The Role of Ellis‐Van Creveld 2(EVC2) in Mice During Cranial Bone Development

EvC syndrome is a type of autosomal‐recessive chondrodysplasia. Previous case studies in patients suggest abnormal craniofacial development, in addition to dwarfism and tooth abnormalities. To investigate how craniofacial development is affected in EvC patients, surface models were generated from micro‐CT scans of control mice, Evc2 global mutant mice and Evc2 neural crest‐specific mutant mice. The anatomic landmarks were placed on the surface model to assess the morphological abnormalities in the Evc2 mutants. Through analyzing the linear and angular measurements between landmarks, we identified a smaller overall skull, shorter nasal bone, shorter frontal bone, and shorter cranial base in the Evc2 global mutants. By comparing neural crest‐specific Evc2 mutants with control mice, we demonstrated that the abnormalities within the mid‐facial regions are not accounted for by the Evc2 mutation within these regions. Additionally, we also identified disproportionate length to width ratios in the Evc2 mutants at all levels from anterior to posterior of the skull. Overall, this study demonstrates a more comprehensive analysis on the craniofacial morphological abnormalities in EvC syndrome and provides the developmental insight to appreciate the impact of Evc2 mutation within the neural crest cells on multiple aspects of skull deformities. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:46–55, 2018. © 2017 Wiley Periodicals, Inc.     

Expression of the Ellis-van Creveld (Evc) gene in the rat tibial growth plate

Ellis-van Creveld (EvC) syndrome is an autosomal recessive chondrodysplasia characterized by short limbs, postaxial polydactyly, natal teeth, and dysplastic nails. The Ellis-van Creveld (EVC) gene, which is mutated in patients with EvC syndrome, has been identified by positional cloning. However, the physiological roles of the EVC gene have not been elucidated. Histopathological analyses of EvC syndrome have shown disturbed chondrocytic phenotypes during cartilage development. We therefore postulated that the EVC gene is a critical factor for chondrocytes during endochondral ossification. The present study focuses on the relationship between the Evc gene and chondrocytes, and examines Evc gene expression in the rat tibial growth plate at the mRNA and protein levels. Evc mRNA in tibial epiphyseal cartilage was expressed at postnatal day (P) 1, P28, and P56 by RT-PCR. Immunohistochemical analyses localized the Evc protein mainly in prehypertrophic and hypertrophic chondrocytes of the epiphyseal growth plate in the tibia during the embryonic and postnatal periods. Evc mRNA was also detected in prehypertrophic and hypertrophic chondrocytes by in situ hybridization. These results indicate that the Evc gene functions mainly in the prehypertrophic and hypertrophic chondrocytes of the epiphyseal growth plate. The data presented here are important for future studies of the underlying mechanism of chondrodysplasia in EvC syndrome.     

Role of primary cilia and Hedgehog signaling in craniofacial features of Ellis–van Creveld syndrome

Ellis–van Creveld syndrome (EvC) is an autosomal recessive genetic disorder involving pathogenic variants of EVC and EVC2 genes and classified as a ciliopathy. The syndrome is caused by mutations in the EVC gene on chromosome 4p16, and EVC2 gene, located close to the EVC gene, in a head-to-head configuration. Regardless of the affliction of EVC or EVC2, the clinical features of Ellis–van Creveld syndrome are similar. Both these genes are expressed in tissues such as, but not limited to, the heart, liver, skeletal muscle, and placenta, while the predominant expression in the craniofacial tissues is that of EVC2. Biallelic mutations of EVC and EVC2 affect Hedgehog signaling and thereby ciliary function, crucial factors in vertebrate development, culminating in the phenotypical features characteristic of EvC. The clinical features of Ellis–van Creveld syndrome are consistent with significant abnormalities in morphogenesis and differentiation of the affected tissues. The robust role of primary cilia in histodifferentiation and morphodifferentiation of oral, perioral, and craniofacial tissues is becoming more evident in the most recent literature. In this review, we give a summary of the mechanistic role of primary cilia in craniofacial development, taking Ellis–van Creveld syndrome as a representative example.     

Biallelic mutations in DYNC2LI1 are a rare cause of Ellis‐van Creveld syndrome

Ellis‐van Creveld syndrome (EvC) is a chondral and ectodermal dysplasia caused by biallelic mutations in the EVC, EVC2 and WDR35 genes. A proportion of cases with clinical diagnosis of EvC, however, do not carry mutations in these genes. To identify the genetic cause of EvC in a cohort of mutation‐negative patients, exome sequencing was undertaken in a family with 3 affected members, and mutation scanning of a panel of clinically and functionally relevant genes was performed in 24 additional subjects with features fitting/overlapping EvC. Compound heterozygosity for the c.2T>C (p.Met1?) and c.662C>T (p.Thr221Ile) variants in DYNC2LI1, which encodes a component of the intraflagellar transport‐related dynein‐2 complex previously found mutated in other short‐rib thoracic dysplasias, was identified in the 3 affected members of the first family. Targeted resequencing detected compound heterozygosity for the same missense variant and a truncating change (p.Val141*) in 2 siblings with EvC from a second family, while a newborn with a more severe phenotype carried 2 DYNC2LI1 truncating variants. Our findings indicate that DYNC2LI1 mutations are associated with a wider clinical spectrum than previously appreciated, including EvC, with the severity of the phenotype likely depending on the extent of defective DYNC2LI1 function.     

Two novel heterozygous mutations of EVC2 cause a mild phenotype of Ellis-van Creveld syndrome in a Chinese family

Ellis–van Creveld syndrome (EvC, chondroectodermal dysplasia; OMIM 225500) is an autosomal recessive skeletal dysplasia with associated multisystem involvement. The syndrome is characterized by short limbs, short ribs, postaxial polydactyly, dysplastic nails, and abnormal teeth. Congenital heart defects occur in 50–60% of cases. In this study, we report EvC in a 6‐year‐old Chinese girl with hypodontia and polydactyly, mild short stature, and abnormalities of the knee joints. No signs of short ribs, narrow thorax, or congenital heart defects were found in this patient. The EvC phenotype shares some similarity with Weyers acrofacial dysostosis (Weyer; OMIM 193530), an autosomal dominant disorder clinically characterized by mild short stature, postaxial polydactyly, nail dystrophy, and dysplastic teeth. Mutations in EVC or EVC2 are associated with both EvC syndrome and Weyers acrodental dysostosis, but the two conditions differ in the severity of the phenotype and their pattern of inheritance. In this study, two novel heterozygous EVC2 mutations, IVS5‐2A > G and c.2653C > T (Arg885X), were identified in the patient. The IVS5‐2A > G mutation was inherited from the patient's mother and the c.2653C > T from her father. Her parents have no phenotypic symptoms similar to those of the patient. These findings extend the mutation spectrum of this malformation syndrome and provide the possibility of prenatal diagnosis for future offspring in this family. © 2011 Wiley‐Liss, Inc.     

Masticatory HyperMuscularity is not Related to Reduced Cranial Volume in Myostatin‐Knockout Mice

It has been suggested recently that masticatory muscle size reduction in humans resulted in greater encephalization through decreased compressive forces on the cranial vault. Following this logic, if masticatory muscle size were increased, then a reduction in brain growth should also occur. This study was designed to test this hypothesis using a myostatin (GDF‐8) knockout mouse model. Myostatin is a negative regulator of skeletal muscle growth, and individuals lacking this gene show significant hypermuscularity. Sixty‐two [32 wild‐type (WT) and 30 GDF‐8 ‐/‐ knockout], 1, 28, 56, and 180‐day‐old CD‐1 mice were used. Body and masseter muscle weights were collected following dissection and standardized lateral and dorsoventral cephalographs were obtained. Cephalometric landmarks were identified on the radiographs and cranial volume was calculated. Mean differences were assessed using a two‐way ANOVA. KO mice had significantly greater body and masseter weights beginning at 28 days compared with WT controls. No significant differences in cranial volumes were noted between KO and WT. Muscle weight was not significantly correlated with cranial volume in 1, 28, or 180‐day‐old mice. Muscle weights exhibited a positive correlation with cranial volume at 56 days. Results demonstrate that masticatory hypermuscularity is not associated with reduced cranial volume. In contrast, there is abundant data demonstrating the opposite, brain growth determines cranial vault growth and masticatory apparatus only affects ectocranial morphology. The results presented here do not support the hypothesis that a reduction in masticatory musculature relaxed compressive forces on the cranial vault allowing for greater encephalization. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Widening the mutation spectrum of EVC and EVC2: ectopic expression of Weyer variants in NIH 3T3 fibroblasts disrupts hedgehog signaling

Autosomal recessive Ellis-van Creveld syndrome and autosomal dominant Weyer acrodental dysostosis are allelic conditions caused by mutations in EVC or EVC2. We performed a mutation screening study in 36 EvC cases and 3 cases of Weyer acrodental dysostosis, and identified pathogenic changes either in EVC or in EVC2 in all cases. We detected 40 independent EVC/EVC2 mutations of which 29 were novel changes in Ellis-van Creveld cases and 2 were novel mutations identified in Weyer pedigrees. Of interest one EvC patient had a T>G nucleotide substitution in intron 7 of EVC (c.940−150T>G), which creates a new donor splice site and results in the inclusion of a new exon. The T>G substitution is at nucleotide +5 of the novel 5′ splice site. The three Weyer mutations occurred in the final exon of EVC2 (exon 22), suggesting that specific residues encoded by this exon are a key part of the protein. Using murine versions of EVC2 exon 22 mutations we demonstrate that the expression of a Weyer variant, but not the expression of a truncated protein that mimics an Ellis-van Creveld syndrome mutation, impairs Hedgehog signal transduction in NIH 3T3 cells in keeping with its dominant effect. Hum Mutat 30:1–9, 2009. © 2009 Wiley-Liss, Inc.     

Nasal Septal and Premaxillary Developmental Integration: Implications for Facial Reduction in Homo

The influence of the chondrocranium in craniofacial development and its role in the reduction of facial size and projection in the genus Homo is incompletely understood. As one component of the chondrocranium, the nasal septum has been argued to play a significant role in human midfacial growth, particularly with respect to its interaction with the premaxilla during prenatal and early postnatal development. Thus, understanding the precise role of nasal septal growth on the facial skeleton is potentially informative with respect to the evolutionary change in craniofacial form. In this study, we assessed the integrative effects of the nasal septum and premaxilla by experimentally reducing facial length in Sus scrofa via circummaxillary suture fixation. Following from the nasal septal‐traction model, we tested the following hypotheses: (1) facial growth restriction produces no change in nasal septum length; and (2) restriction of facial length produces compensatory premaxillary growth due to continued nasal septal growth. With respect to hypothesis 1, we found no significant differences in septum length (using the vomer as a proxy) in our experimental (n = 10), control (n = 9) and surgical sham (n = 9) trial groups. With respect to hypothesis 2, the experimental group exhibited a significant increase in premaxilla length. Our hypotheses were further supported by multivariate geometric morphometric analysis and support an integrative relationship between the nasal septum and premaxilla. Thus, continued assessment of the growth and integration of the nasal septum and premaxilla is potentially informative regarding the complex developmental mechanisms that underlie facial reduction in genus Homo evolution. Anat Rec, 2010. © 2010 Wiley‐Liss, Inc.     

Craniofacial morphology of the tricho-dento-osseous syndrome

Tricho-dento-osseous syndrome (TDO) is characterized by abnormal bone, hair, and tooth morphology. However, the reported craniofacial abnormalities are not well characterized. The purpose of this study was to compare the craniofacial parameters of 25 subjects affected with TDO (A) with those of 15 unaffected relatives (U). Standardized lateral cephalograms were traced and digitized. Each subject's data were compared by age and sex to cephalometric standards (Bolton, Behrents); severity was scored by standard deviations from the standard mean, and then grouped into A vs. U. All cephalograms were evaluated for frontal sinuses, mastoid pneumatization, diploe, and bone density, and cranial thickness was measured. Cranial base length (SN; NBa), cranial base angle (BaSN), and mandibular body length (GoPg) were greater in A than in U (p < 0.05). Both groups had longer total and lower facial heights (NMe; ANSMe) compared with normal standards. Frontal sinuses, mastoid pneumatization and diploe were visible less often in A than in U (p < 0.05). Parietal bone and bone at lambda was significantly thicker (p < 0.05) in A than in U. Variability was substantial in many measures in both A and U. The major TDO craniofacial features involve the cranial base, mandibular body length, absence of visible pneumatized mastoids, frontal sinuses and diploe, and thicker cranial bone.     

Comparison of Dentoalveolar Morphology in WT and P2X7R KO Mice for the Development of Biomechanical Orthodontic Models

It has been suggested that the absence of the P2X7 receptor affects long bone morphology, and that one of the cytokines dependent on its activation may also affect tooth morphology. P2X7R KO (knockout) were compared with C57B/6 WT mice (background strain) to identify differences in a maxillary molar and surrounding bone. Nineteen WT and 12 KO mouse maxillae were scanned and 3D‐reconstructed using microCT. Tooth dimensions were measured and 3D bone morphometry was conducted. A finite element model was constructed based on the results. No statistically significant differences were found in dentoalveolar characteristics between the two mouse types. A single finite element model of the tooth can be used to mechanically represent both strains. P2X7R does not have a major effect on alveolar bone or tooth morphology. The P2X7R effects are site‐specific. Anat Rec, 2009. © 2008 Wiley‐Liss, Inc.     

Secular change in craniofacial morphology

Five craniofacial variables (glabella–occipital length, basion–bregma height, maximum cranial breadth, nasion–prosthion height, and bizygomatic breadth) were used to examine secular change in morphology from the mid-19^th century to the 1970s. The 19^th century data were obtained from the Terry and Hamann-Todd anatomical collections, and the 20^th century data were obtained from the forensic anthropology databank. Data were available for Blacks and Whites of both sexes. Secular change was evaluated by regressing cranial variables on year of birth. Two analyses were conducted, one using the original variables and one using size and shape. Size is defined as the geometric mean of the cranial variables, and shape is the ratio of each variable to size. The results show remarkable changes in the size and shape of the cranial vault. Vault height increases in all groups in both absolute and relative terms. The vault also becomes longer and narrower, but these changes are less pronounced. Face changes are less than the vault changes, but to the extent that they occur, the face becomes narrower and higher. Overall cranial vault size has increased, but shape changes are greater than size changes. The magnitude of secular change in vault height exceeds that for long bones over a comparable time period, but follows a similar course, which suggests that vault height and bone length respond to the same forces. Changes in vault dimensions must occur by early childhood because of the early development of the vault. Am. J. Hum. Biol. 12:327–338, 2000. © 2000 Wiley-Liss, Inc.     

EVC、EVC2基因的研究进展

Ellis-van Creveld综合症（EvC）是一种常染色体隐性遗传病,临床主要表现为短肢、短肋、轴后多指（趾）、牙齿及指（趾）甲发育不良,口腔系带异常增多,心脏房室隔缺损和单个心房。EvC具有遗传异质性,由EVC或EVC2基因突变引起。Weyers acrodental dysostosis作为一种常染色体显性遗传病,具有相似的临床表现和等位的遗传异质性。现将EVC、EVC2基因与这两种遗传病的关系及最新研究进展作一综述。     

Molecular and clinical analysis of Ellis-van Creveld syndrome in the United Arab Emirates

Background  

Ellis-van Creveld (EvC) syndrome is an autosomal recessive chondrodysplastic condition with clinical manifestations that include short-limbs and ribs, postaxial polydactyly and dysplastic nails and teeth. In about two thirds of patients, mutations in either EVC or EVC2 genes have been found to be the underlying cause.     

Maternal environment and craniofacial growth: geometric morphometric analysis of mandibular shape changes with in utero thyroxine overexposure in mice

An estimated 3% of US pregnancies are affected by maternal thyroid dysfunction, with between one and three of every 1000 pregnancies being complicated by overactive maternal thyroid levels. Excess thyroid hormones are linked to neurological impairment and excessive craniofacial variation, affecting both endochondral and intramembranous bone. Using a geometric morphometric approach, this study evaluates the role of in utero thyroxine overexposure on the growth of offspring mandibles in a sample of 241 mice. Canonical variate analysis utilized 16 unilateral mandibular landmarks obtained from 3D micro‐computed tomography to assess shape changes between unexposed controls (n = 63) and exposed mice (n = 178). By evaluating shape changes in the mandible among three age groups (15, 20 and 25 days postnatal) and different dosage levels (low, medium and high), this study found that excess maternal thyroxine alters offspring mandibular shape in both age‐ and dosage‐dependent manners. Group differences in overall shape were significant (P < 0.001), and showed major changes in regions of the mandible associated with muscle attachment (coronoid process, gonial angle) and regions of growth largely governed by articulation with the cranial base (condyle) and occlusion (alveolus). These results compliment recent studies demonstrating that maternal thyroxine levels can alter the cranial base and cranial vault of offspring, contributing to a better understanding of both normal and abnormal mandibular development, as well as the medical implications of craniofacial growth and development.     

Trigonocephaly in rabbits with familial interfrontal suture synostosis: The multiple effects of premature single‐suture fusion

Previous studies from our laboratory have characterized the craniofacial morphology and growth patterns of an inbred strain of rabbits with autosomal dominant coronal suture synostosis. A number of rabbit perinates from this colony have been collected sporadically over a 5‐year period with premature interfrontal suture synostosis. The present study describes the very early onset of craniofacial dysmorphology of these rabbits and compares them to similar‐aged normal control rabbits. A total of 40 perinatal New Zealand White rabbits were used in the present study. Twenty‐one comprised the sample with interfrontal suture synostosis and ranged in age from 27 to 38 days postconception (term = 31 days) with a mean age of 33.53 days (±2.84 days). Nineteen rabbits served as age‐matched, normal controls (mean age = 33.05 days ±2.79 days). Lateral and dorsoventral radiographs were collected from each rabbit. The radiographs were traced, computer digitized, and 12 craniofacial measurements, angles, and indices were obtained. Mean measures were compared using an unpaired Student's t‐test. All synostosed rabbits were stillborn or died shortly after birth. Grossly, these rabbits exhibited extreme frontal bossing, trigonocephaly with sagittal keeling, and midfacial shortening. No somatic anomalies were noted. Radiographically, rabbits with interfrontal suture synostosis had significantly (P < 0.05) narrower bifrontal widths, shorter cranial vault lengths, kyphotic cranial base angles, and different cranial vault indices (shapes) compared to controls. Results reveal severe and early pathological and compensatory cranial vault changes associated with premature interfrontal suture synostosis in this rabbit model. The 100% mortality rate noted in this condition may be related to the inheritance of a lethal genetic mutation or to neural compression from reduced intracranial volume. Results are discussed in light of current pathogenic hypotheses for human infants with premature metopic suture synostosis. Anat Rec 260:238–251, 2000. © 2000 Wiley‐Liss, Inc.     

Feasibility of real‐time cardiac MRI in mice using tiny golden angle radial sparse

Cardiovascular magnetic resonance imaging has proven valuable for the assessment of structural and functional cardiac abnormalities. Even although it is an established imaging method in small animals, the long acquisition times of gated or self‐gated techniques still limit its widespread application. In this study, the application of tiny golden angle radial sparse MRI (tyGRASP) for real‐time cardiac imaging was tested in 12 constitutive nexilin (Nexn) knock‐out (KO) mice, both heterozygous (Het, N = 6) and wild‐type (WT, N = 6), and the resulting functional parameters were compared with a well‐established self‐gating approach. Real‐time images were reconstructed for different temporal resolutions of between 16.8 and 79.8 ms per image. The suggested approach was additionally tested for dobutamine stress and qualitative first‐pass perfusion imaging. Measurements were repeated twice within 2 weeks for reproducibility assessment. In direct comparison with the high‐quality, self‐gated technique, the real‐time approach did not show any significant differences in global function parameters for acquisition times below 50 ms (rest) and 31.5 ms (stress). Compared with WT, the end‐diastolic volume (EDV) and end‐systolic volume (ESV) were markedly higher (P < 0.05) and the ejection fraction (EF) was significantly lower in the Het Nexn‐KO mice at rest (P < 0.001). For the stress investigation, a clear decrease of EDV and ESV, and an increase in EF, but maintained stroke volume, could be observed in both groups. Combined with ECG‐triggering, tyGRASP provided first‐pass perfusion data with a temporal resolution of one image per heartbeat, allowing the quantitative assessment of upslope curves in the blood‐pool and myocardium. Excellent inter‐study reproducibility was achieved in all the functional parameters. The tyGRASP is a valuable real‐time MRI technique for mice, which significantly reduces the scan time in preclinical cardiac functional imaging, providing sufficient image quality for deriving accurate functional parameters, and has the potential to investigate real‐time and beat‐to‐beat changes.     

Long interspersed nuclear element-1 (LINE1)-mediated deletion of EVC, EVC2, C4orf6, and STK32B in Ellis-van Creveld syndrome with borderline intelligence

Previous work has shown Ellis-van Creveld (EvC) patients with mutations either in both alleles of EVC or in both alleles of EVC2. We now report affected individuals with the two genes inactivated on each allele. In a consanguineous pedigree diagnosed with EvC and borderline intelligence, we detected a 520-kb homozygous deletion comprising EVC, EVC2, C4orf6, and STK32B, caused by recombination between long interspersed nuclear element-1 (LINE-1 or L1) elements. Patients homozygous for the deletion are deficient in EVC and EVC2 and have no increase in the severity of the EvC typical features. Similarly deletion carriers demonstrate absence of digenic inheritance in EvC. Further, the phenotype of these patients suggests that the EVC-STK32B deletion also leads to mild mental retardation and reveals that loss of the novel genes C4orf6 and STK32B causes at most mild mental deficit. In an EvC compound heterozygote of different ethnic origin we identified the same LINE-to-LINE rearrangement due to a different recombination event. These findings highlight the importance of L1 repetitive sequences in human genome architecture and disease.     

Suppressive and pro‐inflammatory roles for IL‐4 in the pathogenesis of experimental drug‐induced liver injury

The pathogenesis of immune‐mediated drug‐induced liver injury (DILI) following halogenated anesthetics, carbamazepine or alcohol has not been fully elucidated. Detecting cytochrome P450 2E1 (CYP2E1) IgG4 auto‐antibodies in anesthetic DILI patients suggests a role for IL‐4 in this hapten‐mediated process. We investigated IL‐4‐mediated mechanisms using our model of experimental DILI induced by immunizing BALB/c (WT) and IL‐4^?/? (KO) mice with S100 liver proteins covalently modified by a trifluoroacetyl chloride (TFA) hapten formed following halogenated anesthetic metabolism by CYP2E1. WT mice developed more hepatitis, TFA and S100 antibodies (p<0.01), as well as T‐cell proliferation to CYP2E1 and TFA (p<0.01) than KO mice. Additionally, WT CD4⁺ T cells adoptively transferred hepatitis to naïve Rag^?/? mice (p<0.01). Pro‐inflammatory cytokines were expectedly decreased in TFA hapten‐stimulated KO splenocyte supernatants (p<0.001); however, IL‐2 and IFN‐γ (p<0.05), as well as IL‐6 and IL‐10 (p<0.001) levels were elevated in CYP2E1‐stimulated KO splenocyte supernatants, suggesting dual IL‐4‐mediated pro‐inflammatory and regulatory responses. Anti‐IL‐10 administered to KO mice increased hepatitis, TFA and CYP2E1 antibodies in KO mice confirming a critical role for IL‐4. This is the first demonstration of dual roles for IL‐4 in the pathogenesis of immune‐mediated DILI by suppressing auto‐antigen‐induced regulatory responses while promoting hapten‐induced pro‐inflammatory responses.     

Interleukin-6 modifies mRNA expression in mouse skeletal muscle

Aim: The aim of this study was to test the hypothesis that interleukin (IL)‐6 plays a role in exercise‐induced peroxisome proliferator‐activated receptor γ co‐activator (PGC)‐1α and tumor necrosis factor (TNF)‐α mRNA responses in skeletal muscle and to examine the potential IL‐6‐mediated AMP‐activated protein kinase (AMPK) regulation in these responses. Methods: Whole body IL‐6 knockout (KO) and wildtype (WT) male mice (4 months of age) performed 1 h treadmill exercise. White gastrocnemius (WG) and quadriceps (Quad) muscles were removed immediately (0′) or 4 h after exercise and from mice not run acutely. Results: Acute exercise reduced only in WT muscle glycogen concentration to 55 and 35% (P < 0.05) of resting level in Quad and WG respectively. While AMPK and Acetyl CoA carboxylase (ACC) phosphorylation increased 1.3‐fold (P < 0.05) in WG and twofold in Quad immediately after exercise in WT mice, no change was detected in WG in IL‐6 KO mice. The PGC‐1α mRNA content was in resting WG 1.8‐fold higher (P < 0.05) in WT mice than in IL‐6 KO mice. Exercise induced a delayed PGC‐1α mRNA increase in Quad in IL‐6 KO mice (12‐fold at 4 h) relative to WT mice (fivefold at 0′). The TNF‐α mRNA content was in resting Quad twofold higher (P < 0.05) in IL‐6 KO than in WT, and WG TNF‐α mRNA increased twofold (P < 0.05) immediately after exercise only in IL‐6 KO. Conclusion: In conclusion, IL‐6 affects exercise‐induced glycogen use, AMPK signalling and TNF‐α mRNA responses in mouse skeletal muscle.