Exocyst Research Articles

The Exocyst Is Required for CD36 Fatty Acid Translocase Trafficking and Free Fatty Acid Uptake in Skeletal Muscle Cells.

In obesity, chronic membrane-localization of CD36 free fatty acid (FFA) translocase, but not other FFA transporters, enhances FFA uptake and intracellular lipid accumulation. This ectopic lipid accumulation promotes insulin resistance by inhibiting insulin-induced GLUT4 glucose transporter trafficking and glucose uptake. GLUT4 and CD36 cell surface delivery is triggered by insulin- and contraction-induced signaling, which share conserved downstream effectors. While we have gathered detailed knowledge on GLUT4 trafficking, the mechanisms regulating CD36 membrane delivery and subsequent FFA uptake in skeletal muscle are not fully understood. The exocyst trafficking complex facilitates the docking of membrane-bound vesicles, a process underlying the controlled surface delivery of fuel transporters. The exocyst regulates insulin-induced glucose uptake via GLUT4 membrane trafficking in adipocytes and skeletal muscle cells and plays a role in lipid uptake in adipocytes. Based on the high degree of conservation of the GLUT4 and CD36 trafficking mechanisms in adipose and skeletal muscle tissue, we hypothesized that the exocyst also contributes to lipid uptake in skeletal muscle and acts through the targeted plasma membrane delivery of CD36 in response to insulin and contraction. Here, we show that the exocyst complex is necessary for insulin- and contraction-induced CD36 membrane trafficking and FFA uptake in muscle cells.

The Polarized Redistribution of the Contractile Vacuole to the Rear of the Cell is Critical for Streaming and is Regulated by PI(4,5)P2-Mediated Exocytosis

Dictyostelium discoideum amoebae align in a head to tail manner during the process of streaming during fruiting body formation. The chemoattractant cAMP is the chemoattractant regulating cell migration during this process and is released from the rear of cells. The process by which this cAMP release occurs has eluded investigators for many decades, but new findings suggest that this release can occur through expulsion during contractile vacuole (CV) ejection. The CV is an organelle that performs several functions inside the cell including the regulation of osmolarity, and discharges its content via exocytosis. The CV localizes to the rear of the cell and appears to be part of the polarity network, with the localization under the influence of the plasma membrane (PM) lipids, including the phosphoinositides (PIs), among those is PI(4,5)P2, the most abundant PI on the PM. Research on D. discoideum and neutrophils have shown that PI(4,5)P2 is enriched at the rear of migrating cells. In several systems, it has been shown that the essential regulator of exocytosis is through the exocyst complex, mediated in part by PI(4,5)P2-binding. This review features the role of the CV complex in D. discoideum signaling with a focus on the role of PI(4,5)P2 in regulating CV exocytosis and localization. Many of the regulators of these processes are conserved during evolution, so the mechanisms controlling exocytosis and membrane trafficking in D. discoideum and mammalian cells will be discussed, highlighting their important functions in membrane trafficking and signaling in health and disease.

Grab regulates transferrin receptor recycling and iron uptake in developing erythroblasts

AbstractDeveloping erythroblasts acquire massive amounts of iron through the transferrin (Tf) cycle, which involves endocytosis, sorting, and recycling of the Tf-Tf receptor (Tfrc) complex. Previous studies on the hemoglobin-deficit (hbd) mouse have shown that the exocyst complex is indispensable for the Tfrc recycling; however, the precise mechanism underlying the efficient exocytosis and recycling of Tfrc in erythroblasts remains unclear. Here, we identify the guanine nucleotide exchange factor Grab as a critical regulator of the Tf cycle and iron metabolism during erythropoiesis. Grab is highly expressed in differentiating erythroblasts. Loss of Grab diminishes the Tfrc recycling and iron uptake, leading to hemoglobinization defects in mouse primary erythroblasts, mammalian erythroleukemia cells, and zebrafish embryos. These defects can be alleviated by supplementing iron together with hinokitiol, a small-molecule natural compound that can mediate iron transport independent of the Tf cycle. Mechanistically, Grab regulates the exocytosis of Tfrc-associated vesicles by activating the GTPase Rab8, which subsequently promotes the recruitment of the exocyst complex and vesicle exocytosis. Our results reveal a critical role for Grab in regulating the Tf cycle and provide new insights into iron homeostasis and erythropoiesis.

Vesicle transport: Exocyst follows PIP2 to tether membranes

A new study uses reconstituted, functional octameric exocyst complex to provide new insights into the assembly of this tethering complex and reveal how the activity of the lipid kinase PIP5K1C stimulated by Arf6 on exocytic vesicles allows for exocyst-mediated tethering at the plasma membrane.

Abstract 4238: A novel immunotherapy approach by inhibiting nanotube-mediated mitochondrial trafficking between cancer cells and T cells

Abstract Trafficking of mitochondria from immune cells to cancer cells via physical nanotubes is a new mechanism by which cancer cells undergo immune evasion. This results in depletion of T cell, which can limit the efficacy of classical immune checkpoint inhibitors. Here we introduce a novel pharmacological inhibitor that inhibits nanotube-mediated mitochondria transfer from immune cell to cancer cell. Our preliminary study implicates the exocyst complex in the nanotube assembly. We performed molecular dynamic simulations to identify the potential inhibitors for the exocyst proteins. We have identified a drug candidate, TS-1, which successfully inhibits the mitochondria transfer from immune cell to cancer cell. Currently we are exploring the modification of the structural component to increase the inhibitory potential of the drug. TS-1-loaded liposome significantly inhibited tumor growth in a 4T1 metastatic breast cancer mouse model. We observed considerable increase in intratumoral T cell population with treatment. Furthermore, the use of TS-1 in combination with an anti-PD1 inhibitor resulted in effective tumor reduction in the 4T1 model, which typically responds poorly to anti-PD1 therapy alone. Conclusion: Taken together, the inhibition of nanotube-mediated mitochondrial hijacking from immune cells emerges as an approach for the development of next generation of immunotherapy agents. Citation Format: Tanmoy Saha, Ruparoshni Jaybalan, HaeLin Jang, Shiladitya Sengupta. A novel immunotherapy approach by inhibiting nanotube-mediated mitochondrial trafficking between cancer cells and T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4238.

Xanthomonas counteracts host immunity by targeting the exocyst complex.

Xanthomonas counteracts host immunity by targeting the exocyst complex.

Cancer cells resist antibody-mediated destruction by neutrophils through activation of the exocyst complex

BackgroundNeutrophils kill antibody-opsonized tumor cells using trogocytosis, a unique mechanism of destruction of the target plasma. This previously unknown cytotoxic process of neutrophils is dependent on antibody opsonization, Fcγ receptors...

203-LB: The Role of the Exocyst Trafficking Complex in CD36 Fatty Acid Translocase Trafficking in Skeletal Muscle Cells

Skeletal muscle free fatty acid (FFA) uptake correlates with the amount of fatty acid translocase CD36 on the cell surface. In obesity, chronic membrane-localization of CD36, but not other FFA transporters, augments FFA uptake and intracellular lipid accumulation. This ectopic lipid accumulation then causes insulin resistance (IR) by inhibiting GLUT4 glucose transporter trafficking and glucose uptake in response to insulin. GLUT4 and CD36 cell-surface delivery is stimulated by insulin and contraction signaling, sharing conserved downstream effectors. The eight-protein exocyst complex is responsible for the targeted docking of membrane-bound vesicles, a process underlying cell-surface delivery of fuel transporters. The exocyst indeed regulates insulin-induced glucose uptake via GLUT4 trafficking to the membrane in adipocytes and skeletal muscle. In addition, it controls lipid uptake in adipocytes, but we do not know which of the FFA-transporting proteins the exocyst targets during this process. Based on the high degree of conservation of the fuel transporter trafficking mechanisms in adipose and skeletal muscle tissue, we hypothesized that the exocyst contributes to lipid uptake in skeletal muscle via the targeted trafficking of CD36. Our data shows that the exocyst plays a role in FFA uptake in skeletal muscle cells. Using an L6 GLUT4myc myoblast model we demonstrate that the exocyst is recruited to CD36 vesicles upon insulin and contraction signaling. We also show that disrupted exocyst activity leads to an impaired CD36 surface delivery and decreased FFA uptake in skeletal myoblasts. We are the first to demonstrate that the exocyst is necessary for insulin- and contraction-induced CD36 membrane trafficking and FFA metabolism in muscle cells. Further studies will continue to investigate the mechanism of exocyst-regulated FFA uptake and lipid metabolism in skeletal muscle to help our understanding of ectopic lipid accumulation leading to IR. Disclosure N. K. Nakamura: None. D. S. Tokunaga: None. H. Y. J. Ha: None. N. Polgar: None.

1285-P: Differentiating between Diabetic and Idiopathic Gastroparesis: A Genetic Perspective

Gastroparesis is a serious medical condition characterized by delayed gastric emptying and symptoms of nausea, vomiting, bloating, fullness after meals, and abdominal pain. An innate immune dysregulation and injury to the interstitial cells of Cajal and other components of the enteric nervous system is likely central to the pathogenesis of gastroparesis. Most common etiologies include diabetes, post-surgical but most cases are idiopathic. Thus far, little is known about the underlying genetic risk factors for gastroparesis. We have done a genome-wide association study comparing idiopathic and diabetic cases with controls as well as contrasting idiopathic versus diabetic cases. We report a novel genetic association of SLC15A4 locus with idiopathic gastroparesis. This signal is driven by multiple variants with top missense variant SLC15A4:NM145648:exon2:c.T716C:p.V239A, rs33990080. Altogether, among EUR cohort we report 69 carriers out of 214 versus controls 165 out of 896 (MAF: cases 0.18; MAF: controls 0.09) and OR: 1.9 (p-value<10^-6) . We furthermore differentiate idiopathic from diabetic gastroparesis with an established diabetes genetic risk score, - result that is statistically significant (p-value<0.0004) . We also delineate a number of significant loci implicated in diabetes risk including (HLA-DQB1,HLA-DQA2, EXOC6B) in the idiopathic versus diabetic gastroparesis analysis. Of particular interest are the Exocyst complex component, 6 (EXOC6/6B) with lead variant rs41420. previously identified to play a role in insulin signaling through its interaction with the glucose transporter GLUT4. Current genetic findings suggest that a mechanism directly connected to macrophage polarization may be implicated in the etiology gastroparesis. The GWAS picture that is emerging implicates novels loci implicated in the pathophysiology of gastroparesis differentiating those of diabetic versus idiopathic etiology. Disclosure S.P.Smieszek: None.

The host exocyst complex is targeted by a conserved bacterial type-III effector that promotes virulence.

For most Gram-negative bacteria, pathogenicity largely depends on the type-III secretion system that delivers virulence effectors into eukaryotic host cells. The subcellular targets for the majority of these effectors remain unknown. Xanthomonas campestris, the causal agent of black rot disease of crucifers such as Brassica spp., radish, and turnip, delivers XopP, a highly conserved core-effector protein produced by X. campestris, which is essential for virulence. Here, we show that XopP inhibits the function of the host-plant exocyst complex by direct targeting of Exo70B, a subunit of the exocyst complex, which plays a significant role in plant immunity. XopP interferes with exocyst-dependent exocytosis and can do this without activating a plant NOD-like receptor that guards Exo70B in Arabidopsis. In this way, Xanthomonas efficiently inhibits the host's pathogen-associated molecular pattern (PAMP)-triggered immunity by blocking exocytosis of pathogenesis-related protein-1A, callose deposition, and localization of the FLAGELLIN SENSITIVE2 (FLS2) immune receptor to the plasma membrane, thus promoting successful infection. Inhibition of exocyst function without activating the related defenses represents an effective virulence strategy, indicating the ability of pathogens to adapt to host defenses by avoiding host immunity responses.

A mechanism for exocyst-mediated tethering via Arf6 and PIP5K1C-driven phosphoinositide conversion

SummaryPolarized trafficking is necessary for the development of eukaryotes and is regulated by a conserved molecular machinery. Late steps of cargo delivery are mediated by the exocyst complex, which integrates lipid and protein components to tether vesicles for plasma membrane fusion. However, the molecular mechanisms of this process are poorly defined. Here, we reconstitute functional octameric human exocyst, demonstrating the basis for holocomplex coalescence and biochemically stable subcomplexes. We determine that each subcomplex independently binds to phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), which is minimally sufficient for membrane tethering. Through reconstitution and epithelial cell biology experiments, we show that Arf6-mediated recruitment of the lipid kinase PIP5K1C rapidly converts phosphatidylinositol 4-phosphate (PI(4)P) to PI(4,5)P2, driving exocyst recruitment and membrane tethering. These results provide a molecular mechanism of exocyst-mediated tethering and a unique functional requirement for phosphoinositide signaling on late-stage vesicles in the vicinity of the plasma membrane.

Molecular cloning, inducible expression and function analysis of Epinephelus coioides Sec6 response to SGIV infection

Exocyst complex component 3 Sec6 of mammals, one of the components of the exocyst complex, participates in numerous cellular functions, such as promoting cell migration and inhibiting apoptosis. In this study, the Sec6 was obtained from Epinephelus coioides, an economically important cultured fish. The full length of E. coioides Sec6 was 2655 bp including a 245 bp 5′ UTR, a 154 bp 3′ UTR, and a 2256 bp open reading frame (ORF) encoding 751 amino acids, with a molecular mass of 86.76 kDa and a theoretical pI of 5.57. Sec6 mRNA was detected in all the tissues examined, but the expression level is different in these tissues. Using fluorescence microscopy, Sec6 were distributed in both the nucleus and the cytoplasm. After SGIV infection, the expression of E. coioides Sec6 was significantly up-regulated in both trunk kidney and spleen response to Singapore grouper iridovirus (SGIV), an important pathogens of E. coioides. Sec6 could increase the SGIV-induced cytopathic effects (CPE), the expression of the SGIV genes VP19, LITAF, MCP, ICP18 and MCP, and the viral titers. Besides, E. coioides Sec6 significantly downregulated the promoter of NF-κB and AP-1, and inhibited the SGIV-induced apoptosis. The results demonstrated that E. coioides Sec6 might play important roles in SGIV infection.

EXOC4 Promotes Diffuse-Type Gastric Cancer Metastasis via Activating FAK Signal.

The EXOC4-FAK axis promoted DGC metastasis and could be a potential therapeutic target for patients with DGC.

Diversification of SEC15a and SEC15b isoforms of an exocyst subunit in seed plants is manifested in their specific roles in Arabidopsis sporophyte and male gametophyte.

The exocyst complex is an octameric evolutionarily conserved tethering complex engaged in the regulation of polarized secretion in eukaryotic cells. Here, we focus on the systematic comparison of two isoforms of the SEC15 exocyst subunit, SEC15a and SEC15b. We infer that SEC15 gene duplication and diversification occurred in the common ancestor of seed plants (Spermatophytes). In Arabidopsis, SEC15a represents the main SEC15 isoform in the male gametophyte, and localizes to the pollen tube tip at the plasma membrane. Although pollen tubes of sec15a mutants are impaired, sporophytes show no phenotypic deviations. Conversely, SEC15b is the dominant isoform in the sporophyte and localizes to the plasma membrane in root and leaf cells. Loss-of-function sec15b mutants exhibit retarded elongation of hypocotyls and root hairs, a loss of apical dominance, dwarfed plant stature and reduced seed coat mucilage formation. Surprisingly, the sec15b mutants also exhibit compromised pollen tube elongation in vitro, despite its very low expression in pollen, suggesting a non-redundant role for the SEC15b isoform there. In pollen tubes, SEC15b localizes to distinct cytoplasmic structures. Reciprocally to this, SEC15a also functions in the sporophyte, where it accumulates at plasmodesmata. Importantly, although overexpressed SEC15a could fully complement the sec15b phenotypic deviations in the sporophyte, the pollen-specific overexpression of SEC15b was unable to fully compensate for the loss of SEC15a function in pollen. We conclude that the SEC15a and SEC15b isoforms evolved in seed plants, with SEC15a functioning mostly in pollen and SEC15b functioning mostly in the sporophyte.

A novel nonsense variant in EXOC8 underlies a neurodevelopmental disorder

Human exocyst complex is an evolutionary conserved multimeric complex composed of proteins encoded by eight genes EXOC1-EXOC8. It is known that the exocyst complex plays a role in ciliogenesis, cytokinesis, cell migration, autophagy, and fusion of secretory vesicles. Recently, loss of function variants in EXOC7 and EXOC8 has been associated with abnormalities of cerebral cortical development leading to a neurodevelopmental phenotype. Neurodevelopmental disorders are a huge group of clinically and genetically heterogeneous disorders. In the present study, we recruited a large consanguineous family segregating a neurodevelopmental disorder in an autosomal recessive form. We performed clinical phenotyping by imaging the patient's brain followed by whole exome sequencing examining DNA from two affected individuals. The clinical phenotypes of the disease were suggestive of brain atrophy. Clinical examination revealed intellectual impairment with hypertonia and brisk reflexes. WES followed by Sanger sequencing revealed a novel homozygous nonsense mutation [EXOC8; NM_175876.5; c.1714G > T; p.(Glu572Ter)] in the DNA of affected individuals. Both parents of the patients were heterozygous for the identified mutation. All the pathogenicity prediction softwares predicted the identified variant as disease causing. This study reports a second protein-truncating variant in EXOC8. The findings confirm that loss of function variants in EXOC8 underlies a neurodevelopmental disorder. The identification of a protein-truncating variant in EXOC8 in the current study can be helpful in establishing genotype-phenotype correlations. Our results also provide new insights into genetic counseling and clinical management for the affected individuals.

Identification of Common Hub Genes in Human Dermal Fibroblasts Stimulated by Mechanical Stretch at Both the Early and Late Stages.

BackgroundMechanical stretch is vital for soft tissue regeneration and development and is utilized by plastic surgeons for tissue expansion. Identifying the common hub genes in human dermal fibroblasts (HDFs) stimulated by mechanical stretch at different stages will help elucidate the mechanisms involved and improve the efficiency of tissue expansion.MethodsA gene expression dataset (GSE58389) was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) in HDFs between cyclic mechanical stretching and static samples were identified at 5 and 24 h. Common DEGs overlapped in both the 5 h and 24 h groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed to determine the functions of the DEGs. Protein-protein interaction networks were constructed using the STRING database. The top 10 hub genes were selected using the plug-in Cytohubba within Cytoscape. The regulatory network of hub genes was predicted using NetworkAnalyst.ResultsA total of 669 and 249 DEGs were identified at the early (5 h) and late stages (24 h), respectively. Of these, 152 were present at both stages and were designated as common DEGs. The top enriched GO terms were “regulation of autophagy” at the early stage, and “sterol biosynthetic processes” at the late stage. The top KEGG terms were “pyrimidine metabolism” and “synaptic vesicle cycle” at the early and late stages, respectively. Seven common DEGs [DEAD-box helicase 17 (DDX17), exocyst complex component 7 (EXOC7), CASK interacting protein 1 (CASKIN1), ribonucleoprotein PTB-binding 1 (RAVER1), late cornified envelope 1D (LCE1D), LCE1C, and polycystin 1, transient receptor potential channel interacting (PKD1)] and three common DEGs [5′-3′ exoribonuclease 2 (XRN2), T-complex protein 1 (TCP1), and syntaxin 3 (STX3)] were shown to be upregulated and downregulated hub genes, respectively. The GO terms of the common hub genes were “skin development” and “mRNA processing.” After constructing the regulatory network, hsa-mir-92a-3p, hsa-mir-193b-3p, RNA polymerase II subunit A (POLR2A), SMAD family member 5 (SMAD5), and MYC-associated zinc finger protein (MAZ) were predicted as potential targets in both stages.ConclusionAt the early stage, there were clear changes in gene expression related to DNA and chromatin alterations; at late stages, gene expression associated with cholesterol metabolism was suppressed. Common DEGs related to skin development, transcriptional regulation, and cytoskeleton rearrangement identified in both stages were found to be potential targets for promoting HDF growth and alignment under mechanical stretch.

Rab33b-exocyst interaction mediates localized secretion for focal adhesion turnover and cell migration

SummaryRab proteins are well known regulators of intracellular trafficking; however, more and more studies point to their function also in other cellular processes, including cell migration. In this work, we have performed an siRNA screen to identify Rab proteins that influence cell migration. The screen revealed Rab33b as the strongest candidate that affected cell motility. Rab33b has been previously reported to localize at the Golgi apparatus to regulate Golgi-to-ER retrograde trafficking and Golgi homeostasis. We revealed that Rab33b also mediates post-Golgi transport to the plasma membrane. We further identified Exoc6, a subunit of the exocyst complex, as an interactor of Rab33b. Moreover, our data indicate that Rab33b regulates focal adhesion dynamics by modulating the delivery of cargo such as integrins to focal adhesions. Altogether, our results demonstrate a role for Rab33b in cell migration by regulating the delivery of integrins to focal adhesions through the interaction with Exoc6.

Clathrin-mediated trafficking of phospholipid flippases is required for local plasma membrane/cell wall damage repair in budding yeast

Plasma membrane damage and repair frequently happen in cells. A critical process underlying plasma membrane repair is to redirect repair factors, such as protein kinase C and the exocyst complex, from the polarized site to the damage site. However, the mechanism underlying the repair factor delivery to the damage site remains unknown. Here, we demonstrate that clathrin-mediated trafficking of repair factors is involved in plasma membrane/cell wall repair in budding yeast. Using laser-induced plasma membrane/cell wall damage assay, we identified phospholipid flippases, Lem3-Dnf1/Dnf2 and Cdc50-Drs2, as essential clathrin cargos for plasma membrane/cell wall repair. We found that flippase impairment significantly compromised the recruitment of exocyst Exo70 to the damage site. In contrast, the recruitment of protein kinase C (Pkc1) was only mildly compromised. Taken together, clathrin-mediated trafficking of the phospholipid flippases is critical for the recruitment of exocyst to the damage site. Mechanisms to redirect exocyst via the clathrin and flippase-mediated pathways may be a general feature of effective plasma membrane repair in polarized cells.

Identification of Alternative Splicing Events Associated with Paratuberculosis in Dairy Cattle Using Multi-Tissue RNA Sequencing Data.

Paratuberculosis is a major endemic disease caused by Mycobacterium avium subspecies paratuberculosis (MAP) infection and leads to huge economic loss in the dairy sector worldwide. Alternative splicing (AS) events, playing indispensable regulatory roles in many protein functions and biological pathways, are shown to be associated with complex traits and diseases. In this study, by integrating the RNA sequencing (RNA-seq) data of 24 samples from three tissues (peripheral blood, jejunum and salivary gland) of Holstein cows, we obtained 2,706,541,696 uniquely mapped reads in total that represented 12,870 expressed genes, and detected 4285 differentially expressed genes (DEGs) between MAP-infected and healthy cows (p < 0.05). Of them, 92 differentially expressed splicing factors (DESFs) were included. Further, 119, 150 and 68 differential alternative splicing (DAS) events between MAP-infected and healthy cows were identified in peripheral blood, jejunum and salivary glands, respectively. Of note, six DAS events were highly and significantly correlated with the DESFs (R2 > 0.9; p < 0.01), and their corresponding genes (COPI coat complex subunit gamma 2 gene (COPG2), kinesin family member 2C gene (KIF2C), exocyst complex component 7 (EXOC7), Rab9 effector protein with kelch motifs gene (RABEPK), deoxyribonuclease 1 gene (DNASE1) and early endosome antigen 1 gene (EEA1)) were significantly enriched in immune response such as vesicle-mediated transport, regulation of acute inflammatory response and tuberculosis through gene ontology (GO) and KEGG analysis. KS test showed that the DAS events in the EXOC7 and KIF2C genes indeed displayed differences between MAP-infected cows and healthy cows. The DAS in EXOC7 might produce a new protein sequence with lack of 23 amino acids, and the DAS in KIF2C induced a stop codon of premature occurrence and resulted in a lack of functional domain. In summary, this study identified the DAS events and corresponding genes related to MAP-infection base on the RNA-seq data from multiple tissues of Holstein cows, providing novel insights into the regulatory mechanisms underpinning paratuberculosis in dairy cattle.

EXOC6 (Exocyst Complex Component 6) Is Associated with the Risk of Type 2 Diabetes and Pancreatic β-Cell Dysfunction.

Simple SummaryEXOC6 and EXOC6B (EXOC6/6B) are components of the exocyst complex involved in the secretory granule docking. The exact role of EXOC6/6B in pancreatic β-cell function and risk of type 2 diabetes (T2D) required further investigations. Herein, we showed that EXOC6/6B is associated with the risk of T2D and is essential to maintain the function of pancreatic β-cell. Our study suggests that EXOC6/6B are crucial regulators for insulin secretion and for exocytosis machinery in β-cells. EXOC6 and EXOC6B (EXOC6/6B) components of the exocyst complex are involved in the secretory granule docking. Recently, EXOC6/6B were anticipated as a molecular link between dysfunctional pancreatic islets and ciliated lung epithelium, making diabetic patients more prone to severe SARS-CoV-2 complications. However, the exact role of EXOC6/6B in pancreatic β-cell function and risk of T2D is not fully understood. Herein, microarray and RNA-sequencing (RNA-seq) expression data demonstrated the expression of EXOC6/6B in human pancreatic islets. Expression of EXOC6/6B was not affected by diabetes status. Exploration of the using the translational human pancreatic islet genotype tissue-expression resource portal (TIGER) revealed three genetic variants (rs947591, rs2488071 and rs2488073) in the EXOC6 gene that were associated (p < 2.5 × 10−20) with the risk of T2D. Exoc6/6b silencing in rat pancreatic β-cells (INS1-832/13) impaired insulin secretion, insulin content, exocytosis machinery and glucose uptake without cytotoxic effect. A significant decrease in the expression Ins1, Ins1, Pdx1, Glut2 and Vamp2 was observed in Exoc6/6b-silenced cells at the mRNA and protein levels. However, NeuroD1, Gck and InsR were not influenced compared to the negative control. In conclusion, our data propose that EXOC6/6B are crucial regulators for insulin secretion and exocytosis machinery in β-cells. This study identified several genetic variants in EXOC6 associated with the risk of T2D. Therefore, EXOC6/6B could provide a new potential target for therapy development or early biomarkers for T2D.