  
pp. 397-402 ◽  
Author(s):  
HH Lee ◽  
SF Chang
Keyword(s):  
Donor Site ◽  
Splice Acceptor Site ◽  
Splice Donor Site ◽  
Acceptor Site ◽  
Site Mutation ◽  
Hydroxylase Deficiency ◽  
Exon 2 ◽  
Eukaryotic Genes ◽  
21 Hydroxylase Deficiency ◽  
Intron 2

Maturation of primary RNA transcripts of eukaryotic genes often involves the removal of introns and joining of exons. The fidelity of RNA splicing is dependent on the identity of the nucleotide (nt) sequences at exon/intron boundaries. Most importantly, the highly conserved intronic 5'GT and 3'AG sequences are essential for correct splicing. Substitution of GT by any other nt leads to incomplete mRNA and a disruption of protein structure. We describe here the results of our transfection experiments in COS-1 cells with a CYP21 genomic construct that contained an IVS 2+1G-->A mutation. Analysis of the transcripts by RT-PCR revealed that two different transcripts were generated by this mutant genome. In all the splicing products, we found that the entire exon 2 was deleted. Surprisingly, 30% of the transcripts from this mutant CYP21 genome were accompanied by an inclusion of 3' intron 2 sequences due to the use of a different splice acceptor site. This is the first report of the molecular characterization of a splice donor site mutation in CYP21 via transcription in COS-1 cells.

scholarly journals Lnx2 ubiquitin ligase is essential for exocrine cell differentiation in the early zebrafish pancreas

2015 ◽  
Vol 112 (40) ◽  
pp. 12426-12431 ◽  
Author(s):  
Minho Won ◽  
Hyunju Ro ◽  
Igor B. Dawid
Keyword(s):  
Cell Differentiation ◽  
Ubiquitin Ligase ◽  
Donor Site ◽  
Cell Types ◽  
Splice Donor Site ◽  
Gene Encoding ◽  
Exon 2 ◽  
Exocrine Cell ◽  
Complex Relationships ◽  
Fine Tune

The gene encoding the E3 ubiquitin ligase Ligand of Numb protein-X (Lnx)2a is expressed in the ventral-anterior pancreatic bud of zebrafish embryos in addition to its expression in the brain. Knockdown of Lnx2a by using an exon 2/intron 2 splice morpholino resulted in specific inhibition of the differentiation of ventral bud derived exocrine cell types, with little effect on endocrine cell types. A frame shifting null mutation in lnx2a did not mimic this phenotype, but a mutation that removed the exon 2 splice donor site did. We found that Lnx2b functions in a redundant manner with its paralog Lnx2a. Inhibition of lnx2a exon 2/3 splicing causes exon 2 skipping and leads to the production of an N-truncated protein that acts as an interfering molecule. Thus, the phenotype characterized by inhibition of exocrine cell differentiation requires inactivation of both Lnx2a and Lnx2b. Human LNX1 is known to destabilize Numb, and we show that inhibition of Numb expression rescues the Lnx2a/b-deficient phenotype. Further, Lnx2a/b inhibition leads to a reduction in the number of Notch active cells in the pancreas. We suggest that Lnx2a/b function to fine tune the regulation of Notch through Numb in the differentiation of cell types in the early zebrafish pancreas. Further, the complex relationships among genotype, phenotype, and morpholino effect in this case may be instructive in the ongoing consideration of morpholino use.

A novel pathway for alternative splicing: identification of an RNA intermediate that generates an alternative 5' splice donor site not present in the primary transcript of AMPD1

1990 ◽  
Vol 10 (10) ◽  
pp. 5271-5278
Author(s):  
I Mineo ◽  
P R Clarke ◽  
R L Sabina ◽  
E W Holmes
Keyword(s):  
Alternative Splicing ◽  
Donor Site ◽  
Specific Pattern ◽  
Splice Donor Site ◽  
Splice Donor ◽  
Primary Transcript ◽  
Exon 2 ◽  
Tissue Specific ◽  
Exon 1 ◽  
Alternatively Spliced

AMP deaminase (AMPD) is a central enzyme in eucaryotic energy metabolism, and tissue-specific as well as stage-specific isoforms are found in many vertebrates. This study demonstrates the AMPD1 gene product in rat is alternatively spliced. The second exon, a 12-base miniexon, was found to be excluded or included in a tissue-specific and stage-specific pattern. This example of cassette splicing utilizes a unique pathway through an RNA intermediate that generates an alternative 5' splice donor site at the point where exon 2 is ligated to exon 1. In the analogous intermediate of human AMPD1, the potential 5' splice donor site created at the boundary of exon 1 and exon 2 was a poor substrate for splicing because of differences in exon 2 sequences, and human AMPD1 was not alternatively spliced. These results demonstrate that in some cases alternative splicing may proceed through an RNA intermediate that generates an alternative splice donor site not present in the primary transcript. Discrimination between alternative 5' splice donor sites in the RNA intermediate of AMPD1 is apparently controlled by tissue-specific and stage-specific signals.

scholarly journals Isolation of Protein-Tyrosine Phosphatase-like Member-a Variant from Cementum

2011 ◽  
Vol 91 (2) ◽  
pp. 203-209 ◽  
Author(s):  
A. Valdés De Hoyos ◽  
L. Hoz-Rodríguez ◽  
H. Arzate ◽  
A.S. Narayanan
Keyword(s):  
Amino Acids ◽  
Protein Tyrosine Phosphatase ◽  
Transmembrane Domain ◽  
Tyrosine Phosphatase ◽  
Donor Site ◽  
Splice Donor Site ◽  
Gingival Fibroblast ◽  
Exon 2 ◽  
Protein Tyrosine ◽  
Cementifying Fibroma

Cementum has been shown to contain unique polypeptides that participate in cell recruitment and differentiation during cementum formation. We report the isolation of a cDNA variant for protein-tyrosine phosphatase-like (proline instead of catalytic arginine) member-a (PTPLA) from cementum. A cementifying fibroma-derived λ-ZAP expression library was screened by panning with a monoclonal antibody to cementum attachment protein (CAP), and 1435 bp cDNA (gb AC093525.3) was isolated. This cDNA encodes a 140-amino-acid polypeptide, and its N-terminal 125 amino acids are identical to those of PTPLA. This isoform, designated as PTPLA-CAP, results from a read-through of the PTPLA exon 2 splice donor site, truncating after the second putative transmembrane domain. It contains 15 amino acids encoded within the intron between PTPLA exons 2 and 3, which replace the active site for PTPLA phosphatase activity. The recombinant protein, rhPTPLA-CAP, has Mr 19 kDa and cross-reacts with anti-CAP antibody. Anti-rhPTPLA-CAP antibody immunostained cementum cells, cementum, heart, and liver. Quantitative RT-PCR showed that PTPLA was expressed in all periodontal cells; however, PTPLA-CAP expression was limited to cementum cells. The rhPTPLA-CAP promoted gingival fibroblast attachment. We conclude that PTPLA-CAP is a splice variant of PTPLA, and that, in the periodontium, cementum and cementum cells express this variant.

scholarly journals Glucocorticoid and mineralocorticoid resistance/hypersensitivity syndromes

2001 ◽  
Vol 169 (3) ◽  
pp. 437-445 ◽  
Author(s):  
T Kino ◽  
GP Chrousos
Keyword(s):  
Ligand Binding ◽  
Donor Site ◽  
Sporadic Case ◽  
Glucocorticoid Resistance ◽  
Splice Donor Site ◽  
Host Immune System ◽  
Exon 2 ◽  
Base Pair Deletion ◽  
Hiv 1

Glucocorticoids and mineralocorticoids regulate diverse functions important to maintain central nervous system, cardiovascular, metabolic, and immune homeostasis. The actions of these hormones are mediated by their specific intracellular receptors: the glucocorticoid (GR) and mineralocorticoid (MR) receptors. Pathologic conditions associated with changes of tissue sensitivity to these hormones have been described. The syndrome of familial glucocorticoid resistance is characterized by hypercortisolism without Cushing's syndrome stigmata. The molecular defects of four kindreds and one sporadic case have been elucidated as inactivating mutations in the ligand-binding domain of GR. Two cases developed glucocorticoid resistance at the heterozygous state. In these patients, mutant receptors possessed transdominant negative activity upon the wild type receptor. Insensitivity to mineralocorticoids (which may also be caused by loss of function mutations of the MR gene) was found in one sporadic case and four autosomal dominant cases of Pseudohypoaldosteronism type 1. These included two frameshift mutations and a premature termination codon in exon 2, leading to gene products lacking the entire DNA- and ligand-binding domains, and a single base-pair deletion in the intron-5 splice donor site. Tissue hypersensitivity to glucocorticoids was recently hypothesized in patients with Human Immunodeficiency Virus (HIV) type-1 infection via the accessory proteins Vpr and Tat which enhance GR transactivation. Since HIV-1 long terminal repeat (LTR) and glucocorticoid-responsive promoters use the same set of coactivators, these proteins may stimulate HIV-1-LTR and glucocorticoid-inducible genes concurrently. The former may directly stimulate viral proliferation, while the latter may indirectly enhance viral propagation by suppressing the host immune system through glucocorticoid-mediated mechanisms.

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