Differential Post-Translational Modifications of Proteins in Bladder Ischemia

Abstract

Clinical and basic research suggests that bladder ischemia may be an independent variable in the development of lower urinary tract symptoms (LUTS). We have reported that ischemic changes in the bladder involve differential expression and post-translational modifications (PTMs) of the protein's functional domains. In the present study, we performed in-depth analysis of a previously reported proteomic dataset to further characterize proteins PTMs in bladder ischemia. Our proteomic analysis of proteins in bladder ischemia detected differential formation of non-coded amino acids (ncAAs) that might have resulted from PTMs. In-depth analysis revealed that three groups of proteins in the bladder proteome, including contractile proteins and their associated proteins, stress response proteins, and cell signaling-related proteins, are conspicuously impacted by ischemia. Differential PTMs of proteins by ischemia seemed to affect important signaling pathways in the bladder and provoke critical changes in the post-translational structural integrity of the stress response, contractile, and cell signaling-related proteins. Our data suggest that differential PTMs of proteins may play a role in the development of cellular stress, sensitization of smooth muscle cells to contractile stimuli, and deferential cell signaling in bladder ischemia. These observations may provide the foundation for future research to validate and define clinical translation of the modified biomarkers for precise diagnosis of bladder dysfunction and the development of new therapeutic targets against LUTS.

Keywords: bladder; ischemia; non-coded amino acids; post-translational modifications; protein profiling.

Figure 1

This figure shows samples of bladder microcirculatory blood perfusion measurement with the Speckle Contrast Imaging system in an animal with iliac artery atherosclerosis in comparison with blood perfusion measurement in a sham control animal. Statistical analysis of the blood flow data revealed that the average bladder blood flow of 770 ± 120.31 perfusion units in animals with arterial atherosclerosis was significantly lower in comparison with 1127 ± 219.01 perfusion units in sham controls (p = 0.013), suggesting bladder ischemia in animals with arterial atherosclerosis. Analyzed blood flow values are presented as mean ± standard deviation.

Figure 2

This figure shows the modified residues of contractile proteins and their associated proteins (R² > 0.5, ratio > 2, p < 0.05). Each dot represents the ncAA of a specific protein. The annotation information for each dot is as follows: modified (protein) position, modified amino acid residue, delta mass, and ratio of modification. The horizontal axis represents the amino acid position of each protein; the vertical axis represents the ratio of modification (up or down). aa = amino acid.

Figure 3

This figure shows the modified residues of stress response proteins (R² > 0.5, ratio > 2, p < 0.05). Each dot represents the ncAA of each protein. The annotation information for each dot is as follows: modified (protein) position, modified amino acid residue, delta mass, and ratio of modification. The horizontal axis represents the amino acid position of each protein; the vertical axis represents the ratio of modification (up or down). aa = amino acid.

Figure 4

This figure shows the modified residues of cell signaling-related proteins (R² > 0.5, ratio > 2, p < 0.05). Each dot represents the ncAA of each protein. The annotation information for each dot is as follows: modified (protein) position, modified amino acid residue, delta mass, and ratio of modification. The horizontal axis represents the amino acid position of each protein; the vertical axis represents the ratio of modification (up or down). aa = amino acid.