Jenni Laitila

University of Copenhagen

Hibernation is a period of metabolic suppression utilized by many small and large mammal species to survive during winter periods. As the underlying cellular and molecular mechanisms remain incompletely understood, our study aimed to determine whether skeletal muscle myosin and its metabolic efficiency undergo alterations during hibernation to opti...

Skeletal muscle is an inherently heterogenous tissue comprised primarily of myofibers, which are historically classified into three distinct fiber types in humans: one “slow” (type 1) and two “fast” (type 2A and type 2X), delineated by the expression of myosin heavy chain isoforms (MYHs). However, whether discrete fiber types exist or whether fiber...

It has recently been established that myosin, the molecular motor protein, is able to exist in two conformations in relaxed skeletal muscle. These conformations are known as the super-relaxed (SRX) and disordered-relaxed (DRX) states and are finely balanced to optimize ATP consumption and skeletal muscle metabolism. Indeed, SRX myosins are thought...

Nemaline myopathy (NM) is one of the most common non-dystrophic genetic muscle disorders. NM is often associated with mutations in the NEB gene. Even though the exact NEB -NM pathophysiological mechanisms remain unclear, histological analyses of patients’ muscle biopsies often reveal unexplained accumulation of glycogen and abnormally shaped mitoch...

Nemaline myopathy (NM) is one of the most common congenital myopathies. NM is often related to pathogenic variants in the NEB, ACTA1, TPM2 and TPM3 genes. Even though the exact disease mechanisms remain to be elucidated, histological analyses of NM patients’ muscle biopsies may reveal unexplained accumulation of glycogen and abnormal mitochondria....

It has recently been established that myosin, the molecular motor protein, is able to exist in two conformations in relaxed skeletal muscle. These conformations are known as super-relaxed (SRX) and disordered-relaxed (DRX) states and are finely balanced to optimize skeletal muscle metabo-lism. Indeed, SRX myosins are thought to have a 10-fold reduc...

The nemaline myopathies constitute a large proportion of the congenital or structural myopathies. Common to all patients is muscle weakness and the presence in the muscle biopsy of nemaline rods. The causative genes are at least twelve, encoding structural or regulatory proteins of the thin filament, and the clinical picture as well as the histolog...

The Y-box binding protein 3 (YBX3) has been described as a transcriptional regulator and translational repressor of various proteins in skeletal and heart muscle. Its functions include, among others, the gradual repression of myogenin during myogenesis. By exome sequencing in a Finnish patient with an unusual form of nemaline myopathy, we have foun...

Abstract Nemaline myopathy (NM) caused by mutations in the gene encoding nebulin (NEB) accounts for at least 50% of all NM cases worldwide, representing a significant disease burden. Most NEB-NM patients have autosomal recessive disease due to a compound heterozygous genotype. Of the few murine models developed for NEB-NM, most are Neb knockout mod...

Nemaline myopathies are a heterogenous group of congenital myopathies caused by de novo, dominantly or recessively inherited mutations in at least twelve genes. The genes encoding skeletal α-actin (ACTA1) and nebulin (NEB) are the commonest genetic cause. Most patients have congenital onset characterized by muscle weakness and hypotonia, but the sp...

Nemaline myopathy is a congenital neuromuscular disorder characterized by muscle weakness, fiber atrophy and presence of nemaline bodies within myofibers. However, the understanding of underlying pathomechanisms is lacking. Recently, mutations in KBTBD13, KLHL40 and KLHL41, three substrate adaptors for the E3-ubiquitin ligase Cullin-3, have been as...

We report the first family with a dominantly inherited mutation of the nebulin gene (NEB). This ∼100 kb in-frame deletion encompasses NEB exons 14-89, causing distal nemaline/cap myopathy in a three-generation family. It is the largest deletion characterized in NEB hitherto. The mutated allele was shown to be expressed at the mRNA level and further...

Nebulin is a very large protein required for assembly of the contractile machinery in muscle. Mutations in the nebulin gene NEB are a common cause of nemaline myopathy. Nebulin mRNA is alternatively-spliced so that each mRNA contains either exon 143 or exon 144. We have produced monoclonal antibodies specific for the regions of nebulin encoded by t...

Introduction Nebulin is a giant actin‐binding protein in the thin filament of the skeletal muscle sarcomere. Studies of nebulin interactions are limited by the size, complexity and poor solubility of the protein. We divided the nebulin super‐repeat region into a super‐repeat panel, and studied nebulin/actin interactions. Methods Actin binding was...

Functional studies of YBX3 variants associated with nemaline myopathy

Recently, new large variants have been identified in the nebulin gene (NEB) causing nemaline myopathy (NM). NM constitutes a heterogeneous group of disorders among the congenital myopathies, and disease-causing variants in NEB are a main cause of the recessively inherited form of NM. NEB consists of 183 exons and it includes homologous sequences su...

Mutation analysis of the known nemaline myopathy (NM)-causing genes in a Finnish patient with an unusual form of NM, with legs clearly stronger than arms, did not reveal the cause of the disease. A heterozygous TPM3 splice site mutation, delTAGG, in intron 1 was identified, inherited from the healthy father. The mutation was predicted to be recessi...

Background Nemaline myopathy (NM) is a rare genetic muscle disorder, but one of the most common among the congenital myopathies. NM is caused by mutations in at least nine genes: Nebulin (NEB), α-actin (ACTA1), α-tropomyosin (TPM3), β-tropomyosin (TPM2), troponin T (TNNT1), cofilin-2 (CFL2), Kelch repeat and BTB (POZ) domain-containing 13 (KBTBD13)...

One of the key components in stabilizing and determining the lengths of the actin filaments of the skeletal muscle sarcomere and in the neurons of the brain is the gigantic protein nebulin. Its size varies from 600 to 900 kDa and correlates with the length of the actin filaments. A huge variation in length is produced by differential usage of the a...

The nebulin gene (NEB) has 183 exons encoding transcripts up to 26 kb in length. Mutations found in NEB are dispersed throughout the gene. Mutations cause autosomal recessive nemaline myopathy, distal myopathy and core-rod myopathy, for which no therapy is available. The size of NEB limits the options of gene therapy development. Thus, our research...

Nebulin is a large actin-binding protein of the skeletal muscle sarcomere. Multiple isoforms of nebulin are produced from the 183-exon-containing nebulin gene (NEB). Mutations in NEB cause nemaline myopathy, distal myopathy, and core-rod myopathy. Nebulin mRNA expression was assessed by microarrays and RT-PCR in 21 human leg muscle and 2 brain samp...

The nebulin gene (NEB) has 183 exons encoding transcripts up to 26 kb in length. Mutations found in NEB are dispersed throughout the gene, i.e. no mutational hot spots are evident. Mutations cause autosomal recessive nemaline myopathy, distal nebulin myopathy and core-rod myopathy, for which no therapy is available. The size of NEB limits the optio...