EFEMP1 haploinsufficiency causes a Marfan-like hereditary connective tissue disorder.

Phenotypic features of a hereditary connective tissue disorder, including craniofacial characteristics, hyperextensible skin, joint laxity, kyphoscoliosis, arachnodactyly, inguinal hernia, and diverticulosis associated with biallelic pathogenic variants in EFEMP1 have been previously described in four patients. Genome sequencing on a proband and her mother with comparable phenotypic features revealed that both patients were heterozygous for a stop-gain variant c.1084C>T (p.Arg362*). Complementary RNA-seq on fibroblasts revealed significantly reduced levels of mutant EFEMP1 transcript. Considering the absence of other molecular explanations, we extrapolated that EFEMP1 could be the cause of the patient's phenotypes. Furthermore, nonsense-mediated decay was demonstrated for the mutant allele as the principal mechanism for decreased levels of EFEMP1 mRNA. We provide strong clinical and genetic evidence for the haploinsufficiency of EFEMP1 due to nonsense-medicated decay to cause severe kyphoscoliosis, generalized hypermobility of joints, high and narrow arched palate, and potentially severe diverticulosis. To the best of our knowledge, this is the first report of an autosomal dominant EFEMP1-associated hereditary connective tissue disorder and therefore expands the phenotypic spectrum of EFEMP1 related disorders.

Long-term Sudan virus Ebola survivors maintain multiple antiviral defense mechanisms.

BACKGROUND: The critical issues of sustained memory immunity following ebolavirus disease among long-term survivors (EVD) are still unclear. METHODS: Here, we examine virus-specific immune and inflammatory responses in 12 Sudan virus (SUDV) long-term survivors from Uganda's 2000-1 Gulu outbreak, 15 years after recovery following in vitro challenge. Total RNA from isolated SUDV-stimulated and unstimulated PBMCs was extracted and analyzed. Matched serum samples were also collected to determine SUDV IgG levels and functionality. RESULTS: We detected persistent humoral (58%, 7 of 12) and cellular (33%, 4 of 12) immune responses in SUDV long-term survivors and identified critical molecular mechanisms of innate and adaptive immunity. Gene expression in immune pathways, the IFN signaling system, antiviral defense response, and activation and regulation of T- and B-cell responses were observed. SUDV long-term survivors also maintained robust virus-specific IgG antibodies capable of polyfunctional responses, including neutralizing and innate Fc effector functions. CONCLUSIONS: Data integration identified significant correlations among humoral and cellular immune responses and pinpointed a specific innate and adaptive gene expression signature associated with long-lasting immunity. This could help identify natural and vaccine correlates of protection against ebolavirus disease.

Multiple Mitochondrial Dysfunction Syndrome Type 3: A Likely Pathogenic Homozygous Variant Affecting a Patient of Cuban Descent and Literature Review.

Multiple mitochondrial dysfunction syndrome type 3 (MMDS3) is a rare mitochondrial leukoencephalopathy caused by biallelic pathogenic variants in IBA57. Here, we describe a homozygous variant in IBA57, (NM_001010867.2): c.310G>T (p.Gly104Cys), in a 2-month-old infant of Cuban descent who presented with a one-month history of progressive hypotonia, weakness, and episodes of upgaze deviation. This is the first report of a patient homozygous for this variant and the first report of MMDS3 in a patient of Hispanic descent described to our knowledge. Using in silico tools, we found that the variant resides in a putative mutational hotspot located in the neighborhood of a key active ligand required for iron-sulfur cluster coordination. In addition, while previous case reports/series have reported the variable phenotypic features of the disease, the incidence of these features across the literature has not been well described. In order to construct a clearer global picture of the typical presentation of MMDS3, we reviewed 52 cases across the literature with respect to their clinical, biochemical, genotypic, and neuroradiographic features.

Exosome based analysis for Space Associated Neuro-Ocular Syndrome and health risks in space exploration.

Molecular profiling to characterize the effects of environmental exposures is important from the human health and performance as well as the occupational medicine perspective in space exploration. We have developed a novel exosome-based platform that allows profiling of biological processes in the body from a variety of body fluids. The technology is suitable for diagnostic applications as well as studying the pathophysiology of the Space Associated Neuro-Ocular Syndrome in astronauts and monitoring patients with chronically impaired cerebrospinal fluid drainage or elevated intracranial pressure. In this proof-of-concept, we demonstrate that: (a) exosomes from different biofluids contain a specific population of RNA transcripts; (b) urine collection hardware aboard the ISS is compatible with exosome gene expression technology; (c) cDNA libraries from exosomal RNA can be stored in dry form and at room temperature, representing an interesting option for the creation of longitudinal molecular catalogs that can be stored as a repository for retrospective analysis.

Derivation and Characterization of Murine and Amphibian Müller Glia Cell Lines.

Purpose: Müller glia (MG) in the retina of Xenopus laevis (African clawed frog) reprogram to a transiently amplifying retinal progenitor state after an injury. These progenitors then give rise to new retinal neurons. In contrast, mammalian MG have a restricted neurogenic capacity and undergo reactive gliosis after injury. This study sought to establish MG cell lines from the regeneration-competent frog and the regeneration-deficient mouse. Methods: MG were isolated from postnatal day 5 GLAST-CreERT; Rbfl/fl mice and from adult (3-5 years post-metamorphic) X laevis. Serial adherent subculture resulted in spontaneously immortalized cells and the establishment of two MG cell lines: murine retinal glia 17 (RG17) and Xenopus glia 69 (XG69). They were characterized for MG gene and protein expression by qPCR, immunostaining, and Western blot. Purinergic signaling was assessed with calcium imaging. Pharmacological perturbations with 2'-3'-O-(4-benzoylbenzoyl) adenosine 5'-triphosphate (BzATP) and KN-62 were performed on RG17 cells. Results: RG17 and XG69 cells express several MG markers and retain purinergic signaling. Pharmacological perturbations of intracellular calcium responses with BzATP and KN-62 suggest that the ionotropic purinergic receptor P2X7 is present and functional in RG17 cells. Stimulation of XG69 cells with adenosine triphosphate-induced calcium responses in a dose-dependent manner. Conclusions: We report the characterization of RG17 and XG69, two novel MG cell lines from species with significantly disparate retinal regenerative capabilities. Translational Relevance: RG17 and XG69 cell line models will aid comparative studies between species endowed with varied regenerative capacity and will facilitate the development of new cell-based strategies for treating retinal degenerative diseases.

A novel pathogenic variant at the C-terminal propeptide cleavage site of COL1A1, causing osteogenesis imperfecta with intrafamilial variability.

Osteogenesis imperfecta (OI) is a rare connective tissue disorder with clinical and genetic heterogeneity. The cardinal features of OI are bone fragility and low bone mineral density (BMD). Pathogenic variants in COL1A1 and COL1A2 genes, which encode the proα-1(I) and proα-2(I) chains of Type 1 collagen, are the most common causes of OI. Mutations disrupting the carboxy-terminal propeptide cleavage site of the proα-1(I) and proα-2(I) chains have recently been reported as rare causes of OI with paradoxically normal to high BMD. This report describes a father and daughter with OI who are heterozygous for a novel likely pathogenic variant at the carboxy-terminal propeptide cleavage site of COL1A1 (NM_000088.4): c.3656A>G; (p.Asp1219Gly). We describe their intrafamilial phenotypic variability and overlapping features with other COL1A1-related disorders.

Effects of Mitomycin-C and 5-Fluorouracil on Ocular Adnexal Sebaceous Carcinoma Cells.

PURPOSE: To investigate the effects of mitomycin-C (MMC) and 5-fluorouracil (5-FU) on the viability, proliferation, and migratory capacity of cultured ocular adnexal sebaceous carcinoma (SC) cells. DESIGN: Laboratory investigation. METHODS: Human SC cell lines (Bascom Palmer 50 and 52 [BP50 and BP52]) and human limbal stem cells (LSCs) were treated with various concentrations of MMC and 5-FU. Cytotoxicity was assessed with the tetrazolium MTT colorimetric viability assay on normal corneal vs tumor cells. Growth curves and scratch assays were performed to characterize the effects of these chemotherapeutic agents on SC proliferation and migration, respectively. RESULTS: MMC decreased BP52 cell viability in a dose-dependent manner with a half-maximal effective dose (EC50) of 11.8 µM after 72 hours. SC viability decreased >50% at 80 mM 5-FU after 72 hours. MMC reduced LSC viability in a dose-dependent manner with an EC50 value of 3.24 µM, and 5-FU decreased LSC viability >50% at 160 µM. MMC decreased SC cell proliferation and migration in a dose-dependent manner. 5-FU displayed antiproliferative effects but did not affect cell migration at concentrations below 1000 µM. CONCLUSIONS: Our in vitro data corroborate clinical observations that MMC is efficacious for treating ocular adnexal SC, albeit at the expense of LSC viability. Our findings also demonstrate that topical 5-FU exhibits antiproliferative effects that supersede its cancer-killing and antimigratory effects on cultured SC cells.

Species-Level Profiling of Ixodes pacificus Bacterial Microbiomes Reveals High Variability Across Short Spatial Scales at Different Taxonomic Resolutions.

Background and Aims: Outbreaks of severe and chronic tick-borne diseases (TBDs) are on the rise. This is through the transmission of infectious disease agents to humans during tick feeding. The transmission rate and extent of microbial exchange, however, vary based on the tick microbiome composition. While select microbes are determined to be members of the normal tick microbiome and others are clearly recognized mammalian and/or avian pathogens, the status of many other members of the tick microbiota with respect to human and alternate host pathogenesis remains unclear. Moreover, the species-level 16S microbiome of prominent TBD vectors, including Ixodes pacificus, have not been extensively studied. To elucidate the I. pacificus microbiome composition, we performed a pan-domain species-specific characterization of the bacterial microbiome on adult I. pacificus ticks collected from two regional parks within Western California. Our methods provide for characterizing nuances within cohort microbiomes and their relationships to geo-locale of origin, surrounding fauna, and prevalences of known and suspected pathogens in relation to current TBD epidemiological zones. Methods: Ninety-two adult I. pacificus bacterial microbiomes were characterized using a high-fidelity, pan-domain, species-specific, full-length 16S rRNA amplification method using circular consensus sequencing performed on the Pacific Biosciences Sequel platform. Data analyses were performed with the MCSMRT data analysis package and database. Results: The species-specific I. pacificus microbiome composition illustrates a complex assortment of microflora, including over 900 eubacterial species with high taxonomic diversity, which was revealed to vary by sex and geo-locale, though the use of full-length 16S gene sequencing. The TBD-associated pathogens, such as Borrelia burgdorferi, Anaplasma phagocytophilum, and Rickettsia monacensis, were identified along with a host of bacteria previously unassociated with ticks. Conclusion: Species-level taxonomic classification of the I. pacificus microbiome revealed that full-length bacterial 16S gene sequencing is required for the granularity to elucidate the microbial diversity within and among ticks based on geo-locale.

The North American Registry for Care and Research in Multiple Sclerosis (NARCRMS).

Although many regional multiple sclerosis (MS) databases existed in the United States and Canada, there was no single clinician-derived registry that examined this disease as a group across the North American continent. This distinction is important because information that results from such a database can potentially give perspectives about MS that cannot be derived from any single regional registry. A partnership was forged between the pharmaceutical industry and the Consortium of Multiple Sclerosis Centers (CMSC) to create a registry of patients with MS from Canada and the United States, including Puerto Rico. Case report forms were created to collect physician-derived information, and the Patient-Reported Outcomes Measurement Information System (PROMIS) was selected to capture patient-reported outcomes. As of November 2021, 754 of 1000 patients have been enrolled. Completion of recruitment is expected by the end of 2021. Twenty-five centers are participating, with an expected total of 30, including five centers from Canada. Clinical status, health economic outcomes, magnetic resonance images, and, soon, biomarkers relevant to understanding relapses and progression are collected. The short-term goal is to understand and better treat MS disease progression, and the long-term goal is its prevention. The North American Registry for Care and Research in Multiple Sclerosis (NARCRMS) is one of few clinician/patient-generated registries that examines MS across North America, including Puerto Rico. Information derived from the natural history studies should help physicians, the pharmaceutical industry, and regulatory bodies understand MS better and improve quality of life for patients with MS worldwide.

Utilization of Online Resources by Patients in an Ophthalmic Emergency Department.

Objective To describe the utilization of online resources by patients prior to presentation to an ophthalmic emergency department (ED) and to assess the accuracy of online resources for ophthalmic diagnoses. Methods This is a prospective survey of patients presenting to an ophthalmic ED for initial evaluation of ocular symptoms. Prior to evaluation, patients completed surveys assessing ocular symptoms, Internet usage, and presumed self-diagnoses. Demographics and characteristics of Internet usage were determined. Accuracy of self-diagnoses was compared between Internet users and nonusers. Diagnoses were classified as high or low acuity based on agreement between senior authors. Results A total of 144 patients completed surveys. Mean (standard deviation) age was 53.2 years (18.0). One-third of patients used the Internet for health-related searches prior to presentation. Internet users were younger compared with nonusers (48.2 years [16.5] vs. 55.5 years [18.3], p = 0.02). There were no differences in sex, ethnicity, or race. Overall, there was a threefold difference in proportion of patients correctly predicting their diagnoses, with Internet users correctly predicting their diagnoses more often than nonusers (41 vs. 13%, p < 0.001). When excluding cases of known trauma, the difference in proportion increased to fivefold (Internet users 40% vs. nonusers 8%, p < 0.001). Upon classification by acuity level, Internet users demonstrated greater accuracy than nonusers for both high- (42 vs. 17%, p = 0.03) and low (41 vs. 10%, p = 0.001)-acuity diagnoses. Greatest accuracy was in cases of external lid conditions such as chalazia and hordeola (100% [4/4] of Internet users vs. 40% (2/5) of nonusers), conjunctivitis (43% [3/7] of Internet users vs. 25% [2/8] of nonusers), and retinal traction or detachments (57% [4/7] of Internet users vs. 0% [0/4] of nonusers). The most frequently visited Web sites were Google (82%) and WebMD (40%). Patient accuracy did not change according to the number of Web sites visited, but patients who visited the Mayo Clinic Web site had greater accuracy compared with those who visited other Web sites (89 vs. 30%, p = 0.003). Conclusion Patients with ocular symptoms may seek medical information on the Internet before evaluation by a physician in an ophthalmic ED. Online resources may improve the accuracy of patient self-diagnosis for low- and high-acuity diagnoses.

Insulin degrading enzyme (IDE) expressed by Chinese hamster ovary (CHO) cells is responsible for degradation of insulin in culture media.

Chinese hamster ovary (CHO) cells cultured in serum-free chemically-defined media (CDM) are used for manufacturing of therapeutic proteins. Growth factors, such as insulin are commonly utilized in manufacturing platforms to enhance CHO cell viability and growth. Here we report that insulin is degraded in the culture media over time mainly due to the activity of the insulin degrading enzyme (IDE). Insulin degradation was faster in cell lines that released more IDE, which negatively impacted cell growth and in turn, production titers. Deletion of the IDE gene in a representative CHO cell line nearly abolished insulin degradation in seed train and end-of-production media. In summary, our data suggests that selecting cell lines that have lower IDE expression or targeted-deletion of the IDE gene can improve culture viability and growth for insulin-dependent CHO production platforms.

Maximizing antibody production in a targeted integration host by optimization of subunit gene dosage and position.

Historically, therapeutic protein production in Chinese hamster ovary (CHO) cells has been accomplished by random integration (RI) of expression plasmids into the host cell genome. More recently, the development of targeted integration (TI) host cells has allowed for recombination of plasmid DNA into a predetermined genomic locus, eliminating one contributor to clone-to-clone variability. In this study, a TI host capable of simultaneously integrating two plasmids at the same genomic site was used to assess the effect of antibody heavy chain and light chain gene dosage on antibody productivity. Our results showed that increasing antibody gene copy number can increase specific productivity, but with diminishing returns as more antibody genes are added to the same TI locus. Random integration of additional antibody DNA copies in to a targeted integration cell line showed a further increase in specific productivity, suggesting that targeting additional genomic sites for gene integration may be beneficial. Additionally, the position of antibody genes in the two plasmids was observed to have a strong effect on antibody expression level. These findings shed light on vector design to maximize production of conventional antibodies or tune expression for proper assembly of complex or bispecific antibodies in a TI system.

Genome rearrangements induce biofilm formation in Escherichia coli C - an old model organism with a new application in biofilm research.

BACKGROUND: Escherichia coli C forms more robust biofilms than other laboratory strains. Biofilm formation and cell aggregation under a high shear force depend on temperature and salt concentrations. It is the last of five E. coli strains (C, K12, B, W, Crooks) designated as safe for laboratory purposes whose genome has not been sequenced. RESULTS: Here we present the complete genomic sequence of this strain in which we utilized both long-read PacBio-based sequencing and high resolution optical mapping to confirm a large inversion in comparison to the other laboratory strains. Notably, DNA sequence comparison revealed the absence of several genes thought to be involved in biofilm formation, including antigen 43, waaSBOJYZUL for lipopolysaccharide (LPS) synthesis, and cpsB for curli synthesis. The first main difference we identified that likely affects biofilm formation is the presence of an IS3-like insertion sequence in front of the carbon storage regulator csrA gene. This insertion is located 86 bp upstream of the csrA start codon inside the - 35 region of P4 promoter and blocks the transcription from the sigma32 and sigma70 promoters P1-P3 located further upstream. The second is the presence of an IS5/IS1182 in front of the csgD gene. And finally, E. coli C encodes an additional sigma70 subunit driven by the same IS3-like insertion sequence. Promoter analyses using GFP gene fusions provided insights into understanding this regulatory pathway in E. coli. CONCLUSIONS: Biofilms are crucial for bacterial survival, adaptation, and dissemination in natural, industrial, and medical environments. Most laboratory strains of E. coli grown for decades in vitro have evolved and lost their ability to form biofilm, while environmental isolates that can cause infections and diseases are not safe to work with. Here, we show that the historic laboratory strain of E. coli C produces a robust biofilm and can be used as a model organism for multicellular bacterial research. Furthermore, we ascertained the full genomic sequence of this classic strain, which provides for a base level of characterization and makes it useful for many biofilm-based applications.

Development and characterization of an automated imaging workflow to generate clonally-derived cell lines for therapeutic proteins.

In the development of biopharmaceutical products, the expectation of regulatory agencies is that the recombinant proteins are produced from a cell line derived from a single progenitor cell. A single limiting dilution step followed by direct imaging, as supplemental information, provides direct evidence that a cell line originated from a single progenitor cell. To obtain this evidence, a high-throughput automated imaging system was developed and characterized to consistently ensure that cell lines used for therapeutic protein production are clonally-derived. Fluorescent cell mixing studies determined that the automated imaging workflow and analysis provide ∼95% confidence in accurately and precisely identifying one cell in a well. Manual inspection of the images increases the confidence that the cell line was derived from a single-cell to >99.9%. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:584-592, 2018.

Application of 13C flux analysis to identify high-productivity CHO metabolic phenotypes.

Industrial bioprocesses place high demands on the energy metabolism of host cells to meet biosynthetic requirements for maximal protein expression. Identifying metabolic phenotypes that promote high expression is therefore a major goal of the biotech industry. We conducted a series of 13C flux analysis studies to examine the metabolic response to IgG expression during early stationary phase of CHO cell cultures grown in 3L fed-batch bioreactors. We examined eight clones expressing four different IgGs and compared with three non-expressing host-cell controls. Some clones were genetically manipulated to be apoptosis-resistant by expressing Bcl-2Δ, which correlated with increased IgG production and elevated glucose metabolism. The metabolic phenotypes of the non-expressing, IgG-expressing, and Bcl-2Δ/IgG-expressing clones were fully segregated by hierarchical clustering analysis. Lactate consumption and citric acid cycle fluxes were most strongly associated with specific IgG productivity. These studies indicate that enhanced oxidative metabolism is a characteristic of high-producing CHO cell lines.

Research priorities for managing the impacts and dependencies of business upon food, energy, water and the environment.

Delivering access to sufficient food, energy and water resources to ensure human wellbeing is a major concern for governments worldwide. However, it is crucial to account for the 'nexus' of interactions between these natural resources and the consequent implications for human wellbeing. The private sector has a critical role in driving positive change towards more sustainable nexus management and could reap considerable benefits from collaboration with researchers to devise solutions to some of the foremost sustainability challenges of today. Yet opportunities are missed because the private sector is rarely involved in the formulation of deliverable research priorities. We convened senior research scientists and influential business leaders to collaboratively identify the top forty questions that, if answered, would best help companies understand and manage their food-energy-water-environment nexus dependencies and impacts. Codification of the top order nexus themes highlighted research priorities around development of pragmatic yet credible tools that allow businesses to incorporate nexus interactions into their decision-making; demonstration of the business case for more sustainable nexus management; identification of the most effective levers for behaviour change; and understanding incentives or circumstances that allow individuals and businesses to take a leadership stance. Greater investment in the complex but productive relations between the private sector and research community will create deeper and more meaningful collaboration and cooperation.

A dominant mutation in hexokinase 1 (HK1) causes retinitis pigmentosa.

PURPOSE: To identify the cause of retinitis pigmentosa (RP) in UTAD003, a large, six-generation Louisiana family with autosomal dominant retinitis pigmentosa (adRP). METHODS: A series of strategies, including candidate gene screening, linkage exclusion, genome-wide linkage mapping, and whole-exome next-generation sequencing, was used to identify a mutation in a novel disease gene on chromosome 10q22.1. Probands from an additional 404 retinal degeneration families were subsequently screened for mutations in this gene. RESULTS: Exome sequencing in UTAD003 led to identification of a single, novel coding variant (c.2539G>A, p.Glu847Lys) in hexokinase 1 (HK1) present in all affected individuals and absent from normal controls. One affected family member carries two copies of the mutation and has an unusually severe form of disease, consistent with homozygosity for this mutation. Screening of additional adRP probands identified four other families (American, Canadian, and Sicilian) with the same mutation and a similar range of phenotypes. The families share a rare 450-kilobase haplotype containing the mutation, suggesting a founder mutation among otherwise unrelated families. CONCLUSIONS: We identified an HK1 mutation in five adRP families. Hexokinase 1 catalyzes phosphorylation of glucose to glucose-6-phosphate. HK1 is expressed in retina, with two abundant isoforms expressed at similar levels. The Glu847Lys mutation is located at a highly conserved position in the protein, outside the catalytic domains. We hypothesize that the effect of this mutation is limited to the retina, as no systemic abnormalities in glycolysis were detected. Prevalence of the HK1 mutation in our cohort of RP families is 1%.

Diversity in structure and functions of antibody sialylation in the Fc.

Terminal sialic acid residues of glycoconjugates exhibit remarkable functional and structural diversity. They affect biological activity, serum half-life and structural stability of glycoproteins. Alternatively, they act as mediators for pathogens to invade host systems. These surface exposed N-glycans are easily accessible for interactions with receptors, enzymes, etc. In contrast, Fc N-glycans of IgGs are sequestered within the two CH2 domains and exhibit high degree of heterogeneity. They are required for antibody effector functions including binding to C1q protein. Biological significance of Fc glycans has been extensively studied and importance of terminal galactose, bisecting GlcNAc and core fucose has been realized. This review focuses on the recent advances in structure and functions of terminal sialic acid residues of Fc glycans.

The impact of anti-apoptotic gene Bcl-2∆ expression on CHO central metabolism.

Anti-apoptosis engineering is an established technique to prolong the viability of mammalian cell cultures used for industrial production of recombinant proteins. However, the effect of overexpressing anti-apoptotic proteins on central carbon metabolism has not been systematically studied. We transfected CHO-S cells to express Bcl-2∆, an engineered anti-apoptotic gene, and selected clones that differed in their Bcl-2∆ expression and caspase activity. (13)C metabolic flux analysis (MFA) was then applied to elucidate the metabolic alterations induced by Bcl-2∆. Expression of Bcl-2Δ reduced lactate accumulation by redirecting the fate of intracellular pyruvate toward mitochondrial oxidation during the lactate-producing phase, and it significantly increased lactate re-uptake during the lactate-consuming phase. This flux redistribution was associated with significant increases in biomass yield, peak viable cell density (VCD), and integrated VCD. Additionally, Bcl-2∆ expression was associated with significant increases in isocitrate dehydrogenase and NADH oxidase activities, both rate-controlling mitochondrial enzymes. This is the first comprehensive (13)C MFA study to demonstrate that expression of anti-apoptotic genes has a significant impact on intracellular metabolic fluxes, especially in controlling the fate of pyruvate carbon, which has important biotechnology applications for reducing lactate accumulation and enhancing productivity in mammalian cell cultures.

A novel role for the immunophilin FKBP52 in copper transport.

FK506-binding protein 52 (FKBP52) is an immunophilin that possesses peptidylprolyl cis/trans-isomerase (PPIase) activity and is a component of a subclass of steroid hormone receptor complexes. Several recent studies indicate that immunophilins can regulate neuronal survival and nerve regeneration although the molecular mechanisms are poorly understood. To investigate the function of FKBP52 in the nervous system, we employed a yeast two-hybrid strategy using the PPIase domain (domain I) as bait to screen a neonatal rat dorsal root ganglia cDNA expression library. We identified an interaction between FKBP52 domain I and Atox1, a copper-binding metallochaperone. Atox1 interacts with Menkes disease protein and Wilson disease protein (WD) and functions in copper efflux. The interaction between FKBP52 and Atox1 was observed in both glutathione S-transferase pull-down experiments and when proteins were ectopically expressed in human embryonic kidney (HEK) 293T cells and was sensitive to FK506. Interestingly, the FKBP52/Atox1 interaction was enhanced when HEK 293T cells were cultured in copper-supplemented medium and decreased in the presence of the copper chelator, bathocuproine disulfate, suggesting that the interaction is regulated in part by intracellular copper. Overexpression of FKBP52 increased rapid copper efflux in (64)Cu-loaded cells, as did the overexpression of WD transporter. Taken together, our present findings suggest that FKBP52 is a component of the copper efflux machinery, and in so, may also promote neuroprotection from copper toxicity.