Small GTPases are key molecular switches that bind and hydrolyze GTP in diverse membrane- and cytoskeleton-related cellular processes. Recently, mounting evidences have highlighted the role of various small GTPases, including the members in Arf/Arl, Rab, and Ran subfamilies, in cilia formation and function. Once overlooked as an evolutionary vestige, the primary cilium has attracted more and more attention in last decade because of its role in sensing various extracellular signals and the association between cilia dysfunction and a wide spectrum of human diseases, now called ciliopathies. Here we review recent advances about the function of small GTPases in the context of cilia, and the correlation between the functional impairment of small GTPases and ciliopathies. Understanding of these cellular processes is of fundamental importance for broadening our view of cilia development and function in normal and pathological states and for providing valuable insights into the role of various small GTPases in disease processes, and their potential as therapeutic targets.
Animals ; Cilia ; enzymology ; genetics ; metabolism ; GTP Phosphohydrolases ; metabolism ; Humans

OBJECTIVE: To review the research progress of mitochondrial dynamics mediated by optic atrophy 1 (OPA1) in skeletal system diseases. METHODS: The literatures about OPA1-mediated mitochondrial dynamics in recent years were reviewed, and the bioactive ingredients and drugs for the treatment of skeletal system diseases were summarized, which provided a new idea for the treatment of osteoarthritis. RESULTS: OPA1 is a key factor involved in mitochondrial dynamics and energetics and in maintaining the stability of the mitochondrial genome. Accumulating evidence indicates that OPA1-mediated mitochondrial dynamics plays an important role in the regulation of skeletal system diseases such as osteoarthritis, osteoporosis, and osteosarcoma. CONCLUSION OPA1-mediated mitochondrial dynamics provides an important theoretical basis for the prevention and treatment of skeletal system diseases.
Humans ; GTP Phosphohydrolases/genetics* ; Mitochondrial Dynamics ; Osteoarthritis ; Osteoporosis

BACKGROUND: It is well established that vascular contraction is caused by not only an increase in cytosolic Ca2+ level but also activations of Ca2+-sensitizing mechanisms including protein kinase C (PKC) and low molecular GTP binding protein. However, the roles of PKC and RhoA, a low molecular GTP-binding protein, on the receptor agonist-mediated contraction in swine pulmonary artery has not been clarified. In the present study, we examined the contribution of PKC isoform and RhoA to the arterial stimulants-induced contraction in swine pulmonary artery. METHOD: The large (> 5 mm), medium (1-3 mm) and small (< 1 mm in outer diameter) sized pulmonary arteries were excised and the contractions were recorded isometrically. The contents and subcellular distribution of PKC isoforms and RhoA were detected using immunoblotting. RESULTS: In medium pulmonary artery, norepinephrine (NE, 10 nM-30micrometer) led contraction in a dose-dependent manner. In large and small pulmonary arteries, however, NE failed to induce a contraction. Adding of 12-deoxyphorbol 13-isobutyrate (DPB, 1micrometer), a PKC activator, developed muscle force in 1 mM EGTA-contained Ca2+-free physiological salt solution. The expressions of PKC alpha, elsilon were significantly increased in medium pulmonary artery. NE (10micrometer) evoked the translocation of RhoA from cytosol to the membrane but not those of PKC isoforms. In Ca2+-free physiological salt solution, DPB (1micrometer) caused a translocation of PKC isoforms. CONCLUSIONS: These results support that NE induces contraction via RhoA pathway but not PKC pathway in swine pulmonary artery.
Cytosol ; GTP Phosphohydrolases* ; GTP-Binding Proteins ; Immunoblotting ; Membranes ; Norepinephrine ; Protein Isoforms ; Protein Kinase C* ; Protein Kinases* ; Pulmonary Artery* ; Swine*

PURPOSE: The Rho family of GTPases are involved in actin cytoskeleton organization and are associated with carcinogenesis and progression of human cancers. The clinicopathological significance of RhoA is not yet well known in the case of colorectal cancer. To investigate the expression of RhoA protein in colorectal carcinoma and to evaluate the relationship between RhoA protein expression and invasion and metastasis of colorectal cancer, we examined the expression of RhoA protein by using Western blotting and immunohistochemistry. METHODS: The protein levels of RhoA in colorectal carcinomas of surgical specimens were analyzed in 71 consecutive patients with colorectal cancers by using immunohistochemistry and Western blotting. The relationships between the protein levels of RhoA in tumor tissues and the clinicopathological features of the patients were also assessed. RESULTS: RhoA was highly expressed in 48 colorectal carcinomas (67.6%). There was a significant association between RhoA expression and lymph nodal status. The expression of RhoA protein was related to lymph-node metastasis (P=0.032) and advanced TNM tumor staging (P=0.020). RhoA expression had a significant prognostic value for overall survival. Kaplan-Meier plots of survival in patients with high RhoA showed that high RhoA expression was associated with a shorter overall survival. However, no association was found between RhoA and other pathologic or clinical variables, including age, gender, degree of differentiation, and presence of perineural spread. CONCLUSIONS: The RhoA protein may be related to malignant transformation and development of colorectal caricinomas and may play an important role in the invasion and the metastasis of colorectal carcinomas.
Actin Cytoskeleton ; Blotting, Western ; Colorectal Neoplasms ; GTP Phosphohydrolases ; Humans ; Immunohistochemistry ; Neoplasm Metastasis ; Neoplasm Staging ; rhoA GTP-Binding Protein

Regulators of G-protein signaling (RGS) proteins are regulators of Ca2+ signaling that accelerate the GTPase activity of the G-protein alpha-subunit. RGS1, RGS2, RGS4, and RGS16 are expressed in the pancreas, and RGS2 regulates G-protein coupled receptor (GPCR)-induced Ca2+ oscillations. However, the role of RGS4 in Ca2+ signaling in pancreatic acinar cells is unknown. In this study, we investigated the mechanism of GPCR-induced Ca2+ signaling in pancreatic acinar cells derived from RGS4-/- mice. RGS4-/- acinar cells showed an enhanced stimulus intensity response to a muscarinic receptor agonist in pancreatic acinar cells. Moreover, deletion of RGS4 increased the frequency of Ca2+ oscillations. RGS4-/- cells also showed increased expression of sarco/endoplasmic reticulum Ca2+ ATPase type 2. However, there were no significant alterations, such as Ca2+ signaling in treated high dose of agonist and its related amylase secretion activity, in acinar cells from RGS4-/- mice. These results indicate that RGS4 protein regulates Ca2+ signaling in mouse pancreatic acinar cells.
Acinar Cells ; Amylases ; Animals ; Calcium-Transporting ATPases ; GTP Phosphohydrolases ; GTP-Binding Proteins ; Mice ; Pancreas ; Proteins ; Receptors, Muscarinic ; Reticulum ; RGS Proteins

Although Rap GTPases of the Ras family remained enigmatic for years, extensive studies in this decade have revealed diverse functions of Rap signaling in the control of cell proliferation, differentiation, survival, adhesion, and movement. With the use of gene-engineered mice, we have uncovered essential roles of endogenous Rap signaling in normal lymphocyte development of both T- and B-lineage cells. Deregulation of Rap signaling, on the other hand, results in the development of characteristic leukemia in manners highly dependent on the contexts of cell lineages. These results highlight crucial roles of Rap signaling in the physiology and pathology of lymphocyte development.
Animals ; Cell Lineage ; Cell Proliferation ; GTP Phosphohydrolases ; Hand ; Humans ; Leukemia ; Lymphocytes ; Mice

BACKGROUND AND PURPOSE: MicroRNA (miRNA) expression has been examined in multiple conditions, including various cancers, neurological diseases, and cerebrovascular diseases, particularly stroke. Existing evidence indicates that miRNA biosynthesis and function play crucial roles in ischemic stroke physiology and pathology. In this study, we selected six known polymorphisms in miRNA-biogenesis genes; DICER rs13078A>T, rs3742330A>G; DROSHA rs10719T>C, rs6877842G>C; Ran GTPase (RAN) rs14035C>T; exportin 5 (XPO5) rs11077A>C. METHODS: We analyzed the associations between these polymorphisms and disease status and clinical factors in 585 ischemic stroke patients and 403 controls. Genotyping was performed with the polymerase chain reaction-restriction fragment length polymorphism method. RESULTS: The DICER rs3742330A>G (AA vs. AG+GG: adjusted odds ratio [AOR], 1.360; 95% confidence interval [CI], 1.024 to 1.807; P=0.034) and DROSHA rs10719T>C polymorphisms (TT vs. CC: AOR, 2.038; 95% CI, 1.113 to 3.730; P=0.021) were associated with ischemic stroke prevalence. During a mean follow-up of 4.80±2.11 years, 99 (5.91%) of the stroke patients died. In multivariate Cox proportional hazard regression models, a significant association was found between RAN rs14035 and survival of large artery disease patients with ischemic stroke (CC vs. TT: adjusted hazard ratio, 5.978; P=0.015). CONCLUSIONS: An association was identified between the DICER and DROSHA polymorphisms and ischemic stroke. Specifically, polymorphisms (rs3742330 and rs10719) were more common in stroke patients, suggesting that they may be associated with an increased risk of ischemic stroke.
Arteries ; Cerebrovascular Disorders ; Follow-Up Studies ; GTP Phosphohydrolases ; Humans ; Methods ; MicroRNAs ; Mortality ; Odds Ratio ; Pathology ; Physiology ; Polymorphism, Genetic ; Prevalence ; Stroke

OBJECTIVE: To analyze the subcellular localization of GTPase of immunity-associated protein 2 (GIMAP2) for the further functional study. METHODS: In the study, we first obtained the protein sequences of GTPase of immunity-associated protein 2 (GIMAP2) from National Center for Biotechnology Information (NCBI) database, and then performed a prediction analysis of its transmembrane structure, nuclear localization signal (NLS), nuclear export signal (NES) and subcellular localization through bioinformatics online tools. GIMAP2 gene amplified by PCR was inserted into the expression vector pQCXIP-mCherry-N1 and positive clones were selected by ampicillin resistance. After using methods to extract and purify, the sequenced recombinant plasmid pQCXIP-GIMAP2-mCherry, together with the retroviral packaging plasmids VSVG and Gag/pol, was transferred into HEK293FT cells by liposomes for virus packaging. The virus supernatant was collected 48 h after transfection and directly infected the human breast cancer cell line MDA-MB-436. Immunofluorescence staining was constructed to detect the localization of endogenous and exogenous GIMAP2 in MDA-MB-436 cells. Meanwhile, green fluorescent chemical dyes were used to label mitochondria, endoplasmic reticulum, and lipid droplets in living MDA-MB-436 cells stably expressing the GIMAP2-mCherry fusion protein. Images for the three dye-labeled organelles and GIMAP2-mCherry fusion protein were captured by super-resolution microscope N-SIM. RESULTS: Bioinformatics analysis data showed that GIMAP2 protein composed of 337 amino acids might contain two transmembrane helix (TM) structures at the carboxyl terminus, of which TMs were estimated to contain 40-41 expected amino acids, followed by the residual protein structures toward the cytoplasmic side. NES was located at the 279-281 amino acids of the carboxyl terminus whereas NLS was not found. GIMAP2 might locate in the lumen of the endoplasmic reticulum. Sequencing results indicated that the expression vector pQCXIP-GIMAP2-mCherry was successfully constructed. Fluorescent staining confirmed that GIMAP2-mCherry fusion protein, co-localized well with endogenous GIMAP2, expressed successfully in the endoplasmic reticulum and on the surface of lipid droplets in MDA-MB-436 cells. CONCLUSION GIMAP2 localizes in the endoplasmic reticulum and on the surface of LDs, suggesting potential involvement of GIMAP2 in lipid metabolism.
Amino Acid Sequence ; Cytoplasm ; GTP Phosphohydrolases ; Humans ; Membrane Proteins ; Nuclear Export Signals ; Nuclear Localization Signals ; Recombinant Fusion Proteins ; Transfection

The maturation process of mammalian oocytes accompanies an extensive rearrangement of the cytoskeleton and associated proteins. As this process requires a delicate interplay between the cytoskeleton and its regulators, it is often targeted by various external and internal adversaries that affect the congression and/or segregation of chromosomes. Asymmetric cell division in oocytes also requires specific regulators of the cytoskeleton, including formin-2 and small GTPases. Recent literature providing clues regarding how actin filaments and microtubules interact during spindle migration in mouse oocytes are highlighted in this review.
Actin Cytoskeleton ; Animals ; Asymmetric Cell Division ; Cytoskeleton ; GTP Phosphohydrolases ; Humans ; Mice ; Microtubules ; Monomeric GTP-Binding Proteins ; Nerve Tissue Proteins ; Oocytes ; Proteins

BACKGROUND: The role of small GTPase molecules is poorly understood under high glucose conditions. METHODS: We analyzed the expression pattern of Vav3 in skeletal muscle C2C12 cells under high glucose culture condition with reverse transcription-polymerase chain reaction and Western blot analysis. We also measured glucose uptake using isotope-labelled glucose. RESULTS: We showed that expression of Vav3 (a guanine nucleotide exchange factor for RhoA) increased. mRNA and protein levels in skeletal muscle C2C12 cells under high glucose conditions. The AMP-activated protein kinase (AMPK) activator AMPK agonist 5-aminoimidazole-4-carboxy-amide-1-d-ribofuranoside (AICAR) suppressed high glucose-induced Vav3 induction. In addition, exposure of cells to high glucose concentration increased the phosphorylation of PAK-1, a molecule downstream of RhoA. The phosphorylation of paxillin, a downstream molecule of PAK-1, was also increased by exposure to high glucose. Phosphorylation of these molecules was not observed in the presence of AICAR, indicating that AMPK is involved in the RhoA signal pathway under high glucose conditions. Knock down of Vav3 enhances metformin-mediated glucose uptake. Inhibition of AMPK blocked the increases of Vav3 knock down-induced glucose uptake. Metformin-mediated Glut4 translocation was also increased by Vav3 knock-down, suggesting that Vav3 is involved in metformin-mediated glucose uptake. CONCLUSION: These results demonstrate that Vav3 is involved in the process of metformin-mediated glucose regulation.
AMP-Activated Protein Kinases ; Blotting, Western ; Glucose* ; GTP Phosphohydrolases ; Guanine Nucleotide Exchange Factors ; Metformin ; Muscle, Skeletal ; Paxillin ; Phosphorylation ; RNA, Messenger ; Signal Transduction