DOCK1 regulates the malignant biological behavior of endometrial cancer through c-Raf/ERK pathway.

BACKGROUND: The effect of DOCK1 gene on the biological behavior of endometrial carcinoma cells and its related pathway has not been reported. METHODS: The immunohistochemical method and western blot were utilized to analyze DOCK1 protein expression in endometrial tissues and cells, respectively. CCK-8, BrdU, transwell and flow cytometry were performed to analyze the effect of DOCK1 expression changes on the viability, proliferation, invasion, migration and apoptosis of endometrial cancer cells, respectively. The effects of DOCK1 gene on Bcl-2, MMP9, Ezrin, E-cadherin and c-RAF/ERK1/2 signaling pathway were evaluated by western blot. The xenograft models were constructed to analyze the effect of DOCK1 in vivo. RESULTS: DOCK1 expression was increased in endometrial cancer tissues and cells compared with those in normal adjacent tissues and cells. DOCK1 knockout could inhibit the malignant biological behavior of endometrial cancer cells, while DOCK1 overexpression played the opposite effect. The expression of E-cadherin was upregulated and those of MMP9, Ezrin, Bcl-2, p-c-RAF (S338) and p-ERK1/2 (T202/Y204) were downregulated after DOCK1 knockout, while DOCK1 overexpression played the opposite effect. Additionally, Raf inhibitor LY3009120 reversed the function of DOCK1 on malignant biological behavior. In vivo experiment results showed that the growth and weight of transplanted tumors in nude mice were inhibited after DOCK1 knockout. The changes of E-cadherin, MMP9, Ezrin and Bcl-2 expressions in the transplanted tumors were consistent with those in vitro. CONCLUSION: DOCK1 could enhance the malignant biological behavior of endometrial cancer cells, which might be through c-RAF/ERK1/2 signaling pathways in vitro and in vivo.

High DOCK1 expression identifies a distinct prognostic subgroup of pediatric acute myeloid leukemia: Results of the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 trial.

BACKGROUND: The molecular pathogenesis of acute myeloid leukemia (AML) was dramatically clarified over the latest two decades. Several important molecular markers were discovered in patients with AML that have helped to improve the risk stratification. However, developing new treatment strategies for relapsed/refractory acute myeloid leukemia (AML) is crucial due to its poor prognosis. PROCEDURE: To overcome this difficulty, we performed an assay for transposase-accessible chromatin with sequencing (ATAC-seq) in 10 AML patients with various gene alterations. ATAC-seq is based on direct in vitro sequencing adaptor transposition into native chromatin, and is a rapid and sensitive method for integrative epigenomic analysis. ATAC-seq analysis revealed increased accessibility of the DOCK1 gene in patients with AML harboring poor prognostic factors. Following the ATAC-seq results, quantitative reverse transcription polymerase chain reaction was used to measure DOCK1 gene expression levels in 369 pediatric patients with de novo AML. RESULTS: High DOCK1 expression was detected in 132 (37%) patients. The overall survival (OS) and event-free survival (EFS) among patients with high DOCK1 expression were significantly worse than those patients with low DOCK1 expression (3-year EFS: 34% vs. 60%, p < .001 and 3-year OS: 60% vs. 80%, p < .001). To investigate the significance of high DOCK1 gene expression, we transduced DOCK1 into MOLM14 cells, and revealed that cytarabine in combination with DOCK1 inhibitor reduced the viability of these leukemic cells. CONCLUSIONS: Our results indicate that a DOCK1 inhibitor might reinforce the effects of cytarabine and other anti-cancer agents in patients with AML with high DOCK1 expression.

Genetic change investigation in DOCK1 gene in an Iranian family with sign and symptoms of temporomandibular joint disorder (TMD).

OBJECTIVES: Temporomandibular joint disorder (TMD) is a complex condition with pain and dysfunction in the temporomandibular joint and related muscles. Scientific evidence indicates both genetic and environmental factors play a crucial role in TMD. In this study, we aimed to discover the genetic changes in individuals from 4 generations of an Iranian family with signs and symptoms of TMD and malocclusion Class III. MATERIALS AND METHODS: Whole Exome Sequencing (WES) was performed in 4 patients (IV-8, IV-9, V-4, and V-6) with TMD according to (DC/TMD), along with skeletal Class III malocclusion. Then, PCR sequencing was performed on 23 family members to confirm the WES. RESULTS: In the present study, WES results analysis detected 6 heterozygous non-synonymous Single Nucleotide Variants (SNVs) in 5 genes, including CRLF3, DNAH17, DOCK1, SEPT9, and VWDE. A heterozygous variant, c.2012T > A (p.F671Y), in Exon 20 of the DOCK1 (NM_001290223.2) gene was identified. Then, this variant was investigated in 19 other members of the same family. PCR-Sequencing results showed that 7/19 had heterozygous TA genotype, all of whom were accompanied by malocclusion and TMD symptoms and 12/19 individuals had homozygous TT genotype, 9 of whom had no temporomandibular joint problems or malocclusion. The remaining 3 showed mild TMD clinical symptoms. The 5 other non-synonymous SNVs of CRLF3, DNAH17, SEPT9, and VWDE were not considered plausible candidates for TMD. CONCLUSIONS: The present study identified a heterozygous nonsynonymous c.2012T > A (p.F671Y) variant of the DOCK1 gene is significantly associated with skeletal class III malocclusion, TMD, and its severity in affected individuals in the Iranian pedigree. CLINICAL RELEVANCE: The role of genetic factors in the development of TMD has been described. The present study identified a nonsynonymous variant of the DOCK1 gene as a candidate for TMD and skeletal class III malocclusion in affected individuals in the Iranian pedigree.

Elmo1 function, linked to Rac1 activity, regulates peripheral neuronal numbers and myelination in zebrafish.

Peripheral nervous system development involves a tight coordination of neuronal birth and death and a substantial remodelling of the myelinating glia cytoskeleton to achieve myelin wrapping of its projecting axons. However, how these processes are coordinated through time is still not understood. We have identified engulfment and cell motility 1, Elmo1, as a novel component that regulates (i) neuronal numbers within the Posterior Lateral Line ganglion and (ii) radial sorting of axons by Schwann cells (SC) and myelination in the PLL system in zebrafish. Our results show that neuronal and myelination defects observed in elmo1 mutant are rescued through small GTPase Rac1 activation. Inhibiting macrophage development leads to a decrease in neuronal numbers, while peripheral myelination is intact. However, elmo1 mutants do not show defective macrophage activity, suggesting a role for Elmo1 in PLLg neuronal development and SC myelination independent of macrophages. Forcing early Elmo1 and Rac1 expression specifically within SCs rescues elmo1-/- myelination defects, highlighting an autonomous role for Elmo1 and Rac1 in radial sorting of axons by SCs and myelination. This uncovers a previously unknown function of Elmo1 that regulates fundamental aspects of PNS development.

Circ_DOCK1 regulates USP11 through miR-132-3p to control colorectal cancer progression.

BACKGROUND: Circular RNAs (circRNAs) take part in colorectal cancer malignancies. CircRNA dedicator of cytokinesis 1 (circ_DOCK1) is involved in colorectal cancer progression, but the mechanism underlying this circRNA that takes part in colorectal cancer development remains largely undetermined. METHODS: Tumor and normal para-cancerous tissues were collected from 42 colorectal cancer patients. Human colorectal cancer cell lines (HCT116 and SW480) were used for the experiments in vitro. Circ_DOCK1, microRNA (miR)-132-3p, and ubiquitin-specific protease 11 (USP11) levels were measured through quantitative real-time polymerase chain reaction and Western blotting. Cell growth, metastasis, and apoptosis were investigated via colony formation, 5-ethynyl-2'-deoxyuridine (EdU) staining, MTT, flow cytometry, Western blotting, and transwell analyses. The target association was evaluated via dual-luciferase reporter analysis, RNA pull-down, and immunoprecipitation (RIP). Xenograft assay was performed using HCT116 cells. USP11 and Ki67 levels in tumor tissues were detected via immunohistochemistry. RESULTS: Circ_DOCK1 expression was enhanced in colorectal cancer tissues and cells. Silencing circ_DOCK1 repressed cell growth, migration, and invasion, and facilitated apoptosis. Circ_DOCK1 sponged miR-132-3p, and miR-132-3p silence mitigated the effect of circ_DOCK1 interference on cell growth, metastasis, and apoptosis. MiR-132-3p targeted USP11, and circ_DOCK1 could regulate USP11 level by miR-132-3p. MiR-132-3p suppressed cell growth, metastasis, and apoptosis, and USP11 attenuated these effects. Knockdown of circ_DOCK1 decreased colorectal cancer cell xenograft tumor growth. CONCLUSION: Circ_DOCK1 interference suppressed cell growth and metastasis, and increased apoptosis of colorectal cancer via decreasing USP11 by increasing miR-132-3p.

Identifying and treating ROBO1-ve /DOCK1+ve prostate cancer: An aggressive cancer subtype prevalent in African American patients.

BACKGROUND: There is a need to develop novel therapies which could be beneficial to patients with prostate cancer (CaP) including those who are predisposed to poor outcome, such as African-Americans. This study investigates the role of ROBO1-pathway in predicting outcome and race-based disparity in patients with CaP. METHODS AND RESULTS: Aided by RNA sequencing-based DECIPHER-testing and immunohistochemical (IHC) analysis of tumors we show that ROBO1 is lost during the progressive stages of CaP, a prevalent feature in African-Americans. We show that the loss of ROBO1 predicts high-risk of recurrence, metastasis and poor outcome of androgen-deprivation therapy in radical prostatectomy-treated patients. These data identified an aggressive ROBO1deficient /DOCK1+ve sub-class of CaP. Combined genetic and IHC data showed that ROBO1 loss is accompanied by DOCK1/Rac1 elevation in grade-III/IV primary-tumors and Mets. We observed that the hypermethylation of ROBO1-promoter contributes to loss of expression that is highly prevalent in African-Americans. Because of limitations in restoring ROBO1 function, we asked if targeting the DOCK1 could be an ideal strategy to inhibit progression or treat ROBO1deficient metastatic-CaP. We tested the pharmacological efficacy of CPYPP, a selective inhibitor of DOCK1 under in vitro and in vivo conditions. Using ROBO1-ve and ROBO1+ve CaP models, we determined the median effective concentration of CPYPP for growth. DOCK1-inhibitor treatment significantly decreased the (a) Rac1-GTP/ß-catenin activity, (b) transmigration of ROBO1deficient cells across endothelial lining, and (c) metastatic spread of ROBO1deficient cells through the vasculature of transgenicfl Zebrafish model. CONCLUSION: We suggest that ROBO1 status forms as predictive biomarker of outcome in high-risk populations such as African-Americans and DOCK1-targeting therapy has a clinical potential for treating metastatic-CaP.

DOCK1 inhibition suppresses cancer cell invasion and macropinocytosis induced by self-activating Rac1P29S mutation.

Rac1 is a member of the Rho family of small GTPases that regulates cytoskeletal reorganization, membrane polarization, cell migration and proliferation. Recently, a self-activating mutation of Rac1, Rac1P29S, has been identified as a recurrent somatic mutation frequently found in sun-exposed melanomas, which possesses increased inherent GDP/GTP exchange activity and cell transforming ability. However, the role of cellular Rac1-interacting proteins in the transforming potential of Rac1P29S remains unclear. We found that the catalytic domain of DOCK1, a Rac-specific guanine nucleotide exchange factor (GEF) implicated in malignancy of a variety of cancers, can greatly accelerate the GDP/GTP exchange of Rac1P29S. Enforced expression of Rac1P29S induced matrix invasion and macropinocytosis in wild-type (WT) mouse embryonic fibroblasts (MEFs), but not in DOCK1-deficient MEFs. Consistently, a selective inhibitor of DOCK1 that blocks its GEF function suppressed the invasion and macropinocytosis in WT MEFs expressing Rac1P29S. Human melanoma IGR-1 and breast cancer MDA-MB-157 cells harbor Rac1P29S mutation and express DOCK1 endogenously. Genetic inactivation and pharmacological inhibition of DOCK1 suppressed their invasion and macropinocytosis. Taken together, these results indicate that DOCK1 is a critical regulator of the malignant phenotypes induced by Rac1P29S, and suggest that targeting DOCK1 might be an effective approach to treat cancers associated with Rac1P29S mutation.

The Rac1 regulator ELMO controls basal body migration and docking in multiciliated cells through interaction with Ezrin.

Cilia are microtubule-based organelles that are present on most cells and are required for normal tissue development and function. Defective cilia cause complex syndromes with multiple organ manifestations termed ciliopathies. A crucial step during ciliogenesis in multiciliated cells (MCCs) is the association of future basal bodies with the apical plasma membrane, followed by their correct spacing and planar orientation. Here, we report a novel role for ELMO-DOCK1, which is a bipartite guanine nucleotide exchange factor complex for the small GTPase Rac1, and for the membrane-cytoskeletal linker Ezrin, in regulating centriole/basal body migration, docking and spacing. Downregulation of each component results in ciliopathy-related phenotypes in zebrafish and disrupted ciliogenesis in Xenopus epidermal MCCs. Subcellular analysis revealed a striking impairment of basal body docking and spacing, which is likely to account for the observed phenotypes. These results are substantiated by showing a genetic interaction between elmo1 and ezrin b. Finally, we provide biochemical evidence that the ELMO-DOCK1-Rac1 complex influences Ezrin phosphorylation and thereby probably serves as an important molecular switch. Collectively, we demonstrate that the ELMO-Ezrin complex orchestrates ciliary basal body migration, docking and positioning in vivo.

Dock1 promotes the mesenchymal transition of glioma and is modulated by MiR-31.

AIMS: This research aimed to examine the relationship between Dock1 and miR-31 and to determine the effect of miR-31 on the mesenchymal transition and invasiveness of glioma. METHODS: Real-time PCR was used to measure the expression of miR-31 and other RNAs. The transfection was used to manipulate the expression levels of Dock1 and miR-31 in cancer cells. Western blot was used to detect the expression of Dock1 and other related proteins. Wound healing, Matrigel invasion and chemotaxis assays were performed to detect the invasion and migration of glioma cell lines. The actual binding site of miR-31 to the 3'-untranslated region of Dock1 was confirmed through luciferase assay and RNA immunoprecipitation. Methylation-specific PCR was performed to detect the methylation level of miR-31 in both glioma cell lines and tissues. RESULTS: Dock1 can promote the IL8-induced chemotaxis and mesenchymal transition of glioma cells through the NF-κB/Snail signalling pathway. The protein levels of Dock1 in glioma cell lines and clinical specimens were negatively correlated with miR-31 expression, and Dock1 was directly targeted by miR-31. Animal experiments showed that Dock1 downregulation and miR-31 overexpression reduced glioma cell invasion. Investigation of the underlying molecular mechanism revealed that miR-31 downregulation was attributable to the hypermethylation of the promoter region of miR-31 in glioma cells. CONCLUSION: Dock1 modulation by miR-31 plays an important function in glioma invasion both in vitro and in vivo. This study provides new insights into the invasion of glioma cells and might therefore contribute to the development of new antiglioma strategies.

ClipR-59 interacts with Elmo2 and modulates myoblast fusion.

Recent studies using ClipR-59 knock-out mice implicated this protein in the regulation of muscle function. In this report, we have examined the role of ClipR-59 in muscle differentiation and found that ClipR-59 knockdown in C2C12 cells suppressed myoblast fusion. To elucidate the molecular mechanism whereby ClipR-59 regulates myoblast fusion, we carried out a yeast two-hybrid screen using ClipR-59 as the bait and identified Elmo2, a member of the Engulfment and cell motility protein family, as a novel ClipR-59-associated protein. We showed that the interaction between ClipR-59 and Elmo2 was mediated by the atypical PH domain of Elmo2 and the Glu-Pro-rich domain of ClipR-59 and regulated by Rho-GTPase. We have examined the impact of ClipR-59 on Elmo2 downstream signaling and found that interaction of ClipR-59 with Elmo2 enhanced Rac1 activation. Collectively, our studies demonstrate that formation of an Elmo2·ClipR-59 complex plays an important role in myoblast fusion.

Identification of a novel protein interaction between Elmo1 and Cdc27.

Elmo has no intrinsic catalytic activity but coordinate multiple cellular processes via their interactions with other proteins. Studies thus have been focused on identifying Elmo binding partners, but the number of characterized Elmo-interacting proteins remains limited. Here, we report Cdc27 as a novel Elmo1-interacting protein. In yeast and mammalian cells, Cdc27 specifically interacted with the C-terminal region of Elmo1 essential for Dock1 association and function. The interaction of Elmo1 with Dock1 abrogated binding between Elmo1 and Cdc27, but the Dock1-Elmo1 interaction was unaffected by Cdc27. Similarly, cellular phagocytotic functions mediated by the Elmo1-Dock1-Rac module were unaffected by Cdc27 levels. In summary, a novel binding partner, Cdc27, was identified for Elmo1 and they appear to be independent of Elmo-Dock1-Rac-mediated processes.

Molecular and clinical analyses with neuropsychological assessment of a case of del(10)(q26.2qter) without intellectual disability: Genomic and transcriptomic combined approach and review of the literature.

Terminal deletion of the long arm of the chromosome 10 is a rare but well known abnormality, with a large phenotypic variability. Very few data are available about subtelomeric deletion 10q26 patients without intellectual disability. Herein, we report the case of a young adult with a classical 10q26.2qter deletion. She exhibited mainly short stature at birth and in childhood/adulthood without intellectual disability or behavioral problems. After clinical and neuropsychological assessments, we performed genomic array and transcriptomic analysis and compared our results to the data available in the literature. The patient presents a 6.525 Mb heterozygous 10q26.2qter deletion, encompassed 48 genes. Among those genes, DOCK1, C10orf90, and CALY previously described as potential candidate genes for intellectual disability, were partially or completed deleted. Interestingly, they were not deregulated as demonstrated by transcriptomic analysis. This allowed us to suggest that the mechanism involved in the deletion 10qter phenotype is much more complex that only the haploinsufficiency of DOCK1 or other genes encompassed in the deletion. Genomic and transcriptomic combined approach has to be considered to understand this pathogenesis. © 2016 Wiley Periodicals, Inc.

DOCK1 deficiency drives placental trophoblast cell dysfunction by influencing inflammation and oxidative stress, hallmarks of preeclampsia.

Preeclampsia (PE) is a globally prevalent obstetric disorder, pathologically characterized by abnormal placental development. Dysfunctions of angiogenesis, vasculogenesis and spiral artery remodeling are demonstrated to be involved in PE pathogenesis; however, the underlying mechanisms remain largely unknown. Here, we investigated the role of the dedicator of cytokinesis 1 (DOCK1), crucial molecule in various cellular processes, in PE progression using HTR-8 cells derived from first-trimester placental extravillous trophoblasts. Our analysis revealed an aberrant DOCK1 expression in the placental villi of PE patients and its impact on essential cellular functions for vascular network formation. A deficiency of DOCK1 in HTR-8 cells impaired the vascular network formation, exacerbated the expression of anti-angiogenic factor ENG, and reduced VEGF levels. Moreover, DOCK1 knockout amplified apoptosis, as indicated by an altered BCL2: BAX ratio and enhanced levels of cleaved PARP. DOCK1 depletion also boosted NF-κB activation and pro-inflammatory cytokine production (IL-6 and TNF-α). Furthermore, the mice treated with DOCK1 inhibitor, TBOPP, exhibited PE-like symptoms. These findings highlight the multifaceted roles of DOCK1 in the pathophysiology of PE, demonstrating that its deficiency can lead to placental dysfunction by orchestrating inflammatory responses and oxidative stress. These insights emphasize the pathogenic role of DOCK1 in PE development and suggest potential treatment strategies that require further exploration. In the graphical abstract, a split image of placental villi contrasts the effects of normal and reduced DOCK1 expression on preeclampsia. The left side illustrates adequate DOCK1 levels supporting healthy trophoblast function and effective spiral artery remodeling. The right side highlights the consequences of DOCK1 deficiency, leading to trophoblast dysfunction and impaired spiral artery remodeling, accompanied by angiogenic imbalance, increased inflammation, oxidative stress, and apoptosis, contributing to placental dysfunction and the development of preeclampsia.

TBOPP, a DOCK1 Inhibitor, Potentiates Cisplatin Efficacy in Breast Cancer by Regulating Twist-mediated EMT.

BACKGROUND: DOCK1 has been reported to be involved in tumor progression and resistance. 1-(2-(30-(trifluoromethyl)-[1,10-biphenyl]-4-yl)-2-oxoethyl)-5-pyrrolidinylsulfonyl2(1H)- pyridone (TBOPP) is a selective DOCK1 inhibitor; however, the role and molecular mechanisms of DOCK1 and its inhibition in breast cancer (BC) resistance remain poorly understood. OBJECTIVE: This study aims toinvestigate the underlying mechanisms of DOCK1 in BC resistance. METHODS: DOCK1 or Twist siRNA and Twist plasmid were used to explore the function of DOCK1 in vitro experiments. A mouse xenograft model was used for in vivo experiments. RESULTS: In the present study, we demonstrated that DOCK1 siRNA promoted cisplatin sensitivity in BC cells. Moreover, TBOPP also enhances the therapeutic effect of cisplatin both in vitro and in vivo. Mechanistically, DOCK1 siRNA inhibited EMT. Twist 1 is one of the EMT-inducing transcription factors and is known to induce EMT. To further reveal the effect of DOCK in BC cells, we co-transfected with DOCK1 and Twist1 siRNA to BC cells and found that co-transfection with DOCK1 and Twist siRNA could not further enhance the cisplatin sensitivity of BC cells. Moreover, DOCK1 siRNA failed to reverse the effect of Twist 1 up-regulation. CONCLUSION: Taken together, these results demonstrate that DOCK1 may function as a potential therapeutic target in BC and that combining cisplatin with TBOPP may provide a promising therapeutic strategy for cisplatin-resistant BC patients.

Actin Up: An Overview of the Rac GEF Dock1/Dock180 and Its Role in Cytoskeleton Rearrangement.

Dock1, originally Dock180, was the first identified member of the Dock family of GTPase Exchange Factors. Early biochemical and genetic studies of Dock180 elucidated the functions and regulation of Dock180 and informed our understanding of all Dock family members. Dock180 activates Rac to stimulate actin polymerization in response to signals initiated by a variety of receptors. Dock180 dependent Rac activation is essential for processes such as apoptotic cell engulfment, myoblast fusion, and cell migration during development and homeostasis. Inappropriate Dock180 activity has been implicated in cancer invasion and metastasis and in the uptake of bacterial pathogens. Here, we give an overview of the history and current understanding of the activity, regulation, and impacts of Dock180.

Genome-wide CRISPR screen identifies synthetic lethality between DOCK1 inhibition and metformin in liver cancer.

Metformin is currently a strong candidate anti-tumor agent in multiple cancers. However, its anti-tumor effectiveness varies among different cancers or subpopulations, potentially due to tumor heterogeneity. It thus remains unclear which hepatocellular carcinoma (HCC) patient subpopulation(s) can benefit from metformin treatment. Here, through a genome-wide CRISPR-Cas9-based knockout screen, we find that DOCK1 levels determine the anti-tumor effects of metformin and that DOCK1 is a synthetic lethal target of metformin in HCC. Mechanistically, metformin promotes DOCK1 phosphorylation, which activates RAC1 to facilitate cell survival, leading to metformin resistance. The DOCK1-selective inhibitor, TBOPP, potentiates anti-tumor activity by metformin in vitro in liver cancer cell lines and patient-derived HCC organoids, and in vivo in xenografted liver cancer cells and immunocompetent mouse liver cancer models. Notably, metformin improves overall survival of HCC patients with low DOCK1 levels but not among patients with high DOCK1 expression. This study shows that metformin effectiveness depends on DOCK1 levels and that combining metformin with DOCK1 inhibition may provide a promising personalized therapeutic strategy for metformin-resistant HCC patients.

TLR4 activation induces inflammatory vascular permeability via Dock1 targeting and NOX4 upregulation.

The loss of vascular integrity is a cardinal feature of acute inflammatory responses evoked by activation of the TLR4 inflammatory cascade. Utilizing in vitro and in vivo models of inflammatory lung injury, we explored TLR4-mediated dysregulated signaling that results in the loss of endothelial cell (EC) barrier integrity and vascular permeability, focusing on Dock1 and Elmo1 complexes that are intimately involved in regulation of Rac1 GTPase activity, a well recognized modulator of vascular integrity. Marked reductions in Dock1 and Elmo1 expression was observed in lung tissues (porcine, rat, mouse) exposed to TLR4 ligand-mediated acute inflammatory lung injury (LPS, eNAMPT) in combination with injurious mechanical ventilation. Lung tissue levels of Dock1 and Elmo1 were preserved in animals receiving an eNAMPT-neutralizing mAb in conjunction with highly significant decreases in alveolar edema and lung injury severity, consistent with Dock1/Elmo1 as pathologic TLR4 targets directly involved in inflammation-mediated loss of vascular barrier integrity. In vitro studies determined that pharmacologic inhibition of Dock1-mediated activation of Rac1 (TBOPP) significantly exacerbated TLR4 agonist-induced EC barrier dysfunction (LPS, eNAMPT) and attenuated increases in EC barrier integrity elicited by barrier-enhancing ligands of the S1P1 receptor (sphingosine-1-phosphate, Tysiponate). The EC barrier-disrupting influence of Dock1 inhibition on S1PR1 barrier regulation occurred in concert with: 1) suppressed formation of EC barrier-enhancing lamellipodia, 2) altered nmMLCK-mediated MLC2 phosphorylation, and 3) upregulation of NOX4 expression and increased ROS. These studies indicate that Dock1 is essential for maintaining EC junctional integrity and is a critical target in TLR4-mediated inflammatory lung injury.

Biallelic ELMO3 mutations and loss of function for DOCK-mediated RAC1 activation result in intellectual disability.

The engulfment and cell motility 3 (ELMO3) protein belongs to the ELMO-family of proteins. ELMO proteins form a tight complex with the DOCK1-5 guanine nucleotide exchange factors that regulate RAC1 spatiotemporal activation and signalling. DOCK proteins and RAC1 are known to have fundamental roles in central nervous system development. Here, we searched for homozygous or compound heterozygous mutations in the ELMO3 gene in 390 whole exomes sequenced in trio in individuals with neurodevelopmental disorders compatible with a genetic origin. We found a compound heterozygous mutation in ELMO3 (c.1153A>T, p.Ser385Cys and c.1009 G > A, p.Val337Ile) in a 5 year old male child with autism spectrum disorder (ASD) and developmental delay. These mutations did not interfere with the formation of an ELMO3/DOCK1 complex, but markedly impaired the ability of the complex to promote RAC1-GTP-loading. Consequently, cells expressing DOCK1 and either of the ELMO3 mutants displayed impaired migration and invasion. Collectively, our results suggest that biallelic loss-of-function mutations in ELMO3 may cause a developmental delay and provide new insight into the role of ELMO3 in neurodevelopmental as well as the pathological consequences of ELMO3 mutations.

Further refining the critical region of 10q26 microdeletion syndrome: A possible involvement of INSYN2 and NPS in the cognitive phenotype.

BACKGROUND: The 10q26 subtelomeric microdeletion syndrome is a rare and clinically heterogeneous disorder. The precise relationships between the causative genes and the phenotype are unclear. CASE PRESENTATION: We report two new cases of 860 kb deletion of 10q26.2 identified by array CGH in a fetus with intrauterine growth retardation and his mother. The deleted region encompassed only four coding genes, DOCK1, INSYN2, NPS and FOX12. The proband had dysmorphic facies characterized by a high forehead, malformed ears, a prominent nose, and retrognathia. He had bilateral club feet, clinodactily and mild psychomotor retardation. His mother had a short stature, microcephaly, a long face with a high forehead and bitemporal narrowing, arched and sparse eyebrows, strabismus, prominent nose and chin, a thin upper lip and large protruding ears, and mild intellectual disability. CONCLUSIONS: This study presents the smallest 10q26.2 deletion so far identified, which further refines the minimal critical region associated with the 10q26 microdeletion syndrome. It focuses on three genes potentially responsible for the phenotype: DOCK1, which is the major candidate gene, and INSYN2 and NPS, which could be involved in cognitive functions.

The regulation of DOCK family proteins on T and B cells.

The dedicator of cytokinesis (DOCK) family proteins consist of 11 members, each of which contains 2 domains, DOCK homology region (DHR)-1 and DHR-2, and as guanine nucleotide exchange factors, they mediate activation of small GTPases. Both DOCK2 and DOCK8 deficiencies in humans can cause severe combined immunodeficiency, but they have different characteristics. DOCK8 defect mainly causes high IgE, allergic disease, refractory skin virus infection, and increased incidence of malignant tumor, whereas DOCK2 defect mainly causes early-onset, invasive infection with less atopy and increased IgE. However, the underlying molecular mechanisms causing the disease remain unclear. This paper discusses the role of DOCK family proteins in regulating B and T cells, including development, survival, migration, activation, immune tolerance, and immune functions. Moreover, related signal pathways or molecule mechanisms are also described in this review. A greater understanding of DOCK family proteins and their regulation of lymphocyte functions may facilitate the development of new therapeutics for immunodeficient patients and improve their prognosis.