Angiogenesis-Centered Molecular Cross-Talk in Amyotrophic Lateral Sclerosis Survival: Mechanistic Insights

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that is characterized with progressive muscle atrophy. We have attempted to establish the link between angiogenesis and cellular survival in the pathogenesis of ALS by compiling evidence described in various scientific reports. The phenotypes of human ALS have earlier been captured in the mutant SOD1 mice as well as by targeted deletion of the hypoxia response element (HRE) from the promoter of the mouse gene for vascular endothelial growth factor (VEGF). Indirect evidence shows that angiogenesis can help prevent oxidative stress, and hence, enhance cell survival. VEGF and angiogenin chiefly regulate the process of angiogenesis. Transactive response DNA-binding protein 43 (TDP-43) is usually found inside the nucleus, but in large number of cases of ALS, it accumulates in the cytoplasm (TDP-43 proteinopathy). Interestingly, TDP-43 proteinopathy is found to be aggravated in the presence of the OPTN mutation, which is the genetic factor that is responsible for such accumulation. Interaction of TDP-43 with progranulin can further affect the angiogenesis in ALS patients by regulating activity of VEGF receptors, but conclusive evidence is needed to establish its role in pathogenesis of ALS. Certain mutations in UBQLN2 and UBQLN4 indicate that ubiquitination has a role in ALS pathobiology, but its link to angiogenesis has not been adequately studied. Recent studies have shown that several mutations in RNA-binding proteins (RBPs) can also cause ALS. Conclusively, in this review, we have attempted to argue the role of angiogenesis in enhanced ALS survival rate is probably regulated with the activation of NF-κβ. Additionally, interaction between OPTN and TDP-43 can also impact the transcription of various angiogenic molecules. Whether targeting angiogenic substances or TDP-43 can provide clues about extending ALS survival rate, in combination with current treatments, can only be evaluated after additional studies.