DARPin-Based Inhibition of PARP1 for Muscular Dystrophy and Overtraining Syndrome

Muscular dystrophy (MD) is a hereditary condition that results from the aging of muscles in the human body. Recently, hyperactivation of the Poly(ADP-ribose) polymerase 1 (PARP1) protein present in the fibroblast cells has been linked to MD and overtraining syndrome. Therefore, inhibiting these proteins could inhibit the overactivation of PARP1 and mitigate the disease. The AlphaFold software was used  to create a 3D shape of the PARP1 protein to visualize the amino acid sequence. HDOCK was used to understand the binding interaction between two different biomolecules. The PARP1-DARPins binding energy was computed using the PRODIGY software. Designated Ankyrin Repeat Proteins (DARPins) are a class of engineered, non-antibody binding proteins used in protein diagnostics and therapeutics. The results show that the DARPins bind to the predicted binding site of the PARP1 protein as computed by the P2Rank webserver. The DARPins also bind to the DNA-binding site of the PARP1 protein. There- fore, DARPin binding could inhibit the overfunctioning of the PARP1 protein. Based on binding energy, DARPin D3 (PDB ID: 4K5C) formed the strongest interaction (-13.6 kcal/mol) with the PARP1 protein and was selected as the most appropriate candidate. In future studies, we will be performing DARPin mu- tational studies to enhance the binding affinity towards the PARP1 protein. These results highlight the potential of DARPin-based theragnostic as a novel approach for targeting PARP1-related muscle degrada- tion and help in alleviating the global burden of the disease.