Zinc Transporter Research Articles

Comprehensive analysis of the oligopeptide transporter gene family in maize: Genome-wide identification, structural characterization, and stress-responsive expression

Oligopeptide transporter (OPT) proteins are integral proteins in cell membranes that perform a crucial role in cellular metal homeostasis, mineral uptake, transport of small peptides and abiotic stress tolerance. Hence, in-depth evolutionary, structural, molecular and expression analysis could guide in exploring the mechanism of how these transporters contribute to nutrient balance and abiotic stress tolerance in maize. Following a series of bioinformatic analyses, eight OPTs in maize were identified. These transporters showed significant variations in molecular weight, and have one to five introns, 11 to 15 motifs, 11 to 18 transmembrane domains, multiple beta-strands, multiple alpha and transmembrane helices. ZmOPT1, 5, and 6 are plasma membranes and the rest are endoplasmic reticulum localized. All ZmOPTs are distributed in six different chromosomes having significant phytohormone-responsive cis-elements might be due to their great roles in hormonal regulation in maize. The significant transport activity of these transporters plays a great role in biological processes, cellular components and molecular functions in maize during gene ontology analysis. Co-expression of five genes among eight OPTs with 56 genes might be due to their great role in regulating other genes in multiple signaling pathways or vice-versa. Significant tissue-specific and drought, salinity, nitrogen starvation, and heat stress induced in silico expression following real time PCR validation of ZmOPT1, 7, and 8 genes might guide to elucidate the potential roles of these transporters in specific tissues and abiotic stress tolerance. Hence, the findings of the research might guide plant biologists to develop new varieties of maize having higher efficiency of peptide and metal ion transport, balance, and abiotic stress tolerance. Findings of these structural and expression analyzes might guide the plant biologist for single transgenesis, or developing and transforming programming-based synthetic genetic circuits in maize for advancing research in peptide transport, metal hemostasis, and increasing abiotic stress tolerance in maize.

Characterisation of islet antibody‐negative type 1 diabetes mellitus in Indian children

AbstractAimsIslet antibody‐negative type 1 diabetes mellitus (T1DM) has not been well characterised. We determined the frequency of antibody‐negative T1DM and compared it with antibody‐positive T1DM in a cohort of north Indian children.MethodsIn a multi‐centre, prospective, observational study, 176 Indian children (age 1–18 years) were assessed within 2 weeks of diagnosis of T1DM. Antibodies against GAD65 (GADA), islet antigen‐2 (IA‐2A) and zinc transporter 8 (ZnT8A), were estimated using validated ELISA. HLA‐DRB1, DQA1 and DQB1 alleles were studied by Luminex‐based typing. Monogenic diabetes was determined by targeted next‐generation sequencing using the Illumina platform.ResultsAfter excluding 12 children with monogenic diabetes, GADA, IA‐2A and ZnT8A were present in 124 (76%), 60 (37%) and 62 (38%) o children, respectively, while 24 (15%) were negative for all antibodies. A single antibody (most frequently GADA) was present in 68 (41%) of children, while all three antibodies were found in 34 (21%). Islet antibody‐negative T1DM (n = 24, 15%) did not differ from antibody‐positive children in their clinical features, HbA1c or plasma C‐peptide, both at onset or after 1 year follow‐up (available in 62 children). The frequency of other organ‐specific antibodies or high‐risk HLA‐DR and DQ alleles were also similar. Children with a single islet antibody did not differ from those with multiple antibodies.ConclusionsThe frequency of various islet‐antibodies, in isolation and combination, differed considerably from studies among children of European descent with T1DM. Children with T1DM who were islet antibody‐negative were indistinguishable from those who were antibody‐positive.

Forced Overexpression and Knockout Analysis of SLC30A and SLC39A Family Genes Suggests Their Involvement in Establishing Resistance to Cisplatin in Human Cancer Cells

Abstract: The metabolism of zinc and manganese plays a pivotal role in cancer progression by mediating cancer cell growth and metastasis. The SLC30A family proteins SLC30A3 and SLC30A10 mediate the efflux of zinc, manganese, and probably other transition element ions outside the cytoplasm to the extracellular space or into intracellular membrane compartments. The SLC39A family members SLC39A8 and SLC39A14 are their functional antagonists that transfer these ions into the cytoplasm. Recently, the SLC30A10 gene was suggested as a promising methylation biomarker of colorectal cancer. Here, we investigated whether forced overexpression or inactivation of SLC30A and SLC39A family genes has an impact on the phenotype of cancer cells and their sensitivity to cancer therapeutics. In the human colon adenocarcinoma HCT-15 and duodenal adenocarcinoma HuTu80 cell lines, we generated clones with knockouts of the SLC39A8 and SLC39A14 genes and forced overexpression of the SLC30A3, SLC30A10, and SLC39A8 genes. Gene expression in the mutant and control cells was assessed by RNA sequencing. The cell growth rate, mitochondrial activity, zinc accumulation, and sensitivity to the drugs cetuximab and cisplatin were investigated in functional tests. Overexpression or depletion of SLC30A or SLC39A family genes resulted in the deep reshaping of intracellular signaling and provoked hyperactivation of mitochondrial respiration. Variation in the expression of the SLC30A/SLC39A genes did not increase the sensitivity to cetuximab but significantly altered the sensitivity to cisplatin: overexpression of SLC30A10 resulted in an ~2.7–4 times increased IC50 of cisplatin, and overexpression of SLC30A3 resulted in an ~3.3 times decreased IC50 of cisplatin. The SLC30A/SLC39A genes should be considered as potential cancer drug resistance biomarkers and putative therapeutic targets.

Nanotech‐Enhanced Chemical Energy Storage with DNA

AbstractDNA nanotechnology has revolutionized materials science by harnessing DNA's programmable properties. DNA serves as a versatile biotemplate, facilitating the creation of novel materials such as electrode materials and DNA hydrogels for electrolytes and membranes. These advancements have significantly boosted the performance of energy storage devices. DNA biotemplates not only enhance supercapacitor capacitance and increase Li–S battery cycling stability but also improve metal ion transport in perovskite solar cells, enhancing power conversion efficiency. Additionally, DNA's addressable nature allows precise enzyme positioning in biofuel cells, enhancing enzyme cascade efficiency. Overall, DNA nanotechnology offers a potent strategy for enhancing electrochemical device performance and stability through structural engineering.

ZIP7 contributes to the pathogenesis of diabetic cardiomyopathy by suppressing mitophagy in mouse hearts

BackgroundAlthough the exact role of mitophagy in the pathogenesis of diabetic cardiomyopathy (DCM) caused by type 2 diabetes mellitus (T2DM) remains controversial, recent studies revealed inhibition of mitophagy exacerbates cardiac injury in DCM. The zinc transporter ZIP7 has been reported to be upregulated by high glucose in cardiomyocytes and ZIP7 upregulation leads to inhibition of mitophagy in mouse hearts in the setting of ischemia/reperfusion. Nevertheless, little is known about the role of ZIP7 and its relationship with mitophagy in DCM caused by T2DM.MethodsT2DM was induced with high-fat diet (HFD) and streptozotocin. The cardiac-specific ZIP7 conditional knockout (ZIP7 cKO) mice were generated by adopting CRISPR/Cas9 system. Cardiac function was evaluated with echocardiography. Mitophagy was assessed by detecting mito-LC3II, mitoKeima, and mitoQC. Reactive oxygen species (ROS) were detected with DHE and mitoB.ResultsZIP7 was upregulated by T2DM in mouse hearts and ZIP7 cKO reduced mitochondrial ROS generation in mouse hearts with T2DM. Mitophagy was suppressed by T2DM in mouse hearts, which was prevented by ZIP7 cKO. T2DM inhibited PINK1 and Parkin accumulation in cardiac mitochondria, an effect that was prevented by ZIP7 cKO, pointing to that ZIP7 upregulation mediates T2DM-induced suppression of mitophagy by inhibiting the PINK1/Parkin pathway. T2DM induced mitochondrial hyperpolarization and decrease of mitochondrial Zn2+ and this was blocked by ZIP7 cKO, indicating that upregulation of ZIP7 leads to mitochondrial hyperpolarization by reducing Zn2+ within mitochondria. Finally, ZIP7 cKO prevented cardiac dysfunction and fibrosis caused by T2DM.ConclusionsZIP7 upregulation mediates the inhibition of mitophagy by T2DM in mouse hearts by suppressing the PINK1/Parkin pathway. Reduction of mitochondrial Zn2+ due to upregulation of ZIP7 accounts for the inhibition of the PINK1/Parkin pathway. Prevention of ZIP7 upregulation is essential for the treatment of T2DM-induced cardiomyopathy.

Zinc Deficiency Leads to Reproductive Impairment in Male Mice Through Imbalance of Zinc Homeostasis and Inflammatory Response.

Zinc is an essential trace element crucial for growth and development and plays a significant role in male reproductive function. The aim of this study was explore the mechanism of male reproductive damage caused by different degrees of zinc deficiency. Thirty male ICR mice were randomly assigned to three groups: zinc-normal diet group (ZN, n = 10, Zn content = 30mg/kg), low zinc-deficiency diet group (LZD, n = 10, Zn content = 15mg/kg), and high zinc-deficiency diet group (HZD, n = 10, Zn content = 7.5mg/kg). The mice were maintained for 8weeks. At the end of the experiment, they were sacrificed, and their blood, testicular, and epididymal tissues were collected for further study. Zinc-deficient diet led to weight loss, testicular structural disorder, decreased semen quality, imbalance of zinc homeostasis, and inflammatory damage in mice. Semen quality, testosterone, serum Zn, testicular tissue Zn, testicular free Zn ions, Zrt-, Irt-like protein8 (ZIP8), Zrt-, Irt-like protein5 (ZIP5), and interleukin-10 (IL-10) were significantly decreased; zinc transporter 4(ZnT4), NF-κB p65, P-NF-κB p65, NLRP3, Caspase-8, and Caspase-3 were significantly increased in both LZD and HZD group mice. While compared with the LZD group, Zrt-, Irt-like protein13 (ZIP13), TNF-α, NF-κB p65, P-NF-κB p65, NLRP3, Caspase-1, and GSDMD were significantly increased in the HZD group. Both low and high zinc-deficiency diets can disrupt zinc homeostasis in mice, leading to heightened inflammatory responses, the activation of the NF-κB pathway, and increased apoptosis in testicular cells. Notably, a high zinc-deficiency diet led to an up-regulation of ZIP13 expression, exacerbated inflammation, and induced testicular pyroptosis, resulting in more severe reproductive damage in male mice.

The efflux system CdfX exports zinc that cannot be transported by ZntA in Cupriavidus metallidurans.

Cupriavidus metallidurans is able to survive exposure to high concentrations of transition metals, but is also able to grow under metal starvation conditions. A prerequisite of cellular zinc homeostasis is a flow equilibrium combining zinc uptake and efflux processes. The mutant strain ∆e4 of the parental plasmid-free strain AE104 with a deletion of all four chromosomally encoded genes of previously known efflux systems ZntA, CadA, DmeF, and FieF was still able to efflux zinc in a pulse-chase experiment, indicating the existence of a fifth efflux system. The gene cdfX, encoding a protein of the cation diffusion facilitator (CDF) family, is located in proximity to the cadA gene, encoding a P-type ATPase. Deletion of cdfX in the ∆e4 mutant resulted in a further decrease in zinc resistance. Pulse-chase experiments with radioactive 65Zn(II) and stable-isotope-enriched 67Zn(II) provided evidence that CdfX was responsible for the residual zinc efflux activity of the mutant strain ∆e4. Reporter gene fusions with cdfX-lacZ indicated that the MerR-type regulator ZntR, the main regulator of zntA expression, was responsible for zinc- and cadmium-dependent upregulation of cdfX expression, especially in mutant cells lacking one or both of the previously characterized efflux systems, ZntA and CadA. Expression of zntR also proved to be controlled by ZntR itself as well as by zinc and cadmium availability. These data indicate that the cdfX-cadA region provides C. metallidurans with a backup system for the zinc-cadmium-exporting P-type ATPase ZntA, with CdfX exporting zinc and CadA cadmium.IMPORTANCEBacteria have evolved the ability to supply the important trace element zinc to zinc-dependent proteins, despite external zinc concentrations varying over a wide range. Zinc homeostasis can be understood as adaptive layering of homeostatic systems, allowing coverage from extreme starvation to extreme resistance. Central to zinc homeostasis is a flow equilibrium of zinc comprising uptake and efflux reactions, which adjusts the cytoplasmic zinc content. This report describes what happens when an imbalance in zinc and cadmium concentrations impairs the central inner-membrane zinc efflux system for zinc by competitive inhibition for this exporter. The problem is solved by activation of Cd-exporting CadA or Zn-exporting CdfX as additional efflux systems.

Cryo-EM structures of the zinc transporters ZnT3 and ZnT4 provide insights into their transport mechanisms.

Zinc transporters (ZnTs) act as H+/Zn2+ antiporters, crucial for zinc homeostasis. Brain-specific ZnT3 expressed in synaptic vesicles transports Zn2+ from the cytosol into vesicles and is essential for neurotransmission, with ZnT3 dysfunction associated with neurological disorders. Ubiquitously expressed ZnT4 localized to lysosomes facilitates the Zn2+ efflux from the cytosol to lysosomes, mitigating the cell injury risk. Despite their importance, the structures and Zn2+ transport mechanisms remain unclear. We characterized the three-dimensional structures of human ZnT3 (inward-facing) and ZnT4 (outward-facing) using cryo-electron microscopy. By combining these structures, we assessed the conformational changes that could occur within the transmembrane domain during Zn2+ transport. Our results provide a structural basis for a more comprehensive understanding of the H+/Zn2+ exchange mechanisms exhibited by ZnTs.

The zinc transporter Slc30a1 (ZnT1) in macrophages plays a protective role against attenuated Salmonella.

The zinc transporter Slc30a1 plays an essential role in maintaining cellular zinc homeostasis. Despite this, its functional role in macrophages remains largely unknown. Here, we examine the function of Slc30a1 in host defense using mice models infected with an attenuated stain of Salmonella enterica Typhimurium and primary macrophages infected with the attenuated Salmonella. Bulk transcriptome sequencing in primary macrophages identifies Slc30a1 as a candidate in response to Salmonella infection. Whole-mount immunofluorescence and confocal microscopy imaging of primary macrophage and spleen from Salmonella-infected Slc30a1flag-EGFP mice demonstrate Slc30a1 expression is increased in infected macrophages with localization at the plasma membrane and in the cytosol. Lyz2-Cre-driven Slc30a1 conditional knockout mice (Slc30a1fl/fl;Lyz2-Cre) exhibit increased susceptibility to Salmonella infection compared to control littermates. We demonstrate that Slc30a1-deficient macrophages are defective in intracellular killing, which correlated with reduced activation of nuclear factor kappa B and reduction in nitric oxide (NO) production. Notably, the model exhibits intracellular zinc accumulation, demonstrating that Slc30a1 is required for zinc export. We thus conclude that zinc export enables the efficient NO-mediated antibacterial activity of macrophages to control invading Salmonella.

Gαo1 and Gαo1/Gαo2 deletion differentially affect hippocampal mossy fiber tract anatomy and neuronal morphogenesis.

The heterotrimeric G-protein αo subunit is ubiquitously expressed in the CNS as two splice variants Gαo1 and Gαo2, regulating various brain functions. Here, we investigated the effect of single Gαo1, Gαo2, and double Gαo1/2 knockout on the postnatal development of the murine mossy fiber tract, a central pathway of the hippocampal connectivity circuit. The size of the hippocampal synaptic termination fields covered by mossy fiber boutons together with various fiber length parameters of the tract was analyzed by immunohistochemical staining of the vesicular Zinc transporter 3 (ZnT3) or Synaptoporin at postnatal days 2, 4, 8, 12, 16, and in the adult. Ultimately, Gαo1 knockout resulted in a reduced developmental growth of synaptic mossy fiber terminal fields by 37% in the adult Stratum lucidum and by 30% in the total mossy fiber tract size. Other morphological parameters such as projection length of the infrapyramidal bundle of the tract were increased (+52% in Gαo1 -/- mice). In contrast, Gαo2 knockout had no effects on the mossy fiber tract. Moreover, by using primary heterozygous and homozygous Gαo1 knockout hippocampal cultures, we detected a strongly pronounced reduction in axon and dendrite length (-50% and -38%, respectively) as well as axon and dendrite arborization complexity (-75% and -72% branch nodes, respectively) in the homozygous knockout. Deletion of both splice variants Gαo1 and Gαo2 partially rescued the invivo and completely reconstituted the invitro effects, indicating an opposing functional relevance of the two Gαo splice variants for neuronal development and synaptic connectivity.

PGRMC1 and PAQR4 are promising molecular targets for a rare subtype of ovarian cancer.

The heterogeneity of ovarian cancer (OC) has made developing effective treatments difficult. Nowadays, hormone therapy plays a growing role in the treatment of OC; however, hormone modulators have had only limited success so far. To provide a more rigorous foundation for hormonal therapy for different OC subtypes, the current study used a series of bioinformatics approaches to analyse the expression profiles of genes encoding membrane progesterone (PGRMC1, progestins and the adipoQ receptor [PAQR] family), and androgen (zinc transporter member 9 [ZIP9], OXER1) receptors. Our work investigated also their prognostic value in the context of OC. We found differences in expression of ZIP9 and OXER1 between different OC subtypes, as well as between patient tumour and normal tissues. Expression of mRNA encoding PAQR7 and PAQR8 in a panel of OC cell lines was below the qPCR detection limit and was downregulated in tumour tissue samples, whereas high expression of PGRMC1 and PAQR4 mRNA was observed in rare subtypes of OC cell lines. In addition, chemical inhibition of PGRMC1 reduced the viability of rare OCs represented by COV434 cells. In conclusion, PGRMC1 and PAQR4 are promising targets for anticancer therapy, particularly for rare subtypes of OC. These findings may reflect differences in the observed responses of various OC subtypes to hormone therapy.

The Intestinal Transporter SLC30A1 Plays a Critical Role in Regulating Systemic Zinc Homeostasis.

The essential trace element, zinc, regulates virtually all aspects of cellular physiology, particularly cell proliferation and survival. Diverse families of metal transporters, metallothioneins, and metal-responsive transcriptional regulators are linked to zinc homeostasis. However, the mechanism underlying the regulation of systemic zinc homeostasis remains largely unknown. Here, it is reported that the intestinal transporter SLC30A1 plays an essential role in maintaining systemic zinc homeostasis. Using several lines of tissue-specific knockout mice, it is found that intestinal Slc30a1 plays a critical role in survival. Furthermore, lineage tracing reveals that Slc30a1 is localized to the basolateral membrane of intestinal epithelial cells (IECs). It is also found that Slc30a1 safeguards both intestinal barrier integrity and systemic zinc homeostasis. Finally, an integrative analysis of the cryo-EM structure and site-specific mutagenesis of human SLC30A1 are performed and a zinc transport mechanism of SLC30A1 unique within the SLC30A family, with His43 serving as a critical residue for zinc selectivity, is identified.

Treatment switch from multiple daily insulin injections to sulphonylureas in an African young adult diagnosed with HNF1A MODY: a case report

BackgroundMaturity onset diabetes of the young is one of the commonest causes of monogenic diabetes and can easily be mistaken for type 1 diabetes. A diagnosis of maturity onset diabetes of the young can have direct implications for genetic counseling, family screening, and precision diabetes treatment. However, the cost of genetic testing and identifying individuals to test are the main challenges for diagnosis and management in sub-Saharan Africa. We report the very first documented case of HNF1A maturity onset diabetes of the young in the sub-Saharan African region.Case presentationA 20-year-old female Black African young adult diagnosed with type 1 diabetes aged 14 presented for routine out-patient diabetes consultation. She was on multiple daily insulin injections; total combined dose 0.79 IU/kg/day with an HbA1c of 7.7%. The rest of her laboratory examinations were normal. On extended laboratory analysis, she had good residual insulin secretion with post-meal plasma C-peptide levels at 1150 pmol/L. She tested negative for glutamic acid decarboxylase (GAD65), islet antigen-2 (IA-2), and zinc transporter 8 (ZnT8) islet autoantibodies. Targeted next-generation sequencing (t-NGS) for monogenic diabetes was performed using DNA extracted from a buccal sample. She was diagnosed with HNF1A maturity onset diabetes of the young, with the c.607C > T; p.(Arg203Cys) pathogenic variant, which has never been reported in sub-Saharan Africa. Her clinical practitioners provided genetic and therapeutic counseling. Within 10 months following the diagnosis of maturity onset diabetes of the young, she was successfully switched from multiple daily insulin injections to oral antidiabetic tablets (sulphonylurea) while maintaining stable glycemic control (HBA1c of 7.0%) and reducing hypoglycemia. She expressed a huge relief from the daily finger pricks for blood glucose monitoring.ConclusionThis case reveals that HNF1A maturity onset diabetes of the young (and probably other causes of monogenic diabetes) can present in sub-Saharan Africa. A diagnosis of maturity onset diabetes of the young can have significant life-changing therapeutic implications.

The antivirulent Staphylococcal sRNA SprC regulates CzrB efflux pump to adapt its response to zinc toxicity.

Bacterial regulatory RNAs (sRNAs) are important players to control gene expression. In Staphylococcus aureus, SprC is an antivirulent trans-acting sRNA known to base-pair with the major autolysin atl mRNA, preventing its translation. Using MS2-affinity purification coupled with RNA sequencing, we looked for its sRNA-RNA interactome and identified 14 novel mRNA targets. In vitro biochemical investigations revealed that SprC binds two of them, czrB and deoD, and uses a single accessible region to regulate its targets, including Atl translation. Unlike Atl regulation, the characterization of the SprC-czrB interaction pinpointed a destabilization of the czrAB cotranscript, leading to a decrease of the mRNA level that impaired CzrB zinc efflux pump expression. On a physiological standpoint, we showed that SprC expression is detrimental to combat against zinc toxicity. In addition, phagocyctosis assays revealed a significant, but moderate, increase of czrB mRNA levels in a sprC-deleted mutant, indicating a functional link between SprC and czrB upon internalization in macrophages, and suggesting a role in resistance to both oxidative and zinc bursts. Altogether, our data uncover a novel pathway in which SprC is implicated, highlighting the multiple strategies used by S. aureus to balance virulence using an RNA regulator.

SLC30A2-Mediated Zinc Metabolism Modulates Gastric Cancer Progression via the Wnt/β-Catenin Signaling Pathway.

Gastric cancer (GC) is a significant global health burden with limited treatment options. The purpose of this study was to investigate the role of SLC30A2, a zinc transporter, in GC development and its capacity as a target for therapy. A comprehensive analysis of GC datasets (GSE54129 and stomach adenocarcinoma (STAD) from The Cancer Genome Atlas (TCGA)) was conducted using bioinformatics tools to examine differential gene expression, focusing on SLC30A2. Functional assays, including Cell counting kit-8 (CCK-8) and transwell assays, were carried out on GC cell lines to determine the impact of SLC30A2 knockdown on cell behavior. Flow cytometry was utilized to quantitatively observe cell apoptosis and cell cycle progression. The impact of zinc sulfate (ZnSO4) on GC cells was evaluated by detecting apoptosis markers, Wnt/β-catenin signaling pathway activity, and oxidative stress biomarkers, focusing on the regulatory effect of SLC30A2 overexpression. Our analysis revealed significant upregulation of SLC30A2 in GC samples compared to normal samples, and high SLC30A2 expression was linked to poor prognosis. SLC30A2 knockdown repressed proliferation, invasion, and migration of GC cells, induced apoptosis, as well as arrested the cell cycle. Additionally, ZnSO4 treatment induced cytotoxicity and oxidative stress in GC cells, while SLC30A2 overexpression rescued ZnSO4-induced, migration, invasion, and proliferation. Moreover, ZnSO4 had been shown to bolster apoptosis and trigger the Wnt/β-catenin signaling pathway, effects which were mitigated by the overexpression of SLC30A2. Our results implied that SLC30A2 was essential for GC progression by modulating zinc homeostasis and cellular processes. Targeting SLC30A2 or zinc signaling may represent a potential therapeutic approach for GC treatment.

Structural insights into human zinc transporter ZnT1 mediated Zn2+ efflux

Zinc transporter 1 (ZnT1), the principal carrier of cytosolic zinc to the extracellular milieu, is important for cellular zinc homeostasis and resistance to zinc toxicity. Despite recent advancements in the structural characterization of various zinc transporters, the mechanism by which ZnTs-mediated Zn2+ translocation is coupled with H+ or Ca2+ remains unclear. To visualize the transport dynamics, we determined the cryo-electron microscopy (cryo-EM) structures of human ZnT1 at different functional states. ZnT1 dimerizes via extensive interactions between the cytosolic (CTD), the transmembrane (TMD), and the unique cysteine-rich extracellular (ECD) domains. At pH 7.5, both protomers adopt an outward-facing (OF) conformation, with Zn2+ ions coordinated at the TMD binding site by distinct compositions. At pH 6.0, ZnT1 complexed with Zn2+ exhibits various conformations [OF/OF, OF/IF (inward-facing), and IF/IF]. These conformational snapshots, together with biochemical investigation and molecular dynamic simulations, shed light on the mechanism underlying the proton-dependence of ZnT1 transport.

Xenotransplanted human organoids identify transepithelial zinc transport as a key mediator of intestinal adaptation

Short bowel syndrome (SBS) leads to severe morbidity and mortality. Intestinal adaptation is crucial in improving outcomes. To understand the human gene pathways associated with adaptation, we perform single-cell transcriptomic analysis of human small intestinal organoids explanted from mice with experimental SBS. We show that transmembrane ion pathways, specifically the transepithelial zinc transport pathway genes SLC39A4 and SLC39A5, are upregulated in SBS. This discovery is corroborated by an external dataset, bulk RT-qPCR, and Western blots. Oral zinc supplementation is shown to improve survival and weight gain of SBS mice and increase the proliferation of intestinal crypt cells in vitro. Finally, we identify the upregulation of SLC39A5 and associated transcription factor KLF5 in biopsied intestinal tissue specimens from patients with SBS. Thus, we identify zinc supplementation as a potential therapy for SBS and describe a xenotransplantation model that provides a platform for discovery in other intestinal diseases.

6985 Intravenous Immunoglobulin induced Type 1 diabetes remission

Abstract Disclosure: N. Shahid: None. D. Newbern: None. Introduction: Intravenous immunoglobulin [IVIG] is an immunomodulatory agent used for treatment of autoimmune and inflammatory conditions. However, it is not indicated in patients with type 1 diabetes [T1D] as its efficacy has not been established. Clinical Case: A 9-year-old previously healthy boy presented to the Emergency Department with several days of unexplained bruising and mucosal bleeding with no prior history of trauma, bleeding disorders or other systemic symptoms. Physical examination showed generalized petechiae, ecchymosis and purpura. Vitals were normal including weight and BMI. Initial labs confirmed Immune thrombocytopenic purpura [ITP] as his platelets were less than 1K/µL with otherwise normal peripheral blood cell counts and smear. Concomitantly, labs showed significant hyperglycemia [260mg/dL] with glycosuria and trace ketonuria. Glycated hemoglobin [Hba1c] was elevated at 10.5% and ultimately Pancreatic autoantibodies [GAD65, Zinc transporter-8 and islet cell antibody] came back positive confirming T1D. Other autoimmune disorders such as adrenal insufficiency, thyroiditis, and celiac disease were ruled out. For the treatment of ITP, he the patient received 1 dose of IVIG 1g/kg and responded well with a rise in platelets to 6K/µL. The morning following the infusion, due to fasting hyperglycemia, the patient was started on basal-bolus insulin regimen. By 2nd day post IVIG, he had hypoglycemia, so insulin was discontinued with normalization of blood sugars. He is now 7 months post IVIG with no recurrent episodes of thrombocytopenia. He also remains off insulin with Hba1c in the 5.9-6.5% range. He eats a regular diet with avoidance of simple carbohydrates. He wears onwears a a continuous glucose monitor, which shows that blood sugars are in range 93% of the time He remains euglycemic overnight with transient self-resolving mild post-prandial hyperglycemia. Pancreatic autoantibodies have been reassessed and remain positive Conclusions: This case demonstrates that IVIG used for the treatment of ITP has induced a state of remission in our patient with newly diagnosed with T1D. IVIG is not a standard of treatment for T1D, however, when given for other autoantibody- or T-cell-mediated autoimmune conditions, it may reduce the insulin need in patients with known diabetes or induce remission in patients with newly diagnosed diabetes.

8283 Diabetes Mellitus in Patients with Hemochromatosis- A Diagnostic and Therapeutic Challenge

Abstract Disclosure: U. Rafat: None. M. Siddiqui: None. J.L. Gilden: Other; Self; Novartis Pharmaceuticals. A. Moid: Other; Self; Novartis Pharmaceuticals. Background: Primary Hemochromatosis is a genetic condition most commonly due to two sets of mutations in the Human homeostatic iron regular Protein (HFE) gene. HFE modulates the expression of hepcidin, which regulates intestinal iron absorption, plasma iron concentration and distribution of iron in tissues. Hemochromatosis patients are at high risk for developing diabetes mellitus (DM) due to iron overload in the pancreas with damage to Beta cells and impaired insulin secretory capacity. Hemochromatosis is often called Bronze Diabetes due to brown discoloration of the skin from accumulation of iron, and is characterized by hepatic fibrosis, fatigue, arthralgias, cirrhosis, DM, arthropathy, pigmentation and cardiomyopathy. Case: We present a Caucasian male with homozygous hereditary hemochromatosis, diagnosed by liver biopsy at age 40 due to transaminitis and Ferritin level of 1500 ng/mL and Genetic testing- 2 copies of HFE gene pathogenic variant (C282Y). He was later diagnosed with DM age 51, started on Metformin and referred to Endocrine clinic with abdominal bloating, and polyarticular arthralgias. Physical exam=Vital Signs normal (WT. 231lbs, BMI 34), with splenomegaly, but normal musculoskeletal exam and skin without bronze discoloration. Both parents had T2DM. Lab- Hb a1c 8.7% (0.0-5.6), Iron saturation 71% (10-50), Ferritin 66.3 ng/mL (26-388), C-Peptide 3.30 ng/ml (0.81-3.85), with glucose level of 119 mg/dL, and negative IA-2 <5.4 U/mL, negative Islet cell antibody, GAD 65 <5 IU/mL (nl <5), Insulin Autoantibody <0.4 U/mL (nl <0.4), and Zinc Transporter 8 antibodies <10 U/mL (nl <15). Liver tests- AST 39 U/L(10-37), ALT 77 U/L (10-65), ALP 89 U/L (45-117), total bilirubin 1.1 mg/dL(0.2-1.2). Hormonal evaluation included TSH 1.2 uIU/mL (0.55-4.78), ACTH 19 pg/mL (0-47), AM Cortisol 16.28 ug/d (5.30-22.50) IGF1 158 ng/mL (50-317) FSH 9.6 mIU/mL(l.40-18.10), LH 5.09 mIU/mL (1.50-9.30), Prolactin 7.40 ng/mL(2.10-17.70), total testosterone 374 ng/dL(250-1100), free testosterone 66.2 pg/mL (35.0-155.0). Echocardiogram-left ventricular hypertrophy and thick right ventricular wall with concerns for iron overload. Hba1c improved to 6.6% on Metformin. Fructosamine 351umol/L (151-300). In the absence of advanced cardiac, hepatic and other organ involvement, and presence of elevated C-peptide and high BMI, this patient is being managed as T2DM, with low threshold to initiate insulin therapy considering possibility of concomitant Bronze DM. Conclusion: It is important to determine type of DM, so appropriate management options can be devised. While insulin is recommended for management in Bronze Diabetes, insulin sensitizers, such as metformin and/or GLP 1 agonists can be used in type 2 DM. One must also consider therapy based upon the risk of cancer and acute pancreatitis in the setting of pancreatic iron overload, when considering antihyperglycemic therapies. Presentation: 6/2/2024

7316 A Unique Presentation of Diabetes Mellitus in an 8-Year-Old Male Positive For 3 Different Mutations Related to MODY

Abstract Disclosure: R. Senguttuvan: None. A. Pamfil: None. Background: Maturity-Onset Diabetes of the Young (MODY) is the most common form of inherited non-autoimmune diabetes mellitus, characterized by autosomal dominant inheritance, young age at onset and beta cell dysfunction. There are at least 14 MODY mutations and we present a pediatric case not meeting criteria for type 1[T1DM] or type 2 diabetes mellitus[T2DM], who tested positive for mutations in 3 different genes known to cause MODY. Case: An 8-year-old male, born full term, 2776 grams and 48.3 cm, without history of neonatal hypoglycemia or hyperglycemia, was referred for new onset diabetes mellitus management. While undergoing evaluation for abdominal pain and constipation, he was found to have a fasting glucose of 126 mg/dL (7 mmol/L) and hemoglobin A1C of 6.5%. He endorsed polyuria, but no polydipsia. He had no clinical signs of insulin resistance (e.g., acanthosis nigricans) and a BMI of 23.65 kg/m2, at the 97th percentile. Family history is positive for diabetes mellitus requiring insulin, in father (diagnosed at 11 years) and paternal grandmother and T2DM in paternal aunt. Laboratory evaluation was negative for all 5 antibodies (GAD, IA-2, Anti-islet cell antibody, Zinc Transporter 8 and Insulin antibodies) and revealed an insulin level of 15.9 uIU/mL (RR: <2.0-13.0) and C peptide: 2.3 ng/mL (RR: 1.1-4.4). Lacking diagnostic criteria for T1DM or T2DM, genetic testing was performed. Patient tested heterozygous for mutations in 3 genes known to cause MODY: GCK [(c.350 G>T p. (G117V)], ABCC8 [(c.2270 C>G p.(T757R)], and HNF1B [(c.68A>G p.(K23R)], all variant of uncertain significance. Over an 8-month period, patient's weight decreased from 98 lbs. (44.9 kg) to 90 lbs. (41.1 kg) after meeting with our dietician and implementing healthy dietary changes, and his beta cell function markers improved from diagnosis: Fasting insulin (4.5 uIU/mL), C peptide (1.3 ng/mL), and glucose 119 mg/dL; Hemoglobin A1C remained relatively stable at 6.1%. A kidney ultrasound was normal. No medical intervention were started yet, and patient is being monitored clinically and biochemically every 3-4 months. Discussion: Clinical monitoring over time, genetic testing in the parents, are critical in this patient’s long-term treatment plan and prognosis. To our knowledge, this may be the first case of diabetes mellitus in a pediatric patient, positive for mutations in 3 different genes known to cause MODY. South Texas has one of the highest incidences of T2DM in the USA. In addition to screening for genetic forms of diabetes, in patients with negative T1DM antibodies and atypical phenotype for T2DM, we should consider genetic screening in mildly obese pediatric and young adult patients without significant acanthosis nigricans, who were already diagnosed as T2DM. Presentation: 6/1/2024