Biology subjects

Chang, C. J.

Publications and source records attributed to Chang, C. J..

14 recordsLinked to original sources

bioRxiv2026

A Liver-Targeted Copper Supplement Reduces Metabolic Dysfunction-Associated Liver Steatosis by Increasing Lipolysis and Fatty Acid Oxidation

Metabolic-associated steatotic liver disease (MASLD) is a prevalent liver disease driven by complex dysregulation of hepatic lipid metabolism. Here we show that copper deficiency is a nutrient vulnerability in steatotic liver disease and that selective liver-targeted copper supplementation can reduce excess lipid accumulation. Analysis of steatotic patient and mouse tissues identify widespread alterations in hepatic copper homeostasis markers. Integrated multi-omics analyses reveal that copper induces lipolysis of PLIN2-containing lipid droplets while lipid importer CD36 is downregulated. We show that copper inhibits cAMP hydrolase activity of PDE3B, thus activating PKA-mediated HSL and AMPK activation upstream of lipolysis. Fatty acids liberated through lipolysis are subsequently degraded via enhanced mitochondrial fatty acid oxidation, supported by energetic rewiring toward oxidative phosphorylation (OXPHOS) with increased copper-dependent complex IV and SOD1 activity. Our findings establish a multi-pronged mechanism by which hepatic copper supplementation coordinately regulates lipid metabolism in response to steatosis and unveils a therapeutic metallomedicine strategy to rewire lipid regulation. SummaryLiver-targeted copper supplementation reduces diet-induced liver steatosis by dual activation of lipolysis and fatty acid degradation pathways. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=196 SRC="FIGDIR/small/725917v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@982970org.highwire.dtl.DTLVardef@1c8adb5org.highwire.dtl.DTLVardef@4762dorg.highwire.dtl.DTLVardef@ea95cd_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2026

Reduction in Hepatic Phosphatidylcholine Biosynthesis Promotes MASH Through Copper Deficiency

Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive liver disease for which the mechanisms linking lipid dysregulation to fibrosis remain poorly defined. Hepatic phosphatidylcholine (PC) content is reduced in MASH, but how this alteration drives disease progression is unclear. Here, we identify a role for copper (Cu) homeostasis as a downstream effector of impaired PC biosynthesis. Using single-nucleus RNA sequencing in complementary genetic and dietary mouse models, we found that reduced hepatic PC is associated with marked depletion of hepatic Cu and a concomitant increase in circulating Cu, indicating disrupted Cu distribution. Mechanistically, PC depletion impaired plasma membrane localization of the high-affinity Cu transporter CTR1 (SLC31A1) in hepatocytes, limiting Cu uptake. In human hepatic stellate cells, Cu promoted fibrogenic activation, whereas suppression of Cu import or pharmacologic inhibition of MAPK signaling attenuated fibronectin deposition. In vivo, liver-directed Cu supplementation restored hepatic Cu levels and reduced steatosis but failed to improve fibrosis. In contrast, pharmacologic Cu chelation with bathocuproinedisulfonic acid (BCS) reduced fibrosis without affecting inflammation. Together, these findings identify Cu redistribution as a consequence of impaired PC biosynthesis and implicate Cu-dependent signaling in stellate cell activation, fibrogenesis and MASH pathogenesis. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/723926v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1c2bd52org.highwire.dtl.DTLVardef@1b8295org.highwire.dtl.DTLVardef@1a129dorg.highwire.dtl.DTLVardef@1bc2b87_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2026

Copper Import via CTR1 Supports the β3-Adrenergic Thermogenic Program

Adaptive thermogenesis requires coordinated activation of mitochondrial oxidation and metabolic remodeling, yet the signals driving this coordination are incompletely understood. Here, we show that cold exposure and {beta}3-adrenergic receptor ({beta}3-AR) stimulation upregulate the high-affinity copper (Cu) importer CTR1 and promote Cu accumulation in thermogenic adipose tissues. Adipocyte-specific Ctr1 knockout (ACKO) mice exhibit markedly reduced energy expenditure and develop severe hypothermia during acute cold challenge. Proteomic analysis of brown adipose tissue (BAT) from ACKO mice reveals coordinated suppression of oxidative phosphorylation and thermogenic metabolic programs, accompanied by attenuation of lipolytic pathways. Cu deficiency also impairs cold- and {beta}3-AR-induced lipolytic activation, including reduced HSL phosphorylation and lipid clearance in both BAT and inguinal white adipose tissue (iWAT). Although BAT-specific Ctr1 deletion (BCKO) leaves acute {beta}3-adrenergic responses largely intact, these mice still exhibit cold intolerance, indicating that BAT Cu homeostasis is indispensable for sustaining thermogenic capacity during cold challenge. Treatment with the Cu ionophore elesclomol partially restores mitochondrial oxidative capacity and improves cold tolerance in ACKO mice. Together, these findings identify CTR1-dependent Cu import as a dynamically regulated component of the {beta}3-adrenergic thermogenic program and establish intracellular Cu availability as a key determinant of thermogenic capacity during adaptive thermogenesis.

molecular biology↗

bioRxiv2026

Chiral methionine oxidation reagents reveal stereospecific proteome modifications

Life is predicated on chirality, a molecular asymmetry akin to the left and right versions of human hands. Here we show that privileged protein residues are predisposed for chiral regulation. We developed enantiomeric oxaziridine reagents that systematically identify pro-(S) and pro-(R) methionine oxidation sites across proteomes that can be erased by stereospecific methionine sulfoxide reductase enzymes A and B, respectively. These probes reveal that chiral regulation of methionine oxidation-reduction processes can allosterically regulate protein function, as shown in cell and murine models of oxidative stress where selective (R)-methionine sulfoxide formation on M69 of biphenyl hydrolase-like protein leads to hydrolase inhibition and amplification of proteome N-homocysteinylation modifications. This work introduces a platform for characterizing sites of asymmetric methionine oxidation and the functional consequences concomitant with an individual chiral single-atom modification.

biochemistry↗

bioRxiv2026

Lysosomal Expansion Compartments Mediate Zinc and Copper Homeostasis in Caenorhabditis elegans

Zinc is an essential transition metal that participates in many biological processes. In C. elegans, excess zinc is stored in lysosomes in intestinal cells; this process involves increasing the expression of the zinc transporter CDF-2 and remodeling of lysosomes characterized by an increase in the volume of the expansion compartment. To determine if this is a more general property, we investigated other metals. Here we report that lysosomes are remodeled in response to excess copper, manganese, and cadmium, with each metal causing an increase in the volume of the expansion compartment. Mutants with a reduced number of lysosomes were hypersensitive to growth retardation caused by excess copper and manganese, suggesting metal toxicity is prevented by metal sequestration in lysosomes. Using a novel method to analyze isolated lysosomes by X-ray Fluorescence Microscopy we demonstrated that zinc, copper and manganese are detectable in the lumen of lysosomes. To further analyze copper, we examined localization of CUA-1.1, a copper transporter that moves copper into the lumen of lysosomes. Like the zinc transporter CDF-2, CUA-1.1 localizes to both the acidified and expansion compartments in excess copper. These results indicate that the same intestinal lysosomes store zinc, copper and manganese. Lysosome remodeling characterized by an increase in volume of the expansion compartment is not specific to zinc but is a more general phenomenon during metal storage in lysosomes.

molecular biology↗

bioRxiv2025

Repurposing Melatonin in dual-mode for Wilson disease therapy as a Copper Chelator and an antioxidant agent

Loss-of-function mutations in copper-ATPase ATP7B underlie Wilson disease (WD), a disorder characterized by hepatic copper accumulation and severe hepato-neuropathology. Existing chelation therapeutics remove excess copper but lack intrinsic antioxidant capacity and frequently cause systemic toxicity. Here we evaluate melatonin, an FDA-approved indoleamine with antioxidant and putative metal-chelating activity, as a candidate therapeutic for WD. In ATP7B-/- hepatocytes, melatonin restored copper-induced reactive oxygen species (ROS) to basal levels, reduced apoptosis twofold, and attenuated Nrf2 nuclear translocation leading to reduction of Hemoxygenase-1 abundance. Live-cell ratiometric analysis of GSSG/GSH using GRX1-roGFP2 expressed in melatonin-treated ATP7B-/- hepatocytes revealed a significant reduction in intensity-ratio, indicating an effective mitigation of copper-induced glutathione oxidation. Isothermal calorimetric titration revealed moderate Cu2+ affinity (K ITC=4.54 x 103 M-{superscript 1}), rationalized by MD-simulations showing an interaction energy of 18.5 x 10-3 kcal{middle dot}mol-{superscript 1} via amide-Cu{superscript 2} coordination. In-cellulo studies also revealed that copper-induced vesicularized ATP7B reinstates to Golgi in melatonin-treated hepatocytes. In vivo, melatonin treatment reduced copper-induced oxidative stress in zebrafish embryos and lowered copper burden in Caenorhabditis elegans WD model. Our studies revealed that encapsulation of melatonin within an engineered polymeric nanocapsules having dithiol linkers, susceptible to cleavage by GSH, extended melatonins circulatory half-life ten-fold and enhanced its ROS-scavenging efficacy three-fold relative to free melatonin. This work introduces a unique dual-function therapeutic strategy that integrates antioxidant activity with copper chelation, simultaneously addressing copper overload and redox imbalance. Repurposing melatonin, with its established clinical safety, offers rapid and cost-effective translational pathway toward WD-therapy while providing a generalizable platform for redox- and metal-associated disorders.

cell biology↗

bioRxiv2025

The PBAF chromatin remodeling complex contributes to metal homeostasis through Mtf1 regulation

SWI/SNF chromatin remodeling complexes regulate gene expression by modulating nucleosome positioning, yet their roles in metal homeostasis during skeletal muscle development remain unclear. Here, we uncover distinct functions of the BAF, PBAF, and ncBAF complexes in myoblast proliferation under metal stress. While knockdown (KD) of Baf250a (BAF-specific) or Brd9 (ncBAF-specific) reduces myoblast proliferation, Baf180 (PBAF-specific) KD does not impair cell proliferation under basal conditions. Interestingly, supplementation with copper (Cu) or zinc (Zn) rescues proliferation in Baf250a- and Brd9-deficient myoblasts but paradoxically inhibits growth in Baf180 KD cells. Mechanistically, Baf180 KD disrupts Cu and Zn homeostasis, leading to intracellular Cu accumulation without labile Cu pools and impaired expression of Atp7a, a key Cu exporter. Transcriptomic analyses reveal widespread gene dysregulation in metal-treated Baf180-deficient cells, while metal supplementation promotes pro-proliferative gene expression in Baf250a- and Brd9-KD myoblasts. CUT&RUN assays demonstrate that metal-responsive transcription factor Mtf1 exhibits increased chromatin binding upon Cu treatment, targeting genes involved in stress response and myogenesis. Notably, Mtf1 colocalizes with Baf180 in the nucleus and co-immunoprecipitates with both conserved SWI/SNF subunits and Baf180, suggesting a functional interplay between PBAF and Mtf1 in regulating metal-dependent gene expression. Our findings establish the PBAF complex as a crucial regulator of Cu/Zn homeostasis in myoblast proliferation via Mtf1, while metal supplementation compensates for BAF and ncBAF dysfunction but exacerbates defects in PBAF-deficient cells. This study reveals a novel link between chromatin remodeling, metal signaling, and muscle development, with implications for stress adaptation and metabolic regulation in myogenesis.

molecular biology↗

bioRxiv2025

Endothelial Cu Uptake Transporter CTR1 Senses Disturbed Flow to Promote Atherosclerosis through Cuproptosis

Endothelial cells (ECs) lining blood vessels sense disturbed blood flow (D-flow), which drives mitochondrial dysfunction and atherosclerosis. Copper (Cu) is an essential micronutrient, and its disruption of homeostasis has been implicated in atherosclerosis. Cellular Cu levels are tightly controlled by Cu transport proteins including the Cu importer CTR1. Cuproptosis is a recently discovered form of regulated cell death triggered by mitochondrial Cu accumulation, but its endogenous stimulants and role in atherosclerosis remain unknown. Using EC-specific CTR1-deficient mice and cultured ECs, we show that endothelial CTR1 responds to D-flow by increasing mitochondrial Cu levels through its interaction with the mitochondrial Cu transporter SLC25A3 at caveolae/lipid rafts. This leads to the aggregation of lipoylated mitochondrial proteins, mitochondrial dysfunction, and cuproptosis, thereby exacerbating atherosclerosis. Importantly, mitochondria-targeted Cu-chelating nanoparticles effectively mitigate D-flow-induced cuproptosis and atherosclerosis, highlighting the endothelial CTR1-SLC25A3-mitochondrial Cu axis as a potential therapeutic target.

cell biology↗

bioRxiv2023

Glial swip-10 expression controls systemic mitochondrial function, oxidative stress, and neuronal viability via copper ion homeostasis

Cuprous copper (Cu(I)) is an essential cofactor for enzymes supporting many cellular functions including mitochondrial respiration and suppression of oxidative stress. Neurons are particularly dependent on these pathways, with multiple neurodegenerative diseases, including Alzheimers disease (AD), Parkinsons disease, associated with their dysfunction. Key features of Cu(I) contributions to neuronal health in vivo remain to be defined, owing largely to the complex processes involved in Cu(I) production, intracellular transport, and systemic redistribution. Here, we provide genetic and pharmacological evidence that swip-10 is a critical determinant of systemic Cu(I) levels in C. elegans, with deletion leading to systemic deficits in mitochondrial respiration, production of oxidative stress, and neurodegeneration. These phenotypes can be reproduced in wild-type worms by Cu(I)-specific chelation and offset in swip-10 mutants by growth on the Cu(I) enhancing molecule elesclomol, as well as by glial expression of wildtype swip-10. MBLAC1, the most closely related mammalian ortholog to swip-10, encodes for a pre-mRNA processing enzyme for H3 histone, a protein whose actions surprisingly include an enzymatic capacity to produce Cu(I) via the reduction of Cu(II). Moreover, genome-wide association studies and post-mortem molecular studies implicate reductions of MBLAC1 expression in risk for AD with cardiovascular disease comorbidity. Consistent with these studies, we demonstrate that the deposition of {beta}-amyloid plaques, an AD pathological hallmark, in worms engineered to express human A{beta}1-42, is greatly exaggerated by mutation of swip-10. Together, these studies identify a novel glial-expressed, and pathway for Cu(I) production that may be targeted for the treatment of AD and other neurodegenerative diseases. Significance StatementDevastating neurodegenerative diseases such as Alzheimers disease, and Parkinsons disease are associated with disruptions in copper (Cu) homeostasis. Alterations in Cu(I) give rise to increased oxidative stress burden, mitochondrial and metabolic dysfunction, and can accelerate production and/or potentiate toxicity of disease-associated protein aggregates. Here, using the model system Caenorhabditis elegans, we establish a role for the gene swip-10 in systemic Cu(I) homeostasis. Perturbation of this pathway in worms recapitulates biochemical, histological, and pathological features seen in human neurodegenerative disease. We reveal that these changes can be suppressed pharmacologically and arise when swip-10 expression is eliminated from glial cells. Our work implicates swip-10 and orthologs as key players in Cu(I) homeostasis that may be exploitable to treat multiple neurodegenerative diseases.

neuroscience↗

bioRxiv2023

Disruption of Aldehyde Dehydrogenase 2 protects against 1 bacterial infection

The ALDH2*2 (rs671) variant present in >500 million individuals reduces ALDH2 function, impairing aldehyde detoxification. While aldehyde accumulation in these individuals is associated with numerous negative health consequences, a previous study showed a cohort of ALDH2*2 carriers are less likely to develop active pulmonary tuberculosis. Here, we present additional human data that support this finding and show ALDH2-deficiency in mice provides a fitness advantage during bacterial infections. We found aldehydes normally detoxified by ALDH2 killed the bacterial pathogens Mycobacterium tuberculosis and Francisella tularensis. Infected macrophages from Aldh2-/-mice had higher levels of formaldehyde and 4-hydroxynonenal, which enhanced their microbicidal capacity. Aldh2-/- mice were more resistant to infection with Mycobacterium tuberculosis and Francisella tularensis than parental mice and displayed elevated inflammatory cytokine and chemokine levels, accompanied by an increased accumulation of inflammatory monocytes and macrophages. These findings support a model in which host-derived aldehydes are robust innate immune effectors, limiting bacterial infection through both direct microbicidal activity and immune modulation. Collectively, this work may explain why the ALDH2*2 allele was selected for in humans.

microbiology↗

bioRxiv2023

Leishmania major-induced alteration of host cellular and systemic copper homeostasis drives the fate of infection

Copper plays a key role in host-pathogen interaction. We found that during Leishmania major infection, the parasite-harboring macrophage regulates its copper homeostasis pathway in a way to facilitate copper-mediated neutralization of the pathogen. Copper-ATPase ATP7A transports copper to amastigote-harboring phagolysosomes to induce stress on parasites. Leishmania in order to evade the copper stress, utilizes a variety of manipulative measures to lower the host-induced copper stress. It induces deglycosylation and degradation of host-ATP7A and downregulation of copper importer, CTR1 by cysteine oxidation. Additionally, Leishmania induces CTR1 endocytosis that arrests copper uptake. In mouse model of infection, we report an increase in systemic bioavailable copper in infected animals. Heart acts as the major organ for diverting its copper reserves to systemic circulation to fight-off infection by downregulating its CTR1. Our study explores reciprocal mechanism of manipulation of host copper homeostasis pathway by macrophage and Leishmania to gain respective advantages in host-pathogen interaction.

cell biology↗

bioRxiv2021

PLEKHA5, PLEKHA6 and PLEKHA7 bind to PDZD11 to target the Menkes ATPase ATP7A to the cell periphery and regulate copper homeostasis

Copper homeostasis is crucial for cellular physiology and development, and its dysregulation leads to disease. The Menkes ATPase ATP7A plays a key role in copper efflux, by trafficking from the Golgi to the plasma membrane upon cell exposure to elevated copper, but the mechanisms that target ATP7A to the cell periphery are poorly understood. PDZD11 interacts with the C-terminus of ATP7A, which contains sequences involved in ATP7A trafficking, but the role of PDZD11 in ATP7A localization is unknown. Here we identify PLEKHA5 and PLEKHA6 as new interactors of PDZD11, which similarly to the junctional protein PLEKHA7 bind to PDZD11 N-terminus through their WW domains. Using CRISPR-KO kidney epithelial cells, we show by immunofluorescence that WW-PLEKHAs (PLEKHA5, PLEKHA6, PLEKHA7) recruit PDZD11 to distinct plasma membrane localizations, and that they are required for the efficient anterograde targeting of ATP7A to the cell periphery in elevated copper. Pulldown experiments show that WW-PLEKHAs promote PDZD11 interaction with the C-terminus of ATP7A. However, WW-PLEKHAs and PDZD11 are not necessary for ATP7A Golgi localization in basal copper, ATP7A copper-induced exit from the Golgi, and ATP7A retrograde trafficking to the Golgi. Finally, measuring bioavailable copper with the labile copper probe CF4 shows that WW-PLEKHAs and PDZD11 are required to maintain low intracellular copper levels when cells are exposed to elevated copper. These data indicate that WW-PLEKHAs-PDZD11 complexes regulate the localization and function of ATP7A to modulate cellular copper homeostasis.

cell biology↗

bioRxiv2019

Systematic identification of engineered methionines and oxaziridines for efficient, stable, and site-specific antibody bioconjugation

Chemical modification of antibodies is one of the most important bioconjugations utilized by biologists and biotechnology. To date, the field has been dominated by random modification of lysines or more site-specific labeling of cysteines, each with attendant challenges. Recently we have developed oxaziridine chemistry for highly selective and efficient sulfimide modification of methionine called redox-activated chemical tagging (ReACT). Here, we systematically scanned methionines throughout one of the most popular antibody scaffolds, trastuzumab, for antibody engineering and drug conjugation. We tested the expression, reactivities, and stabilities of 123 single engineered methionines distributed over the surface of the antibody when reacted with oxaziridine. We found uniformly high expression for these mutants and generally good reaction efficiencies with the panel of oxaziridines. Remarkably, the stability to hydrolysis of the sulfimide varied more than ten-fold depending on temperature and the site of the engineered methionine. Interestingly, the most stable and reactive sites were those that were partially buried, likely because of their reduced access to water. There was also a ten-fold variation in stability depending on the nature of the oxaziridine, which we determined was inversely correlated with the electrophilic nature of the sulfimide. Importantly, the stabilities of the best analogs and antibody drug conjugate potencies were comparable to those reported for cysteine-maleimide modifications of trastuzumab. We also found our antibody drug conjugates to be potent in a breast cancer mouse xenograft model. These studies provide a roadmap for broad application of ReACT for efficient, stable, and site-specific antibody and protein bioconjugation.

bioengineering↗

bioRxiv2019

Activity-Based Ratiometric FRET Probe Reveals Oncogene-Driven Changes in Labile Copper Pools Induced by Altered Glutathione Metabolism

Copper is essential for life, and beyond its well-established ability to serve as a tightly-bound, redox-active active site cofactor for enzyme function, emerging data suggest that cellular copper also exists in labile pools, defined as loosely bound to low molecular weight ligands, which can regulate diverse transition metal signaling processes spanning neural communication and olfaction, lipolysis, rest-activity cycles, and kinase pathways critical for oncogenic signaling. To help decipher this growing biology, we report a first-generation ratiometric fluorescence resonance energy transfer (FRET) copper probe, FCP-1, for activity-based sensing of labile Cu(I) pools in live cells. FCP-1 links fluorescein and rhodamine dyes through a tris[(2-pyridyl)methyl]amine (TPA) bridge. Bioinspired Cu(I)-induced oxidative cleavage decreases FRET between fluorescein donor and rhodamine acceptor. FCP-1 responds to Cu(I) with high metal selectivity and oxidation-state specificity and facilitates ratiometric measurements that minimize potential interferences arising from variations in sample thickness, dye concentration, and light intensity. FCP-1 enables imaging of dynamic changes in labile Cu(I) pools in live cells in response to copper supplementation/depletion, differential expression of the copper importer CTR1, and redox stress induced by manipulating intracellular glutathione levels and GSH/GSSG ratios. FCP-1 imaging reveals a labile Cu(I) deficiency induced by oncogene-driven cellular transformation that promotes fluctuations in glutathione metabolism, where lower GSH/GSSG ratios decrease labile Cu(I) availability without affecting total copper levels. By connecting copper dysregulation and glutathione stress in cancer, this work provides a valuable starting point to study broader crosstalk between metal and redox pathways in health and disease with activity-based probes.\n\nSignificanceCopper is a required metal nutrient for life, yet its altered homeostasis is associated with many diseases. Thus, to develop new methods to help decipher copper biology, we present an activity-based ratiometric FRET probe that exploits a biomimetic, copper(I)-dependent cleavage reaction to enable imaging of loosely-bound, labile copper pools in cells with metal and oxidation state selectivity and a self-calibrating ratiometric response. Application of this technology to cellular models of cancer reveals that oncogene-driven changes in the metabolism of glutathione, a major cellular redox buffer, leads to a labile copper(I) deficiency. This work establishes the relevance of copper dysregulation to cancer metabolism and presages further opportunities for activity-based sensing in studies of metal biology.

biochemistry↗