Multi-Parametric Analysis and Modeling of Relationships between Mitochondrial Morphology and Apoptosis

Abstract

Mitochondria exist as a network of interconnected organelles undergoing constant fission and fusion. Current approaches to study mitochondrial morphology are limited by low data sampling coupled with manual identification and classification of complex morphological phenotypes. Here we propose an integrated mechanistic and data-driven modeling approach to analyze heterogeneous, quantified datasets and infer relations between mitochondrial morphology and apoptotic events. We initially performed high-content, multi-parametric measurements of mitochondrial morphological, apoptotic, and energetic states by high-resolution imaging of human breast carcinoma MCF-7 cells. Subsequently, decision tree-based analysis was used to automatically classify networked, fragmented, and swollen mitochondrial subpopulations, at the single-cell level and within cell populations. Our results revealed subtle but significant differences in morphology class distributions in response to various apoptotic stimuli. Furthermore, key mitochondrial functional parameters including mitochondrial membrane potential and Bax activation, were measured under matched conditions. Data-driven fuzzy logic modeling was used to explore the non-linear relationships between mitochondrial morphology and apoptotic signaling, combining morphological and functional data as a single model. Modeling results are in accordance with previous studies, where Bax regulates mitochondrial fragmentation, and mitochondrial morphology influences mitochondrial membrane potential. In summary, we established and validated a platform for mitochondrial morphological and functional analysis that can be readily extended with additional datasets. We further discuss the benefits of a flexible systematic approach for elucidating specific and general relationships between mitochondrial morphology and apoptosis.

Unique morphological characteristics of mitochondrial subtypes in the heart: the effect of ischemia and ischemic preconditioning

“…Although the role of mitochondrial morphology in cellular physiology has become clearer in recent years, the exact morphological behavior of cardiac mitochondria under normal and pathological settings have not been comprehensively studied and are For mainly confined to IMF and SSM mitochondria 13,20–23 . Furthermore, the morphological status of mitochondria within cells are directly linked with their function 24,25 instance, H2O2 insult of neonatal rat ventricular myocytes induces a dysregulation of Ca 2+ handling and dissipation of mitochondrial membrane potential which in turn increases the measure of mitochondrial roundness 26 . Similarly, IRI simulation in H9C2 cells has been shown to induce the formation of circular donut shaped mitochondria which possess lower membrane potential and altered K + cannel activity in comparison to their elongated counterparts which further supports the link between the morphology of mitochondria and their function 27 .…”

Analysis of mitochondrial structure and function in the Drosophila larval musculature

“…Computerized methods have been developed to rapidly assess mitochondrial dynamics in mammalian cell culture models (Chevrollier et al, 2012; Koopman et al, 2006; Leonard et al, 2015; Lihavainen et al, 2012; Peng et al, 2011; Reis et al, 2012). These methods have clear advantages, including automated fluorescence microscopy followed by high throughput computational binning of mitochondria into distinct morphological subclasses.…”

Cell death detection by quantitative three-dimensional single-cell tomography

“…Many parametric analytic methods have been used to address this issue, including speckle fluctuation in time-lapse images [25–27]. It was confirmed that back-scattering signals are lower in apoptotic cells [28], which is most likely due to the perturbation of mitochondrial morphology during apoptosis [29]. Nuclear disintegration after chromatin condensation provides high-signal-intensity peaks that facilitate the identification of apoptotic cells.…”