Sonic hedgehog is a survival factor for hypaxial muscles during mouse development

Sonic hedgehog (Shh) has been proposed to function as an inductive and trophic signal that controls development of epaxial musculature in vertebrate embryos. In contrast, development of hypaxial muscles was assumed to occur independently of Shh. We here show that formation of limb muscles was severely affected in two different mouse strains with inactivating mutations of the Shh gene. The limb muscle defect became apparent relatively late and initial stages of hypaxial muscle development were unaffected or only slightly delayed. Micromass cultures and cultures of tissue fragments derived from limbs under different conditions with or without the overlaying ectoderm indicated that Shh is required for the maintenance of the expression of myogenic regulatory factors (MRFs) and, consecutively, for the formation of differentiated limb muscle myotubes. We propose that Shh acts as a survival and proliferation factor for myogenic precursor cells during hypaxial muscle development. Detection of a reduced but significant level of Myf5 expression in the epaxial compartment of somites of Shh homozygous mutant embryos at E9.5 indicated that Shh might be dispensable for the initiation of myogenesis both in hypaxial and epaxial muscles. Our data suggest that Shh acts similarly in both somitic compartments as a survival and proliferation factor and not as a primary inducer of myogenesis.

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Lbx1 is required for muscle precursor migration along a lateral pathway into the limb

Development ◽

10.1242/dev.127.2.413 ◽

2000 ◽

Vol 127 (2) ◽

pp. 413-424 ◽

Cited By ~ 5

Author(s):

M.K. Gross ◽

L. Moran-Rivard ◽

T. Velasquez ◽

M.N. Nakatsu ◽

K. Jagla ◽

...

Keyword(s):

Muscle Development ◽

Muscle Loss ◽

Limb Muscle ◽

Lateral Migration ◽

Muscle Precursor ◽

Hindlimb Muscles ◽

Limb Muscles ◽

Mammalian Embryos ◽

Myogenic Precursor ◽

Hypaxial Muscle

In mammalian embryos, myogenic precursor cells emigrate from the ventral lip of the dermomyotome and colonize the limbs, tongue and diaphragm where they differentiate and form skeletal muscle. Previous studies have shown that Pax3, together with the c-Met receptor tyrosine kinase and its ligand Scatter Factor (SF) are necessary for the migration of hypaxial muscle precursors in mice. Lbx1 and Pax3 are co-expressed in all migrating hypaxial muscle precursors, raising the possibility that Lbx1 regulates their migration. To examine the function of Lbx1 in muscle development, we inactivated the Lbx1 gene by homologous recombination. Mice lacking Lbx1 exhibit an extensive loss of limb muscles, although some forelimb and hindlimb muscles are still present. The pattern of muscle loss suggests that Lbx1 is not required for the specification of particular limb muscles, and the muscle defects that occur in Lbx1(−/−) mice can be solely attributed to changes in muscle precursor migration. c-Met is expressed in Lbx1 mutant mice and limb muscle precursors delaminate from the ventral dermomyotome but fail to migrate laterally into the limb. Muscle precursors still migrate ventrally and give rise to tongue, diaphragm and some limb muscles, demonstrating Lbx1 is necessary for the lateral, but not ventral, migration of hypaxial muscle precursors. These results suggest that Lbx1 regulates responsiveness to a lateral migration signal which emanates from the developing limb.

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Pax-3 expression in segmental mesoderm marks early stages in myogenic cell specification

Development ◽

10.1242/dev.120.4.785 ◽

1994 ◽

Vol 120 (4) ◽

pp. 785-796 ◽

Cited By ~ 54

Author(s):

B.A. Williams ◽

C.P. Ordahl

Keyword(s):

Muscle Development ◽

Paraxial Mesoderm ◽

Limb Muscle ◽

Differential Modulation ◽

Back Muscle ◽

Cell Specification ◽

Myogenic Lineage ◽

Late Step ◽

Myogenic Precursor ◽

Migratory Cell

Specification of the myogenic lineage begins prior to gastrulation and culminates in the emergence of determined myogenic precursor cells from the somites. The myoD family (MDF) of transcriptional activators controls late step(s) in myogenic specification that are closely followed by terminal muscle differentiation. Genes expressed in myogenic specification at stages earlier than MDFs are unknown. The Pax-3 gene is expressed in all the cells of the caudal segmental plate, the early mesoderm compartment that contains the precursors of skeletal muscle. As somites form from the segmental plate and mature, Pax-3 expression is progressively modulated. Beginning at the time of segmentation, Pax-3 becomes repressed in the ventral half of the somite, leaving Pax-3 expression only in the dermomyotome. Subsequently, differential modulation of Pax-3 expression levels delineates the medial and lateral halves of the dermomyotome, which contain precursors of axial (back) muscle and limb muscle, respectively. Pax-3 expression is then repressed as dermomyotome-derived cells activate MDFs. Quail-chick chimera and ablation experiments confirmed that the migratory precursors of limb muscle continue to express Pax-3 during migration. Since limb muscle precursors do not activate MDFs until 2 days after they leave the somite, Pax-3 represents the first molecular marker for this migratory cell population. A null mutation of the mouse Pax-3 gene, Splotch, produces major disruptions in early limb muscle development (Franz, T., Kothary, R., Surani, M. A. H., Halata, Z. and Grim, M. (1993) Anat. Embryol. 187, 153–160; Goulding, M., Lumsden, A. and Paquette, A. (1994) Development 120, 957–971). We conclude, therefore, that Pax-3 gene expression in the paraxial mesoderm marks earlier stages in myogenic specification than MDFs and plays a crucial role in the specification and/or migration of limb myogenic precursors.

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Distinct signaling molecules control Hoxa-11 and Hoxa-13 expression in the muscle precursor and mesenchyme of the chick limb bud

Development ◽

10.1242/dev.126.12.2771 ◽

1999 ◽

Vol 126 (12) ◽

pp. 2771-2783 ◽

Cited By ~ 1

Author(s):

K. Hashimoto ◽

Y. Yokouchi ◽

M. Yamamoto ◽

A. Kuroiwa

Keyword(s):

Growth Factor ◽

Muscle Development ◽

Hox Genes ◽

Expression Patterns ◽

Precursor Cells ◽

Limb Bud ◽

Posterior Region ◽

Limb Muscle ◽

Limb Mesenchyme ◽

Myogenic Precursor

The limb muscles, originating from the ventrolateral portion of the somites, exhibit position-specific morphological development through successive splitting and growth/differentiation of the muscle masses in a region-specific manner by interacting with the limb mesenchyme and the cartilage elements. The molecular mechanisms that provide positional cues to the muscle precursors are still unknown. We have shown that the expression patterns of Hoxa-11 and Hoxa-13 are correlated with muscle patterning of the limb bud (Yamamoto et al., 1998) and demonstrated that muscular Hox genes are activated by signals from the limb mesenchyme. We dissected the regulatory mechanisms directing the unique expression patterns of Hoxa-11 and Hoxa-13 during limb muscle development. HOXA-11 protein was detected in both the myogenic cells and the zeugopodal mesenchymal cells of the limb bud. The earlier expression of HOXA-11 in both the myogenic precursor cells and the mesenchyme was dependent on the apical ectodermal ridge (AER), but later expression was independent of the AER. HOXA-11 expression in both myogenic precursor cells and mesenchyme was induced by fibroblast growth factor (FGF) signal, whereas hepatocyte growth factor/scatter factor (HGF/SF) maintained HOXA-11 expression in the myogenic precursor cells, but not in the mesenchyme. The distribution of HOXA-13 protein expression in the muscle masses was restricted to the posterior region. We found that HOXA-13 expression in the autopodal mesenchyme was dependent on the AER but not on the polarizing region, whereas expression of HOXA-13 in the posterior muscle masses was dependent on the polarizing region but not on the AER. Administration of BMP-2 at the anterior margin of the limb bud induced ectopic HOXA-13 expression in the anterior region of the muscle masses followed by ectopic muscle formation close to the source of exogenous BMP-2. In addition, NOGGIN/CHORDIN, antagonists of BMP-2 and BMP-4, downregulated the expression of HOXA-13 in the posterior region of the muscle masses and inhibited posterior muscle development. These results suggested that HOXA-13 expression in the posterior muscle masses is activated by the posteriorizing signal from the posterior mesenchyme via BMP-2. On the contrary, the expression of HOXA-13 in the autopodal mesenchyme was affected by neither BMP-2 nor NOGGIN/CHORDIN. Thus, mesenchymal HOXA-13 expression was independent of BMP-2 from polarizing region, but was under the control of as yet unidentified signals from the AER. These results showed that expression of Hox genes is regulated differently in the limb muscle precursor and mesenchymal cells.

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MyoD and Myf-5 define the specification of musculature of distinct embryonic origin

Biochemistry and Cell Biology ◽

10.1139/o98-107 ◽

1998 ◽

Vol 76 (6) ◽

pp. 1079-1091 ◽

Cited By ~ 44

Author(s):

Boris Kablar ◽

Atsushi Asakura ◽

Kirsten Krastel ◽

Chuyan Ying ◽

Linda L May ◽

...

Keyword(s):

Abdominal Wall ◽

Expression Pattern ◽

Branchial Arch ◽

Precursor Cells ◽

Mouse Development ◽

Unique Role ◽

Branchial Arches ◽

Embryonic Origin ◽

Body Wall Muscles ◽

Myogenic Precursor

Mounting evidence supports the notion that Myf-5 and MyoD play unique roles in the development of epaxial (originating in the dorso-medial half of the somite, e.g. back muscles) and hypaxial (originating in the ventro-lateral half of the somite, e.g. limb and body wall muscles) musculature. To further understand how Myf-5 and MyoD genes co-operate during skeletal muscle specification, we examined and compared the expression pattern of MyoD-lacZ (258/-2.5lacZ and MD6.0-lacZ) transgenes in wild-type, Myf-5, and MyoD mutant embryos. We found that the delayed onset of muscle differentiation in the branchial arches, tongue, limbs, and diaphragm of MyoD-/- embryos was a consequence of a reduced ability of myogenic precursor cells to progress through their normal developmental program and not because of a defect in migration of muscle progenitor cells into these regions. We also found that myogenic precursor cells for back, intercostal, and abdominal wall musculature in Myf-5-/-embryos failed to undergo normal translocation or differentiation. By contrast, the myogenic precursors of intercostal and abdominal wall musculature in MyoD-/- embryos underwent normal translocation but failed to undergo timely differentiation. In conclusion, these observations strongly support the hypothesis that Myf-5 plays a unique role in the development of muscles arising after translocation of epithelial dermamyotome cells along the medial edge of the somite to the subjacent myotome (e.g., back or epaxial muscle) and that MyoD plays a unique role in the development of muscles arising from migratory precursor cells (e.g., limb and branchial arch muscles, tongue, and diaphragm). In addition, the expression pattern of MyoD-lacZ transgenes in the intercostal and abdominal wall muscles of Myf-5-/- and MyoD-/- embryos suggests that appropriate development of these muscles is dependent on both genes and, therefore, these muscles have a dual embryonic origin (epaxial and hypaxial).Key words: epaxial and hypaxial muscle, Myf-5, MyoD, mouse development, somite.

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Bone and muscle development in three inbred female mouse strains

Osteologie/Osteology ◽

10.1055/a-1287-6016 ◽

2021 ◽

Author(s):

Ursula Föger-Samwald ◽

Maria Papageorgiou ◽

Katharina Wahl-Figlash ◽

Katharina Kerschan-Schindl ◽

Peter Pietschmann

Keyword(s):

Trabecular Bone ◽

Muscle Development ◽

Bone Growth ◽

Volume Fraction ◽

Bone Structure ◽

Bone Development ◽

Mouse Strains ◽

Structural Reorganization ◽

Bone Volume Fraction ◽

Trabecular Thickness

AbstractMuscle force is thought to be one of the main determinants of bone development. Hence, peak muscle growth is expected to precede peak bone growth. In this study, we investigated muscle and bone development in female C57BL/6 J, DBA/2JRj, and C3H/HeOuJ mice. Femoral cortical and trabecular bone structure and the weights of selected muscles were assessed at the ages of 8, 16, and 24 weeks. Muscle mass increased from 8 to 24 weeks in all 3 strains, suggesting peak muscle development at 24 weeks or later. Bone volume fraction, trabecular number, and connectivity density of the femur decreased or remained unchanged, whereas trabecular density and trabecular thickness largely increased. These results suggest a peak in trabecular bone accrual at 8 weeks or earlier followed by further increases in density and structural reorganization of trabeculae. Cortical density, cortical thickness, and cortical cross sectional area increased over time, suggesting a peak in cortical bone accrual at 24 weeks or later. In conclusion, our data provide evidence that growth of muscle lags behind trabecular bone accrual.

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105 THE Oct4/Cdx2 EXPRESSION AND CELL FATE OF INDIVIDUAL TWO-CELL BLASTOMERES IN TWO MOUSE STRAINS

Reproduction Fertility and Development ◽

10.1071/rdv20n1ab105 ◽

2008 ◽

Vol 20 (1) ◽

pp. 133

Author(s):

M. Katayama ◽

R. M. Roberts

Keyword(s):

Cell Mass ◽

Strain Differences ◽

Lineage Tracing ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Mouse Strains ◽

Mouse Development ◽

Cell Stage ◽

Developmental Potential ◽

Nih Swiss

Fertile adults and occasionally twins have been derived from murine blastomeres at the 2-cell stage, indicating that such blastomeres may be equivalently totipotent, but there are conflicting reports that individual blastomeres from 2-cell stage murine conceptuses make different contributions to the embryonic and abembryonic regions of the blastocyst, implying that they differ in developmental potential. Here, we have re-examined this subject using 2 mouse strains, CF1 and NIH Swiss (SW), and 2 experimental approaches, random blastomere destruction at the 2-cell stage by repeated insertion of a needle into its nucleus and lineage tracing with the dye, DiI-CM. The manipulated conceptuses and untreated controls were cultured in KSOM-AA to morula and blastocyst stages (84 or 108 h pc, respectively), fixed, and immunostained for Oct4 and Cdx2. Antigen distribution, number of nuclei (stained by 42,6-diamidino-2-phenylindole), and cell progeny labeled with DiI-CM were examined by confocal laser scanning microscopy. Cell numbers are means � SD and were analyzed by a Student t-test. Cells positive for Cdx2 were assumed to represent trophectoderm or trophectoderm precursors, ones positive for Oct4 but negative for Cdx2 (Oct+Cdx–) inner cell mass. Ablation of a blastomere failed to prevent developmental progression in either strain, but the total number of cells at both morula (SW 11.4 � 3.3 v. 19.2 � 7.1; CF1 10.1 � 2.5 v. 22.1 � 6.4) and blastocyst (SW 48.6 � 7.4 v. 69.4 � 9.9; CF1 24.8 � 6.2 v. 53.8 � 13.5) was significantly reduced. In SW, the average fraction of Oct+Cdx– cells after blastomere ablation was significantly lower (P < 0.05) than in controls in morulae (0.47 � 0.2 v. 0.65 � 0.1) but not in blastocysts (0.33 � 0.1 and 0.34 � 0.1). In CF1, the fraction of Oct+Cdx– cells was lower (P < 0.05) than controls in both morulae and blastocysts (0.31 � 0.2 v. 0.58 � 0.2 and 0.18 � 0.1 v. 0.27 � 0.04, respectively). The CF1 morulae fell mainly into 2 groups, one low fraction (≤0.3, 54%) of Oct+Cdx– cells and the other with a more normal fraction (0.3 to 0.8, 43%) relative to controls. A majority of NIH Swiss morulae had an Oct+Cdx– cell fraction >0.4 and in this respect resembled controls. We then examined these strain differences by lineage tracing. The majority of SW blastocysts (65%, n = 34) demonstrated a random localization of DiI-labeled cell progeny (i.e., there was no preferential distribution of labeled cells to either the embryonic or abembryonic poles). By contrast, in CF1 (n = 38), 32% of blastocysts had labeled cells confined to their embryonic end and 42% with DiI-labeled, Cdx2-positive cells clustered at the abembryonic locale. A random localization was observed in 26% of blastocysts. In conclusion, these data confirm that there is plasticity in early mouse development but also suggest that in CF1, but not in SW conceptuses, blastomeres at the 2-cell stage differ in their abilities to contribute to the embryonic pole. Similar strain differences may explain the disagreements among studies on lineage tracing in early cleavage stage conceptuses.

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Osteopenia in Sparc (osteonectin)-deficient mice: characterization of phenotypic determinants of femoral strength and changes in gene expression

Physiological Genomics ◽

10.1152/physiolgenomics.00151.2007 ◽

2007 ◽

Vol 32 (1) ◽

pp. 64-73 ◽

Cited By ~ 32

Author(s):

Fiona C. Mansergh ◽

Timothy Wells ◽

Carole Elford ◽

Samuel L. Evans ◽

Mark J. Perry ◽

...

Keyword(s):

Bone Marrow ◽

Bone Mineral ◽

Mouse Strains ◽

Mineral Density ◽

Background Strain ◽

Marrow Adiposity ◽

Strength Tests ◽

Deficient Mice ◽

Inactivating Mutations

Sparc null mutants have been generated independently via targeted mutations in exons 4 and 6. Previous studies have identified low-turnover osteopenia in the 129Sv/C57BL/6 exon 4 knockout. Since both Sparc null mutations result in complete absence of Sparc protein, similar phenotypic outcomes are likely. However, genetic background (strain) and/or linkage disequilibrium effects can influence phenotype. Different inactivating mutations should be tested in various mouse strains; similar phenotypic outcomes can then confidently be assigned to the mutated gene. We have evaluated the bone phenotype in the 129Sv/EvSparc tm1cam exon 6 knockout at 4 and 9 mo, using physical measurement, mechanical strength tests, and DXA scanning. We have also quantified bone marrow adiposity and circulating leptin levels to assess adipose tissue metabolism. 129Sv/EvSparc tm1cam null mice show decreased bone mineral density and bone mineral content and increased mechanical fragility of bone, in line with previous studies. Differences were also noted. Increased body weight and levels of bone marrow adiposity but decreased circulating leptin concentrations were identified at 4, but not 9 mo, and 129Sv/EvSparc tm1cam null mice also had shorter femurs. Molecular phenotyping was carried out using mouse HGMP NIA microarrays with cortical femur samples at various ages, using semiquantitative RT-PCR validation. We identified 429 genes highly expressed in normal bone. Six genes (Sparc, Zfp162, Bysl, E2F4, two ESTs) are differentially regulated in 129Sv/EvSparc tm1cam cortical femur vs. 129Sv/Ev controls. We confirm low-turnover osteopenia as a feature of the Sparc null phenotype, identifying the usefulness of this mouse as a model for human osteoporosis.

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