Biology subjects

Secic, D.

Publications and source records attributed to Secic, D..

4 recordsLinked to original sources

bioRxiv2026

Copper transport to mitochondria by SLC25A3 contributes to skeletal myoblast differentiation and is required for survival of differentiated myotubes

Differentiation of skeletal muscle is associated with increased mitochondrial biogenesis and reliance of oxidative phosphorylation (OXPHOS). The terminal enzyme complex in the electron transport chain, cytochrome c oxidase (COX), requires copper for its assembly and activity, and copper delivery to mitochondria is essential for OXPHOS. However, when mitochondrial copper becomes essential during skeletal myoblast differentiation is not known. Here, we show that genetic deficiency of the mitochondrial copper and phosphate carrier SLC25A3 induced prior to myoblast differentiation leads to the formation of smaller myotubes, but SLC25A3 deficiency induced in mature myotubes leads to cell death and detachment. Both phenotypes are recapitulated upon genetic knockdown of COX17, a critical assembly protein for both COX copper cofactors, or by chemical inhibition of COX. Importantly, myotube death caused by SLC25A3 deficiency is rescued by copper supplementation or expression of an SLC25A3 variant that transports copper but not phosphate. Taken together these data support a model wherein copper transport by SLC25A3 and copper delivery to COX is critical for survival in mature myotubes.

cell biology↗

bioRxiv2025

Dynamic assessment of the allocation of copper to cytochrome c oxidase using size-exclusion chromatography (SEC) combined with inductively coupled plasma mass spectrometry (ICP-MS)

Copper (Cu) is an essential trace element required for mitochondrial respiration via its incorporation into cytochrome c oxidase (CuCOX), the terminal enzyme of the electron transport chain. In this study, we employed size-exclusion chromatography coupled with inductively coupled plasma mass spectrometry (SEC-ICP-MS), UV-Vis spectroscopy, and immunoblotting to identify and validate a high-molecular-weight Cu-containing peak in SEC-ICP-MS chromatogram as representative of CuCOX activity. We demonstrate that this CuCOX peak is enhanced under metabolic conditions favoring oxidative phosphorylation, such as high Cu supplementation or galactose-containing media, and correlates with increased mitochondrial respiration. By tracing exogenously supplied 63Cu, we characterized the time- and dose-dependent incorporation of newly acquired Cu into CuCOX. Functional RNA interference (RNAi) experiments targeting key Cu transporters revealed that CuCOX formation is independent of the high-affinity Cu importer CTR1, but instead relies on alternative transporters including DMT1, LAT1, and the mitochondrial carrier SLC25A3. These findings offer new insight into the cellular pathways governing Cu trafficking and allocation to mitochondria under physiologically relevant conditions. Furthermore, our work establishes SEC-ICP-MS as a sensitive and specific method for quantifying CuCOX and assessing mitochondrial metabolism. This platform holds promise for the identification of Cu-related biomarkers and therapeutic targets, particularly in the context of diseases such as renal cell carcinoma (RCC), where dysregulated Cu homeostasis plays a critical role.

biochemistry↗

bioRxiv2024

Copper drives remodeling of metabolic state and progression of clear cell renal cell carcinoma

Copper (Cu) is an essential trace element required for mitochondrial respiration. Late-stage clear cell renal cell carcinoma (ccRCC) accumulates Cu and allocates it to mitochondrial cytochrome c oxidase. We show that Cu drives coordinated metabolic remodeling of bioenergy, biosynthesis and redox homeostasis, promoting tumor growth and progression of ccRCC. Specifically, Cu induces TCA cycle-dependent oxidation of glucose and its utilization for glutathione biosynthesis to protect against H2O2 generated during mitochondrial respiration, therefore coordinating bioenergy production with redox protection. scRNA-seq determined that ccRCC progression involves increased expression of subunits of respiratory complexes, genes in glutathione and Cu metabolism, and NRF2 targets, alongside a decrease in HIF activity, a hallmark of ccRCC. Spatial transcriptomics identified that proliferating cancer cells are embedded in clusters of cells with oxidative metabolism supporting effects of metabolic states on ccRCC progression. Our work establishes novel vulnerabilities with potential for therapeutic interventions in ccRCC. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/575895v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@14e1b89org.highwire.dtl.DTLVardef@f1c83forg.highwire.dtl.DTLVardef@191aff8org.highwire.dtl.DTLVardef@1b7ccd1_HPS_FORMAT_FIGEXP M_FIG C_FIG O_LIAccumulation of copper is associated with progression and relapse of ccRCC and drives tumor growth. C_LIO_LICu accumulation and allocation to cytochrome c oxidase (CuCOX) remodels metabolism coupling energy production and nucleotide biosynthesis with maintenance of redox homeostasis. C_LIO_LICu induces oxidative phosphorylation via alterations in the mitochondrial proteome and lipidome necessary for the formation of the respiratory supercomplexes. C_LIO_LICu stimulates glutathione biosynthesis and glutathione derived specifically from glucose is necessary for survival of CuHi cells. Biosynthesis of glucose-derived glutathione requires activity of glutamyl pyruvate transaminase 2, entry of glucose-derived pyruvate to mitochondria via alanine, and the glutamate exporter, SLC25A22. Glutathione derived from glucose maintains redox homeostasis in Cu-treated cells, reducing Cu-H2O2 Fenton-like reaction mediated cell death. C_LIO_LIProgression of human ccRCC is associated with gene expression signature characterized by induction of ETC/OxPhos/GSH/Cu-related genes and decrease in HIF/glycolytic genes in subpopulations of cancer cells. Enhanced, concordant expression of genes related to ETC/OxPhos, GSH, and Cu characterizes metabolically active subpopulations of ccRCC cells in regions adjacent to proliferative subpopulations of ccRCC cells, implicating oxidative metabolism in supporting tumor growth. C_LI

cancer biology↗

bioRxiv2022

MAP1LC3C regulates lysosomal exocytosis and induces zinc reprogramming in renal cancer cells

MAP1LC3C (LC3C) is a member of the microtubule associated family of proteins that are essential in the formation of autophagosomes and lysosomal degradation of cargo. LC3C has tumor suppressing activity and its expression is dependent on kidney cancer tumor suppressors, such as VHL and FLCN. Recently we demonstrated that LC3C autophagy is regulated by noncannonical upstream regulatory complexes and targets for degradation postdivision midbody rings associated with cancer cells stemness. Here we show that loss of LC3C leads to peripheral positioning of the lysosomes and lysosomal exocytosis (LE) in a subset of cells. This process is independent of the autophagic activity of LC3C. Analysis of isogenic cells with low and high LE shows substantial transcriptomic reprogramming with altered expression of Zn-related genes and activity of Polycomb Repressor Complex 2 (PRC2), accompanied by a robust decrease in intracellular Zn. Metabolomic analysis revealed alterations in amino acid steady-state levels. Cells with augmented LE show tumor initiation properties and form aggressive tumors in xenograft models. Immunocytochemistry identified high levels of LAMP1 on the plasma membrane of cancer cells in human ccRCC and reduced levels of Zn, an indication that LE is a frequent event in ccRCC, potentially contributing to the loss of Zn. Overall, these data indicate that an important tumor suppressing activity of LC3C is contributing to the reprogramming of lysosomal activity and Zn metabolism with implication for epigenetic remodeling in a subpopulation of tumor propagating properties of cancer cells.

cell biology↗