Dyssegmental dysplasia Rolland-Desbuquois type is caused by pathogenic variants in HSPG2 - a founder haplotype shared in five patients.

Dyssegmental dysplasia (DD) is a severe skeletal dysplasia comprised of two subtypes: lethal Silverman-Handmaker type (DDSH) and nonlethal Rolland-Desbuquois type (DDRD). DDSH is caused by biallelic pathogenic variants in HSPG2 encoding perlecan, whereas the genetic cause of DDRD remains undetermined. Schwartz-Jampel syndrome (SJS) is also caused by biallelic pathogenic variants in HSPG2 and is an allelic disorder of DDSH. In SJS and DDSH, 44 and 8 pathogenic variants have been reported in HSPG2, respectively. Here, we report that five patients with DDRD carried four pathogenic variants in HSPG2: c.9970 G > A (p.G3324R), c.559 C > T (p.R187X), c7006 + 1 G > A, and c.11562 + 2 T > G. Two patients were homozygous for p.G3324R, and three patients were heterozygous for p.G3324R. Haplotype analysis revealed a founder haplotype spanning 85,973 bp shared in the five patients. SJS, DDRD, and DDSH are allelic disorders with pathogenic variants in HSPG2.

Impact of the heparan sulfate proteoglycan perlecan on human disease and health.

Perlecan, a basement membrane-type heparan sulfate proteoglycan, is an important molecule in the functional diversity of organisms because of the diversity of its glycan chains and the multifunctionality of its core proteins. Human diseases associated with perlecan have been identified using gene-deficient mice. Two human diseases related to perlecan have been reported. One is Silverman-Handmaker type dyssegmental dysplasia, resulting from the complete loss of function of the HSPG2 gene that encodes perlecan core protein, which is mapped to chromosome 1p36. The other is Schwartz-Jampel syndrome resulting from the partial loss of function of the HSPG2 gene. Subsequent in vivo and in vitro studies have revealed the organ-specific functions of perlecan, suggesting its involvement in the pathogenesis of various human diseases. In this review, we discuss the role of perlecan in human diseases and summarize our knowledge about perlecan as a future therapeutic target to treat related diseases and for healthy longevity.

Regulation of fractone heparan sulfate composition in young and aged subventricular zone neurogenic niches.

Fractones, specialized extracellular matrix structures found in the subventricular zone (SVZ) neurogenic niche, can capture growth factors, such as basic fibroblast growth factor, from the extracellular milieu through a heparin-binding mechanism for neural stem cell (NSC) presentation, which promotes neurogenesis. During aging, a decline in neurogenesis correlates with a change in the composition of heparan sulfate (HS) within fractones. In this study, we used antibodies that recognize specific short oligosaccharides with varying sulfation to evaluate the HS composition in fractones in young and aged brains. To further understand the conditions that regulate 6-O sulfation levels and its impact on neurogenesis, we used endosulfatase Sulf1 and Sulf2 double knockout (DKO) mice. Fractones in the SVZ of Sulf1/2 DKO mice showed immunoreactivity for the HS epitope, suggesting higher 6-O sulfation. While neurogenesis declined in the aged SVZ of both wild-type and Sulf1/2 DKO mice, we observed a larger number of neuroblasts in the young and aged SVZ of Sulf1/2 DKO mice. Together, these results show that the removal of 6-O-sulfation in fractones HS by endosulfatases inhibits neurogenesis in the SVZ. Our findings advance the current understanding regarding the extracellular environment that is best suited for NSCs to thrive, which is critical for the design of future stem cell therapies.

Increased Risk of Aortic Dissection with Perlecan Deficiency.

Perlecan (HSPG2), a basement membrane-type heparan sulfate proteoglycan, has been implicated in the development of aortic tissue. However, its role in the development and maintenance of the aortic wall remains unknown. Perlecan-deficient mice (Hspg2-/--Tg: Perl KO) have been found to show a high frequency (15-35%) of aortic dissection (AD). Herein, an analysis of the aortic wall of Perl KO mice revealed that perlecan deficiency caused thinner and partially torn elastic lamina. Compared to the control aortic tissue, perlecan-deficient aortic tissue showed a significant decrease in desmosine content and an increase in soluble tropoelastin levels, implying the presence of immature elastic fibers in Perl KO mice. Furthermore, the reduced expression of the smooth muscle cell contractile proteins actin and myosin in perlecan-deficient aortic tissue may explain the risk of AD. This study showed that a deficiency in perlecan, which is localized along the elastic lamina and at the interface between elastin and fibrillin-1, increased the risk of AD, largely due to the immaturity of extracellular matrix in the aortic tissue. Overall, we proposed a new model of AD that considers the deficiency of extracellular molecule perlecan as a risk factor.

Fibulin-7 is overexpressed in glioblastomas and modulates glioblastoma neovascularization through interaction with angiopoietin-1.

Glioblastoma (GBM) is pathologically characterized by highly malignant neoplastic cells, focal necrosis and aberrant blood vessels composed of disorganized endothelial cells and pericytes. The recent cancer microarray database revealed upregulation of fibulin-7 (Fbln7), a member of the fibulin family, but provided no information on the tissue localization or biological function. In the present study, we demonstrated that Fbln7 is markedly overexpressed by the GBM tissue among astrocytic tumors, and immunolocalized mainly to endothelial cells and pericytes of the glomeruloid and hypertrophied microvessels. The production of Fbln7 by endothelial cells and pericytes was confirmed in cultured human umbilical vein endothelial cells (HUVEC) and human brain vascular pericytes (HBVP) and vascular endothelial growth factor (VEGF) stimulated the Fbln7 expression in HUVEC. Fbln7 bound to angiopoietin-1, but not angiopoietin-2 or Tie2 receptor, through interaction between the N-terminal portions of Fbln7 and angiopoietin-1, and it blocked phosphorylation of Tie2 receptor in HUVEC. In a coculture assay using HUVEC and HBVP, multilayered and irregular-shaped tube-like structures of HUVEC were induced by treatment with a high concentration of VEGF. This was accompanied by Fbln7 overproduction by HUVEC and angiopoietin-1 expression by HBVP. The production of aberrant VEGF-induced tube-like structures was attenuated by treatment with antibody or synthetic peptides specific to the Fbln7 N-terminal domain or knockdown of Fbln7. These data demonstrate that Fbln7 is overexpressed by endothelial cells and pericytes of the abnormal microvessels in GBM, and suggest that Fbln7 may contribute to the aberrant vessel formation by modulation of the angiopoietin-1/angiopoietin-2-Tie2 axis.

A nationwide observational study of locomotive syndrome in Japan using the ResearchKit: The Locomonitor study.

BACKGROUND: We developed the Locomonitor application (app), the world's first iOS app to study locomotive syndrome, using the ResearchKit and examined the prevalence and risk factors for locomotive syndrome in Japanese general individuals 20-69 years old in a nationwide cross-sectional observational study. METHODS: The participants were recruited from February to August 2016. The outcome measures for the locomotive function were evaluated by locomotive syndrome risk tests (LSRTs) using the Locomonitor app. The chi-squared test, a linear-by-linear association trend analysis, and Spearman's correlation test were performed as statistical analyses. RESULTS: A total of 2177 subjects from all prefectures in Japan were included (average 42.2 years old). The Locomo25 and Stand-Up test scores in female participants and the Two-Step test scores in male participants showed age-dependent deterioration. In the overall population, the incidence of Locomo stage 1 and 2, as evaluated by the Locomo25, Stand-Up test or Two-Step test, was 30.2% and 29.2%, respectively. In subjects without locomotive syndrome (40.5%), LSRT scores showed age-dependent deterioration in both sexes. Locomotive syndrome in participants with a body mass index (BMI) of ≥25 kg/m2 was more frequent than in those with a BMI of <25 kg/m2 (age- and gender-adjusted odds ratio [OR] 1.344 [95% confidence interval {CI} 1.03-1.75, p = 0.027]). Locomotive syndrome in participants with an exercise habit was less frequent than in those without an exercise habit (age- and gender-adjusted OR 0.499 [95% CI 0.33-0.755, p < 0.0001]). CONCLUSIONS: The Locomonitor app, a newly developed remote platform, revealed that approximately 20%-30% of Japanese individuals 20-69 years old in the general population met the definition of locomotive syndrome. Locomotive syndrome in participants with obesity was more frequent than those without obesity, while locomotive syndrome in participants with an exercise habit was less frequent than those without an exercise habit.

Altered expression of laminin alpha1 in aganglionic colon of endothelin receptor-B null mouse model of Hirschsprung's disease.

PURPOSE: Laminin, an extracellular matrix molecule, is essential for normal development of the nervous system. The alpha1 subunit of laminin-1 (LAMA1) has been reported to promote neurites and outgrowth and is expressed only during embryogenesis. Previously, we developed a Sox10 transgenic version of the Endothelin receptor-B (Ednrb) mouse to visualize Enteric neural crest-derived cell (ENCC)s with a green fluorescent protein, Venus. We designed this study to investigate the expression of LAMA1 using Sox10-VENUS mice gut. METHODS: We harvested the gut on days 13.5 (E13.5) and 15.5 (E15.5) of gestation. Sox10-VENUS+/Ednrb -/- mice (n = 8) were compared with Sox10-VENUS+/Ednrb +/+ mice (n = 8) as controls. Gene expression of LAMA1 was analysed by real-time RT-PCR. Fluorescent immunohistochemistry was performed to assess protein distribution. RESULTS: The relative mRNA expression levels of LAMA1 were significantly increased in HD in the proximal and distal colon on E15.5 compared to controls (p < 0.05), whereas there were no significant differences on E13.5. LAMA1 was expressed in the serosa, submucosa and basal lamina in the gut, and was markedly increased in the proximal and distal colon of HD on E15.5. CONCLUSIONS: Altered LAMA1 expression in the aganglionic region may contribute to impaired ENCC migration, resulting in HD. These data could help in understanding the pathophysiologic interactions between LAMA1 and ENCC migration.

Heparan sulfate alterations in extracellular matrix structures and fibroblast growth factor-2 signaling impairment in the aged neurogenic niche.

Adult neurogenesis in the subventricular zone of the lateral ventricle decreases with age. In the subventricular zone, the specialized extracellular matrix structures, known as fractones, contact neural stem cells and regulate neurogenesis. Fractones are composed of extracellular matrix components, such as heparan sulfate proteoglycans. We previously found that fractones capture and store fibroblast growth factor 2 (FGF-2) via heparan sulfate binding, and may deliver FGF-2 to neural stem cells in a timely manner. The heparan sulfate (HS) chains in the fractones of the aged subventricular zone are modified based on immunohistochemistry. However, how aging affects fractone composition and subsequent FGF-2 signaling and neurogenesis remains unknown. The formation of the FGF-fibroblast growth factor receptor-HS complex is necessary to activate FGF-2 signaling and induce the phosphorylation of extracellular signal-regulated kinase (Erk1/2). In this study, we observed a reduction in HS 6-O-sulfation, which is critical for FGF-2 signal transduction, and failure of the FGF-2-induced phosphorylation of Erk1/2 in the aged subventricular zone. In addition, we observed increased HS 6-O-endo-sulfatase, an enzyme that may be responsible for the HS modifications in aged fractones. In conclusion, the data revealed that heparan sulfate 6-O-sulfation is reduced and FGF-2-dependent Erk1/2 signaling is impaired in the aged subventricular zone. HS modifications in fractones might play a role in the reduced neurogenic activity in aging brains.

Identification of peptides derived from the C-terminal domain of fibulin-7 active for endothelial cell adhesion and tube formation disruption.

Despite the research done on pathological angiogenesis, there is still a need for the development of new therapies against angiogenesis-related diseases. Fibulin-7 (Fbln7) is a member of the extracellular matrix fibulin protein family. The Fbln7 C-terminal fragment, Fbln7-C, binds to endothelial cells and inhibits their tube formation in culture. In this study, we screened 12 synthetic peptides, covering the fibulin-globular domain of Fbln7-C, to identify active sites for endothelial cell adhesion and in vitro antiangiogenic activity. Three peptides, fc10, fc11, and fc12, promoted Human Umbilical Vein Endothelial Cells (HUVECs) adhesion, and the morphology of HUVECs on fc10 was similar to that on Fbln7-C. EDTA and the anti-integrin ß1 function-blocking antibody inhibited HUVECs adhesion to both fc10 and fc12, and heparin inhibited HUVECs adhesion to both fc11 and fc12. fc10 and fc11 inhibited HUVECs tube formation. Our results suggest that three peptides from Fbln7-C are biologically active for endothelial cell adhesion and disrupt the tube formation, suggesting a potential therapeutic use of these peptides for angiogenesis-related diseases. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 184-195, 2016.

Laminin α1 regulates age-related mesangial cell proliferation and mesangial matrix accumulation through the TGF-ß pathway.

Laminin α1 (LAMA1), a subunit of the laminin-111 basement membrane component, has been implicated in various biological functions in vivo and in vitro. Although LAMA1 is present in kidney, its roles in the kidney are unknown because of early embryonic lethality. Herein, we used a viable conditional knockout mouse model with a deletion of Lama1 in the epiblast lineage (Lama1(CKO)) to study the role of LAMA1 in kidney development and function. Adult Lama1(CKO) mice developed focal glomerulosclerosis and proteinuria with age. In addition, mesangial cell proliferation was increased, and the mesangial matrix, which normally contains laminin-111, was greatly expanded. In vitro, mesangial cells from Lama1(CKO) mice exhibited significantly increased proliferation compared with those from controls. This increased proliferation was inhibited by the addition of exogenous LAMA1-containing laminin-111, but not by laminin-211 or laminin-511, suggesting a specific role for LAMA1 in regulating mesangial cell behavior. Moreover, the absence of LAMA1 increased transforming growth factor (TGF)-ß1-induced Smad2 phosphorylation, and inhibitors of TGF-ß1 receptor I kinase blocked Smad2 phosphorylation in both control and Lama1(CKO) mesangial cells, indicating that the increased Smad2 phosphorylation occurred in the absence of LAMA1 via the TGF-ß1 receptor. These findings suggest that LAMA1 plays a critical role in kidney function and kidney aging by regulating the mesangial cell population and mesangial matrix deposition through TGF-ß/Smad signaling.

Teneurin-4 promotes cellular protrusion formation and neurite outgrowth through focal adhesion kinase signaling.

Teneurin-4 (Ten-4), a transmembrane protein, is highly expressed in the central nervous system; however, its cellular and molecular function in neuronal differentiation remains unknown. In this study, we aimed to elucidate the function of Ten-4 in neurite outgrowth. Ten-4 expression was induced during neurite outgrowth of the neuroblastoma cell line Neuro-2a. Ten-4 protein was localized at the neurite growth cones. Knockdown of Ten-4 expression in Neuro-2a cells decreased the formation of the filopodia-like protrusions and the length of individual neurites. Conversely, overexpression of Ten-4 promoted filopodia-like protrusion formation. In addition, knockdown and overexpression of Ten-4 reduced and elevated the activation of focal adhesion kinase (FAK) and Rho-family small GTPases, Cdc42 and Rac1, key molecules for the membranous protrusion formation downstream of FAK, respectively. Inhibition of the activation of FAK and neural Wiskott-Aldrich syndrome protein (N-WASP), which is a downstream regulator of FAK and Cdc42, blocked protrusion formation by Ten-4 overexpression. Further, Ten-4 colocalized with phosphorylated FAK in the filopodia-like protrusion regions. Together, our findings show that Ten-4 is a novel positive regulator of cellular protrusion formation and neurite outgrowth through the FAK signaling pathway.

A C-terminal fragment of fibulin-7 interacts with endothelial cells and inhibits their tube formation in culture.

We have previously demonstrated that fibulin-7 (Fbln7) is expressed in teeth by pre-odontoblast and odontoblast cells, localized in the basement membrane and dentin matrices, and is an adhesion molecule for dental mesenchyme cells and odontoblasts. Fbln7 is also expressed in blood vessels by endothelial cells. In this report, we show that a recombinant C-terminal Fbln7 fragment (Fbln7-C) bound to Human Umbilical Vein Endothelial Cells (HUVECs) but did not promote cell spreading and actin stress fiber formation. Fbln7-C binding to HUVECs induced integrin clustering at cell adhesion sites with other focal adhesion molecules, and sustained activation of FAK, p130Cas, and Rac1. In addition, RhoA activation was inhibited, thereby preventing HUVEC spreading. As endothelial cell spreading is an important step for angiogenesis, we examined the effect of Fbln7-C on angiogenesis using in vitro assays for endothelial cell tube formation and vessel sprouting from aortic rings. We found that Fbln7-C inhibited the HUVEC tube formation and the vessel sprouting in aortic ring assays. Our findings suggest potential anti-angiogenic activity of the Fbln7 C-terminal region.

Beyond 2D: A scalable and highly sensitive method for a comprehensive 3D analysis of kidney biopsy tissue.

The spatial organization of various cell populations is critical for the major physiological and pathological processes in the kidneys. Most evaluation of these processes typically comes from a conventional 2D tissue cross-section, visualizing a limited amount of cell organization. Therefore, the 2D analysis of kidney biopsy introduces selection bias. The 2D analysis potentially omits key pathological findings outside a 1- to 10-µm thin-sectioned area and lacks information on tissue organization, especially in a particular irregular structure such as crescentic glomeruli. In this study, we introduce an easy-to-use and scalable method for obtaining high-quality images of molecules of interest in a large tissue volume, enabling a comprehensive evaluation of the 3D organization and cellular composition of kidney tissue, especially the glomerular structure. We show that CUBIC and ScaleS clearing protocols could allow a 3D analysis of the kidney tissues in human and animal models of kidney disease. We also demonstrate that the paraffin-embedded human biopsy specimens previously examined via 2D evaluation could be applicable to 3D analysis, showing a potential utilization of this method in kidney biopsy tissue collected in the past. In summary, the 3D analysis of kidney biopsy provides a more comprehensive analysis and a minimized selection bias than 2D tissue analysis. Additionally, this method enables a quantitative evaluation of particular kidney structures and their surrounding tissues, with the potential utilization from basic science investigation to applied diagnostics in nephrology.

Teneurin-4 is a novel regulator of oligodendrocyte differentiation and myelination of small-diameter axons in the CNS.

Myelination is essential for proper functioning of the CNS. In this study, we have identified a mouse mutation, designated furue, which causes tremors and hypomyelination in the CNS, particularly in the spinal cord, but not in the sciatic nerve of the PNS. In the spinal cord of the furue mice, myelination of small-diameter axons was dramatically reduced, and differentiation of oligodendrocytes, the myelin-forming cells in the CNS, was inhibited. We subsequently found that the furue mutation was associated with a transgene insertion into the teneurin-4 (Ten-4, Ten-m4/Odz4) gene, encoding a transmembrane protein of unknown function. Ten-4 was strongly expressed in the spinal cord of wild-type mice and was induced during normal oligodendrocyte differentiation. In contrast, in the furue mice, the expression of Ten-4 was absent. Differentiation and cellular process formation of oligodendrocytes were inhibited in primary cell culture from the furue mice. Cell differentiation and process formation were also inhibited in the oligodendrocyte progenitor cell line CG-4 after suppression of Ten-4 expression by shRNA. Furthermore, Ten-4 positively regulated focal adhesion kinase, an essential signaling molecule for oligodendrocyte process formation and myelination of small-diameter axons. These findings suggest that Ten-4 is a novel regulator of oligodendrocyte differentiation and that it plays a critical role in the myelination of small-diameter axons in the CNS.

Laminin-1 promotes enteric nervous system development in mouse embryo.

BACKGROUND/AIM: Neuronal development is regulated by extracellular environmental factors including nerve growth factor (NGF) and laminin. We have previously demonstrated that laminin-1 promotes neurite outgrowth of dorsal root ganglion cells by modulating NGF and integrin signaling. However, information about their effects on the enteric nervous system (ENS) is limited. Recently, we succeeded in visualizing enteric neural crest-derived cell (ENCC) migration using SOX10-Venus transgenic mice, in which ENCC are labeled with a green fluorescent protein, Venus. In this study, we examine the effects of NGF and laminin-1 in ENCC migration using SOX10-Venus mice gut. METHODS: Pregnant SOX10-Venus mice were killed on day 12.5 of gestation. The colorectum was dissected from embryos (n = 10) and placed in culture medium including NGF with or without laminin-1 for 12 h. Extension rates of ENCC migration, colorectum and ENCC migration per colorectum were calculated. RESULTS: Venus positive-ENCC extension rate was significantly higher in the laminin group (n = 5) compared to control (n = 5), 22.84 and 13.96 %, respectively (p < 0.05). The extension rate of the colorectum was not significantly different between the two groups. CONCLUSIONS: Our results suggest that laminin promotes ENCC migration in mice. This technique allowed us to visualize the effects of extracellular molecules on ENCC migration and it potentially provides us with an insight into the pathophysiology of developmental disorders of the ENS, such as Hirschsprung's disease.

Oligodendrocyte Cell Line OLP6 Successfully Differentiates on Decellularized Brain Tissue.

Objectives: The mechanisms of mental and neurological diseases have been proposed to be related not only to disorders of the neurons but also to the environment surrounding neurons, such as glial cells and the extracellular matrix (ECM). The chondroitin sulfate (CS) chain, which comprises CS proteoglycans (CSPGs), is one of the major sulfated glycosaminoglycans in the brain. CSPGs play an important role in the development, aging, and pathological conditions of the central nervous system. In particular, CSPGs play critical roles in oligodendrocyte differentiation and cell activity. Conventional two-dimensional culture in a glass chamber hardly replicates the complexity of the ECM structure or mimics in vivo conditions. Therefore, to solve this issue, this study aimed to use a culture system with decellularized tissue as a scaffold of organized ECM, thereby enabling the observation of cell differentiation and interactions between cells and the surrounding ECM. Materials and Methods: We investigated the differentiation potential of the OLP6 cell line using decellularized brain tissue as the substrate. Results: We observed that OLP6 differentiated faster on decellularized brain tissues than on conventional 2D-coated surfaces. The relative mRNA expression levels of CNP, PNP, and MBP as well as CSPGs were increased under 3D culture conditions. Conclusions: Our study provides the first evidence of the advantages of cell culture on decellularized tissues for the investigation of oligodendrocyte differentiation and cell/ECM interactions.

Evaluation of Human-Induced Pluripotent Stem Cells Derived from a Patient with Schwartz-Jampel Syndrome Revealed Distinct Hyperexcitability in the Skeletal Muscles.

Schwartz-Jampel syndrome (SJS) is an autosomal recessive disorder caused by loss-of-function mutations in heparan sulfate proteoglycan 2 (HSPG2), which encodes the core basement membrane protein perlecan. Myotonia is a major criterion for the diagnosis of SJS; however, its evaluation is based solely on physical examination and can be challenging in neonates and young children. Furthermore, the pathomechanism underlying SJS-related myotonia is not fully understood, and effective treatments for SJS are limited. Here, we established a cellular model of SJS using patient-derived human-induced pluripotent stem cells. This model exhibited hyper-responsiveness to acetylcholine as a result of abnormalities in the perlecan molecule, which were confirmed via comparison of their calcium imaging with calcium imaging of satellite cells derived from Hspg2-/--Tg mice, which exhibit myotonic symptoms similar to SJS symptoms. Therefore, our results confirm the utility of creating cellular models for investigating SJS and their application in evaluating myotonia in clinical cases, while also providing a useful tool for the future screening of SJS therapies.

Evaluation of a Medical Interview-Assistance System Using Artificial Intelligence for Resident Physicians Interviewing Simulated Patients: A Crossover, Randomized, Controlled Trial.

Medical interviews are expected to undergo a major transformation through the use of artificial intelligence. However, artificial intelligence-based systems that support medical interviews are not yet widespread in Japan, and their usefulness is unclear. A randomized, controlled trial to determine the usefulness of a commercial medical interview support system using a question flow chart-type application based on a Bayesian model was conducted. Ten resident physicians were allocated to two groups with or without information from an artificial intelligence-based support system. The rate of correct diagnoses, amount of time to complete the interviews, and number of questions they asked were compared between the two groups. Two trials were conducted on different dates, with a total of 20 resident physicians participating. Data for 192 differential diagnoses were obtained. There was a significant difference in the rate of correct diagnosis between the two groups for two cases and for overall cases (0.561 vs. 0.393; p = 0.02). There was a significant difference in the time required between the two groups for overall cases (370 s (352-387) vs. 390 s (373-406), p = 0.04). Artificial intelligence-assisted medical interviews helped resident physicians make more accurate diagnoses and reduced consultation time. The widespread use of artificial intelligence systems in clinical settings could contribute to improving the quality of medical care.

Myocyte Culture with Decellularized Skeletal Muscle Sheet with Observable Interaction with the Extracellular Matrix.

In skeletal muscles, muscle fibers are highly organized and bundled within the basement membrane. Several microfabricated substrate models have failed to mimic the macrostructure of native muscle, including various extracellular matrix (ECM) proteins. Therefore, we developed and evaluated a system using decellularized muscle tissue and mouse myoblasts C2C12 to analyze the interaction between native ECM and myocytes. Chicken skeletal muscle was sliced into sheets and decellularized to prepare decellularized skeletal muscle sheets (DSMS). C2C12 was then seeded and differentiated on DSMS. Immunostaining for ECM molecules was performed to examine the relationship between myoblast adhesion status, myotube orientation, and collagen IV orientation. Myotube survival in long-term culture was confirmed by calcein staining. C2C12 myoblasts adhered to scaffolds in DSMS and developed adhesion plaques and filopodia. Furthermore, C2C12 myotubes showed orientation along the ECM orientation within DSMS. Compared to plastic dishes, detachment was less likely to occur on DSMS, and long-term incubation was possible. This culture technique reproduces a cell culture environment reflecting the properties of living skeletal muscle, thereby allowing studies on the interaction between the ECM and myocytes.

α-1,6-Fucosyltransferase Is Essential for Myogenesis in Zebrafish.

Glycosylation is an important mechanism regulating various biological processes, including intercellular signaling and adhesion. α-1,6-fucosyltransferase (Fut8) belongs to a family of enzymes that determine the terminal structure of glycans. Fut8 is widely conserved from Caenorhabditis elegans to humans, and its mutants have been reported in humans, mice, and zebrafish. Although mutants show various symptoms, such as spinal deformity and growth retardation, its effects on skeletal muscles are unknown. We aimed to elucidate the function of Fut8 in skeletal muscle using zebrafish and C2C12 cells for evaluation. We observed that most fut8a morphants died at 2 days post-fertilization (dpf) or in earlier developmental stages even at low concentrations of morpholino oligonucleotides (MOs). Mutant juveniles also had small body sizes, and abnormal myocepta and sarcomere structures, suggesting that Fut8a plays important roles in myogenesis. Moreover, treatment of C2C12 cells with 2-fluorofucose (2FF), a fucosylation inhibitor, during cell differentiation dramatically reduced the expression of myogenic genes, such as Myomaker and other myogenic fusion genes, and inhibited myotube formation. These results indicate that Fut8 is an important factor in myogenesis, and myofusion in particular.