Vesicle-mediated transport of proteins is a highly regulated, multi-step process. When the vesicle is approaching its target membrane compartment, many factors are required to provide specificity and tethering between the incoming vesicle and the target membrane, before vesicle fusion can occur. Tethering factors, which include multisubunit complexes, coiled-coil proteins, with the help of small GTPases, provide the initial interaction between the vesicle and its target membrane. Of the multisubunit tethering factors, the transport protein particle (TRAPP) complexes function in a number of trafficking steps, including endoplasmic reticulum (ER)-to-Golgi transport, intra- and post-Golgi traffic and autophagosome formation. In this review, we summarize the updated progress in structure and function of TRAPP complexes as well as human diseases caused by genetic mutations in TRAPP.
Animals ; Endoplasmic Reticulum ; pathology ; physiology ; Golgi Apparatus ; pathology ; physiology ; Humans ; Mutation ; Protein Transport ; Vesicular Transport Proteins ; genetics ; physiology

The constitutive androstane receptor (CAR, NR1I3) plays a crucial role in the regulation of drug metabolism, energy homeostasis, and cancer development through modulating the transcription of its numerous target genes. Different from prototypical nuclear receptors, CAR can be activated by either direct ligand binding or ligand-independent (indirect) mechanisms both initiated with nuclear translocation of CAR from the cytoplasm. In comparison to the well-defined ligand-based activation, indirect activation of CAR appears to be exclusively involved in the nuclear translocation through mechanisms yet to be fully understood. Accumulating evidence reveals that without activation, CAR forms a protein complex in the cytoplasm where it can be functionally affected by multiple signaling pathways. In this review, we discuss recent progresses in our understanding of the signaling regulation of CAR nuclear accumulation and activation. We expect that this review will also provide greater insight into the similarity and difference between the mechanisms of direct vs. indirect human CAR activation.
Active Transport, Cell Nucleus ; genetics ; Cytoplasm ; metabolism ; Hepatocytes ; metabolism ; Humans ; Ligands ; Protein Transport ; genetics ; Receptors, Cytoplasmic and Nuclear ; genetics ; metabolism ; Signal Transduction ; genetics

OBJECTIVETo analyze the interaction between the microRNA-338 and its targeting proteins during the cerebral ischemia and reperfusion injury.

METHODSTargetScan was used to predict the targets of microRNA-338. The potential targeting proteins were then selected according to their secondary structures using RNA structure 4.6 software and their involvement in cerebral ischemia and reperfusion injury was studied. Dual-luciferase reporter assay was used to testify whether microRNA-338 can recognize the 3'UTR of target protein. Western blot was applied to analyze the expression of eiF4E3 in both experimental group and control group.

RESULTEiF4E3 was the most likely potential targeting protein of microRNA-338. The secondary structure of local region of eiF4E3 recognizing microRNA-338 was conservative. The ratio of firefly to renilla luciferase activity in the experimental group was much higher than that of control group. However, there was no significant difference in the expression of eiF4E3 between these two groups.

CONCLUSIONMicroRNA-338 can recognize the 3'UTR of eiF4E3 while it has no significant effect on the expression of eiF4E3. The post-target-recognizing regulation for miRNA do exist and this mechanism is possibly related to the tertiary structure of target mRNA.

3' Untranslated Regions ; genetics ; Animals ; Eukaryotic Initiation Factor-4E ; genetics ; Gene Expression Regulation ; MicroRNAs ; genetics ; PC12 Cells ; Protein Structure, Secondary ; Protein Transport ; genetics ; RNA, Messenger ; genetics ; Rats

Timely cell cycle regulation is conducted by sequential activation of a family of serine-threonine kinases called cycle dependent kinases (CDKs). Tight CDK regulation involves cyclin dependent kinase inhibitors (CKIs) which ensure the correct timing of CDK activation in different phases of the cell cycle. One CKI of importance is p27(KIP1). The regulation and cellular localization of p27(KIP1) can result in biologically contradicting roles when found in the nucleus or cytoplasm of both normal and tumor cells. The p27(KIP1) protein is mainly regulated by proteasomal degradation and its downregulation is often correlated with poor prognosis in several types of human cancers. The protein can also be functionally inactivated by cytoplasmic localization or by phosphorylation. The p27(KIP1) protein is an unconventional tumor suppressor because mutation of its gene is extremely rare in tumors, implying the normal function of the protein is deranged during tumor development. While the tumor suppressor function is mediated by p27(KIP1)'s inhibitory interactions with the cyclin/CDK complexes, its oncogenic function is cyclin/CDK independent, and in many cases correlates with cytoplasmic localization. Here we review the basic features and novel aspects of the p27(KIP1) protein, which displays genetically separable tumor suppressing and oncogenic functions.
Animals ; Cyclin-Dependent Kinases/genetics/*metabolism ; Humans ; Intracellular Signaling Peptides and Proteins/genetics/*metabolism ; Mutation ; Neoplasms/genetics/*metabolism ; Phosphorylation/genetics ; Protein Transport/genetics ; Tumor Suppressor Proteins/genetics/*metabolism

This study was aimed to explore if the intracellular transportation direction of von Willebrand factor-cleaving protease (ADAMTS13, vWF-CP) after synthesis is determined by the carboxyl terminal TSP2-8CUB1+2 domains of ADAMTS13 and to decipher the relationship between the structure and function of ADAMTS13. The recombinant plasmids pcDNA3.1-ADAMTS13 and pcDNA3.1-delTSP2-8CUB1+2 ADAMTS13 were introduced into Madin-Darby canine kidney cells (MDCK) by lipofectamine-mediated DNA transfection. Positive cell clones gained after antibiotic-screening were grown on 6-well transwell filter units with a zeolite membrane in the middle layer. The conditioned culture media in both apical and basolateral wells were collected when cells reached confluency and the tight cell monolayer formed. ADAMTS13 proteases in the conditioned media were determined by Western blot, and the direction of ADAMTS13 secretion in polarized cells was comparatively analyzed. The results showed that Madin-Darby canine kidney cells stably expressing wild-type ADAMTS13 were grown on 6-well transwell filter units, then ADAMTS13 protease was only determined in the apical area of the transwell filter units by Western blot, but the recombinant ADAMTS13 protease was determined both in the apical and basolateral area of cells in the group of expressing TSP2-8CUB-1+2 domain-deleted ADAMTS13. It is concluded that the metalloprotease ADAMTS13 is sorted apically in polarized cells, and the carboxyl-terminal TSP2-8 and CUB1+2 domains of ADAMTS13 are important for the direction of ADAMTS13 protease transportation in the cells after being synthesized.
ADAM Proteins ; biosynthesis ; ADAMTS13 Protein ; Animals ; Dogs ; Madin Darby Canine Kidney Cells ; Plasmids ; Protein Interaction Domains and Motifs ; Protein Transport ; genetics ; Transfection ; von Willebrand Factor ; genetics ; metabolism ; secretion

The human ether-a-go-go related gene (HERG) encodes the α -subunit of the rapid component of the delayed rectifier K(+) channel, which is essential for the third repolarization of the action potential of human myocardial cells. Mutations of the HERG gene can cause type II hereditary long QT syndrome (LQT2), characterized by prolongation of the QT interval, abnormal T wave, torsade de pointes, syncope and sudden cardiac death. So far more than 300 HERG mutations have been identified, the majority of which can cause LQT2 due to HERG protein trafficking defect. It has been reported that certain drugs can induce acquired long QT syndrome through directly blocking the pore and/or affecting the HERG trafficking. The trafficking defects and K(+) currents can be restored with low temperature and certain drugs. However, the mechanisms underlying defective trafficking caused by HERG mutations and the inhibition/restoration of HERG trafficking by drugs are still unknown. This review summarizes the current understanding of the molecular mechanisms including HERG trafficking under physiological and pathological conditions, and the effects of drugs on the HERG trafficking, in order to provide theoretical evidence for the diagnosis and treatment of long QT syndrome.
Animals ; ERG1 Potassium Channel ; Ether-A-Go-Go Potassium Channels ; genetics ; metabolism ; Humans ; Long QT Syndrome ; genetics ; metabolism ; physiopathology ; Protein Transport

OBJECTIVETo study the nuclear localization of insulin-like growth factor binding protein-6(IGFBP-6) in PC-3M cells.

METHODSThe two fragments of the nuclear localization sequence (NLS)-deleted IGFBP-6 and the NLS-mutated IGFBP-6 were obtained by overlapping PCR, and then the fragment was inserted into a pEGFP-C1 vector. PC-3M cells were transfected with the expression constructs containing wild-type IGFBP-6 or the two mutants (pEGFP-C1-BP6 Delta NLS and pEGFP-C1-BP6-Mut), and the different distribution of the three EGFP-fusion proteins was observed by confocal laser microscope. The statistical analysis of the ratio of the nuclear fluorescence to the cytoplasmic fluorescence (Fn/c) was performed. Results Confocal microscopic images of transfected cells showed that the green fluorescence of EGFP-IGFBP-6 was concentrated mostly in the nuclei, whereas the control cells expressing EGFP showed green fluorescence distributed uniformly. The results of Fn/c from EGFP and EGFP-IGFBP-6 were significant different (P<0.05). The NLS-deleted IGFBP-6 completely eliminated nuclear accumulation of the green fluorescent signal; in contrast, nuclear accumulation was only slightly reduced for the NLS-mutated IGFBP-6; compared with wild-type IGFBP-6, both mutants were significantly different (P<0.05). Conclusions IGFBP-6 can be translocated to the nucleus in PC-3M cell that is mediated by a putative NLS sequence. Our study provides new evidence for further studies on the insulin-like growth factor-independent activity of IGFBP-6.

Cell Line, Tumor ; Cell Nucleus ; metabolism ; Genetic Vectors ; Humans ; Insulin-Like Growth Factor Binding Protein 6 ; genetics ; metabolism ; Plasmids ; genetics ; Protein Transport ; genetics ; Transfection

Idiopathic myelofibrosis is a type of chronic myeloproliferative disorders characterized by splenomegaly, a leukoerythroblastic blood picture, teardrop poikilocytosis, in various degrees of bone marrow fibrosis and extramedullary hematopoiesis. In this paper, the biological characters and pathogenesis of idiopathic myelofibrosis such as mutation of tyrosine kinase receptor, mutation of GABA transporter 1, JAK2 mutation and c-MPl mutation, as well as other pathogenesis related with idiopathic myelofibrosis were reviewed.
GABA Plasma Membrane Transport Proteins ; genetics ; Humans ; Janus Kinase 2 ; genetics ; Mutation ; Primary Myelofibrosis ; etiology ; genetics ; Receptor Protein-Tyrosine Kinases ; genetics ; Receptors, Thrombopoietin ; genetics

OBJECTIVE: To explore the characteristics of SLC25A13 gene variants in 16 infants with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). METHODS: The infants were subjected to high-throughput DNA sequencing for coding exons and flanking regions of the target genes. Suspected variants were verified by Sanger sequencing and bioinformatic analysis. RESULTS: Among the 16 NICCD cases, 15 were found to harbor pathogenic variants. Among these, IVS14-9A>G, c.1640G>A, c.762T>A, c.736delG, c.1098Tdel and c.851G>A were previously unreported. CONCLUSION Six novel SLC25A13 variants were found by high-throughput sequencing, which has enriched the spectrum of SLC25A13 gene variants and provided a basis for genetic counseling and prenatal diagnosis.
Calcium-Binding Proteins/genetics* ; Cholestasis, Intrahepatic/genetics* ; Citrullinemia/genetics* ; Humans ; Infant ; Infant, Newborn ; Mitochondrial Membrane Transport Proteins/genetics* ; Mutation ; Organic Anion Transporters/genetics* ; Protein Deficiency

OBJECTIVETo investigate the additive effects of uncoupling protein 2 (UCP2) gene Ala55Val variation and ADR beta(3) gene Trp64Arg variation on the obesity in Chinese Han population.

METHODSThe UCP2 gene Ala55Val variation and ADR beta(3) gene Trp64Arg variation were examined by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) in 119 obese subject with mean BMI (27.9+/-2.98)kg/m(2) and in 177 control subjects with mean BMI(21.9+/-1.9)kg/m(2). The additive effects of the two gene mutations were analyzed.

RESULTS(1) The frequency of ADR beta(3) gene Trp64Arg variation in obese subjects was not significantly different from that in control subjects. In control subjects, the Trp64Arg variation carriers had higher fasting glucose level and 2-hour-post-prandial glucose level than did non-carriers. (2) The frequency of homozygote of UCP2 gene Ala55Val variation in obese subjects was higher than that in the control subjects (OR=3.71, P=0.001). In control subjects the Ala55Val variation carriers had higher BMI. (3) When there was only UCP2 gene or ADR beta(3) gene mutation, the frequency of gene mutation in obese subjects was not significantly different from that in control subjects (P>0.05). But when there were simultaneously two gene mutations, the frequency of gene mutations was higher in obese subjects than in control subjects (OR=2.57, P=0.009). (4) The genotype carriers with Val/Val+ Trp/Arg were the greatest relation to obese obesity (OR=8.58, P=0.002).

CONCLUSIONThe homozygote of UCP2 gene Ala55Val mutation increases the risk of obesity. Though the UCP2 gene mutation alone or the ADR beta(3) gene mutation alone is not associated with obesity, the possible additive effects of the two micro-genes increase the occurring of obesity.

Adult ; Aged ; Female ; Humans ; Ion Channels ; Male ; Membrane Transport Proteins ; genetics ; Middle Aged ; Mitochondrial Proteins ; genetics ; Mutation ; Obesity ; genetics ; Receptors, Adrenergic, beta-3 ; genetics ; Uncoupling Protein 2