Fig 1: Diaphragm muscle fibers in E18.5 Abl2 mutant mice are extraordinarily long, and the central tendon is diminished in size.Whole mounts of muscle were stained with antibodies to myosin heavy chain (MHC). (A) Costal muscle fibers in E18.5 embryonic diaphragm muscle normally extend from the ribcage and attach medially to the central tendon (CT). (B) The mean myofiber length, measured in the ventral quadrant of the costal diaphragm muscle, is ~1.7 fold longer in E18.5 Abl2 mutant than in wild type (wt) mice. (C,D) The area of the central tendon, circumscribed by Scx RNA expression, was reduced in Abl2-/- mice. **p<0.01, ****p<0.001.
Fig 2: Abl2 acts in myoblasts to regulate muscle development.(A,B) Abl2 mRNA is highly expressed in the muscle but not within the central tendon (CT) of the diaphragm. (C) Muscle and tendon development appear normal in Abl2flox/+ control mice (Abl2f/+). Muscle length is increased and tendon size is reduced by conditionally inactivating Abl2 in (D) muscle precursors (Abl2f/-; Pax3cre), or (E) committed myoblasts (Abl2f/-; Myodicre). (F) Muscle and tendon development appear normal by inactivating Abl2 in mature myotubes (Abl2f/-; Mck::cre). Scale bars are 500 µm in A and C.
Fig 3: Myoblast proliferation is enhanced by a loss of Abl2.(A,B) In vivo labeling of E13.5-E14.5 diaphragm muscles shows that EdU incorporation is greater in Abl2-/- myoblasts than wild type (wt) myoblasts. (C) Representative images of cultured diaphragm cells stained with MyoD to label myoblasts, DAPI to label all cells and EdU to label proliferating cells. (D) At initial plating, a similar number of MyoD+ cells are isolated from Abl2-/- and wild type mice. (E) Cultured MyoD+ myoblasts from Abl2-/- diaphragm muscles showed increased EdU incorporation. (F) In contrast, non-muscle cells (MyoD-) from Abl2 mutant and wild type mice proliferate at similar rates. (G) Abl2 heterozygous myoblasts proliferated at a rate that was intermediate between wild type and Abl2 homozygous mutant myoblasts. (H) Representative images of cultured diaphragm cells stained with MyoD to label myoblasts, DAPI to label all cells, and phospho-Histone H3 (pHH3), a marker for mitotic cells. (I) MyoD+ myoblasts, cultured from the diaphragm muscle of Abl2-/- mice, showed a greater percentage of mitotic figures than myoblasts isolated from wild type mice. *p=0.1, **p<0.05, ****p<0.001.
Fig 4: Enhanced myoblast proliferation in Abl2-/- mice leads to enhanced myoblast fusion.Primary cultures from the diaphragm muscle of E18.5 mice were stained with antibodies to myosin heavy chain (MHC) to label differentiated muscle fibers and MyoD to label myoblasts. (A) Representative images of diaphragm muscle cells, which were proliferated for 2 days before a switch to differentiation medium. (B) Under these conditions, Abl2 mutant myoblasts displayed enhanced myotube formation. (C) The number of nuclei per myotube was quantified. Differentiated Abl2 mutant myotubes incorporated more nuclei per myotube. (D) Representative images of Abl2 mutant myoblasts, which were plated at confluent density and directly into differentiation media. (E) Confluent cultures, which did not have an opportunity to proliferate, formed myotubes like wild type myoblasts. Scale bars are 50 µm in A,I, and L. **p<0.01, ****p<0.001.
Fig 5: Ectopic muscle islands, which are found in the central tendon of mice that are heterozygous for Abl2, induce tendon cell differentiation.(A,B) Whole mount diaphragms, stained with antibodies to myosin heavy chain (MHC), revealed 1 to 4 ectopic islands in the central tendon of Abl2+/- mice. (C) Scx RNA expression is enhanced at the ends of muscle fibers in the ectopic islands (black arrows) as well as at the normal MTJ in the diaphragm muscle. (D) Lineage-tracing experiments in Abl2+/- mice reveal that tendon cells, marked by tdTomato (arrowheads), intercalate between MHC-stained muscle fibers within the ectopic islands but do not contribute to myofibers. (E) Whole mount images reveal ectopic muscles in the central tendon of muscle conditional Abl2 heterozygous mice (Abl2f/+; Pax3cre). Scale bar is 250 µm in D.
Supplier Page from Proteintech Group Inc for ABL2 antibody