Search

Due to their cardiac origin, H9c2 cells rank among the most popular cell lines in current cardiovascular research, yet molecular phenotype remains elusive. Hence, in this study we used proteomic approach to describe molecular phenotype of H9c2 cells in their undifferentiated (i.e., most frequently used) state, and its functional response to cardiotoxic drug doxorubicin. Of 1671 proteins identified by iTRAQ IEF/LC-MSMS analysis, only 12 proteins were characteristic for striated muscle cells and none was cardiac phenotype-specific. Targeted LC-SRM and western blot analyses confirmed that undifferentiated H9c2 cells are phenotypically considerably different to both primary neonatal cardiomyocytes and adult myocardium. These cells lack proteins essential for formation of striated muscle myofibrils or they express only minor amounts thereof. They also fail to express many proteins important for metabolism of muscle cells. The challenge with clinically relevant concentrations of doxorubicin did not induce a proteomic signature that has been previously noted in primary cardiomyocytes or adult hearts. Instead, several alterations previously described in other cells of mesodermal origin, such as fibroblasts, were observed (e.g., severe down-regulation of collagen synthesis pathway). In conclusion, the molecular phenotype of H9c2 cells resembles very immature myogenic cells with skeletal muscle commitment upon differentiation and thus, translatability of findings obtained in these cells deserves caution., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Chronic anthracycline cardiotoxicity is a feared complication of cancer chemotherapy. However, despite several decades of primarily hypothesis-driven research, the molecular basis of this phenomenon remains poorly understood. The aim of this study was to obtain integrative molecular insights into chronic anthracycline cardiotoxicity and the resulting heart failure. Cardiotoxicity was induced in rabbits (daunorubicin 3mg/kg, weekly, 10weeks) and changes in the left ventricular proteome were analyzed by 2D-DIGE. The protein spots with significant changes (p<0.01, >1.5-fold) were identified using MALDI-TOF/TOF. Key data were corroborated by immunohistochemistry, qRT-PCR and enzyme activity determination and compared with functional, morphological and biochemical data. The most important alterations were found in mitochondria - especially in proteins crucial for oxidative phosphorylation, energy channeling, antioxidant defense and mitochondrial stress. Furthermore, the intermediate filament desmin, which interacts with mitochondria, was determined to be distinctly up-regulated and disorganized in its expression pattern. Interestingly, the latter changes reflected the intensity of toxic damage in whole hearts as well as in individual cells. In addition, a marked drop in myosin light chain isoforms, activation of proteolytic machinery (including the proteasome system), increased abundance of chaperones and proteins involved in chaperone-mediated autophagy, membrane repair as well as apoptosis were found. In addition, dramatic changes in proteins of basement membrane and extracellular matrix were documented. In conclusion, for the first time, the complex proteomic signature of chronic anthracycline cardiotoxicity was revealed which enhances our understanding of the basis for this phenomenon and it may enhance efforts in targeting its reduction., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Light microscopy (LM) approaches are commonly used to attain a description of the cell structure. Even though LM, if compared to electron microscopy (EM), represents a very fast approach, its resolution is, in principle, much lower than in the case of EM. To improve the LM resolution, computational methods based on removal of the image blur are frequently implemented in cell biology studies. One of the standard deblurring approaches is image restoration through deconvolution algorithms. Even though this method of mathematical remodeling of microscopically observed objects represents an efficient tool of current cell biology, it is legitimate to ask what the limits of its use are. We demonstrate that, in the specific case of the fluorescence mapping of active ribosomal genes in HeLa cell nucleoli, restoration generates a biased result. On restoration of model images, we demonstrate the difficulties of one of the most effective deconvolution algorithms during the restoration of ring-shaped fluorescent objects of a diameter comparable to the microscope resolution limit. In the case involving the mapping of nucleolar transcription in HeLa cells, not the restored fluorescence images, but rather the EM images show the true distribution of active ribosomal genes.