OBJECTIVES: To investigate the subcellular localization and biological functions of transmembrane protein 240 (TMEM240). METHODS: NCBI BLAST and TMHMM bioinformatics software were used for protein sequence analysis and prediction of transmembrane domain of TMEM240. Brain tissues from male C57BL/6 mice (18-20 days old) were examined for distribution of TMEM240 using in situ hybridization, and qPCR and Western blotting were used to detect TMEM240 expression in different mouse tissues and in cortical neurons at different time points (n=3). In the in vitro experiment, HepG2 and Neuro-2a cells were transfected with plasmids for overexpression of TMEM240, and subcellular localization of TMEM240 was analyzed using cell imaging. In primary cultures of cortical neurons isolated from C57BL/6 mice, TMEM240 expression and its biological functions were investigated using qPCR, Western blotting, and immunofluorescence staining. RESULTS: Human and mouse TMEM240 proteins share a 97.69% similarity in the protein sequences, and both are transmembrane proteins with two transmembrane domains. TMEM240 mRNA and protein were highly expressed in mouse brain tissues and cortical neurons. In isolated mouse cortical neurons, TMEM240 expression reached the peak level after primary culture for 9 days and distributed in scattered spots within the cells. In HepG2 cells, TMEM240 was characterized as intracellular membrane structures and showed 80% colocalization with peroxisomes. In Neuro-2a cells, TMEM240 overexpression caused significant enhancement of the expressions of Rho GDP dissociation inhibitor β (ARHGDIB) at both the mRNA and protein levels. CONCLUSIONS TMEM240 is a novel intracellular subcellular structure specifically expressed in neurons with significant potential for targeted cellular function regulation.
Animals ; Humans ; Mice ; Peroxisomes/metabolism* ; Membrane Proteins/genetics* ; Mice, Inbred C57BL ; Neurons/metabolism* ; Male ; rho-Specific Guanine Nucleotide Dissociation Inhibitors ; Hep G2 Cells ; Brain/metabolism*

OBJECTIVETo investigate the expression of RhoGDIalpha in human testes and spermatozoa, and compare the expression of RhoGDIalpha in the ejaculated spermatozoa from normozoospermic me and infertile patients men receiving in vitro fertilization (IVF).

METHODSThe localization of RhoGDIalpha in the human testis was determined by immunohistochemistry, and that in the pre-capacitated, capacitated and acrosome-reacted sperm by immunofluorescence. Western blot was used to detect the expression of RhoGDIalpha in the semen samples obtained from normozoospermic males (n = 10), IVF patients with high fertilization rates (> or = 60%, n = 12) and those with low fertilization rates (< 60%, n = 13).

RESULTSImmunohistochemistry showed that the RhoGDIalpha protein was located in all spermatogenic cells and highly expressed in the elongated spermatids. Immunofluorescence exhibited a high expression of RhoGDIalpha in the acrosome and flagellum of human sperm, which decreased in the acrosome after capacitation and disappeared after acrosome reaction. Western blot revealed an obviously decreased expression of RhoGDIalpha in the spermatozoa of the IVF patients with low fertilization rates (0.66 +/- 0.18), with statistically significant difference from those with high fertilization rates (0.97 +/- 0.17) and the normozoospermic men (1.13 +/- 0.21).

CONCLUSIONThe RhoGDIalpha protein is located in the acrosome and flagellum of human sperm, and might be involved in sperm movement, capacitation and acrosome reaction. The significantly reduced expression of RhoGDIalpha in the sperm of low-fertilization patients suggests that it may be a new diagnostic biomarker for male infertility, and has a potential application value in sperm selection for IVF.

Fertilization in Vitro ; Guanine Nucleotide Dissociation Inhibitors ; metabolism ; Humans ; Infertility, Male ; Male ; Sperm Motility ; Spermatozoa ; metabolism ; Testis ; metabolism ; rho Guanine Nucleotide Dissociation Inhibitor alpha ; rho-Specific Guanine Nucleotide Dissociation Inhibitors

OBJECTIVETo investigate the expression of Rho-GDI in the decidual tissues of patients preeclampsia and explore its clinical implication.

METHODSReal-time PCR, Western blotting and immunohistochemistry were used to detect the mRNA and protein expressions of Rho-GDI in the decidual tissues from 30 normal women with full-term pregnancy, 30 patients with early-onset severe preeclampsia and 30 with late-onset severe preeclampsia.

RESULTSRho-GDI expression was found mainly on the cell membrane and in the cytoplasm and nuclei of the decidual cells, occasionally occurring in the stroma. Both the mRNA and protein expressions of Rho-GDI in the decidual tissues were significantly higher in the normal pregnancy group than in the two severe preeclampsia groups (P<0.05), and the patients with late-onset severe preeclampsia had the lowest expressions of Rho-GDI.

CONCLUSIONThe lowered expression of Rho-GDI in the deciduas might be involved in the pathogenesis and progression of preeclampsia.

Adult ; Decidua ; metabolism ; Female ; Guanine Nucleotide Dissociation Inhibitors ; genetics ; metabolism ; Humans ; Pre-Eclampsia ; metabolism ; Pregnancy ; RNA, Messenger ; genetics ; metabolism ; Real-Time Polymerase Chain Reaction ; methods ; Young Adult ; rho-Specific Guanine Nucleotide Dissociation Inhibitors

Annexin A3 ; genetics ; metabolism ; Cells, Cultured ; Guanine Nucleotide Dissociation Inhibitors ; genetics ; metabolism ; Hepatocytes ; drug effects ; metabolism ; Humans ; Lactoylglutathione Lyase ; genetics ; metabolism ; RNA, Messenger ; genetics ; Trichloroethylene ; toxicity ; rho-Specific Guanine Nucleotide Dissociation Inhibitors

BACKGROUNDBeta(2)-adrenoceptor (beta(2)AR) desensitization is a common problem in clinical practice. beta(2)AR desensitization proceeds by at least such three mechanisms as heterologous desensitization, homologous desensitization and a kind of agonist-induced rapid phosphorylation by a variety of serine/threonine kinases. It is not clear whether there are other mechanisms. This study aimed to investigate potential mechanisms of beta(2)AR desensitization.

METHODSTwenty-four BALB/c (6-8 weeks old) mice were divided into three groups, which is, group A, phosphate buffered saline (PBS)-treated; group B, ovalbumin (OVA)-induced; and group C, salbutamol-treated. Inflammatory cell counts, cytokine concentrations of bronchoalveolar lavage fluid (BALF), pathological sections, total serum IgE, airway responsiveness, membrane receptor numbers and total amount of beta(2)AR were observed. Asthmatic mouse model and beta(2)AR desensitization asthmatic mouse model were established. Groups B and C were selected for two-dimensional gel electrophoresis (2DE) analysis so as to find key protein spots related to beta(2)AR desensitization.

RESULTSAsthmatic mouse model and beta(2)AR desensitization asthmatic mouse model were verified by inflammatory cell count, cytokine concentration of BALF, serum IgE level, airway hyperreactivity measurement, radioligand receptor binding assay, Western blot analysis, and pathologic examination. Then the two groups (groups B and C) were subjected to 2DE. Two key protein spots associated with beta(2)AR desensitization, Rho GDP-dissociation inhibitor 2 (RhoGDI(2)) and peroxiredoxin 5, were found by comparative proteomics (2DE and mass spectrum analysis).

CONCLUSIONOxidative stress and small G protein regulators may play an important role in the process of beta(2)AR desensitization.

Albuterol ; therapeutic use ; Animals ; Asthma ; drug therapy ; metabolism ; Disease Models, Animal ; Electrophoresis, Gel, Two-Dimensional ; Female ; Guanine Nucleotide Dissociation Inhibitors ; analysis ; Lung ; chemistry ; pathology ; Mice ; Mice, Inbred BALB C ; Oxidative Stress ; Peroxiredoxins ; analysis ; Proteomics ; Receptors, Adrenergic, beta-2 ; physiology ; rho-Specific Guanine Nucleotide Dissociation Inhibitors

The release of neurotransmitter is regulated in the processes of membrane docking and membrane fusion between synaptic vesicles and presynaptic plasma membranes. Synaptic vesicles contain a diverse set of proteins that participate in these processes. Small GTP-binding proteins exist in the synaptic vesicles and are suggested to play roles for the regulation of neurotransmitter release. We have examined a possible role of GTP-binding proteins in the regulation of protein phosphorylation in the synaptic vesicles. GTPgammaS stimulated the phosphorylation of 46 kappa Da protein (p46) with pI value of 5.0-5.2, but GDPbetaS did not. The p46 was identified as protein interacting with C-kinase 1 (PICK-1) by MALDI-TOF mass spectroscopy analysis, and anti-PICK-1 antibody recognized the p46 spot on 2-dimensional gel electrophoresis. Rab guanine nucleotide dissociation inhibitor (RabGDI), which dissociates Rab proteins from SVs, did not affect phosphorylation of p46. Ca2+/ calmodulin (CaM), which causes the small GTP- binding proteins like Rab3A and RalA to dissociate from the membranes and stimulates CaM- dependnet protein kinase(s) and phosphatase, strongly stimulate the phosphorylation of p46 in the presence of cyclosporin A and cyclophylin. However, RhoGDI, which dissociates Rho proteins from membranes, reduced the phosphorylation of p46 to the extent of about 50%. These results support that p46 was PICK-1, and its phosphorylation was stimulated by GTP and Ca2+/CaM directly or indirectly through GTP-binding protein(s) and Ca2+/CaM effector protein(s). The phosphorylation of p46 (PICK-1) by GTP and Ca2+/CaM may be important for the regulation of transporters and neurosecretion.
Animals ; Calcium/*metabolism ; Calmodulin/*metabolism ; Carrier Proteins/*chemistry/*metabolism ; Guanine Nucleotide Dissociation Inhibitors/metabolism ; Guanosine Triphosphate/metabolism/*pharmacology ; Molecular Weight ; Monomeric GTP-Binding Proteins/metabolism ; Phosphorylation/drug effects ; Rats ; Recombinant Fusion Proteins/*chemistry/*metabolism ; Synaptic Membranes/chemistry/drug effects/*metabolism ; Synaptic Vesicles/chemistry/drug effects/*metabolism