Pathomechanisms of Monoallelic variants in TTN causing skeletal muscle disease.

Pathogenic variants in the titin gene (TTN) are known to cause a wide range of cardiac and musculoskeletal disorders, with skeletal myopathy mostly attributed to biallelic variants. We identified monoallelic truncating variants (TTNtv), splice site or internal deletions in TTN in probands with mild, progressive axial and proximal weakness, with dilated cardiomyopathy frequently developing with age. These variants segregated in an autosomal dominant pattern in 7 out of 8 studied families.

Myosin-binding protein H-like regulates myosin-binding protein distribution and function in atrial cardiomyocytes.

Mutations in atrial-enriched genes can cause a primary atrial myopathy that can contribute to overall cardiovascular dysfunction. encodes myosin-binding protein H-like (MyBP-HL), an atrial sarcomere protein that shares domain homology with the carboxy-terminus of cardiac myosin-binding protein-C (cMyBP-C). The function of MyBP-HL and the relationship between MyBP-HL and cMyBP-C is unknown.

The Pulmonary Endothelial Glycocalyx Modifications in Glypican 1 Knockout Mice Do Not Affect Lung Endothelial Function in Physiological Conditions.

The endothelial glycocalyx is a dynamic signaling surface layer that is involved in the maintenance of cellular homeostasis. The glycocalyx has a very diverse composition, with glycoproteins, proteoglycans, and glycosaminoglycans interacting with each other to form a mesh-like structure. Due to its highly interactive nature, little is known about the relative contribution of each glycocalyx constituent to its overall function.

Removal of MuRF1 Increases Muscle Mass in Nemaline Myopathy Models, but Does Not Provide Functional Benefits.

Nemaline myopathy (NM) is characterized by skeletal muscle weakness and atrophy. No curative treatments exist for this debilitating disease. NM is caused by mutations in proteins involved in thin-filament function, turnover, and maintenance.

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

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.

The number of Z-repeats and super-repeats in nebulin greatly varies across vertebrates and scales with animal size.

Nebulin is a skeletal muscle protein that associates with the sarcomeric thin filaments and has functions in regulating the length of the thin filament and the structure of the Z-disk. Here we investigated the nebulin gene in 53 species of birds, fish, amphibians, reptiles, and mammals. In all species, nebulin has a similar domain composition that mostly consists of ∼30-residue modules (or simple repeats), each containing an actin-binding site.

Nebulin and Lmod2 are critical for specifying thin-filament length in skeletal muscle.

Regulating the thin-filament length in muscle is crucial for controlling the number of myosin motors that generate power. The giant protein nebulin forms a long slender filament that associates along the length of the thin filament in skeletal muscle with functions that remain largely obscure. Here nebulin's role in thin-filament length regulation was investigated by targeting entire super-repeats in the gene; nebulin was either shortened or lengthened by 115 nm.

Triggering typical nemaline myopathy with compound heterozygous nebulin mutations reveals myofilament structural changes as pathomechanism.

Nebulin is a giant protein that winds around the actin filaments in the skeletal muscle sarcomere. Compound-heterozygous mutations in the nebulin gene (NEB) cause typical nemaline myopathy (NM), a muscle disorder characterized by muscle weakness with limited treatment options. We created a mouse model with a missense mutation p.

Correction to: Expressing a Z-disk nebulin fragment innebulin-deficient mouse muscle: effects on muscle structure and function.

Following the publication of this paper [1], it was brought to the authors' attention that one of the contributing authors was left off of the paper. The authors apologize for the unfortunate oversight. In this correction paper, they have included Dr.

Expressing a Z-disk nebulin fragment in nebulin-deficient mouse muscle: effects on muscle structure and function.

Background: Nebulin is a critical thin filament-binding protein that spans from the Z-disk of the skeletal muscle sarcomere to near the pointed end of the thin filament. Its massive size and actin-binding property allows it to provide the thin filaments with structural and regulatory support. When this protein is lost, nemaline myopathy occurs.

Fine mapping titin's C-zone: Matching cardiac myosin-binding protein C stripes with titin's super-repeats.

Titin is largely comprised of serially-linked immunoglobulin (Ig) and fibronectin type-III (Fn3) domains. Many of these domains are arranged in an 11 domain super-repeat pattern that is repeated 11 times, forming the so-named titin C-zone in the A-band region of the sarcomere. Each super-repeat is thought to provide binding sites for thick filament proteins, such as cMyBP-C (cardiac myosin-binding protein C).

A missense variant in the titin gene in Doberman pinscher dogs with familial dilated cardiomyopathy and sudden cardiac death.

The dog provides a large animal model of familial dilated cardiomyopathy for the study of important aspects of this common familial cardiovascular disease. We have previously demonstrated a form of canine dilated cardiomyopathy in the Doberman pinscher breed that is inherited as an autosomal dominant trait and is associated with a splice site variant in the pyruvate dehydrogenase kinase 4 (PDK4) gene, however, genetic heterogeneity exists in this species as well and not all affected dogs have the PDK4 variant. Whole genome sequencing of a family of Doberman pinchers with dilated cardiomyopathy and sudden cardiac death without the PDK4 variant was performed.

Nebulin stiffens the thin filament and augments cross-bridge interaction in skeletal muscle.

Nebulin is a giant sarcomeric protein that spans along the actin filament in skeletal muscle, from the Z-disk to near the thin filament pointed end. Mutations in nebulin cause muscle weakness in nemaline myopathy patients, suggesting that nebulin plays important roles in force generation, yet little is known about nebulin's influence on thin filament structure and function. Here, we used small-angle X-ray diffraction and compared intact muscle deficient in nebulin (using a conditional nebulin-knockout, Neb cKO) with control (Ctrl) muscle.

The giant protein titin regulates the length of the striated muscle thick filament.

The contractile machinery of heart and skeletal muscles has as an essential component the thick filament, comprised of the molecular motor myosin. The thick filament is of a precisely controlled length, defining thereby the force level that muscles generate and how this force varies with muscle length. It has been speculated that the mechanism by which thick filament length is controlled involves the giant protein titin, but no conclusive support for this hypothesis exists.

Deleting titin's I-band/A-band junction reveals critical roles for titin in biomechanical sensing and cardiac function.

Titin, the largest protein known, forms a giant filament in muscle where it spans the half sarcomere from Z disk to M band. Here we genetically targeted a stretch of 14 immunoglobulin-like and fibronectin type 3 domains that comprises the I-band/A-band (IA) junction and obtained a viable mouse model. Super-resolution optical microscopy (structured illumination microscopy, SIM) and electron microscopy were used to study the thick filament length and titin's molecular elasticity.

Microvessel Density Is Associated with VEGF and α-SMA Expression in Different Regions of Human Gastrointestinal Carcinomas.

Tumor angiogenesis is known to be regulated by growth factors secreted by host and tumor cells. Despite the importance of tumor vasculature and angiogenic heterogeneity in solid tumors, few studies have compared the vasculature in different regions of human cancer. Blood vessels from different regions of carcinomas might have morphofunctional implications in tumor angiogenesis.

Reduced myofibrillar connectivity and increased Z-disk width in nebulin-deficient skeletal muscle.

A prominent feature of striated muscle is the regular lateral alignment of adjacent sarcomeres. An important intermyofibrillar linking protein is the intermediate filament protein desmin, and based on biochemical and structural studies in primary cultures of myocytes it has been proposed that desmin interacts with the sarcomeric protein nebulin. Here we tested whether nebulin is part of a novel biomechanical linker complex, by using a recently developed nebulin knockout (KO) mouse model and measuring Z-disk displacement in adjacent myofibrils of both extensor digitorum longus (EDL) and soleus muscle.

Relationship between VEGF and p53 expression and tumor cell proliferation in human gastrointestinal carcinomas.

Purpose: The vascular endothelial growth factor (VEGF) and p53 play important roles in the growth of tumor. However, the relationship between the expression of VEGF and p53 and tumor cell proliferation in human gastrointestinal cancer remains unknown. In the present study, therefore, we have examined the relationship between VEGF and p53 expression and tumor cell proliferation in gastrointestinal carcinoma (GITC), as well as the association between these biomarkers and clinicopathological factors.

Is hypothermia a stress condition in HepG2 cells? Expression and localization of Hsp70 in human hepatoma cell line.

To understand hypothermia as a stress condition we determined the expression and localization of Hsp70 under hyperthermic and hypothermic stress in human hepatoma HepG2 cells. Western blot analysis indicates that there was a statistically significant increase of Hsp70 expression under thermal stresses. Immunohistochemically, the distribution of inducible Hsp70 in stressed cells showed a granular pattern mostly in the cytoplasm.

Mass determination of native smooth muscle myosin filaments by scanning transmission electron microscopy.

The thick filaments of vertebrate smooth muscle have a fundamentally different arrangement of myosin molecules from the bipolar, helical organization present in striated muscle filaments. This side-polar, non-helical structure is probably critical to the ability of smooth muscles to shorten by large amounts; however, details of myosin organization beyond this general description are unknown. The non-helical arrangement of myosin precludes the use of helical reconstruction methods for structural determination, and a tomographic approach is required.