Limits...
Notch and bone morphogenetic protein differentially act on dermomyotome cells to generate endothelium, smooth, and striated muscle.

Ben-Yair R, Kalcheim C - J. Cell Biol. (2008)

Bottom Line: Notch activity is necessary for smooth muscle production while inhibiting striated muscle differentiation, yet it does not affect initial development of endothelial cells.Hence, although different mechanisms are responsible for smooth muscle and endothelium generation, the choice to become smooth versus striated muscle depends on a single signaling system.Altogether, these findings underscore the spatial and temporal complexity of lineage diversification in an apparently homogeneous epithelium.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.

ABSTRACT
We address the mechanisms underlying generation of skeletal muscle, smooth muscle, and endothelium from epithelial progenitors in the dermomyotome. Lineage analysis shows that of all epithelial domains, the lateral region is the most prolific producer of smooth muscle and endothelium. Importantly, individual labeled lateral somitic cells give rise to only endothelial or mural cells (not both), and endothelial and mural cell differentiation is driven by distinct signaling systems. Notch activity is necessary for smooth muscle production while inhibiting striated muscle differentiation, yet it does not affect initial development of endothelial cells. On the other hand, bone morphogenetic protein signaling is required for endothelial cell differentiation and/or migration but inhibits striated muscle differentiation and fails to impact smooth muscle cell production. Hence, although different mechanisms are responsible for smooth muscle and endothelium generation, the choice to become smooth versus striated muscle depends on a single signaling system. Altogether, these findings underscore the spatial and temporal complexity of lineage diversification in an apparently homogeneous epithelium.

Show MeSH

Related in: MedlinePlus

Notch signaling affects the balance between myotomal and mural cells derived from the lateral DM. (A) Histogram summarizing the relative phenotypic distribution of labeled cells derived from lateral DMs that were electroporated with either GFP, N1-ICD, N2-ICD, or Numb, 40 h after transfection. Notch overactivation biases cells to a mural fate at the expense of myotomal cells, whereas Numb biases cells to a myotomal fate at the expense of other fates. Results represent mean ± SEM. Significance of results of the different treatments was examined vis-a-vis GFP controls (*, P < 0.05; **, P < 0.01; ***, P < 0.001). (B–D) Electroporations of control GFP (B), N1-ICD/GFP (C), or Numb (D) to lateral E2.5 DMs. GFP or Numb immunoreactivity is green, QH1 is red, and HOECHST is blue. (B) In control GFP-treated epithelium, myotomal and dermal cells are produced along with mural and endothelial cells, which are seen in the wall of the CV. (C) Notch1 biases cells to a mural fate (see E–G). Note the presence of many GFP+/QH1− cells in the walls of BVs. Similar results were obtained with N2-ICD. (D) Numb+ cells are predominantly localized in the myotome. (E–G) N2-ICD, N1-ICD, or GFP electroporations to lateral E2.5 DMs. SMA is red in E and desmin is red in F and G. HOECHST is blue. (E) N2-ICD electroporation enhances SMA expression on the treated side and also stimulates the number of GFP+/SMA+ cells in the wall of the CV and between the VLL and CV. This is also apparent in the enlarged image appearing in the inset. (F) N1-ICD had a similar effect as revealed by desmin immunostaining. (G) GFP electroporation does not increase desmin staining in the CV wall or between the CV and VLL. WD, Wolffian duct. Bars: (B) 26 μm; (C and D) 60 μm; (E and G) 81 μm; (F) 74 μm; (E and G, inset) 55 μm; (F, inset) 65 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2234248&req=5

fig3: Notch signaling affects the balance between myotomal and mural cells derived from the lateral DM. (A) Histogram summarizing the relative phenotypic distribution of labeled cells derived from lateral DMs that were electroporated with either GFP, N1-ICD, N2-ICD, or Numb, 40 h after transfection. Notch overactivation biases cells to a mural fate at the expense of myotomal cells, whereas Numb biases cells to a myotomal fate at the expense of other fates. Results represent mean ± SEM. Significance of results of the different treatments was examined vis-a-vis GFP controls (*, P < 0.05; **, P < 0.01; ***, P < 0.001). (B–D) Electroporations of control GFP (B), N1-ICD/GFP (C), or Numb (D) to lateral E2.5 DMs. GFP or Numb immunoreactivity is green, QH1 is red, and HOECHST is blue. (B) In control GFP-treated epithelium, myotomal and dermal cells are produced along with mural and endothelial cells, which are seen in the wall of the CV. (C) Notch1 biases cells to a mural fate (see E–G). Note the presence of many GFP+/QH1− cells in the walls of BVs. Similar results were obtained with N2-ICD. (D) Numb+ cells are predominantly localized in the myotome. (E–G) N2-ICD, N1-ICD, or GFP electroporations to lateral E2.5 DMs. SMA is red in E and desmin is red in F and G. HOECHST is blue. (E) N2-ICD electroporation enhances SMA expression on the treated side and also stimulates the number of GFP+/SMA+ cells in the wall of the CV and between the VLL and CV. This is also apparent in the enlarged image appearing in the inset. (F) N1-ICD had a similar effect as revealed by desmin immunostaining. (G) GFP electroporation does not increase desmin staining in the CV wall or between the CV and VLL. WD, Wolffian duct. Bars: (B) 26 μm; (C and D) 60 μm; (E and G) 81 μm; (F) 74 μm; (E and G, inset) 55 μm; (F, inset) 65 μm.

Mentions: Constitutively active Notch1 (N1-ICD) or Notch2 (N2-ICD) constructs were coelectroporated with a GFP-encoding plasmid into the lateral DM and embryos were incubated for an additional 40 h. Electroporation of either Notch construct increased the proportions of mural cells out of total GFP+ cells by threefold when compared with control GFP (n = 4 embryos out of 20 with a similar phenotype; Fig. 3, A–C and E–G, compare B and C with E–G). Many Notch-overexpressing cells were located in the walls of the great vessels, especially in the CV, causing a small but consistent increase in SMA/desmin staining in the vein on the treated compared with the untreated side or to control GFP-treated segments (Fig. 3, B, C, and E–G). Interestingly, many Notch-overexpressing cells that stained positive for SMA and desmin were apparent between the ventrolateral lip (VLL) of the DM and the CV. This feature was not detected under control conditions although, occasionally, a few control GFP-expressing cells lacking smooth muscle markers were visible at this location (Fig. 3, E–G, insets). We suggest that these are migrating cells en route to the CV and that Notch signaling strikingly increases their number while prematurely inducing expression of smooth muscle markers. Consistent with the latter notion, premature expression of SMA was already detected around BVs 16–20 h after N2-ICD transfection, which is before the onset of normal expression of this marker under control conditions (Fig. 4, A and B).


Notch and bone morphogenetic protein differentially act on dermomyotome cells to generate endothelium, smooth, and striated muscle.

Ben-Yair R, Kalcheim C - J. Cell Biol. (2008)

Notch signaling affects the balance between myotomal and mural cells derived from the lateral DM. (A) Histogram summarizing the relative phenotypic distribution of labeled cells derived from lateral DMs that were electroporated with either GFP, N1-ICD, N2-ICD, or Numb, 40 h after transfection. Notch overactivation biases cells to a mural fate at the expense of myotomal cells, whereas Numb biases cells to a myotomal fate at the expense of other fates. Results represent mean ± SEM. Significance of results of the different treatments was examined vis-a-vis GFP controls (*, P < 0.05; **, P < 0.01; ***, P < 0.001). (B–D) Electroporations of control GFP (B), N1-ICD/GFP (C), or Numb (D) to lateral E2.5 DMs. GFP or Numb immunoreactivity is green, QH1 is red, and HOECHST is blue. (B) In control GFP-treated epithelium, myotomal and dermal cells are produced along with mural and endothelial cells, which are seen in the wall of the CV. (C) Notch1 biases cells to a mural fate (see E–G). Note the presence of many GFP+/QH1− cells in the walls of BVs. Similar results were obtained with N2-ICD. (D) Numb+ cells are predominantly localized in the myotome. (E–G) N2-ICD, N1-ICD, or GFP electroporations to lateral E2.5 DMs. SMA is red in E and desmin is red in F and G. HOECHST is blue. (E) N2-ICD electroporation enhances SMA expression on the treated side and also stimulates the number of GFP+/SMA+ cells in the wall of the CV and between the VLL and CV. This is also apparent in the enlarged image appearing in the inset. (F) N1-ICD had a similar effect as revealed by desmin immunostaining. (G) GFP electroporation does not increase desmin staining in the CV wall or between the CV and VLL. WD, Wolffian duct. Bars: (B) 26 μm; (C and D) 60 μm; (E and G) 81 μm; (F) 74 μm; (E and G, inset) 55 μm; (F, inset) 65 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2234248&req=5

fig3: Notch signaling affects the balance between myotomal and mural cells derived from the lateral DM. (A) Histogram summarizing the relative phenotypic distribution of labeled cells derived from lateral DMs that were electroporated with either GFP, N1-ICD, N2-ICD, or Numb, 40 h after transfection. Notch overactivation biases cells to a mural fate at the expense of myotomal cells, whereas Numb biases cells to a myotomal fate at the expense of other fates. Results represent mean ± SEM. Significance of results of the different treatments was examined vis-a-vis GFP controls (*, P < 0.05; **, P < 0.01; ***, P < 0.001). (B–D) Electroporations of control GFP (B), N1-ICD/GFP (C), or Numb (D) to lateral E2.5 DMs. GFP or Numb immunoreactivity is green, QH1 is red, and HOECHST is blue. (B) In control GFP-treated epithelium, myotomal and dermal cells are produced along with mural and endothelial cells, which are seen in the wall of the CV. (C) Notch1 biases cells to a mural fate (see E–G). Note the presence of many GFP+/QH1− cells in the walls of BVs. Similar results were obtained with N2-ICD. (D) Numb+ cells are predominantly localized in the myotome. (E–G) N2-ICD, N1-ICD, or GFP electroporations to lateral E2.5 DMs. SMA is red in E and desmin is red in F and G. HOECHST is blue. (E) N2-ICD electroporation enhances SMA expression on the treated side and also stimulates the number of GFP+/SMA+ cells in the wall of the CV and between the VLL and CV. This is also apparent in the enlarged image appearing in the inset. (F) N1-ICD had a similar effect as revealed by desmin immunostaining. (G) GFP electroporation does not increase desmin staining in the CV wall or between the CV and VLL. WD, Wolffian duct. Bars: (B) 26 μm; (C and D) 60 μm; (E and G) 81 μm; (F) 74 μm; (E and G, inset) 55 μm; (F, inset) 65 μm.
Mentions: Constitutively active Notch1 (N1-ICD) or Notch2 (N2-ICD) constructs were coelectroporated with a GFP-encoding plasmid into the lateral DM and embryos were incubated for an additional 40 h. Electroporation of either Notch construct increased the proportions of mural cells out of total GFP+ cells by threefold when compared with control GFP (n = 4 embryos out of 20 with a similar phenotype; Fig. 3, A–C and E–G, compare B and C with E–G). Many Notch-overexpressing cells were located in the walls of the great vessels, especially in the CV, causing a small but consistent increase in SMA/desmin staining in the vein on the treated compared with the untreated side or to control GFP-treated segments (Fig. 3, B, C, and E–G). Interestingly, many Notch-overexpressing cells that stained positive for SMA and desmin were apparent between the ventrolateral lip (VLL) of the DM and the CV. This feature was not detected under control conditions although, occasionally, a few control GFP-expressing cells lacking smooth muscle markers were visible at this location (Fig. 3, E–G, insets). We suggest that these are migrating cells en route to the CV and that Notch signaling strikingly increases their number while prematurely inducing expression of smooth muscle markers. Consistent with the latter notion, premature expression of SMA was already detected around BVs 16–20 h after N2-ICD transfection, which is before the onset of normal expression of this marker under control conditions (Fig. 4, A and B).

Bottom Line: Notch activity is necessary for smooth muscle production while inhibiting striated muscle differentiation, yet it does not affect initial development of endothelial cells.Hence, although different mechanisms are responsible for smooth muscle and endothelium generation, the choice to become smooth versus striated muscle depends on a single signaling system.Altogether, these findings underscore the spatial and temporal complexity of lineage diversification in an apparently homogeneous epithelium.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.

ABSTRACT
We address the mechanisms underlying generation of skeletal muscle, smooth muscle, and endothelium from epithelial progenitors in the dermomyotome. Lineage analysis shows that of all epithelial domains, the lateral region is the most prolific producer of smooth muscle and endothelium. Importantly, individual labeled lateral somitic cells give rise to only endothelial or mural cells (not both), and endothelial and mural cell differentiation is driven by distinct signaling systems. Notch activity is necessary for smooth muscle production while inhibiting striated muscle differentiation, yet it does not affect initial development of endothelial cells. On the other hand, bone morphogenetic protein signaling is required for endothelial cell differentiation and/or migration but inhibits striated muscle differentiation and fails to impact smooth muscle cell production. Hence, although different mechanisms are responsible for smooth muscle and endothelium generation, the choice to become smooth versus striated muscle depends on a single signaling system. Altogether, these findings underscore the spatial and temporal complexity of lineage diversification in an apparently homogeneous epithelium.

Show MeSH
Related in: MedlinePlus