Inherited myogenic abilities in muscle precursor cells defined by the mitochondrial complex I-encoding protein.

Skeletal muscle comprises different muscle fibers, including slow- and fast-type muscles, and satellite cells (SCs), which exist in individual muscle fibers and possess different myogenic properties. Previously, we reported that myoblasts (MBs) from slow-type enriched soleus (SOL) had a high potential to self-renew compared with cells derived from fast-type enriched tibialis anterior (TA). However, whether the functionality of myogenic cells in adult muscles is attributed to the muscle fiber in which they reside and whether the characteristics of myogenic cells derived from slow- and fast-type fibers can be distinguished at the genetic level remain unknown. Global gene expression analysis revealed that the myogenic potential of MBs was independent of the muscle fiber type they reside in but dependent on the region of muscles they are derived from. Thus, in this study, proteomic analysis was conducted to clarify the molecular differences between MBs derived from TA and SOL. NADH dehydrogenase (ubiquinone) iron-sulfur protein 8 (Ndufs8), a subunit of NADH dehydrogenase in mitochondrial complex I, significantly increased in SOL-derived MBs compared with that in TA-derived cells. Moreover, the expression level of Ndufs8 in MBs significantly decreased with age. Gain- and loss-of-function experiments revealed that Ndufs8 expression in MBs promoted differentiation, self-renewal, and apoptosis resistance. In particular, Ndufs8 suppression in MBs increased p53 acetylation, followed by a decline in NAD/NADH ratio. Nicotinamide mononucleotide treatment, which restores the intracellular NAD+ level, could decrease p53 acetylation and increase myogenic cell self-renewal ability in vivo. These results suggested that the functional differences in MBs derived from SOL and TA governed by the mitochondrial complex I-encoding gene reflect the magnitude of the decline in SC number observed with aging, indicating that the replenishment of NAD+ is a possible approach for improving impaired cellular functions caused by aging or diseases.

Resolution of fibrosis in mdx dystrophic mouse after oral consumption of N-163 strain of Aureobasidium pullulans produced ß-glucan.

Recent advances in the management of Duchenne muscular dystrophy (DMD), such as exon skipping and gene therapy, though have reached a clinical stage, the outcome at its best is still considered suboptimal. In this study, we evaluated a novel N-163 strain of Aureobasidium pullulans produced ß-glucan (Neu-REFIX) for its potential as an adjuvant to slow down the progression of the disease by anti-inflammatory and anti-fibrotic effects. In this study, 45 mice in the three groups, 15 each in a group; Gr. 1 normal mice, Gr.2 mdx mice as vehicle, and Gr.3 mdx mice administered the N-163 ß-glucan for 45 days. The N-163 ß-glucan group showed a significant decrease in the plasma ALT, AST, and LDH levels (126 ± 69 U/l, 634 ± 371 U/l, 3335 ± 1258 U/l) compared with the vehicle group (177 ± 27 U/l, 912 ± 126 U/l, 4186 ± 398 U/l). Plasma TGF-ß levels increased, and plasma IL-13 levels decreased in the N-163 group. The inflammation score of HE-stained muscle sections in the N-163 group (1.5 ± 0.8) was lower than that in the vehicle group (2.0 ± 0.8). The N-163 strain ß-glucan group (24.22 ± 4.80) showed a significant decrease in the fibrosis area (Masson's Trichrome-positive area) compared with the vehicle group (36.78 ± 5.74). The percentage of centrally nucleated fibres evaluated by Masson's trichrome staining was 0 in the normal group, while it increased to 80% in the vehicle group but remained at 76.8% in the N-163 group. The N-163 ß-glucan group showed a significant decrease in the fibrosis area. Considering their safety and easy oral consumption, Neu-REFIX ß-glucan could be worth large multicentre clinical studies as adjuvant in slowing down the progress of DMD.

Bicc1 ribonucleoprotein complexes specifying organ laterality are licensed by ANKS6-induced structural remodeling of associated ANKS3.

Organ laterality of vertebrates is specified by accelerated asymmetric decay of Dand5 mRNA mediated by Bicaudal-C1 (Bicc1) on the left side, but whether binding of this or any other mRNA to Bicc1 can be regulated is unknown. Here, we found that a CRISPR-engineered truncation in ankyrin and sterile alpha motif (SAM)-containing 3 (ANKS3) leads to symmetric mRNA decay mediated by the Bicc1-interacting Dand5 3' UTR. AlphaFold structure predictions of protein complexes and their biochemical validation by in vitro reconstitution reveal a novel interaction of the C-terminal coiled coil domain of ANKS3 with Bicc1 that inhibits binding of target mRNAs, depending on the conformation of ANKS3 and its regulation by ANKS6. The dual regulation of RNA binding by mutually opposing structured protein domains in this multivalent protein network emerges as a novel mechanism linking associated laterality defects and possibly other ciliopathies to perturbed dynamics in Bicc1 ribonucleoparticle (RNP) formation.

Role of Wnt signaling and planar cell polarity in left-right asymmetry.

Wnt signaling plays essential roles in multiple steps of left-right (L-R) determination in development. First, canonical Wnt signaling is required to form the node, where L-R symmetry breaking takes place. Secondly, planar cell polarity (PCP) driven by non-canonical Wnt signaling polarizes node cells along the anterio-posterior (A-P) axis and provides the tilt of rotating cilia at the node, which generate the leftward fluid flow. Thus, reciprocal expression of Wnt5a/5b and their inhibitors Sfrp1, 2, 5 generates a gradient of Wnt5 activity along the embryo's anterior-posterior (A-P) axis. This polarizes cells at the node, by placing PCP core proteins on the anterior or posterior side of each node cell. Polarized PCP proteins subsequently induce asymmetric organization of microtubules along the A-P axis, which is thought to push the centrally localized basal body toward the posterior side of a node cell. Motile cilia that extend from the posteriorly-shifted basal body is tilted toward the posterior side of the embryo. Thirdly, canonical-Wnt signaling regulates the level and expansion of Nodal activity and establishes L-R asymmetric Nodal activity at the node, the first molecular asymmetry in the mouse embryo. Overall, both canonical and non-canonical Wnt signalings are essential for L-R symmetry breaking.

Techniques for Injury, Cell Transplantation, and Histological Analysis in Skeletal Muscle.

Skeletal muscle can adjust to changes in physiological and pathological environments by regenerating using myogenic progenitor cells or adapting muscle fiber sizes and types, metabolism, and contraction ability. To study these changes, muscle samples should be appropriately prepared. Therefore, reliable techniques to accurately analyze and evaluate skeletal muscle phenotypes are required. However, although technical approaches to genetically investigating skeletal muscle are improving, the fundamental strategies for capturing muscle pathology are the same over the decades. Hematoxylin and eosin (H&E) staining or antibodies are the simplest and standard methodologies for assessing skeletal muscle phenotypes. In this chapter, we describe fundamental techniques and protocols for inducing skeletal muscle regeneration by using chemicals and cell transplantation, in addition to methods of preparing and evaluating skeletal muscle samples.

Immotile cilia mechanically sense the direction of fluid flow for left-right determination.

Immotile cilia at the ventral node of mouse embryos are required for sensing leftward fluid flow that breaks left-right symmetry of the body. However, the flow-sensing mechanism has long remained elusive. In this work, we show that immotile cilia at the node undergo asymmetric deformation along the dorsoventral axis in response to the flow. Application of mechanical stimuli to immotile cilia by optical tweezers induced calcium ion transients and degradation of Dand5 messenger RNA (mRNA) in the targeted cells. The Pkd2 channel protein was preferentially localized to the dorsal side of immotile cilia, and calcium ion transients were preferentially induced by mechanical stimuli directed toward the ventral side. Our results uncover the biophysical mechanism by which immotile cilia at the node sense the direction of fluid flow.

Size-tunable PEG-grafted copolymers as a polymeric nanoruler for passive targeting muscle tissues.

Muscle-targeted drug delivery is a major challenge in nanomedicine. The extravasation of nanomedicines (or nanoparticles) from the bloodstream into muscle tissues is hindered by the continuous endothelium, the so-called blood-muscle barrier. This study aimed to evaluate the optimal size of macromolecular drugs for extravasation (or passive targeting) into muscle tissues. We constructed a size-tunable polymeric delivery platform as a polymeric nanoruler by grafting poly(ethylene glycol)s (PEGs) onto the poly(aspartic acid) (PAsp) backbone. A series of PEG-grafted copolymers (gPEGs) with a narrow size distribution between 11 and 32 nm in hydrodynamic diameter (DH) were prepared by changing the molecular weight of the PEGs. Biodistribution analyses revealed that accumulation amounts of gPEGs in the muscle tissues of normal mice tended to decrease above their size of ~15 nm (or ~11 nm for the heart). The gPEGs accumulated in the skeletal muscles of Duchenne muscular dystrophy model mice (mdx mice) at a 2-3-fold higher level than in the skeletal muscles of normal mice. At the same time, there was a reduced accumulation of gPEGs in the spleen and liver. Intravital confocal laser scanning microscopy and immunohistochemical analysis showed extravasation and locally enhanced accumulation of gPEGs in the skeletal muscle of mdx mice. This study outlined the pivotal role of macromolecular drug size in muscle-targeted drug delivery and demonstrated the enhanced permeability of 11-32 nm-sized macromolecular drugs in mdx mice.

Planar cell polarity-dependent asymmetric organization of microtubules for polarized positioning of the basal body in node cells.

For left-right symmetry breaking in the mouse embryo, the basal body must become positioned at the posterior side of node cells, but the precise mechanism for this has remained unknown. Here, we examined the role of microtubules (MTs) and actomyosin in this basal body positioning. Exposure of mouse embryos to agents that stabilize or destabilize MTs or F-actin impaired such positioning. Active myosin II was detected at the anterior side of node cells before the posterior shift of the basal body, and this asymmetric activation was lost in Prickle and dachsous mutant embryos. The organization of basal-body associated MTs (baMTs) was asymmetric between the anterior and posterior sides of node cells, with anterior baMTs extending horizontally and posterior baMTs extending vertically. This asymmetry became evident after polarization of the PCP core protein Vangl1 and before the posterior positioning of the basal body, and it also required the PCP core proteins Prickle and dachsous. Our results suggest that the asymmetry in baMT organization may play a role in correct positioning of the basal body for left-right symmetry breaking.

Bicc1 and Dicer regulate left-right patterning through post-transcriptional control of the Nodal inhibitor Dand5.

Rotating cilia at the vertebrate left-right organizer (LRO) generate an asymmetric leftward flow, which is sensed by cells at the left LRO margin. Ciliary activity of the calcium channel Pkd2 is crucial for flow sensing. How this flow signal is further processed and relayed to the laterality-determining Nodal cascade in the left lateral plate mesoderm (LPM) is largely unknown. We previously showed that flow down-regulates mRNA expression of the Nodal inhibitor Dand5 in left sensory cells. De-repression of the co-expressed Nodal, complexed with the TGFß growth factor Gdf3, drives LPM Nodal cascade induction. Here, we show that post-transcriptional repression of dand5 is a central process in symmetry breaking of Xenopus, zebrafish and mouse. The RNA binding protein Bicc1 was identified as a post-transcriptional regulator of dand5 and gdf3 via their 3'-UTRs. Two distinct Bicc1 functions on dand5 mRNA were observed at pre- and post-flow stages, affecting mRNA stability or flow induced translational inhibition, respectively. To repress dand5, Bicc1 co-operates with Dicer1, placing both proteins in the process of flow sensing. Intriguingly, Bicc1 mediated translational repression of a dand5 3'-UTR mRNA reporter was responsive to pkd2, suggesting that a flow induced Pkd2 signal triggers Bicc1 mediated dand5 inhibition during symmetry breakage.

Fluid flow-induced left-right asymmetric decay of Dand5 mRNA in the mouse embryo requires a Bicc1-Ccr4 RNA degradation complex.

Molecular left-right (L-R) asymmetry is established at the node of the mouse embryo as a result of the sensing of a leftward fluid flow by immotile cilia of perinodal crown cells and the consequent degradation of Dand5 mRNA on the left side. We here examined how the fluid flow induces Dand5 mRNA decay. We found that the first 200 nucleotides in the 3' untranslated region (3'-UTR) of Dand5 mRNA are necessary and sufficient for the left-sided decay and to mediate the response of a 3'-UTR reporter transgene to Ca2+, the cation channel Pkd2, the RNA-binding protein Bicc1 and their regulation by the flow direction. We show that Bicc1 preferentially recognizes GACR and YGAC sequences, which can explain the specific binding to a conserved GACGUGAC motif located in the proximal Dand5 3'-UTR. The Cnot3 component of the Ccr4-Not deadenylase complex interacts with Bicc1 and is also required for Dand5 mRNA decay at the node. These results suggest that Ca2+ currents induced by leftward fluid flow stimulate Bicc1 and Ccr4-Not to mediate Dand5 mRNA degradation specifically on the left side of the node.

CFAP45 deficiency causes situs abnormalities and asthenospermia by disrupting an axonemal adenine nucleotide homeostasis module.

Axonemal dynein ATPases direct ciliary and flagellar beating via adenosine triphosphate (ATP) hydrolysis. The modulatory effect of adenosine monophosphate (AMP) and adenosine diphosphate (ADP) on flagellar beating is not fully understood. Here, we describe a deficiency of cilia and flagella associated protein 45 (CFAP45) in humans and mice that presents a motile ciliopathy featuring situs inversus totalis and asthenospermia. CFAP45-deficient cilia and flagella show normal morphology and axonemal ultrastructure. Proteomic profiling links CFAP45 to an axonemal module including dynein ATPases and adenylate kinase as well as CFAP52, whose mutations cause a similar ciliopathy. CFAP45 binds AMP in vitro, consistent with structural modelling that identifies an AMP-binding interface between CFAP45 and AK8. Microtubule sliding of dyskinetic sperm from Cfap45-/- mice is rescued with the addition of either AMP or ADP with ATP, compared to ATP alone. We propose that CFAP45 supports mammalian ciliary and flagellar beating via an adenine nucleotide homeostasis module.

Role of Ca2+ transients at the node of the mouse embryo in breaking of left-right symmetry.

Immotile cilia sense extracellular signals such as fluid flow, but whether Ca2+ plays a role in flow sensing has been unclear. Here, we examined the role of ciliary Ca2+ in the flow sensing that initiates the breaking of left-right (L-R) symmetry in the mouse embryo. Intraciliary and cytoplasmic Ca2+ transients were detected in the crown cells at the node. These Ca2+ transients showed L-R asymmetry, which was lost in the absence of fluid flow or the PKD2 channel. Further characterization allowed classification of the Ca2+ transients into two types: cilium-derived, L-R-asymmetric transients (type 1) and cilium-independent transients without an L-R bias (type 2). Type 1 intraciliary transients occurred preferentially at the left posterior region of the node, where L-R symmetry breaking takes place. Suppression of intraciliary Ca2+ transients delayed L-R symmetry breaking. Our results implicate cilium-derived Ca2+ transients in crown cells in initiation of L-R symmetry breaking in the mouse embryo.

The absence of SOX2 in the anterior foregut alters the esophagus into trachea and bronchi in both epithelial and mesenchymal components.

In the anterior foregut (AFG) of mouse embryos, the transcription factor SOX2 is expressed in the epithelia of the esophagus and proximal branches of respiratory organs comprising the trachea and bronchi, whereas NKX2.1 is expressed only in the epithelia of respiratory organs. Previous studies using hypomorphic Sox2 alleles have indicated that reduced SOX2 expression causes the esophageal epithelium to display some respiratory organ characteristics. In the present study, we produced mouse embryos with AFG-specific SOX2 deficiency. In the absence of SOX2 expression, a single NKX2.1-expressing epithelial tube connected the pharynx and the stomach, and a pair of bronchi developed in the middle of the tube. Expression patterns of NKX2.1 and SOX9 revealed that the anterior and posterior halves of SOX2-deficient AFG epithelial tubes assumed the characteristics of the trachea and bronchus, respectively. In addition, we found that mesenchymal tissues surrounding the SOX2-deficient NKX2.1-expressing epithelial tube changed to those surrounding the trachea and bronchi in the anterior and posterior halves, as indicated by the arrangement of smooth muscle cells and SOX9-expressing cells and by the expression of Wnt4 (esophagus specific), Tbx4 (respiratory organ specific), and Hoxb6 (distal bronchus specific). The impact of mesenchyme-derived signaling on the early stage of AFG epithelial specification has been indicated. Our study demonstrated an opposite trend where epithelial tissue specification causes concordant changes in mesenchymal tissues, indicating a reciprocity of epithelial-mesenchymal interactions.

Nodal paralogues underlie distinct mechanisms for visceral left-right asymmetry in reptiles and mammals.

Unidirectional fluid flow generated by motile cilia at the left-right organizer (LRO) breaks left-right (L-R) symmetry during early embryogenesis in mouse, frog and zebrafish. The chick embryo, however, does not require motile cilia for L-R symmetry breaking. The diversity of mechanisms for L-R symmetry breaking among vertebrates and the trigger for such symmetry breaking in non-mammalian amniotes have remained unknown. Here we examined how L-R asymmetry is established in two reptiles, Madagascar ground gecko and Chinese softshell turtle. Both of these reptiles appear to lack motile cilia at the LRO. The expression of the Nodal gene at the LRO in the reptilian embryos was found to be asymmetric, in contrast to that in vertebrates such as mouse that are dependent on cilia for L-R patterning. Two paralogues of the Nodal gene derived from an ancient gene duplication are retained and expressed differentially in cilia-dependent and cilia-independent vertebrates. The expression of these two Nodal paralogues is similarly controlled in the lateral plate mesoderm but regulated differently at the LRO. Our in-depth analysis of reptilian embryos thus suggests that mammals and non-mammalian amniotes deploy distinct strategies dependent on different Nodal paralogues for rendering Nodal activity asymmetric at the LRO.

Ciliogenesis-coupled accumulation of IFT-B proteins in a novel cytoplasmic compartment.

Cluap1/IFT38 is a ciliary protein that belongs to the IFT-B complex and is required for ciliogenesis. In this study, we have examined the behaviors of Cluap1 protein in nonciliated and ciliated cells. In proliferating cells, Cluap1 is located at the distal appendage of the mother centriole. When cells are induced to form cilia, Cluap1 is found in a novel noncentriolar compartment, the cytoplasmic IFT spot, which mainly exists once in a cell. Other IFT-B proteins such as IFT46 and IFT88 are colocalized in this spot. The cytoplasmic IFT spot is present in mouse embryonic fibroblasts (MEFs) but is absent in ciliogenesis-defective MEFs lacking Cluap1, Kif3a or Odf2. The cytoplasmic IFT spot is also found in mouse embryos but is absent in the Cluap1 mutant embryo. When MEFs are induced to form cilia, the cytoplasmic IFT spot appears at an early step of ciliogenesis but starts to disappear when ciliogenesis is mostly completed. These results suggest that IFT-B proteins such as Cluap1 accumulate in a previously undescribed cytoplasmic compartment during ciliogenesis.

A Wnt5 Activity Asymmetry and Intercellular Signaling via PCP Proteins Polarize Node Cells for Left-Right Symmetry Breaking.

Polarization of node cells along the anterior-posterior axis of mouse embryos is responsible for left-right symmetry breaking. How node cells become polarized has remained unknown, however. Wnt5a and Wnt5b are expressed posteriorly relative to the node, whereas genes for Sfrp inhibitors of Wnt signaling are expressed anteriorly. Here we show that polarization of node cells is impaired in Wnt5a-/-Wnt5b-/- and Sfrp mutant embryos, and also in the presence of a uniform distribution of Wnt5a or Sfrp1, suggesting that Wnt5 and Sfrp proteins act as instructive signals in this process. The absence of planar cell polarity (PCP) core proteins Prickle1 and Prickle2 in individual cells or local forced expression of Wnt5a perturbed polarization of neighboring wild-type cells. Our results suggest that opposing gradients of Wnt5a and Wnt5b and of their Sfrp inhibitors, together with intercellular signaling via PCP proteins, polarize node cells along the anterior-posterior axis for breaking of left-right symmetry.

TTC25 Deficiency Results in Defects of the Outer Dynein Arm Docking Machinery and Primary Ciliary Dyskinesia with Left-Right Body Asymmetry Randomization.

Multiprotein complexes referred to as outer dynein arms (ODAs) develop the main mechanical force to generate the ciliary and flagellar beat. ODA defects are the most common cause of primary ciliary dyskinesia (PCD), a congenital disorder of ciliary beating, characterized by recurrent infections of the upper and lower airways, as well as by progressive lung failure and randomization of left-right body asymmetry. Using a whole-exome sequencing approach, we identified recessive loss-of-function mutations within TTC25 in three individuals from two unrelated families affected by PCD. Mice generated by CRISPR/Cas9 technology and carrying a deletion of exons 2 and 3 in Ttc25 presented with laterality defects. Consistently, we observed immotile nodal cilia and missing leftward flow via particle image velocimetry. Furthermore, transmission electron microscopy (TEM) analysis in TTC25-deficient mice revealed an absence of ODAs. Consistent with our findings in mice, we were able to show loss of the ciliary ODAs in humans via TEM and immunofluorescence (IF) analyses. Additionally, IF analyses revealed an absence of the ODA docking complex (ODA-DC), along with its known components CCDC114, CCDC151, and ARMC4. Co-immunoprecipitation revealed interaction between the ODA-DC component CCDC114 and TTC25. Thus, here we report TTC25 as a new member of the ODA-DC machinery in humans and mice.

Extraction of DNA from human embryos after long-term preservation in formalin and Bouin's solutions.

The "Kyoto Collection of Human Embryos" at Kyoto University was begun in 1961. Although morphological analyses of samples in the Kyoto Collection have been performed, these embryos have been considered difficult to genetically analyze because they have been preserved in formalin or Bouin's solution for 20-50 years. Owing to the recent advances in molecular biology, it has become possible to extract DNA from long-term fixed tissues. The purpose of this study was to extract DNA from wet preparations of human embryo samples after long-term preservation in fixing solution. We optimized the DNA extraction protocol to be suitable for tissues that have been damaged by long-term fixation, including DNA-protein crosslinking damage. Diluting Li2 CO3 with 70% ethanol effectively removed picric acid from samples fixed in Bouin's solution. Additionally, 20.0 mg/mL proteinase was valuable to lyse the long-term fixed samples. The extracted DNA was checked with PCR amplification using several sets of primers and sequence analysis. The PCR products included at least 295- and 838-bp amplicons. These results show that the extracted DNA is applicable for genetic analyses, and indicate that old embryos in the Kyoto Collection should be made available for future studies. The protocol described in this study can successfully extract DNA from old specimens and, with improvements, should be applicable in research aiming to understand the molecular mechanisms of human congenital anomalies.

Self-regulated left-right asymmetric expression of Pitx2c in the developing mouse limb.

The transcription factor Pitx2c is expressed in primordial visceral organs in a left-right (L-R) asymmetric manner and executes situs-specific morphogenesis. Here we show that Pitx2c is also L-R asymmetrically expressed in the developing mouse limb. Human PITX2c exhibits the same transcriptional activity in the mouse limb. The asymmetric expression of Pitx2c in the limb also exhibits dorsal-ventral and anterior-posterior polarities, being confined to the posterior-dorsal region of the left limb. Left-sided Pitx2c expression in the limb is regulated by Nodal signaling through a Nodal-responsive enhancer. Pitx2c is expressed in lateral plate mesoderm (LPM)-derived cells in the left limb that contribute to various limb connective tissues. The number of Pitx2c(+) cells in the left limb was found to be negatively regulated by Pitx2c itself. Although obvious defects were not apparent in the limb of mice lacking asymmetric Pitx2c expression, Pitx2c may regulate functional L-R asymmetry of the limb.

Prenatal findings in congenital leukemia: a case report.

We here describe a case of congenital leukemia that ended in intrauterine fetal demise at 30 weeks of gestation. Acute enlargement of the fetal trunk, elevated pulsatility index of the umbilical artery with concomitant decline of pulsatility index of the middle cerebral artery, pleural effusion, and polyhydramnios preceded the fetal death. Diagnosis of congenital myeloid leukemia was suggested by microscopic examination of the placental tissue, revealing immature myeloid precursors filling the lumina of fetal vessels in the umbilical cord and chorionic villi. Extensive vascular involvement of the placenta by leukemic cells was considered to be a primary cause of the fetal death.