Biology subjects

Vest, K. E.

Publications and source records attributed to Vest, K. E..

6 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

The copper chaperone ATOX1 exhibits differential protein-protein interactions and contributes to skeletal myoblast differentiation

Copper is an essential but potentially toxic nutrient required for a variety of biological functions. Mammalian cells use a complex network of copper transporters and metallochaperones to maintain copper homeostasis. Previous work investigating the role of copper in various disease states has highlighted the importance of copper transporters and metallochaperones. However, questions remain about how copper distribution changes under dynamic conditions like tissue differentiation. We previously reported that the copper exporter ATP7A is required for skeletal myoblast differentiation and that its expression changes in a differentiation dependent manner. Here, we sought to further understand the ATP7A-mediated copper export pathway by examining ATOX1, the copper chaperone that delivers copper to ATP7A. To investigate the role of ATOX1 in a dynamic cellular context, we characterized its binding partners during myoblast differentiation using the proximity labeling protein APEX2 to biotinylate proteins near ATOX1. We discovered that the ATOX1 interactome undergoes dramatic changes as myoblasts differentiate. These dynamic interactions correlate with distinct phenotypes of ATOX1 deficiency in proliferating and differentiated cells. Together, our results highlight the dynamic interactome of ATOX1 and its contribution to myoblast differentiation.

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↗

bioRxiv2020

Intrinsic and extrinsic factors collaborate to activate pharyngeal satellite cells without muscle injury

Satellite cells (SCs), adult muscle stem cells in craniofacial muscles proliferate and differentiate/fuse without injury, unlike quiescent SCs in uninjured limb muscle. However, whether intrinsic or extrinsic factors driving their increased basal activity are largely unknown. We compared SCs from the pharynx, which contains constrictor muscles critical for swallowing, to SCs from limb muscle. Pharyngeal SCs are intrinsically more proliferative and contain higher mitochondrial content relative to limb SCs. Pharyngeal SCs occupy less quiescent microenvironments containing collagen V and pharyngeal muscles provide a distinctive SC niche enriched with neighboring resident macrophages and fibroadipogenic progenitors. Loss of SCs impacts pharyngeal myofiber cross-sectional area and the number of neighboring cells, suggesting that SCs are required to maintain pharyngeal muscle homeostasis and its unique niche. Taken together, this study gives new insights to explain the distinctive SC activity of craniofacial muscles, which may explain their unique susceptibility to various muscular dystrophies.

cell biology↗

bioRxiv2018

Manganese influx and expression of ZIP8 is essential in primary myoblasts and contributes to activation of SOD2

Trace elements such as copper (Cu), zinc (Zn), iron (Fe), and manganese (Mn) are enzyme cofactors and second messengers in cell signaling. Trace elements are emerging as key regulators of differentiation and development of mammalian tissues including blood, brain, and skeletal muscle. We previously reported an influx of Cu and dynamic expression of various metal transporters during differentiation of skeletal muscle cells. Here, we demonstrate that during differentiation of skeletal myoblasts an increase of additional trace elements such as Mn, Fe and Zn occurs. Interestingly the Mn increase is concomitant with increased Mn-dependent SOD2 levels. To better understand the Mn import pathway in skeletal muscle cells, we probed the functional relevance of the closely related proteins ZIP8 and ZIP14, which are implicated in Zn, Mn, and Fe transport. Partial depletion of ZIP8 severely impaired growth of myoblasts and led to cell death under differentiation conditions, indicating that ZIP8-mediated metal transport is essential in skeletal muscle cells. Moreover, knockdown of Zip8 impaired activity of the Mn-dependent SOD2. Growth defects were partially rescued by Mn supplementation to the medium, suggesting additional functions for ZIP8 in the skeletal muscle lineage. Knockdown of Zip14, on the other hand, had only a mild effect on myotube size, consistent with a role for ZIP14 in muscle hypertrophy. This is the first report on the functional relevance of two members of the ZIP family of metal transporters in the skeletal muscle lineage, and further supports the paradigm that trace metal transporters are critical modulators of mammalian tissue development.

cell biology↗