Downregulation of Dock1 and Elmo1 suppresses the migration and invasion of triple-negative breast cancer epithelial cells through the RhoA/Rac1 pathway

BmElmo is a factor for inhibiting Autographa Californica nucleopolyhedrovirus infection in silkworm, Bombyx mori

Autographa californica nucleopolyhedrovirus (AcMNPV) is a DNA virus with multiple host domains, and elucidating the mechanisms of its interactions with silkworms is crucial for its widespread use. Identifying key antiviral genes and analyzing their functions is an urgent task currently. Therefore, the identification and study of host genes associated with AcMNPV invasion is of great significance in solving the issue. Engulfment and cell motility (Elmo) is an identified viral infection-associated gene primarily involved in the regulation of cell motility and essential for phagocytosis and immune responses. However, its function in the silkworm response to viruses is still unclear. In this study, the sequence of BmElmo was analyzed first. It has a CED-12 functional domain that has been highly conserved among different species. Its expression peaks during the silkworm pupal stage, followed by the moth stage. Among various tissues, BmElmo expression is highest in the gonads, followed by the silk glands. BmElmo exhibits differential expression between resistant and susceptible strains. AcMNPV replication increased significantly after BmElmo knockdown in BmN cells, and decreased significantly after BmElmo overexpression. Furthermore, the expression of Janus kinase (JNK) pathway-related genes downstream of BmElmo showed altered expression that correlated positively with the expression of BmElmo. Hence, BmElmo may inhibit AcMNPV replication in the silkworm by activating the JNK pathway. The results of this study bridge the gap in understanding the role of Elmo genes in insect immunity and provides a theoretical reference for studying the interaction between insects and baculoviruses.

DOCK1/ELMO1/Rac1 Signaling is Essential for Vitreous-Induced Migration and Contraction of ARPE19 Cells

Purpose: To test the effects of dedicator of cytokinesis protein 1 (DOCK1) with its binding partner engulfment and cell motility protein 1 (ELMO1)-Rac1 axis on the vitreous-induced biological functions of retinal pigment epithelial (RPE) cells. Methods: Rac1 activity in RPE cells after vitreous stimulation was detected via a pull-down assay. The related protein expression levels were examined via western blot analysis. DOCK1 and ELMO1 knockdown cells were generated via CRISPR-Cas9 technology. Cytoskeletal reorganization was detected by immunofluorescent localization of F-actin. Cell proliferation, migration, invasion, and contraction ability were measured via the CCK8 assay, wound healing assay, transwell invasion assay, and collagen contraction assay. Results: Rac1 activity was significantly elevated in ARPE-19 cells stimulated with vitreous fluid for 30 min to 3 h. Depletion of either DOCK1 or ELMO1 with CRISPR/Cas9 attenuated vitreous-stimulated Rac1 activity, thus reversing the vitreous-induced cytoskeletal rearrangements. The functional cell biology results revealed that deficiencies of DOCK1 and ELMO1 significantly impeded the migration, invasion, and contraction abilities of vitreous-stimulated human RPE cells. Conclusion: This study demonstrated that the DOCK1/ELMO1-Rac1 axis plays an essential role in the pathogenesis of proliferative vitreoretinopathy (PVR), thus suggesting that interruption of this axis has potential for PVR therapy.

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 re-sistance.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.

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.

Overexpression of Dock180 and Elmo1 in Melanoma is Associated with Cell Survival and Migration

BACKGROUND

Melanoma is one of the most aggressive and metastatic skin cancers. Although overexpression of Dock180 and Elmo1 has been identified in various cancers, including glioma, ovarian cancer, and breast cancer, their expression and functions in melanoma remain unknown.

OBJECTIVE

This study aims to confirm the expression of Dock180 and Elmo1, their underlying mechanisms, and roles in melanoma.

METHODS

Both immunohistochemical staining and Western blotting were used to confirm expression of Dock180 and Elmo1 in human melanoma. To identify roles of Dock180 and Elmo1 in cell survival, apoptosis and migration, downregulation of Dock180 or Elmo1 in melanoma cells with small interfering RNA (siRNA) was performed.

RESULTS

We identified overexpression of Dock180 and Elmo1 in human melanoma compared to normal skin ex vivo. Inhibition of Dock180 or Elmo1 following siRNA in melanoma cells reduced cell viability and increased apoptosis as supported by increased proportion of cells with Annexin V-PE (+) staining and sub-G0/G1 peak in cell cycle analysis. Moreover, inhibition of Dock180 or Elmo1 regulated apoptosis-related proteins, showing downregulation of Bcl-2, caspase-3, and PARP and upregulation of Bax, PUMA, cleaved caspase-3, and cleaved PARP. Furthermore, knockdown of Dock180 and Elmo1 in melanoma cells reduced cell migration and changed cellular signaling pathways including ERK and AKT. Vemurafenib decreased cell viability in concentration-dependent manner, while transfection with Dock180- or Elmo1-specific siRNA in melanoma cells significantly reduced cell viability.

CONCLUSION

Our results suggest that both Dock180 and Elmo1 may be associated with cancer progression, and can be potential targets for treatment of melanoma.

Association between genome-wide epigenetic and genetic alterations in breast cancer tissue and response to HER2-targeted therapies in HER2-positive breast cancer patients: new findings and a systematic review

Recent evidence suggests that genetic and epigenetic mechanisms might be associated with acquired resistance to cancer therapies. The aim of this study was to assess the association of genome-wide genetic and epigenetic alterations with the response to anti-HER2 agents in HER2-positive breast cancer patients. PubMed was screened for articles published until March 2021 on observational studies investigating the association of genome-wide genetic and epigenetic alterations, measured in breast cancer tissues or blood, with the response to targeted treatment in HER2-positive breast cancer patients. Sixteen studies were included in the review along with ours, in which we compared the genome-wide DNA methylation pattern in breast tumor tissues of patients who acquired resistance to treatment (case group, n = 6) to that of patients who did not develop resistance (control group, n = 6). Among genes identified as differentially methylated between the breast cancer tissue of cases and controls, one of them, PRKACA, was also reported as differentially expressed in two studies included in the review. Although included studies were heterogeneous in terms of methodology and study population, our review suggests that genes of the PI3K pathway may play an important role in developing resistance to anti-HER2 agents in breast cancer patients. Genome-wide genetic and epigenetic alterations measured in breast cancer tissue or blood might be promising markers of resistance to anti-HER2 agents in HER2-positive breast cancer patients. Further studies are needed to confirm these data.

A Drug Screening Reveals Minocycline Hydrochloride as a Therapeutic Option to Prevent Breast Cancer Cells Extravasation across the Blood-Brain Barrier

Among breast cancer (BC) patients, 15-25% develop BC brain metastases (BCBM), a severe condition due to the limited therapeutic options, which points to the need for preventive strategies. We aimed to find a drug able to boost blood-brain barrier (BBB) properties and prevent BC cells (BCCs) extravasation, among PI3K, HSP90, and EGFR inhibitors and approved drugs. We used BCCs (4T1) and BBB endothelial cells (b.End5) to identify molecules with toxicity to 4T1 cells and safe for b.End5 cells. Moreover, we used those cells in mixed cultures to perform a high-throughput microscopy screening of drugs' ability to ameliorate BBB properties and prevent BCCs adhesion and migration across the endothelium, as well as to analyse miRNAs expression and release profiles. KW-2478, buparlisib, and minocycline hydrochloride (MH) promoted maximal expression of the junctional protein β-catenin and induced 4T1 cells nucleus changes. Buparlisib and MH further decreased 4T1 adhesion. MH was the most promising in preventing 4T1 migration and BBB disruption, tumour and endothelial cytoskeleton-associated proteins modifications, and miRNA deregulation. Our data revealed MH's ability to improve BBB properties, while compromising BCCs viability and interaction with BBB endothelial cells, besides restoring miRNAs' homeostasis, paving the way for MH repurposing for BCBM prevention.

Turning Platelets Off and On: Role of RhoGAPs and RhoGEFs in Platelet Activity

Platelet cytoskeletal reorganisation is a critical component of platelet activation and thrombus formation in haemostasis. The Rho GTPases RhoA, Rac1 and Cdc42 are the primary drivers in the dynamic reorganisation process, leading to the development of filopodia and lamellipodia which dramatically increase platelet surface area upon activation. Rho GTPases cycle between their active (GTP-bound) and inactive (GDP-bound) states through tightly regulated processes, central to which are the guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). GEFs catalyse the dissociation of GDP by inducing changes in the nucleotide binding site, facilitating GTP binding and activating Rho GTPases. By contrast, while all GTPases possess intrinsic hydrolysing activity, this reaction is extremely slow. Therefore, GAPs catalyse the hydrolysis of GTP to GDP, reverting Rho GTPases to their inactive state. Our current knowledge of these proteins is constantly being updated but there is considerably less known about the functionality of Rho GTPase specific GAPs and GEFs in platelets. In the present review, we discuss GAP and GEF proteins for Rho GTPases identified in platelets, their regulation, biological function and present a case for their further study in platelets.

DNA Hypomethylation of DOCK1 Leading to High Expression Correlates with Neurologic Deterioration and Poor Function Outcomes after Spontaneous Intracerebral Hemorrhage

Objective

Spontaneous intracerebral hemorrhage (ICH) is a blood clot arising in the brain parenchyma in the absence of trauma or surgery and accounts for 10% to 15% of all strokes, leading to higher rates of mortality and morbidity than either ischemic stroke or subarachnoid hemorrhage. We sought to investigate the potential association of DOCK1 with neurological deficits and outcomes in patients with spontaneous ICH.

Methods

Identification of methylation-regulated differentially expressed genes (MeDEGs) between ICH patients and matched controls was performed by analyzing the raw data from the GSE179759 and GSE125512 datasets deposited in the Gene Expression Omnibus. A total of 114 patients who were admitted to our hospital for spontaneous ICH were retrospectively analyzed, with 108 healthy volunteers who had received physical examinations at the same period as controls. The mRNA expression of DOCK1 was determined by quantitative real-time polymerase chain reaction (qRT-PCR). The hematoma volume was calculated according to the Coniglobus formula. The severity of neurological deficits was evaluated using National Institutes of Health Stroke Scale (NIHSS) scores and function outcomes were evaluated by modified Rankin Scale (mRS) scores.

Results

A total of 15 MeDEGs between ICH patients and matched controls were identified. The mRNA expression of DOCK1 was remarkably higher in the serum samples of patients with spontaneous ICH than in the healthy controls. According to hematoma volume after ICH attack, small (<10 mL), medium (10 to 30 mL), and large (>30 mL) groups were arranged. The proportions of male patients and patients aged ≥60 years were significantly higher in the large group than in the small and medium groups (P < 0.05). The mRNA expression of DOCK1 was significantly higher in the large group than in the small and medium groups (P < 0.05). According to NIHSS scores, mild (NIHSS scores ≤15), moderate (NIHSS scores from 16 to 30), and severe (NIHSS scores from 31 to 45) groups were classified. It was observed that the severe group had higher proportions of male patients and patients aged ≥60 years than the mild and moderate groups (P < 0.05). The severe group exhibited a higher mRNA expression of DOCK1 than the mild and moderate groups (P < 0.05). According to mRS scores, higher proportions of male patients and patients aged ≥60 years were observed in the unfavorable group than the favorable group (P < 0.05). The patients in the unfavorable group showed an elevated DOCK1 mRNA expression compared to those in the favorable group (P < 0.05).

Conclusion

The study provided evidence that male gender, older age, and higher DOCK1 mRNA expression were related to higher admission hematoma volume, neurologic deterioration, and poor function outcomes in patients with spontaneous ICH.

Fe65: A Scaffolding Protein of Actin Regulators

The scaffolding protein family Fe65, composed of Fe65, Fe65L1, and Fe65L2, was identified as an interaction partner of the amyloid precursor protein (APP), which plays a key function in Alzheimer’s disease. All three Fe65 family members possess three highly conserved interaction domains, forming complexes with diverse binding partners that can be assigned to different cellular functions, such as transactivation of genes in the nucleus, modulation of calcium homeostasis and lipid metabolism, and regulation of the actin cytoskeleton. In this article, we rule out putative new intracellular signaling mechanisms of the APP-interacting protein Fe65 in the regulation of actin cytoskeleton dynamics in the context of various neuronal functions, such as cell migration, neurite outgrowth, and synaptic plasticity.

RHO to the DOCK for GDP disembarking: Structural insights into the DOCK GTPase nucleotide exchange factors

The human dedicator of cytokinesis (DOCK) family consists of 11 structurally conserved proteins that serve as atypical RHO guanine nucleotide exchange factors (RHO GEFs). These regulatory proteins act as mediators in numerous cellular cascades that promote cytoskeletal remodeling, playing roles in various crucial processes such as differentiation, migration, polarization, and axon growth in neurons. At the molecular level, DOCK DHR2 domains facilitate nucleotide dissociation from small GTPases, a process that is otherwise too slow for rapid spatiotemporal control of cellular signaling. Here, we provide an overview of the biological and structural characteristics for the various DOCK proteins and describe how they differ from other RHO GEFs and between DOCK subfamilies. The expression of the family varies depending on cell or tissue type, and they are consequently implicated in a broad range of disease phenotypes, particularly in the brain. A growing body of available structural information reveals the mechanism by which the catalytic DHR2 domain elicits nucleotide dissociation and also indicates strategies for the discovery and design of high-affinity small-molecule inhibitors. Such compounds could serve as chemical probes to interrogate the cellular function and provide starting points for drug discovery of this important class of enzymes.

B3GNT3 acts as a carcinogenic factor in endometrial cancer via facilitating cell growth, invasion and migration through regulating RhoA/RAC1 pathway-associated markers

BACKGROUND

Aberrant expression of beta-1,3-N-acetylglucosaminyltransferase-3 (B3GNT3) has been frequently clarified in various cancers, however, its role in endometrial cancer (EC) has not been assessed in detail.

PURPOSE

This study aimed to investigate the biological role of B3GNT3 in EC and simply explored the detailed mechanism.

METHODS

The EC RNA-Seq dataset from TCGA database was applied to evaluate the expression of B3GNT3 and assess its role on prognostic value. HEC-1-A and KLE cell lines of EC were used to perform loss- and gain-of-function B3GNT3 assays respectively. Quantitative real-time PCR (qRT-PCR) and western blot were used to measure the mRNA and protein levels of indicated molecules respectively. Cell counting kit-8, clone formation tests, and Transwell assay served to determine the changes of proliferative, invasive and migratory abilities of EC cells after altering the expression of B3GNT3.

RESULTS

B3GNT3 was found to be highly expressed in EC tissues compared to normal tissues according to the online public databases, which confirmed by the following qRT-PCR in 3 EC cell lines. Besides, high B3GNT3 expression presented a worse overall survival in EC patients as compared with low B3GNT3 expression group. Furthermore, functional experiments in vitro indicated that B3GNT3 could facilitate the cell growth, invasion and migration. Moreover, we found that downregulation of B3GNT3 significantly reduced the expression level of GTP-RhoA and GTP-RAC1, whereas upregulation of B3GNT3 presented the opposite results.

CONCLUSION

The results of current study demonstrate that B3GNT3 acts as an oncogene that promotes EC cells growth, invasion and migration possibly through regulating the RhoA/RAC1 signaling pathway-related markers, suggesting that B3GNT3 may be a candidate biomarker for EC therapeutic intervention.

Engulfment and cell motility 1 promotes tumor progression via the modulation of tumor cell survival in gastric cancer

BACKGROUND/AIM

Engulfment and cell motility 1 (ELMO1) protein has been implicated in phagocytosis of apoptotic cells, cell migration, neurite outgrowth, cancer cell invasion and metastasis, and poor prognosis in various cancers. We investigated the role of ELMO1 in mediating the oncogenic behavior of gastric cancer (GC) cells. We also investigated the correlation between expression of ELMO1 in GC tissues and various clinicopathological parameters.

METHODS

We studied the impact of ELMO1 on tumor cell behavior using the pcDNA-myc vector and small interfering RNA in AGS and SNU1750 GC cell lines. We performed western blotting and immunohistochemistry to investigate the expression of ELMO1 in GC cells and tissues.

RESULTS

ELMO1 overexpression inhibited apoptosis via the modulation of PARP, caspase-3 and caspase-7 in GC cells. ELMO1 overexpression led to significant increase in the number of migrating and invading GC cells. The expression of E-cadherin decreased and that of Snail increased in GC cells upon ELMO1 overexpression. Phosphorylation of PI3K/Akt and GSK-3β was increased and that of β-catenin was decreased upon ELMO1 overexpression in GC cells. These results were reversed after ELMO1 knockdown. ELMO1 expression was significantly associated with tumor size, cancer stage, lymph node metastasis and survival. ELMO1-positive tumors had significantly higher mean of Ki-67 labeling index than ELMO1-negative tumors. There was no significant relationship between ELMO1 expression and the mean value of the apoptotic index.

CONCLUSIONS

Our results indicate that ELMO1 promotes tumor progression by modulating tumor cell survival in human GC.

Identification of afzelin potential targets in inhibiting triple-negative breast cancer cell migration using reverse docking

BACKGROUND

Triple-negative breast cancer (TNBC) tends to be aggressive and metastatic, characteristics attributable to its cellular migration capabilities. Afzelin is a chemical compound with anti-metastatic potentials. This study aimed to predict proteins involved in TNBC cell migration which could be inhibited by afzelin.

METHODS

The protein database was constructed from the Kyoto Encyclopedia of Genes and Genomes pathways collection which related to cell motility, then screened for druggability using SuperTarget and Therapeutic Target Database. The involvement of druggable proteins in the TNBC metastasis process was investigated through existing publications in The National Center for Biotechnology Information PubMed database. Inhibitory potential of afzelin toward target proteins was compared to the proteins' known-inhibitor, using the reverse docking method.

RESULTS

Ten proteins identified as potential targets of afzelin, with the top 3 being ERK2, KRas, and FAK, respectively. Afzelin's 3-O-rhamnoside group played a dominant role in forming hydrogen bonds with the target proteins. Further analysis with STRING suggested that afzelin might be able to inhibit chemotaxis and haptotaxis of TNBC cells.

CONCLUSIONS

Afzelin was predicted to inhibit TNBC cell motility, by targeting ERK2, KRas, and FAK activation.

TBOPP enhances the anticancer effect of cisplatin by inhibiting DOCK1 in renal cell carcinoma

The treatment of renal cell carcinoma (RCC) with chemotherapy remains a challenge; therefore, improving the knowledge of the molecular mechanisms underlying RCC chemoresistance and developing novel therapeutic strategies is important. Dedicator of cytokinesis 1 (DOCK1), the first member of the DOCK family to be discovered, displays various roles during tumorigenesis; however, its role during RCC progression is not completely understood. Therefore, the present study aimed to clarify the function of DOCK1 and 1‑[2‑(3'‑(trifluoromethyl)‑(1,1'‑biphenyl)‑4‑yl)‑2‑oxoethyl]‑5‑pyrrolidinylsulfonyl‑2 (1H)‑pyridone (TBOPP), a DOCK1‑sensitive inhibitor, during RCC development and chemoresistance. The results of CCK‑8 and EdU assay indicated that TBOPP decreased RCC cell viability and proliferation compared with the control group, and sensitized RCC cells to cisplatin. Moreover, RCC cells with high DOCK1 expression levels displayed increased resistance to cisplatin, whereas DOCK1 knockdown enhanced the lethal effects of cisplatin on RCC cells. Furthermore, the results determined by western blotting, CCK‑8 and cell apoptosis assay indicated that TBOPP effectively reduced DOCK1 expression levels compared with the control group, and the TBOPP‑mediated cisplatin sensitizing effect was mediated by DOCK1 inhibition. The present study suggests that DOCK1 plays a vital role in RCC cell chemoresistance to cisplatin; therefore, TBOPP may serve as a novel therapeutic agent for RCC chemoresistance.

Inhalation exposure to cigarette smoke and inflammatory agents induces epigenetic changes in the lung

Smoking-related lung tumors are characterized by profound epigenetic changes including scrambled patterns of DNA methylation, deregulated histone acetylation, altered gene expression levels, distorted microRNA profiles, and a global loss of cytosine hydroxymethylation marks. Here, we employed an enhanced version of bisulfite sequencing (RRBS/oxRRBS) followed by next generation sequencing to separately map DNA epigenetic marks 5-methyl-dC and 5-hydroxymethyl-dC in genomic DNA isolated from lungs of A/J mice exposed whole-body to environmental cigarette smoke for 10 weeks. Exposure to cigarette smoke significantly affected the patterns of cytosine methylation and hydroxymethylation in the lungs. Differentially hydroxymethylated regions were associated with inflammatory response/disease, organismal injury, and respiratory diseases and were involved in regulation of cellular development, function, growth, and proliferation. To identify epigenetic changes in the lung associated with exposure to tobacco carcinogens and inflammation, A/J mice were intranasally treated with the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), the inflammatory agent lipopolysaccharide (LPS), or both. NNK alone caused minimal epigenetic alterations, while exposure either to LPS or NNK/LPS in combination led to increased levels of global cytosine methylation and formylation, reduced cytosine hydroxymethylation, decreased histone acetylation, and altered expression levels of multiple genes. Our results suggest that inflammatory processes are responsible for epigenetic changes contributing to lung cancer development.

A blood-based 22-gene expression signature for hepatocellular carcinoma identification

Background

Hepatocellular carcinoma (HCC) is one of the most common and lethal malignancies. Early detection of HCC could largely reduce mortalities. Ultrasonography (US) and serum Alpha Fetoprotein (AFP) test are the screening methods that are most frequently applied to high-risk populations. Due to the poor performance of AFP testing, and the highly operator-dependent nature of US, a biomarker for HCC early diagnosis is highly sought after. We developed a method for HCC screening using a 22-gene expression signature.

Methods

Peripheral whole blood of 98 patients were processed through microarrays for the first round of feature selection via two strategies, Minimal Redundancy Maximal Relevance and Least Absolute Shrinkage and Selection Operator combined with Support Vector Machine (SVM). Candidate genes were combined for further validation through qPCR in an enlarged population with 316 samples with 104 chronic hepatitis, 112 liver cirrhosis (LC), and 100 HCC.

Results

A 22-gene signature was established in classifying HCC and non-cancer samples with good performance. The area under curve reached 0.94 in all of the samples and 0.93 in the AFP -negative samples.

Conclusions

We have established a blood mRNA signature with high performance for HCC screening. Our results show transcriptome of peripheral blood could be valuable source for biomarkers.

Coordination between Rac1 and Rab Proteins: Functional Implications in Health and Disease

The small GTPases of the Rho family regulate many aspects of actin dynamics, but are functionally connected to many other cellular processes. Rac1, a member of this family, besides its known function in the regulation of actin cytoskeleton, plays a key role in the production of reactive oxygen species, in gene transcription, in DNA repair, and also has been proven to have specific roles in neurons. This review focuses on the cooperation between Rac1 and Rab proteins, analyzing how the coordination between these GTPases impact on cells and how alterations of their functions lead to disease.