Mitochondrial Processes during Early Development of Dictyostelium discoideum: From Bioenergetic to Proteomic Studies

Abstract

The slime mold Dictyostelium discoideum’s life cycle includes different unicellular and multicellular stages that provide a convenient model for research concerning intracellular and intercellular mechanisms influencing mitochondria’s structure and function. We aim to determine the differences between the mitochondria isolated from the slime mold regarding its early developmental stages induced by starvation, namely the unicellular (U), aggregation (A) and streams (S) stages, at the bioenergetic and proteome levels. We measured the oxygen consumption of intact cells using the Clarke electrode and observed a distinct decrease in mitochondrial coupling capacity for stage S cells and a decrease in mitochondrial coupling efficiency for stage A and S cells. We also found changes in spare respiratory capacity. We performed a wide comparative proteomic study. During the transition from the unicellular stage to the multicellular stage, important proteomic differences occurred in stages A and S relating to the proteins of the main mitochondrial functional groups, showing characteristic tendencies that could be associated with their ongoing adaptation to starvation following cell reprogramming during the switch to gluconeogenesis. We suggest that the main mitochondrial processes are downregulated during the early developmental stages, although this needs to be verified by extending analogous studies to the next slime mold life cycle stages.

From biosynthesis and beyond—Loss or overexpression of the cytokinin synthesis gene, iptA, alters cytokinesis and mitochondrial and amino acid metabolism in Dictyostelium discoideum

“…This method was different from our earlier CK profiling assessing early development, for which cells were starved for 6 h in KK2, and samples were collected with distinct streams and aggregation centers 13 . A recent publication assessing mitochondrial dynamics in vegetative growth and early development in D. discoideum through bioenergetics and proteomics found that the main mitochondrial processes are downregulated during early development and that there was less mitochondrial yield overall in early developmental samples compared to vegetative cells 73 . Therefore, sampling a larger population of cells in early development may have helped make the findings in mitochondrial content more comparable to what was analyzed in the vegetative samples.…”

“…13 A recent publication assessing mitochondrial dynamics in vegetative growth and early development in D. discoideum through bioenergetics and proteomics found that the main mitochondrial processes are downregulated during early development and that there was less mitochondrial yield overall in early developmental samples compared to vegetative cells. 73 Therefore, sampling a larger population of cells in early development may have helped make the findings in mitochondrial content more comparable to what was analyzed in the vegetative samples. Sampling after the streaming and aggregation centers have formed would provide an insightful follow-up to this analysis.…”

Generation of a mitochondrial protein compendium in Dictyostelium discoideum

“…Despite the growing interest in using D. discoideum as a model organism to study many conserved mitochondrial processes and some unique biology, a comprehensive list of the mitochondrial proteins has yet to be established. A recent proteomic study detected 294 proteins in D. discoideum mitochondria ( Mazur et al., 2021 ), which we believe is far from complete. Nuclear-encoded mitochondrial proteins, which constitute over 90% of the total mitochondrial proteome, are synthesized in the cytoplasm and then imported to mitochondria.…”