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Regulation of slow and fast muscle myofibrillogenesis by Wnt/beta-catenin and myostatin signaling.

Tee JM, van Rooijen C, Boonen R, Zivkovic D - PLoS ONE (2009)

Bottom Line: Deviation from proper muscle development or homeostasis results in various myopathic conditions.Employing genetic as well as chemical intervention, we provide evidence that a tight regulation of Wnt/beta-catenin signaling is essential for muscle fiber growth and maintenance.Epistatic analyses suggest a possible genetic interaction between Wnt/beta-catenin and Myostatin in regulation of slow and fast twitch muscle myofibrillogenesis.

View Article: PubMed Central - PubMed

Affiliation: Hubrecht Institute for Developmental Biology and Stem Cell Research and University Medical Center, Utrecht, The Netherlands.

ABSTRACT
Deviation from proper muscle development or homeostasis results in various myopathic conditions. Employing genetic as well as chemical intervention, we provide evidence that a tight regulation of Wnt/beta-catenin signaling is essential for muscle fiber growth and maintenance. In zebrafish embryos, gain-of-Wnt/beta-catenin function results in unscheduled muscle progenitor proliferation, leading to slow and fast muscle hypertrophy accompanied by fast muscle degeneration. The effects of Wnt/beta-catenin signaling on fast muscle hypertrophy were rescued by misexpression of Myostatin or p21(CIP/WAF), establishing an in vivo regulation of myofibrillogenesis by Wnt/beta-catenin signaling and Myostatin. Epistatic analyses suggest a possible genetic interaction between Wnt/beta-catenin and Myostatin in regulation of slow and fast twitch muscle myofibrillogenesis.

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Myotome hyperproliferation and sustained differentiation in axin/apc1 embryos.(A) BrdU pulse was performed at 36 hpf, chased for 12 hours, and imaged at 48 hpf. Embryos were imaged at the level of the yolk extension. Scale bar, 25 µm. BrdU+ pulse was performed at 28 hpf or 36 hpf, and quantification of number of BrdU+ proliferating cells per somite was done 12 hours later at 40 hpf or 48 hpf, respectively. (C) HUA treatment of embryos from 24 hpf until fixation at 54 hpf. Inhibition of proliferation with HUA from 24 hpf results in rescue of muscle hypertrophy. Muscle fibers were stained with Phalloidin, and imaged at 54 hpf at the level of the yolk extension. Compare with untreated wild-types in Fig. 2A (right panels). Scale bar, 25 µm. Quantification of number of somites is increased in axin1/apc1 mutants upon HUA treatment. (E) Colocalization of Pax3/7+ and PH 3+ cells shows proliferating muscle progenitors. Quantification of proliferating Pax3/7+ and Pax3/7- cells in the wild-types vs. axin1/apc1 mutant embryos shows significantly more proliferating Pax3/7+ cells in the mutants. Scale bar, 50 µm.
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pone-0005880-g004: Myotome hyperproliferation and sustained differentiation in axin/apc1 embryos.(A) BrdU pulse was performed at 36 hpf, chased for 12 hours, and imaged at 48 hpf. Embryos were imaged at the level of the yolk extension. Scale bar, 25 µm. BrdU+ pulse was performed at 28 hpf or 36 hpf, and quantification of number of BrdU+ proliferating cells per somite was done 12 hours later at 40 hpf or 48 hpf, respectively. (C) HUA treatment of embryos from 24 hpf until fixation at 54 hpf. Inhibition of proliferation with HUA from 24 hpf results in rescue of muscle hypertrophy. Muscle fibers were stained with Phalloidin, and imaged at 54 hpf at the level of the yolk extension. Compare with untreated wild-types in Fig. 2A (right panels). Scale bar, 25 µm. Quantification of number of somites is increased in axin1/apc1 mutants upon HUA treatment. (E) Colocalization of Pax3/7+ and PH 3+ cells shows proliferating muscle progenitors. Quantification of proliferating Pax3/7+ and Pax3/7- cells in the wild-types vs. axin1/apc1 mutant embryos shows significantly more proliferating Pax3/7+ cells in the mutants. Scale bar, 50 µm.

Mentions: The ability of Wnts to enhance proliferation in the dermomyotome [27] led us to hypothesize that unscheduled proliferation in the somites might lead to muscle hypertrophy in axin1/apc1 mutants. While at 16 hpf there was no difference in proliferation between mutants and wildtypes (data not shown), from 28 hpf onwards, BrdU pulse experiments identified a sharp increase in number of cells in S-phase (Fig. 4A), which was confirmed by increased labeling of phosphohistone H3 (PH 3)+ mitotic cells (data not shown) and their quantification by FACS (Fig. S2B). To investigate whether this unscheduled increased proliferation caused muscle hypertrophy, we partially inhibited cell division with a combination of aphidicolin [28] and hydroxyurea (HUA) [29] from 24 hpf until fixation at 54 hpf. Strikingly, the fast muscle hypertrophy (Fig. 4B; compare to Fig. 2A, right panels) and degeneration (Fig. S3A) as well as the number of somites were partially rescued (Fig. 4B) confirming that hyperproliferation leads to the fast muscle hypertrophy and degeneration.


Regulation of slow and fast muscle myofibrillogenesis by Wnt/beta-catenin and myostatin signaling.

Tee JM, van Rooijen C, Boonen R, Zivkovic D - PLoS ONE (2009)

Myotome hyperproliferation and sustained differentiation in axin/apc1 embryos.(A) BrdU pulse was performed at 36 hpf, chased for 12 hours, and imaged at 48 hpf. Embryos were imaged at the level of the yolk extension. Scale bar, 25 µm. BrdU+ pulse was performed at 28 hpf or 36 hpf, and quantification of number of BrdU+ proliferating cells per somite was done 12 hours later at 40 hpf or 48 hpf, respectively. (C) HUA treatment of embryos from 24 hpf until fixation at 54 hpf. Inhibition of proliferation with HUA from 24 hpf results in rescue of muscle hypertrophy. Muscle fibers were stained with Phalloidin, and imaged at 54 hpf at the level of the yolk extension. Compare with untreated wild-types in Fig. 2A (right panels). Scale bar, 25 µm. Quantification of number of somites is increased in axin1/apc1 mutants upon HUA treatment. (E) Colocalization of Pax3/7+ and PH 3+ cells shows proliferating muscle progenitors. Quantification of proliferating Pax3/7+ and Pax3/7- cells in the wild-types vs. axin1/apc1 mutant embryos shows significantly more proliferating Pax3/7+ cells in the mutants. Scale bar, 50 µm.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2690692&req=5

pone-0005880-g004: Myotome hyperproliferation and sustained differentiation in axin/apc1 embryos.(A) BrdU pulse was performed at 36 hpf, chased for 12 hours, and imaged at 48 hpf. Embryos were imaged at the level of the yolk extension. Scale bar, 25 µm. BrdU+ pulse was performed at 28 hpf or 36 hpf, and quantification of number of BrdU+ proliferating cells per somite was done 12 hours later at 40 hpf or 48 hpf, respectively. (C) HUA treatment of embryos from 24 hpf until fixation at 54 hpf. Inhibition of proliferation with HUA from 24 hpf results in rescue of muscle hypertrophy. Muscle fibers were stained with Phalloidin, and imaged at 54 hpf at the level of the yolk extension. Compare with untreated wild-types in Fig. 2A (right panels). Scale bar, 25 µm. Quantification of number of somites is increased in axin1/apc1 mutants upon HUA treatment. (E) Colocalization of Pax3/7+ and PH 3+ cells shows proliferating muscle progenitors. Quantification of proliferating Pax3/7+ and Pax3/7- cells in the wild-types vs. axin1/apc1 mutant embryos shows significantly more proliferating Pax3/7+ cells in the mutants. Scale bar, 50 µm.
Mentions: The ability of Wnts to enhance proliferation in the dermomyotome [27] led us to hypothesize that unscheduled proliferation in the somites might lead to muscle hypertrophy in axin1/apc1 mutants. While at 16 hpf there was no difference in proliferation between mutants and wildtypes (data not shown), from 28 hpf onwards, BrdU pulse experiments identified a sharp increase in number of cells in S-phase (Fig. 4A), which was confirmed by increased labeling of phosphohistone H3 (PH 3)+ mitotic cells (data not shown) and their quantification by FACS (Fig. S2B). To investigate whether this unscheduled increased proliferation caused muscle hypertrophy, we partially inhibited cell division with a combination of aphidicolin [28] and hydroxyurea (HUA) [29] from 24 hpf until fixation at 54 hpf. Strikingly, the fast muscle hypertrophy (Fig. 4B; compare to Fig. 2A, right panels) and degeneration (Fig. S3A) as well as the number of somites were partially rescued (Fig. 4B) confirming that hyperproliferation leads to the fast muscle hypertrophy and degeneration.

Bottom Line: Deviation from proper muscle development or homeostasis results in various myopathic conditions.Employing genetic as well as chemical intervention, we provide evidence that a tight regulation of Wnt/beta-catenin signaling is essential for muscle fiber growth and maintenance.Epistatic analyses suggest a possible genetic interaction between Wnt/beta-catenin and Myostatin in regulation of slow and fast twitch muscle myofibrillogenesis.

View Article: PubMed Central - PubMed

Affiliation: Hubrecht Institute for Developmental Biology and Stem Cell Research and University Medical Center, Utrecht, The Netherlands.

ABSTRACT
Deviation from proper muscle development or homeostasis results in various myopathic conditions. Employing genetic as well as chemical intervention, we provide evidence that a tight regulation of Wnt/beta-catenin signaling is essential for muscle fiber growth and maintenance. In zebrafish embryos, gain-of-Wnt/beta-catenin function results in unscheduled muscle progenitor proliferation, leading to slow and fast muscle hypertrophy accompanied by fast muscle degeneration. The effects of Wnt/beta-catenin signaling on fast muscle hypertrophy were rescued by misexpression of Myostatin or p21(CIP/WAF), establishing an in vivo regulation of myofibrillogenesis by Wnt/beta-catenin signaling and Myostatin. Epistatic analyses suggest a possible genetic interaction between Wnt/beta-catenin and Myostatin in regulation of slow and fast twitch muscle myofibrillogenesis.

Show MeSH
Related in: MedlinePlus