A mechanism for semaphorin-induced apoptosis: DNA damage of endothelial and myogenic cells in primary cultures from skeletal muscle

Abstract

One hallmark of cancer is its ability to recruit a vascular supply to support rapid growth. Suppression of angiogenesis holds potential as a second-line or adjuvant therapy to stunt cancer growth, progression, metastasis, and post-resection regeneration. To begin to test the hypothesis that semaphorin 3A and 3F together, will induce endothelial cell apoptosis by inducing DNA damage, mixed primary cultures isolated from normal adult mouse skeletal muscle were treated for 48 hr with Sema3A ± Sema3F (100ng/mL). Changes in surviving-cell density, DNA synthesis, DNA repair (gamma-Histone 2AX, γH2AX, an indirect measure for DNA damage), and apoptotic DNA fragmentation (TUNEL staining) were assayed in cultures of CD31+ endothelial and desmin+ muscle cells. Sema3F increased DNA damage-associated DNA repair in both cell types. Co-treatment with Sema3A+3F increased γH2AX staining ~25-fold over control levels, and further increased apoptosis compared to control and Sema3A alone. Results were negated by treatment with neutralizing anti-semaphorin antibodies and are interpreted as suggesting that Sema3A may sensitize endothelial but not muscle cells to Sema3F-induced DNA damage. These preliminary findings on a complex system of interacting cells may contribute to developing applications that could target angiogenic regulatory mechanisms for their therapeutic potential against cancer progression and metastasis.

Premature satellite cell activation before injury accelerates myogenesis and disrupts neuromuscular junction maturation in regenerating muscle

“…Such changes are also consistent with reports that high HGF (76), traumatic preparation of HGF-containing crushed muscle extract (4,88) and observations that Marcaine (another myotoxin), inhibited SC activation on cultured fibers (4). Possible CTX effects on damage-associated DNA repair (37), if confirmed, could help decipher the interactions of injury type, SC preactivation by ISDN, and relative contributions of DNA repair and S-phase in SCs in the current study.…”

“…observed so soon after CR injury was puzzling. BrdU labeling at day 0 in untreated CR muscles suggests the possibility of early apoptotic changes and rapid DNA repair from DNA damage (37), which requires DNA synthesis (92). Studies including TUNEL staining would determine whether DNA synthesis at day 0 in CR muscle was uncoupled from S-phase and due to apoptosis, as previously reported (37).…”

“…BrdU labeling at day 0 in untreated CR muscles suggests the possibility of early apoptotic changes and rapid DNA repair from DNA damage (37), which requires DNA synthesis (92). Studies including TUNEL staining would determine whether DNA synthesis at day 0 in CR muscle was uncoupled from S-phase and due to apoptosis, as previously reported (37). Myogenic cells have inherent susceptibility to DNA damage (37) and a DNA repair deficiency (20), so cells labeled at day 0 would not likely survive to contribute to later proliferation or myotube formation, as shown in the now classical studies of SC proliferation after muscle damage (10,49,53).…”

Simultaneous miRNA and mRNA Transcriptome Profiling of Differentiating Equine Satellite Cells Treated with Gamma-Oryzanol and Exposed to Hydrogen Peroxide

“…Apoptosis, which is a type of cell death occurring during the development of mammalian muscles, plays an important role in removing unnecessary, damaged, or potentially dangerous cells [19]. A number of factors induce apoptosis, like DNA damaging factors, oxidative stress, or partial ischemia.…”