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Desmin
Desmin
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DES
Identifiers
AliasesDES, CSM1, CSM2, LGMD2R, desmin, LGMD1D, CMD1F, CDCD3, LGMD1E
External IDsOMIM: 125660; MGI: 94885; HomoloGene: 56469; GeneCards: DES; OMA:DES - orthologs
Orthologs
SpeciesHumanMouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)

NM_001927

NM_010043

RefSeq (protein)

NP_034173

Location (UCSC)Chr 2: 219.42 – 219.43 MbChr 1: 75.34 – 75.35 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Desmin is a protein that in humans is encoded by the DES gene.[5][6] Desmin is a muscle-specific, type III intermediate filament[7] that integrates the sarcolemma, Z disk, and nuclear membrane in sarcomeres and regulates sarcomere architecture.[8][9]

Structure

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Desmin is a 53.5 kD protein composed of 470 amino acids, encoded by the human DES gene located on the long arm of chromosome 2.[10][11] There are three major domains to the desmin protein: a conserved alpha helix rod, a variable non alpha helix head, and a carboxy-terminal tail.[12] Desmin, as all intermediate filaments, shows no polarity when assembled.[12] The rod domain consists of 308 amino acids with parallel alpha helical coiled coil dimers and three linkers to disrupt it.[12] The rod domain connects to the head domain. The head domain 84 amino acids with many arginine, serine, and aromatic residues is important in filament assembly and dimer-dimer interactions.[12] The tail domain is responsible for the integration of filaments and interaction with proteins and organelles. Desmin is only expressed in vertebrates, however homologous proteins are found in many organisms.[12] Desmin is a subunit of intermediate filaments in cardiac muscle, skeletal muscle and smooth muscle tissue.[13] In cardiac muscle, desmin is present in Z-discs and intercalated discs. Desmin has been shown to interact with desmoplakin[14] and αB-crystallin.[15]

Function

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Desmin was first described in 1976,[16] first purified in 1977,[17] the gene was cloned in 1989,[6] and the first knockout mouse was created in 1996. The function of desmin has been deduced through studies in knockout mice. Desmin is one of the earliest protein markers for muscle tissue in embryogenesis as it is detected in the somites.[12][18] Although it is present early in the development of muscle cells, it is only expressed at low levels, and increases as the cell nears terminal differentiation. A similar protein, vimentin, is present in higher amounts during embryogenesis while desmin is present in higher amounts after differentiation. This suggests that there may be some interaction between the two in determining muscle cell differentiation. However desmin knockout mice develop normally and only experience defects later in life.[13] Since desmin is expressed at a low level during differentiation another protein may be able to compensate for desmin's function early in development but not later on.[19]

In adult desmin-null mice, hearts from 10 week-old animals showed drastic alterations in muscle architecture, including a misalignment of myofibrils and disorganization and swelling of mitochondria; findings that were more severe in cardiac relative to skeletal muscle. Cardiac tissue also exhibited progressive necrosis and calcification of the myocardium.[20] A separate study examined this in more detail in cardiac tissue and found that murine hearts lacking desmin developed hypertrophic cardiomyopathy and chamber dilation combined with systolic dysfunction.[21] In adult muscle, desmin forms a scaffold around the Z-disk of the sarcomere and connects the Z-disk to the subsarcolemmal cytoskeleton.[22] It links the myofibrils laterally by connecting the Z-disks.[12] Through its connection to the sarcomere, desmin connects the contractile apparatus to the cell nucleus, mitochondria, and post-synaptic areas of motor endplates.[12] These connections maintain the structural and mechanical integrity of the cell during contraction while also helping in force transmission and longitudinal load bearing.[22][23]

In human heart failure, desmin expression is upregulated, which has been hypothesized to be a defense mechanism in an attempt to maintain normal sarcomere alignment amidst disease pathogenesis.[24] There is some evidence that desmin may also connect the sarcomere to the extracellular matrix (ECM) through desmosomes which could be important in signalling between the ECM and the sarcomere which could regulate muscle contraction and movement.[23] Finally, desmin may be important in mitochondria function. When desmin is not functioning properly there is improper mitochondrial distribution, number, morphology and function.[25][26] Since desmin links the mitochondria to the sarcomere it may transmit information about contractions and energy need and through this regulate the aerobic respiration rate of the muscle cell.

Clinical significance

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Desmin-related myofibrillar myopathy (DRM or desminopathy) is a subgroup of the myofibrillar myopathy diseases [27] and is the result of a mutation in the gene that codes for desmin which by changing the protein structure [28] prevents it from forming protein filaments, and rather, forms aggregates of desmin and other proteins throughout the cell.[8][12] Desmin (DES) mutations have been associated with restrictive,[29] dilated,[30][31] idiopathic,[32][33] arrhythmogenic [34][35][36][37] and non-compaction cardimyopathy.[38][39] Even within the same family the observed cardiac phenotype could be broad and diverse. The N-terminal part of the 1A desmin subdomain is a genetic hot spot region for mutations affecting filament assembly.[40][41] Some of these DES mutations cause an aggregation of desmin within the cytoplasm.[41][42][43] Some mutations like p.A120D or p.R127P were discovered in families, where several members had sudden cardiac death.[44] In addition, DES mutations cause frequently cardiac conduction diseases.[45]

Desmin has been evaluated for role in assessing the depth of invasion of urothelial carcinoma in TURBT specimens.[46]

References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
Desmin is a muscle-specific type III intermediate filament protein encoded by the DES gene located on the long arm of chromosome 2 (2q35) in humans, consisting of 470 amino acids with a molecular weight of approximately 53 kDa. It forms a crucial cytoskeletal scaffold in skeletal, cardiac, and smooth muscle cells, surrounding Z-discs in striated muscles and dense bodies in smooth muscles to link myofibrils to the plasma membrane, nucleus, mitochondria, and other organelles, thereby ensuring mechanical stability, force transmission during contraction, and overall muscle integrity. Expressed early in myogenesis and highly abundant in differentiated muscle tissues—such as 2% of total protein in cardiac muscle and 0.35% in skeletal muscle—desmin is regulated by multiple transcription factors and plays a key role in sarcomere organization, mitochondrial function, and proteostasis. Structurally, desmin features a conserved central α-helical rod domain (residues 83–423) divided into subdomains (1A, 1B, 2A, 2B) separated by linker regions (L1 and L2), flanked by an N-terminal head domain rich in sites and a C-terminal tail domain that facilitates interactions with other proteins. This architecture enables desmin monomers to dimerize, tetramerize, and assemble into 10-nm-wide intermediate filaments that interconnect the contractile apparatus with the via costameres and intercalated discs. In desmin-deficient models, such as mice, progressive skeletal , , and impaired force transmission emerge postnatally, underscoring its indispensable role in and function. Mutations in the DES gene, including missense variants (e.g., R350P, A337P) and deletions, disrupt filament assembly and lead to desmin-related myopathies, a spectrum of disorders collectively known as desminopathies. These include autosomal dominant or recessive myofibrillar myopathy type 1 (MFM1), characterized by protein aggregates, muscle weakness, and respiratory failure; familial dilated cardiomyopathy 1I (CMD1I); arrhythmogenic right ventricular cardiomyopathy; restrictive cardiomyopathy; and rare conditions like Kaeser syndrome, which affects proximal and distal muscles. Such genetic changes often result in cytoplasmic aggregates, compromised Z-disc integrity, and cardiac conduction defects, highlighting desmin's clinical significance in neuromuscular and cardiovascular health.

Genetics and Biosynthesis

Gene Characteristics

The DES gene, which encodes the muscle-specific intermediate filament protein desmin, is located on the long arm of human chromosome 2 at band q35 (2q35). Orthologs of the DES gene are present in other vertebrates, including mice (Des on chromosome 1) and rats, reflecting its essential role in muscle structure across species. The gene structure comprises 9 exons spanning approximately 8.4 kb of genomic DNA, with introns ranging from 0.1 to 2.2 kb in length; these exons collectively encode a 470-amino-acid protein. The overall gene sequence shows high evolutionary conservation among vertebrates, with particularly preserved regions in the exon sequences corresponding to functional domains essential for filament assembly. Transcriptional regulation of the DES is governed by promoter elements, including a classical and associated initiation sites approximately 400 base pairs upstream of the transcription start site, which direct basal expression. A muscle-specific enhancer, spanning 280 base pairs between -693 and -973 base pairs upstream, is critical for high-level, tissue-restricted expression in skeletal and . Additional regulatory elements, such as conserved DNase I hypersensitive sites within a locus control region (LCR), facilitate long-range enhancement and integration with ubiquitous factors to modulate transcription across muscle types.

Expression and Regulation

Desmin is predominantly expressed in striated muscle cells, including skeletal and cardiac myocytes, as well as in cells, where it forms a key component of the network essential for cellular integrity. This tissue-specific pattern underscores its role as a muscle-selective marker, with expression levels significantly higher in these cell types compared to others. Low levels of desmin have also been detected in certain non-muscle cells, such as endothelial cells and , though these do not constitute primary sites of accumulation. During development, desmin expression is dynamically upregulated in the context of , initiating in committed myoblasts as one of the earliest indicators of myogenic differentiation and progressively increasing to peak levels in mature myofibers. This temporal pattern aligns with the transition from proliferating myoblasts to fusing myotubes, where desmin precedes the expression of many other muscle-specific proteins, facilitating cytoskeletal reorganization during muscle formation. In embryonic and regenerative contexts, desmin transcripts and protein become detectable shortly after myoblast commitment, supporting subsequent assembly and force transmission. The regulation of desmin expression at the transcriptional level involves key muscle-specific transcription factors, including MyoD, myogenin, and members of the MEF2 family, which bind to conserved E-box and MEF2 sites within the desmin promoter and enhancer regions to drive tissue-specific activation. These factors synergize to ensure high-level expression during myogenic commitment and differentiation, with MyoD initiating early transcription and MEF2 contributing to sustained activity in maturing muscle cells. Epigenetic mechanisms further fine-tune this process; for instance, acetylation of histones H3 and H4, along with dimethylation and trimethylation of histone H3 at lysine 4 (H3K4me2 and H3K4me3), are enriched at the desmin locus control region and promoter in myoblasts and myotubes, promoting an open chromatin conformation conducive to transcription. In contrast, repressive marks like H3K27me3 predominate in non-expressing cells, silencing the gene. Post-transcriptional regulation of desmin also plays a critical role in modulating its protein levels, particularly through microRNA-mediated mechanisms that influence stability and translation efficiency. For example, miR-21 indirectly downregulates desmin protein levels by targeting YOD1, a , thereby promoting desmin ubiquitination and degradation via the ubiquitin-proteasome pathway during infection in cardiomyocytes. Similarly, miR-338-3p directly targets desmin mRNA to suppress its levels, thereby promoting phenotypic shifts in vascular cells. These interactions allow for rapid adjustments in desmin abundance without altering transcriptional rates, contributing to adaptive responses in muscle and disease.

Molecular Structure

Primary Sequence and Domains

Desmin, a type III protein, consists of a primary sequence comprising 470 residues in humans, with a calculated molecular weight of approximately 53.6 kDa and an of 5.21. This sequence features a tripartite domain organization typical of proteins, enabling its structural and functional roles in muscle cells. The N-terminal head domain spans residues 1-82 and is non-helical, rich in basic , and involved in regulating filament dynamics through interactions that influence assembly and disassembly. The central rod domain, encompassing residues 83-423 and divided into subdomains (1A, 1B, 2A, 2B) separated by linker regions (L1 and L2), forms an α-helical coiled-coil structure approximately 310-340 residues long, which is crucial for parallel dimerization and subsequent filament elongation via staggered antiparallel tetramer formation. The C-terminal domain, residues 424-470, is also non-helical and globular, facilitating lateral associations between protofilaments to stabilize higher-order filament structures. Post-translational modifications, particularly , occur predominantly in the head and tail domains and modulate desmin's and filament assembly. (PKC) phosphorylates serine residues such as Ser-12, Ser-38, and Ser-56 within the head domain, while (PKA) targets sites like Ser-6, Ser-27, and Ser-31, both of which inhibit and promote filament disassembly . Similar phosphorylation events in the tail domain further alter , allowing dynamic responses to cellular signals. As a type III protein, desmin exhibits of approximately 50-60% with other family members, including (mesenchymal cells) and (GFAP; glial cells), particularly in the conserved rod domain where identity reaches up to 70%.

Filament Formation

Desmin, a type III protein, assembles through a hierarchical process that begins with the , a single polypeptide chain featuring a central α-helical rod domain flanked by non-α-helical head and tail domains. The initial step involves the formation of a parallel coiled-coil dimer, where two desmin monomers align via hydrophobic interactions between their rod domains, particularly involving conserved heptad repeats in the coil segments that stabilize the dimer structure. This dimerization is driven primarily by the rod domain's hydrophobic residues, ensuring a stable, elongated unit approximately 46 nm in length. Subsequent assembly progresses to the tetramer, the fundamental soluble building block of desmin filaments, formed by the antiparallel, staggered association of two dimers in a head-to-tail overlap configuration. This arrangement, often described as half-staggered, positions the rod domains to overlap corresponding to the lengths of subdomains such as coil 1B and coil 2B (approximately 16-22 nm in staggered configurations), facilitating lateral and longitudinal interactions through electrostatic and hydrophobic contacts that prevent aggregation and promote ordered . Tetramers then align laterally to form protofilaments, which further associate into unit-length filaments (ULFs) of approximately 58-60 nm, serving as precursors for higher-order structures. The final stage yields the mature 10-nm through end-to-end annealing of ULFs, followed by radial compaction involving eight protofilaments, resulting in a rope-like with a diameter of 10-12 nm. , desmin polymerization is pH-dependent, occurring optimally at neutral (7.0-7.5) in buffers like 25 mM Tris-HCl with physiological salt concentrations (100-150 mM NaCl), conditions that mimic cellular environments and allow rapid assembly within minutes at 37°C. These parameters highlight the protein's sensitivity to , where low salt favors tetramer , and higher salt triggers filament elongation. Desmin filaments exhibit dynamic behavior, with turnover rates characterized by slow subunit exchange along the filament length in steady-state conditions. Disassembly is primarily triggered by phosphorylation of serine residues in the head domain by kinases such as (PKA) or (Cdk1), which disrupts head domain interactions and promotes into soluble oligomers, enabling cytoskeletal remodeling. This phosphorylation-dependent regulation ensures filament plasticity without compromising structural integrity under normal conditions.

Physiological Roles

Structural Integration in Muscle

Desmin plays a crucial role in the structural integration of the muscle by forming a network of intermediate filaments that anchors and aligns key cellular components, ensuring the mechanical stability of sarcomeres during contraction and relaxation. This network connects the Z-disks of adjacent myofibrils, the , the , and mitochondria, thereby maintaining the overall architecture of muscle cells and facilitating efficient force transmission. In skeletal and , desmin filaments link Z-disks laterally to prevent misalignment under tensile forces, while also tethering myofibrils to the through costamere structures, which distribute contractile stresses across the . These connections extend to the via interactions with the LINC complex and plectin, providing mechanotransduction support, and to mitochondria, positioning them optimally near the for ATP and calcium handling. In this way, desmin imparts tensile strength to resist contraction-induced deformation, regulating fiber volume and mechanical properties to avoid myofibrillar disarray. Desmin exhibits adaptations across muscle subtypes to suit their distinct architectures. In , it predominantly localizes to transverse costameres, reinforcing the lateral linkage of myofibrils to the and for high-force endurance activities. In , desmin concentrates at intercalated discs and desmosomes, forming transcellular networks that mechanically couple adjacent cardiomyocytes and stabilize Z-disks against cyclic hemodynamic loads. In , desmin serves as the primary , linking dense bodies (analogous to Z-disks) laterally and integrating the , though at lower abundance compared to striated muscles. Evidence from animal models underscores desmin's essential structural function. Desmin-null mice display severe disarray, with disrupted lateral alignment, impaired anchorage to the , and mislocalization of mitochondria and nuclei, leading to progressive , cardiomyocyte , and systolic dysfunction in both skeletal and cardiac tissues. These phenotypes highlight desmin's role in maintaining cytoskeletal integrity without which mechanical forces cause architectural failure and reduced contractile efficiency.

Interactions and Signaling

Desmin forms a complex network of interactions with various cytoskeletal and junctional proteins to maintain cellular architecture and facilitate force transmission in muscle cells. It binds to plectin, a cytolinker protein that connects s to microfilaments and , thereby integrating the desmin with other filament systems for enhanced structural stability. Desmin also associates with synemin and paranemin, accessory proteins that expand the network by promoting filament bundling and linkage to additional cellular components. At desmosomes, desmin interacts with desmoplakin, anchoring s to intercellular junctions and supporting mechanical cohesion in cardiomyocytes and fibers. In signaling contexts, desmin acts as a in mechanotransduction pathways, particularly by facilitating activation of the MAPK/ERK cascade in response to mechanical loading. Transverse stretching of muscle fibers, which desmin helps integrate through its lateral connections at Z-discs, preferentially activates ERK1/2 and downstream effectors like p90RSK and AP-1, linking cytoskeletal tension to gene expression changes for muscle adaptation. Additionally, desmin upregulation enhances integrin β1 expression, amplifying MAPK phosphorylation and cellular sensitivity to substrate stiffness, as observed in chondrogenic models where desmin knockdown impairs ERK signaling and remodeling. Desmin further influences mitochondrial dynamics and positioning through its interplay with Drp1-mediated fission; desmin filaments normally anchor mitochondria along myofibrils, but excessive Drp1 activity disrupts desmin assembly via phosphorylation at Ser-31, leading to mitochondrial redistribution toward subsarcolemmal regions and nuclear proximity. Phosphorylation of desmin serves as a key regulatory mechanism modulating its interactions under physiological stress. During acute resistance exercise, desmin at Ser-31 decreases, stabilizing filament networks and reducing susceptibility to disassembly, which supports adaptive remodeling in human skeletal muscle. In response to mechanical loading or , site-specific by kinases like Cdk-1 alters desmin's affinity for binding partners, enabling dynamic cytoskeletal reorganization while preserving overall network integrity.

Pathological Implications

Mutations and Mechanisms

Mutations in the DES gene, which encodes desmin, encompass a variety of types including missense, , and splice-site variants, with over 190 pathogenic or likely pathogenic variants reported as of 2025. Missense mutations are the most common, often occurring in the highly conserved rod domain; a representative example is the R350P substitution, which alters the at position 350 to in the 2B helical subdomain. mutations introduce premature stop codons leading to truncated proteins, while splice-site variants disrupt exon-intron boundaries, resulting in aberrant mRNA processing such as . These mutations predominantly exert dominant-negative effects, where mutant desmin interferes with the assembly of wild-type filaments, leading to their destabilization and aggregation into insoluble inclusions. Mechanisms include impaired dimerization and tetramerization due to structural disruptions in the rod domain, as well as altered sites that affect filament dynamics and solubility. Protein misfolding is a key consequence, promoting the formation of toxic aggregates that disrupt cytoskeletal integrity and trigger cellular stress responses. patterns vary, with autosomal dominant transmission being the most frequent (accounting for the majority of cases), alongside rarer autosomal recessive and sporadic (de novo) forms. DES mutations represent a significant genetic contributor within myofibrillar myopathies. Experimental studies provide direct evidence for these mechanisms; in vitro expression of mutant desmin, such as the R350P variant, results in the formation of insoluble aggregates that fail to assemble into proper intermediate filaments. Cellular models using transfected cell lines (e.g., SW13 or BHK-21 cells) demonstrate disrupted filament networks and perinuclear accumulation of aggregates when expressing desmin mutants, highlighting the dominant-negative interference with endogenous filament organization.

Disease Manifestations and Diagnosis

Desminopathies encompass a spectrum of rare inherited disorders primarily affecting skeletal and cardiac muscles due to mutations in the DES gene, manifesting as myofibrillar myopathies with variable involvement of these systems. Skeletal muscle involvement typically presents as progressive weakness, often beginning distally in the lower limbs (such as foot drop) and spreading proximally to involve the thighs, trunk, neck flexors, and occasionally facial muscles, leading to gait disturbances, frequent falls, and eventual wheelchair dependence in severe cases. Cardiac manifestations include restrictive or dilated cardiomyopathy, conduction system defects (e.g., atrioventricular blocks), and arrhythmias, which can result in palpitations, syncope, chronic heart failure, or sudden cardiac death. Multisystem features may also occur, such as respiratory muscle weakness causing nocturnal hypoventilation that progresses to daytime respiratory failure, requiring ventilatory support. The age of onset varies widely, from infancy or childhood in recessive forms to the second or third decade in dominant cases, with progression being slowly relentless and influenced by and sex—males often experiencing more severe cardiac outcomes. Early symptoms may include or mild weakness, evolving over years to profound ; for instance, skeletal affects approximately 55% of patients, either in isolation or combined with cardiac issues, while major adverse cardiac events like ventricular arrhythmias or occur in over half of cases, with a onset around 36 years. Respiratory complications and sudden death further contribute to morbidity, with overall prognosis poor in advanced stages, though phenotypic variability allows some individuals to remain until late adulthood. Epidemiologically, desminopathies are rare, with an unknown exact prevalence but estimated to account for 1-2% of cases and less than 1% of all skeletal myopathies; they exhibit autosomal dominant inheritance in approximately 70% of cases, with recessive forms rarer and often more severe. Higher incidence has been noted in certain populations due to founder effects, though global cases remain sporadic and underdiagnosed due to phenotypic overlap with other myopathies. Diagnosis relies on a combination of clinical , histopathological findings, , and genetic confirmation. Muscle is a , revealing characteristic intracellular aggregates of desmin and other proteins, often with granulofilamentous material on , alongside dystrophic changes like fiber size variation, vacuoles, and fatty infiltration. Genetic sequencing of the DES identifies pathogenic variants in up to 100% of confirmed cases, confirming the when correlated with family history. Cardiac assessment via (ECG) detects conduction abnormalities or arrhythmias, while or cardiac MRI evaluates ; skeletal muscle MRI highlights selective and fatty replacement patterns, such as early involvement of calf and posterior muscles, aiding in distinguishing desminopathy from mimics like other distal myopathies.

References

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