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

Monika Mazur,Daria Wojciechowska,Ewa Sitkiewicz,Agata Malinowska,Małgorzata Wojtkowska,Hanna Kmita,Bianka Świderska

doi:10.3390/genes12050638

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.

Highlights

The unicellular slime mold Dictyostelium discoideum, one of the 150 species of Dictyostelia belonging to the Amoebozoa eukaryotic supergroup, displays the multicellularity form, namely aggregative or sorocarp multicellularity [1,2]
The slime mold aggregates, which results in an intermediate migrating ‘slug’ stage and cells specializing into spores as well as three somatic cell types forming a stalk and structures to support the stalk and spore mass (Figure 1)
The respiratory state of mitochondria is a dynamic state resulting from crosstalk between the two bioenergetic states termed state 3 and state 4 [16,19]

Summary

Introduction

The unicellular slime mold Dictyostelium discoideum, one of the 150 species of Dictyostelia belonging to the Amoebozoa eukaryotic supergroup, displays the multicellularity form, namely aggregative or sorocarp multicellularity [1,2]. The slime mold aggregates, which results in an intermediate migrating ‘slug’ stage and cells specializing into spores as well as three somatic cell types forming a stalk and structures to support the stalk and spore mass (Figure 1). This process is mainly based on chemical signals settled on cAMP and cAMP-dependent kinase (PkaC) [3], which induces the expression of the genes responsible for aggregation such as the receptor of cAMP (CarA), adenylate cyclase (AcaA), and cAMP phosphodiesterase (PdsA) [2,4]. These genes are responsible for cell adhesion and are known as the marker genes of post-aggregative cell differentiation [6]

Objectives

Methods

Results