scholarly journals hnRNP U protein is required for normal pre-mRNA splicing and postnatal heart development and function

2015 ◽  
Vol 112 (23) ◽  
pp. E3020-E3029 ◽  
Author(s):  
Junqiang Ye ◽  
Nadine Beetz ◽  
Sean O’Keeffe ◽  
Juan Carlos Tapia ◽  
Lindsey Macpherson ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Heart Development ◽  
Specific Protein ◽  
Protein Product ◽  
Conclusive Evidence ◽  
Mrna Splicing ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Hnrnp U ◽  
And Function

We report that mice lacking the heterogeneous nuclear ribonucleoprotein U (hnRNP U) in the heart develop lethal dilated cardiomyopathy and display numerous defects in cardiac pre-mRNA splicing. Mutant hearts have disorganized cardiomyocytes, impaired contractility, and abnormal excitation–contraction coupling activities. RNA-seq analyses of Hnrnpu mutant hearts revealed extensive defects in alternative splicing of pre-mRNAs encoding proteins known to be critical for normal heart development and function, including Titin and calcium/calmodulin-dependent protein kinase II delta (Camk2d). Loss of hnRNP U expression in cardiomyocytes also leads to aberrant splicing of the pre-mRNA encoding the excitation–contraction coupling component Junctin. We found that the protein product of an alternatively spliced Junctin isoform is N-glycosylated at a specific asparagine site that is required for interactions with specific protein partners. Our findings provide conclusive evidence for the essential role of hnRNP U in heart development and function and in the regulation of alternative splicing.

scholarly journals A new view of transcriptome complexity and regulation through the lens of local splicing variations

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Jorge Vaquero-Garcia ◽  
Alejandro Barrera ◽  
Matthew R Gazzara ◽  
Juan González-Vallinas ◽  
Nicholas F Lahens ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Alternative Splicing ◽  
Gene Function ◽  
Specific Protein ◽  
Mrna Splicing ◽  
New Approach ◽  
Genome Wide ◽  
Mouse Tissues ◽  
Splice Variation ◽  
Novel Isoforms

Alternative splicing (AS) can critically affect gene function and disease, yet mapping splicing variations remains a challenge. Here, we propose a new approach to define and quantify mRNA splicing in units of local splicing variations (LSVs). LSVs capture previously defined types of alternative splicing as well as more complex transcript variations. Building the first genome wide map of LSVs from twelve mouse tissues, we find complex LSVs constitute over 30% of tissue dependent transcript variations and affect specific protein families. We show the prevalence of complex LSVs is conserved in humans and identify hundreds of LSVs that are specific to brain subregions or altered in Alzheimer's patients. Amongst those are novel isoforms in the Camk2 family and a novel poison exon in Ptbp1, a key splice factor in neurogenesis. We anticipate the approach presented here will advance the ability to relate tissue-specific splice variation to genetic variation, phenotype, and disease.

scholarly journals Excitation-contraction coupling and its relation to synaptic dysfunction in Drosophila

2020 ◽  
Author(s):  
Kiel G. Ormerod ◽  
Anthony E. Scibelli ◽  
J. Troy Littleton
Keyword(s):  
Muscle Performance ◽  
Synaptic Dysfunction ◽  
Muscle Contractility ◽  
Detailed Characterization ◽  
Synaptic Development ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
And Function ◽  
Identification And Characterization

AbstractThe Drosophila neuromuscular system is widely used to characterize synaptic development and function. However, little is known about how specific synaptic deficits alter neuromuscular transduction and muscle contractility that ultimately dictate behavioural output. Here we develop a system for detailed characterization of excitation-contraction coupling at Drosophila larval NMJs and demonstrate how specific synaptic and neuronal manipulations disrupt muscle contractility. Muscle contraction force increases with motoneuron stimulation frequency and duration, showing considerable plasticity between 5-40 Hz, while saturating above 50 Hz. Temperature is negatively correlated with muscle performance and enhanced at lower temperatures. A screen for modulators of muscle contractility led to the identification and characterization of the molecular and cellular pathway by which a specific FMRFa peptide, TPAEDFMRFa, increases muscle performance. These findings indicate Drosophila NMJs provide a robust system to relate synaptic dysfunction to alterations in excitation-contraction coupling.

scholarly journals The relationship between form and function throughout the history of excitation–contraction coupling

2018 ◽  
Vol 150 (2) ◽  
pp. 189-210 ◽  
Author(s):  
Clara Franzini-Armstrong
Keyword(s):  
Skeletal Muscle ◽  
Recent Work ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Form And Function ◽  
History Of ◽  
Experimental Approaches ◽  
And Function ◽  
The Relationship ◽  
Rapid Contraction

The concept of excitation–contraction coupling is almost as old as Journal of General Physiology. It was understood as early as the 1940s that a series of stereotyped events is responsible for the rapid contraction response of muscle fibers to an initial electrical event at the surface. These early developments, now lost in what seems to be the far past for most young investigators, have provided an endless source of experimental approaches. In this Milestone in Physiology, I describe in detail the experiments and concepts that introduced and established the field of excitation–contraction coupling in skeletal muscle. More recent advances are presented in an abbreviated form, as readers are likely to be familiar with recent work in the field.

scholarly journals The Emerging Role of the RBM20 and PTBP1 Ribonucleoproteins in Heart Development and Cardiovascular Diseases

Genes ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 402 ◽  
Author(s):  
Stefania Fochi ◽  
Pamela Lorenzi ◽  
Marilisa Galasso ◽  
Chiara Stefani ◽  
Elisabetta Trabetti ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Cell Fate ◽  
Heart Development ◽  
Cardiac Tissue ◽  
Altered Expression ◽  
Tissue Organization ◽  
Polypyrimidine Tract Binding Protein ◽  
Human Genes ◽  
Alternative Splicing Events ◽  
And Function

Alternative splicing is a regulatory mechanism essential for cell differentiation and tissue organization. More than 90% of human genes are regulated by alternative splicing events, which participate in cell fate determination. The general mechanisms of splicing events are well known, whereas only recently have deep-sequencing, high throughput analyses and animal models provided novel information on the network of functionally coordinated, tissue-specific, alternatively spliced exons. Heart development and cardiac tissue differentiation require thoroughly regulated splicing events. The ribonucleoprotein RBM20 is a key regulator of the alternative splicing events required for functional and structural heart properties, such as the expression of TTN isoforms. Recently, the polypyrimidine tract-binding protein PTBP1 has been demonstrated to participate with RBM20 in regulating splicing events. In this review, we summarize the updated knowledge relative to RBM20 and PTBP1 structure and molecular function; their role in alternative splicing mechanisms involved in the heart development and function; RBM20 mutations associated with idiopathic dilated cardiovascular disease (DCM); and the consequences of RBM20-altered expression or dysfunction. Furthermore, we discuss the possible application of targeting RBM20 in new approaches in heart therapies.

scholarly journals Raptor Ablation in Skeletal Muscle Affects the Structure and Function of the Excitation-Contraction Coupling Macromolecular Complex

2014 ◽  
Vol 106 (2) ◽  
pp. 123a
Author(s):  
Ruben Lopez ◽  
Barbara Mosca ◽  
Leda Bergamelli ◽  
Markus A. Ruegg ◽  
Florian C. Bentzinger ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Structure And Function ◽  
Macromolecular Complex ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
And Function

scholarly journals Titin M-line insertion sequence 7 is required for proper cardiac function in mice

2021 ◽  
Vol 134 (18) ◽  
Author(s):  
Ariane Biquand ◽  
Simone Spinozzi ◽  
Paola Tonino ◽  
Jérémie Cosette ◽  
Joshua Strom ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Mouse Model ◽  
Cardiac Function ◽  
Insertion Sequence ◽  
Primary Role ◽  
Molecular Analyses ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Sarcomeric Protein ◽  
Line Insertion

ABSTRACT Titin is a giant sarcomeric protein that is involved in a large number of functions, with a primary role in skeletal and cardiac sarcomere organization and stiffness. The titin gene (TTN) is subject to various alternative splicing events, but in the region that is present at the M-line, the only exon that can be spliced out is Mex5, which encodes for the insertion sequence 7 (is7). Interestingly, in the heart, the majority of titin isoforms are Mex5+, suggesting a cardiac role for is7. Here, we performed comprehensive functional, histological, transcriptomic, microscopic and molecular analyses of a mouse model lacking the Ttn Mex5 exon (ΔMex5), and revealed that the absence of the is7 is causative for dilated cardiomyopathy. ΔMex5 mice showed altered cardiac function accompanied by increased fibrosis and ultrastructural alterations. Abnormal expression of excitation–contraction coupling proteins was also observed. The results reported here confirm the importance of the C-terminal region of titin in cardiac function and are the first to suggest a possible relationship between the is7 and excitation–contraction coupling. Finally, these findings give important insights for the identification of new targets in the treatment of titinopathies.

scholarly journals Methylation at nucleotide C62 in spliceosomal RNA U6 alters mRNA splicing which is important for embryonic development

2019 ◽  
Author(s):  
Allison Ogren ◽  
Nataliya Kibiryeva ◽  
Jennifer Marshall ◽  
James E. O’Brien ◽  
Douglas C. Bittel
Keyword(s):  
Alternative Splicing ◽  
Congenital Heart Defects ◽  
Congenital Heart ◽  
Heart Defects ◽  
Mrna Splicing ◽  
Developmental Defects ◽  
Small Noncoding Rnas ◽  
Spliceosomal Rnas ◽  
Mrna Transcripts ◽  
And Function

AbstractUnderstanding the regulation of development can help elucidate the pathogenesis behind many developmental defects found in humans and other vertebrates. Evidence has shown that alternative splicing of messenger RNA (mRNA) plays a role in developmental regulation, but our knowledge of the underlying mechanisms that regulate alternative splicing are inadequate. Notably, a subset of small noncoding RNAs known as scaRNAs (small cajal body associated RNAs) contribute to spliceosome maturation and function through covalently modifying spliceosomal RNAs by either methylating or pseudouridylating specific nucleotides, but the developmental significance of these modifications is not well understood. Our focus is on one such scaRNA, known as SNORD94 or U94, that methylates one specific cytosine (C62) on spliceosomal RNA U6, thus potentially altering spliceosome function during embryogenesis. We previously showed that mRNA splicing is significantly different in myocardium from infants with congenital heart defects (CHD) compared to controls. Furthermore, we showed that modifying expression of scaRNAs alters mRNA splicing in human cells, and zebrafish embryos. Here we present evidence that SNORD94 levels directly influence levels of methylation at C62 in U6, which we have previously shown is associated with altered splicing and congenital heart defects. The potential importance of scaRNAs as a developmentally important regulatory mechanism controlling alternative splicing of mRNA is unappreciated and needs more research.Author summarySplicing of mRNA transcripts by removal of introns and some non-critical exons is a crucial part of mRNA processing, gene expression, and cell function, and regulation of this process is still under investigation. Alternative splicing of mRNA transcripts of genes is tissue and time specific throughout life, although this process occurs everywhere in the body according to local tissue needs and signals. The spliceosome, the large ribonucleoprotein complex that carries out splicing, is biochemically modified by small noncoding RNAs, which is important for its structure and function. Here we show that the amount of 2’-O-ribose methylation at nucleotide C62 in spliceosomal RNA U6 is dependent on the level of the scaRNA SNORD94. We hypothesize that alternative splicing is dependent, at least in part, on biochemical modification to the spliceosomal RNAs. Furthermore, when scaRNA directed modifications are dysregulated, the result causes inappropriate alternative splicing that may contribute to developmental defects such as congenital heart defects. To our knowledge, this is the first demonstration that 2’-O-ribose methylation is indeed dependent on scaRNA levels in human cells and tissues.

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