Rhesus Monkeys Research Articles

Evolution of the complex growth hormone gene cluster in macaques.

In higher primates, unlike other mammals, the growth hormone (GH) gene locus is complex, comprising several GH-like genes, resulting from gene duplication and divergent evolution, expressed in pituitary and placenta. There are 5 genes in this GH gene cluster in human and 5-7 in apes and most Old-World monkeys, but in macaques the cluster has expanded further. Here the nature and evolution of the GH locus in this important primate genus is explored. Analysis of genomic data for Macaca fascicularis (crab-eating macaque) revealed that the GH gene cluster in this species is variable, with at least 5 different haplotypes, comprising 11-14 GH-like genes. Gene-number heterozygosity was also detected in M. mulatta (rhesus macaque) with 9-13 genes. Analysis of genomic data for other macaque species revealed GH gene clusters containing 8-14 GH-like genes, but gene-number heterozygosity was not detected. Expression of GH-like genes in pituitary and placenta was examined for M. fascicularis. This analysis has established that complexity of the GH gene cluster increased during the evolution of macaques, by gene duplication and divergent evolution, and that these processes continue within at least two extant species. Analysis of rate of sequence change, and distribution of substitutions within the 3D structure, shows that for at least one GH-like gene (GH2) the changes reflect positive selection, implying adaptive biological change. Whether this involves changes in physiological (endocrine) function or response to viral or other pathogenic challenge is not yet clear.

Linking individual variation in facial musculature to facial behavior in rhesus macaques.

Facial expression is a key component of primate communication, and primates (including humans) have a complex system of facial musculature underpinning this behavior. Human facial musculature is highly variable across individuals, but to date, whether other primate species exhibit a similar level of inter-individual variation is unknown. Whether individual-level variation in facial musculature covaries with significant differences in facial movement within the same individual is also unknown. Here, we use facial dissection data from 31 adult rhesus macaques, the largest sample to date, to quantify inter-individual variation in facial muscle presence. We used a subsample of eight individuals to measure covariation between facial muscle presence and the presence of external facial movements (action units in the Facial Action Coding System, or FACS). We found, in contrast to humans, limited inter-individual variation in muscle presence, but the zygomatic region exhibited more gross anatomical variation in muscle presence and morphology than any other region of the macaque face. We also found a good correspondence between facial muscle presence and the presence of the associated action units. Our results indicate that the observed variation in rhesus macaque facial expressivity is not likely driven primarily by variation in facial muscle presence but may instead be due to other factors such as learned behavior and/or physiological differences. These findings provide insight into the anatomical basis of inter-individual variation in facial behavior in primates and suggest potential differences in variation between humans and other primate species.

Connectivity profile and function of uniquely human cortical areas.

Determining the brain specializations unique to humans requires directly comparative anatomical information from other primates, especially our closest relatives. Human (Homo sapiens) (m/f), chimpanzee (Pan troglodytes) (f), and rhesus macaque (Macaca mulatta) (m/f) white matter atlases were used to create connectivity blueprints, i.e., descriptions of the cortical grey matter in terms of the connectivity with homologous white matter tracts. This allowed a quantitative comparative of cortical organization across the species. We identified human-unique connectivity profiles concentrated in temporal and parietal cortices, and hominid-unique organization in prefrontal cortex. Functional decoding revealed human-unique hotspots correlated with language processing and social cognition. Overall, our results counter models that assign primacy to prefrontal cortex for human uniqueness.Significance statement Understanding what makes the human brain unique requires direct comparisons with other primates, particularly our closest relatives. Using connectivity blueprints, we compared to cortical organization of the human to that of the macaque and, for the first time, the chimpanzee. This approach revealed human-specific connectivity patterns in the temporal and parietal lobes, regions linked to language and social cognition. These findings challenge traditional views that prioritize the prefrontal cortex in defining human cognitive uniqueness, emphasizing instead the importance of temporal and parietal cortical evolution in shaping our species' abilities.

Exploring the genetic mechanisms driving KIR diversification.

Killer cell immunoglobulin-like receptors (KIRs) are key modulators of natural killer cell activity, displaying either activating or inhibitory potential upon recognition of major histocompatibility complex (MHC) class I molecules. The genomic organization of KIR genes is complex, involving copy number variation and allelic polymorphism, which is probably due to their coevolution with highly polymorphic MHC ligands. The KIR diversity is reflected by more than 70 similar region configurations encountered in humans, generated through meiotic recombination events. Rhesus macaques happen to display even more diversity, and over 100 distinct configurations were identified in a relatively small cohort of animals. More than half of these region configurations feature hybrid KIR genes, suggesting a more pronounced mode of diversification in macaques. The molecular mechanism facilitating meiotic rearrangements in the KIR region is poorly understood. Examination of 21 rhesus macaque and 14 human KIR region configurations revealed the presence of long terminal repeats and PRDM9 binding motifs associated with recombination hotspots. The variable DNA recognition patterns of PRDM9 could potentially contribute to the differing recombination activities documented for the KIR region in humans and macaques. The diversification process of the KIR repertoire in natural killer cells is fundamentally distinct from the mechanisms generating T and B cell receptor diversity or MHC polymorphisms. This sophisticated recombination machinery preserves the functional integrity by the frequent generation of in-frame KIR genes. A diverse KIR repertoire contributes to the protection of individuals and populations against pathogen evasion and subversion.

Density-dependent feedback across nested levels of organization in a social primate.

The strength and direction of density-dependent mechanisms acting on individual reproduction and survival may vary across the nested levels of organization social animals live in, such that complex patterns of density dependence shape fitness and population growth. Yet knowledge of such processes of population regulation where individuals are simultaneously subjected to contrasting density effects remains limited. We quantify and contrast density effects on components of individual fitness across two nested levels of organization: the population and the social group, using 45 years of demographic data of rhesus macaques. Our analysis reveals opposing density feedback on individual reproduction and survival across levels of organization and shows that density does not affect all life stages equally. While increased population density reduced female reproduction during maturation, females in larger groups were more likely to reproduce. Infant survival was optimal at intermediate population densities, and monkeys in larger groups showed increased survival. Our work shows that population-level density effects on individual reproduction and survival can be as strong as group-level effects and suggests different roles of the philopatric (i.e. females) and dispersing (i.e. males) sexes on the regulation of individual demographic performance. In this way, our work posits testable mechanistic hypotheses for evaluating density effects on components of individual fitness and highlights the need to explicitly consider the organization and demographic structure of social animals when quantifying individual performance and population dynamics.

GDC: Integration of Multi-Omic and Phenotypic Resources to Unravel the Genetic Pathogenesis of Hearing Loss.

Effective research and clinical application in audiology and hearing loss (HL) require the integration of diverse data, yet the absence of a dedicated database impedes understanding and insight extraction in HL. To address this, the Genetic Deafness Commons (GDC) is developed by consolidating extensive genetic and genomic data from 51 public databases and the Chinese Deafness Genetics Consortium. This repository comprises 5983613 variants across 201 HL genes, revealing the genetic landscape of HL and identifying six novel mutational hotspots within the DNA-binding domains of transcription factors. Comparative phenotypic analyses highlighted considerable disparities between human and mouse models. Among the 201 human HL genes, 133 exhibit hearing abnormalities in mice; 35 have been tested in mice without exhibiting a hearing loss phenotype; and 33 lack auditory testing data. Moreover, gene expression analyses in the cochleae of mice, humans, and rhesus macaques demonstrated a notable correlation (R2 0.718-0.752). Utilizing gene expression, function, pathway, and phenotype data, a SMOTE-Random Forest model identified 18 candidate HL genes, including TBX2, newly confirmed as an HL gene. As a comprehensive and unified repository, the GDC advances audiology research and practice by improving data accessibility and usability, ultimately fostering deeper insights into hearing disorders.

The oral drug obeldesivir protects nonhuman primates against lethal Ebola virus infection.

Obeldesivir (ODV; GS-5245) is an orally administered ester prodrug of the parent nucleoside GS-441524 that has broad spectrum antiviral activity inhibiting viral RNA-dependent RNA polymerases. We recently showed that ODV completely protects cynomolgus macaques against lethal infection with Sudan virus when given 24 hours after parenteral exposure. Here, we report that once daily oral ODV treatment of cynomolgus and rhesus macaques for 10 days confers 80 and 100% protection, respectively, against lethal Ebola virus infection when treatment is initiated 24 hours after mucosal (conjunctival) exposure. ODV treatment delayed viral replication to abate excessive inflammation and promote adaptive immunity. For outbreak response, oral antivirals might present substantial advantages over now approved intravenous drugs, such as easy supply, storage, distribution, and administration. Furthermore, these results support the potential of ODV as an oral postexposure prophylaxis with broad spectrum activity across filoviruses.

Monkeys (Macaca mulatta) rank lists using multiple cognitive mechanisms simultaneously.

Memorizing the relations between items and learning relational rules are two ways in which sets of items can be ranked. We investigated the interaction of these types of learning in a series of five experiments with six adult male rhesus monkeys. We presented monkeys with three types of image sets. Scene sets were random images of natural scenes or cityscapes with no perceptually evident pattern by which to rank them. Relations among these images had to be learned through trial and error. Patterned sets were shapes that varied systematically along a physical dimension such as size such that a single rule for ranking them could be applied across images. Disordered sets were the same as Patterned sets, but monkeys were trained to rank them in an arbitrary order that was not consistent with differences along a physical dimension. Monkeys learned Scene sets more quickly than Patterned sets and Disordered sets, suggesting that monkeys memorize the relations between images relatively easily. In follow-up experiments, we found that monkeys also learned rules for the Patterned sets, indicated by the fact that they generalized performance to novel images and reversed ranks across the whole set after training with a single reversed pair. In Experiments 4 and 5, we investigated the interaction of memorization and relational rule learning with compound image sets that included both systematic physical variation and arbitrary visual content. We found further evidence that monkeys ordered images by both memorization and rules. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Deep learning-based automated segmentation of cardiac real-time MRI in non-human primates.

Deep learning-based automated segmentation of cardiac real-time MRI in non-human primates.

The pentameric complex is not required for congenital CMV transmission in seronegative rhesus macaques

Congenital cytomegalovirus (cCMV) is the leading infectious cause of neonatal neurological impairment worldwide, but the viral factors enabling vertical spread across the placenta remain undetermined. The pentameric complex (PC), composed of the subunits gH/gL/UL128/UL130/UL131A, has been demonstrated to be important for entry into nonfibroblast cells in vitro. These findings link the PC to broad cell tropism and virus dissemination in vivo, denoting all subunits as potential targets for intervention strategies and vaccine development. To determine the relevance of the PC for congenital transmission in a translational nonhuman primate model, we engineered a rhesus CMV (RhCMV) mutant lacking the orthologs of UL128 and UL130, which demonstrated diminished infection of epithelial cells in vitro. However, intravenous inoculation of either CD4 + T cell–depleted or immunocompetent RhCMV-seronegative pregnant rhesus macaques (RMs) in the early second trimester with the PC-deficient mutant resulted in maternal RhCMV peak plasma viremia similar to inoculations with PC-intact RhCMV, although virus shedding in saliva and urine was limited. Infections with the PC-intact virus induced IgG responses that neutralized RhCMV entry into epithelial cells in tissue culture. These responses were reduced, but not absent, from animals infected with the PC-deficient virus, which also induced IgG responses against gH. Moreover, congenital CMV transmission was confirmed in multiple animals infected with PC-deficient virus by detecting viral DNA in the amniotic fluid, indicating that transplacental transmission in RMs is not contingent on the PC.

Evaluating Pupillometry as a Tool for Assessing Facial and Emotional Processing in Nonhuman Primates

Non-human primates (NHPs) are extensively utilized to investigate the neural mechanisms underlying face processing; however, measuring their brain activity necessitates a diverse array of technologies. Pupillometry emerges as a convenient, cost-effective, and non-invasive alternative for indirectly assessing brain activity. To evaluate the efficacy of pupillometry in assessing facial and emotional processing in NHPs, this study designed a face fixation task for experimental monkeys (Rhesus macaque) and recorded variations in their pupil size in response to face images with differing characteristics, such as species, emotional expression, viewing angles, and orientation (upright vs. inverted). All face images were balanced with luminance and spatial frequency. A sophisticated eye-tracking system (Eye-link 1000 plus) was employed to observe the pupils and track the viewing trajectories of monkeys as they examined images of faces. Our findings reveal that monkeys exhibited larger pupil sizes in response to carnivore faces (versus human faces, p = 0.035), negative conspecific faces (versus human faces, p = 0.018), and profile viewing angles (versus frontal view angles, p = 0.010). Notably, pupil size recorded during the 500–1000 ms post-stimulus interval was negatively correlated with their gaze durations directed at those images (r = −0.357, p = 0.016). Overall, this study demonstrates that pupillometry effectively captures subtle differences in facial and emotional processing, underscoring its potential as a valuable tool in future cognitive research and the diagnosis of disorders.

Haemato-biochemical Profile Assessment of Immobilized Wild Rhesus Macaques (Macaca mulatta) in Jabalpur, India

Indian rhesus macaque has been extensively used in biomedical research, particularly in disease studies and drug discovery. Accurate assessment of clinical pathology parameters is crucial for evaluating their health status, particularly in studies involving disease modeling and drug development. However, comprehensive data on hematological and biochemical parameters, especially in wild rhesus macaques, remain limited. Due to increased use of non-human primates in research studies, it is necessary to understand the effect of immobilizing drugs on haemato-biochemical values in wild rhesus macaques. The study focuses on the immobilization of wild adult male rhesus macaques using anesthetic drug combination viz. Inj. Xylazine at the rate of 2mg/kg body weight combined with Inj. Ketamine hydrochloride at the rate of 5mg/kg body weight and their impact on blood parameter estimation. This study has aimed to present an accurate hematological and biochemical values of anesthetized wild Indian rhesus macaques. These findings provide essential baseline reference values for the species and highlight the influence of immobilization on blood parameters on wild adult male rhesus macaques. The mean values of TEC, TLC, PCV and Hb observed in the present study were towards lower side of the normal reference range, however, the mean values of DLC, MCV, MCH and MCHC remained within the normal reference range. This study contributes to the refinement of biomedical research protocols by ensuring accurate health assessments and improving animal welfare in both laboratory and field settings.

Supplemental Material for Monkeys (Macaca mulatta) Rank Lists Using Multiple Cognitive Mechanisms Simultaneously

Supplemental Material for Monkeys (Macaca mulatta) Rank Lists Using Multiple Cognitive Mechanisms Simultaneously

Persistent Postirradiation Skeletal Muscle Protein and Insulin Sensitivity Changes in Nonhuman Primates.

Increased incidence of diabetes has been reported after whole-body irradiation in cancer survivors and in the years after exposure in research studies of nonhuman primates. Type 2 diabetes presents in the absence of obesity and suggests that skeletal muscle, the predominant organ responsible for minute-to-minute glucose disposal, is persistently dysfunctional. We evaluated skeletal muscle (SkM) from control (CTL, n = 8) and irradiated (IRRAD, n = 16) male rhesus macaques (Macaca mulatta) that had been exposed to an average whole-body dose of 6.5 Gy after an average of 4 years of follow-up. Irradiated animals had deficient SkM basal and insulin-stimulated receptor activation that was unrelated to histologically assessed fiber size, extracellular matrix and endothelial components. Protein extracted from irradiated muscle showed that Akt2, downstream of insulin receptor activation, was sulfenyl-modified and thus a target for radiation-related glycemic dysregulation. Shotgun proteomics identified upregulation of many mitochondrial and peroxisome-associated proteins, and increases were confirmed by immunoblotting of select protein targets. Proteomic pathway enrichment mapping showed distinct protein clustering between CTL and IRRAD groups. Mitochondrial proteins were surveyed and confirm that mitochondrial turnover may be increased after irradiation with higher fission and fusion markers. The results indicate that irradiated muscle is persistently insulin resistant, with evidence of intracellular protein oxidation and shifts in mitochondrial dynamics and function.

KRAS G12D -Specific Targeting with Engineered Exosomes Reprograms the Immune Microenvironment to Enable Efficacy of Immune Checkpoint Therapy in PDAC Patients.

Oncogenic KRAS drives initiation and maintenance of pancreatic ductal adenocarcinoma (PDAC). Here, we show that engineered exosomes with Kras G12D specific siRNA (iExoKras G12D ) reveal impressive biodistribution in pancreas with negligible toxicity in preclinical studies in mice and Rhesus macaques. Clinical testing of iExoKras G12D in the iEXPLORE (iExoKras G12D in Pancreatic Cancer) Phase I study employed a classical 3+3 dose escalation design (Phase Ia), followed by an accelerated titration design (Phase Ib) ( NCT03608631 ). Patients with advanced metastatic disease were enrolled after failure of multiple lines of therapy. iExoKras G12D therapy was well-tolerated with no reported dose-limiting toxicity with some cases of stable disease response, and maximum tolerated infusion was not reached even at the highest dose. Downregulation of KRAS G12D DNA and suppression of phopho-Erk was documented with increased intratumoral in CD8 + T cell infiltration in patient samples upon treatment. The CD8 + T cell recruitment priming by iExoKras G12D informed on potential efficacy of immune checkpoint therapy and lead to validation testing in preclinical PDAC models. Combination therapy of iExoKras G12D and anti-CTLA-4 antibodies, but not anti-PD1, revealed robust anti-tumor efficacy via FAS mediated CD8 + T cell anti-tumor activity. This first-in-human, precision medicine clinical trial offers new insights into priming of immunotherapy by oncogenic Kras inhibitor and an opportunistic combination therapy for PDAC patients.

The Long-term Effects of Acute Total-Body Irradiation on Pre-irradiation Measles-vaccine-induced Immunological Memory.

Acute total-body irradiation (TBI) leads to transient dose-dependent lymphopenia. While lymphocyte numbers gradually recover, there remain subtle but long-lasting changes to B and T cell populations years after radiation exposure. The degree to which immunological memory is retained after TBI is unknown; however, it is conceivable that vaccine-induced protective immunity is jeopardized. To test this hypothesis, samples were collected from a cohort of rhesus macaques that were vaccinated against measles virus, irradiated, and then allowed to recover from the acute radiation effects for at least a year. Animals received 0 to 7.5 Gy TBI or 10 Gy with 5% bone marrow shielding. Plasma from 109 animals were evaluated for measles-binding antibodies and the ability to neutralize live measles virus. Females exhibited higher measles binding and neutralizing titers, and irradiated animals of both sexes exhibited significant radiation-dose dependent reductions in measles binding IgG and neutralizing titers. Peripheral blood mononuclear cells (PBMC) from the vaccinated, irradiated animals were then stimulated in vitro with measles antigens to evaluate cellular responses. No radiation-dose effects on CD8 T cell responses to measles antigens were detected. In contrast, PBMC from vaccinated, irradiated males exhibited radiation dose-dependent reductions in the percentages of CD4 T cells expressing activation-associated markers and cytokines in response to measles antigens. There were also significant dose- or dose/sex-interacting effects on the levels of IP10, MIP1β, and IL-6 present in the antigen-stimulated PBMC cultures. Cells from animals receiving 10 Gy with 5% bone marrow shielding exhibited signs of T-cell anergy. PBMC from females exhibited only weak responses to measles antigen stimulation regardless of radiation exposure. Collectively, these in vitro studies indicate that radiation can cause protracted dose- and sex-dependent damage to established humoral and cellular immunological memories of measles.

Ivermectin Inhibits Zika Virus Replication inVitro But Does Not Prevent Zika Virus Infection in Rhesus Macaques (Macaca mulatta).

Zika virus (ZIKV) outbreaks occur sporadically in tropical and subtropical regions. At present, there are no licensed vaccines or specific treatments available for ZIKV. Ivermectin is approved for use in humans as an antiparasitic drug. In this study, we conducted invitro cell culture and invivo experiments in rhesus macaque hosts and Aedes aegypti vectors to investigate the potential of ivermectin as an inhibitor of ZIKV infection. In LLC-MK2 mammalian cells, ivermectin inhibited ZIKV growth invitro with 50% inhibitory concentration (IC50) values in the ranges of 7.4-21.3 µM and 4.0-11.6 µM for African and Asian genotypes, respectively. In C6/36 mosquito cells, ivermectin inhibited ZIKV growth invitro with IC50 values in the ranges of 10.1-17.4 µM and 8.0-15.6 µM for the African and Asian genotypes, respectively. Despite these invitro results, high-dose ivermectin prophylaxis (1.2 mg/kg for 3 consecutive days) failed to prevent ZIKV infection in rhesus macaque and did not alter ZIKV IgM antibody production. The secondary transfer of ivermectin from nonhuman primate blood to mosquito vectors at 3 days post-ZIKV inoculation and after the last dose of ivermectin administration showed no reduction in ZIKV replication in mosquitoes. However, mosquito survival rates were significantly (P <0.0001) lower after exposure to ivermectin, thereby potentially impacting ZIKV transmission through increased vector mortality. However, further investigation is needed to determine dosing regimens that may realize these effects invivo.

Caloric restriction reprograms adipose tissues in rhesus monkeys.

Caloric restriction (CR) is a dietary intervention that delays the onset of age-related diseases and enhances survival in diverse organisms, and although changes in adipose tissues have been implicated in the beneficial effects of CR the molecular details are unknown. Here we show shared and depot-specific adaptations to life-long CR in subcutaneous and visceral adipose depots taken from advanced age male rhesus monkeys. Differential gene expression and pathway analysis identified key differences between the depots in metabolic, immune, and inflammatory pathways. In response to CR, RNA processing and proteostasis-related pathways were enriched in both depots but changes in metabolic, growth, and inflammatory pathways were depot-specific. Commonalities and differences that distinguish adipose depots are shared among monkeys and humans and the response to CR is highly conserved. These data reveal depot-specificity in adipose tissue adaptation that likely reflects differences in function and contribution to age-related disease vulnerability.

Safety and biocompatibility of a novel biodegradable aflibercept-drug delivery system in rhesus macaques

A clinical need exists for more effective intravitreal (IVT) drug delivery systems (DDS). This study tested the hypothesis that a novel biodegradable, injectable microsphere-hydrogel drug delivery system loaded with aflibercept (aflibercept-DDS) would exhibit long-term safety and biocompatibility in a non-human primate (NHP) model. We generated aflibercept-loaded poly (lactic-co-glycolic acid) microparticles with a modified double emulsion technique then embedded them into a biodegradable, thermo-responsive poly (ethylene glycol)-co-(L-lactic-acid) diacrylate/N-isopropylacrylamide hydrogel. Aflibercept-DDS (50 µL, 15 µg) was injected into the right eye of 23 healthy rhesus macaques. A complete ophthalmic examination, intraocular pressure (IOP), corneal pachymetry, specular microscopy, A-scan biometry, streak retinoscopy, spectral-domain optical coherence tomography (SD-OCT), fluorescein angiography (FA), and electroretinography (ERG) were performed monthly. Globes from 7 NHPs were histologically examined. Aflibercept-DDS was visualized in the vitreous up to 9 months post-IVT injection, slightly impeding fundoscopy in 4 of 23 eyes; no other consistent abnormalities were appreciated during ophthalmic examination. The IOP and total retinal thickness remained normal in all animals over all timepoints. Central corneal thickness, endothelial cell density, axial globe length, and refractive error did not significantly differ from baseline. Scotopic mixed rod-cone implicit times and amplitudes along with photopic cone response implicit times and amplitudes did not significantly differ from control values. No retinal or choroidal vascular abnormalities were detected with FA and normal retinal architecture was preserved using SD-OCT. Intravitreal injection of a biodegradable aflibercept-DDS was safe and well tolerated in NHPs up to 24 months.

Elevated COMMD1 Contributes to Cardiomyocyte Copper Efflux in Chronic Myocardial Ischemia: Insights From Rhesus Monkey.

Copper deficiency, commonly observed in myocardial infarction, leads to cardiomyocyte loss and cardiac dysfunction, yet the mechanism driving copper efflux remains unclear. To further elucidate the relationship between copper transporters and cardiac copper efflux during chronic myocardial ischemia, a rhesus monkey model was established by performing the permanent ligation of the left anterior descending coronary artery. A dramatic decrease in copper concentration within ischemic cardiomyocytes was observed alongside declining cardiac function. Among major copper transporters, COMMD1 and ATP7B were significantly upregulated in the ischemic myocardium. COMMD1 was specifically localised in cardiomyocytes undergoing copper efflux, whereas increased ATP7B was restricted to cardiac fibroblasts. This indicates that elevated COMMD1 regulates copper efflux in cardiomyocytes during chronic myocardial ischemia, functioning independently of its interactions with P-type ATPase transporters. Given the discrepancy between RNA and protein levels of COMMD1 in ischemic myocardium, post-translational modification is likely responsible for regulating COMMD1 expression. We found that the copper-binding protein with E3 ubiquitin ligase activity, XIAP, augmented before the rise in COMMD1 expression within ischemic cardiomyocytes. Excessive XIAP specifically interacted with COMMD1 to enhance its protein levels under copper-deprivation conditions and vice versa. Overall, our findings reveal a positive feedback loop among XIAP, COMMD1 and copper, highlighting the intricate interplay between XIAP and COMMD1 in regulating copper efflux in cardiomyocytes. This loop sets the stage for further investigation into therapeutic strategies to manage copper homeostasis in chronic myocardial ischemia.