Journal: bioRxiv
Article Title: Developmentally Regulated GTP-binding Protein Drg1 defines a translational decision point that protects mitochondrial integrity
doi: 10.64898/2026.02.23.707305
Figure Lengend Snippet: Loss of Drg1 impairs mitochondrial protein import. A. Schematic of a mitochondrial import reporter consisting of the SOD2 mitochondrial targeting sequence (MTS) and SOD2 3′UTR flanking an eGFP coding region. SOD2 is a nuclear-encoded mitochondrial enzyme (mitochondrial peroxidase), and the MTS/3′UTR elements promote delivery of newly synthesized eGFP to mitochondria after transfection into HEK293T cells. Import efficiency is quantified by eGFP fluorescence. B. Drg1 loss compromises mitochondrial protein import. (i) Localization of the eGFP mRNA to the mitochondria. The DNA construct shown in (A) was cloned and transfected into HEK293T cells. Following mitochondrial and cytosolic fractionation, translating ribosomes were pelleted and mRNA was extracted. qPCR analysis confirms the presence of construct mRNA in the mitochondrial polysome fraction. (ii). Functional eGFP proteins are only found in mitochondria. HEK293T cells were transfected with the plasmid containing the cloned DNA construct. Fluorescence confocal imaging reveals eGFP (green) localizing to mitochondria that were labeled with MitoTracker (red). Nuclei were counterstained with DAPI (blue). (iii) A reduced median of eGFP fluorescence signal in ΔDrg1 cells. A reduced median of eGFP fluorescence signal in ΔDrg1 cells expressing the reporter compared to WT cells, as measured by flow cytometry. This observation is consistent with decreased mitochondrial import capacity in the absence of Drg1. B. Loss of Drg1 alone does not induce apoptosis. MTT assay measuring cellular viability and proliferation shows no significant difference between WT and ΔDrg1 cells despite changes in mitochondrial morphology and function.
Article Snippet: HEK293T cells were grown and transfected with plasmid expressing N-terminal V5-APEX-10AA linker tagged Drg1 gene with Transit (MIR2705, MirusBio) and serum free media (Gibco) at ∼70-80% confluency.
Techniques: Sequencing, Synthesized, Transfection, Fluorescence, Construct, Clone Assay, Fractionation, Functional Assay, Plasmid Preparation, Imaging, Labeling, Expressing, Flow Cytometry, MTT Assay