GTPrS-dependent phospholipase D activity in human neutrophils was investigated using exogenous phospholipid as a substrate. Both cytosolic and membrane- associated phospholipase D activities were identified. The previously described 50 kDa cytosolic activating factor was resolved chromatographically from the cytosolic phospholipase D. Using exogenous phospholipid as substrate along with chromatographically resolved 50 kDa factor and recombinant ADP-ribosylation factor 1, plasma membrane was required for activity, indicating that the activity which was previously seen using endogenous phospholipid substrate was due to a phospholipase D located in the plasma membrane. In addition, ADP-ribosylation factor and the 50 kDa factor activated synergistically. Using neutrophil plasma membranes, a third regulator of neutrophil membrane phospholipase D was identified from bovine brain cytosol. This factor was resolved from ADP-ribosylation factor and Rho A by successive column chromatographies. The brain factor showed a synergistic effect with the 50 kDa neutrophil activator but an additive effect with recombinant ADP- ribosylation factor. Whether or not ADP-ribosylation factor or the brain factor were present, high activities were seen only when the 50 kDa factor was present, indicating that the 50 kDa cytosolic factor is a major activating factor for the neutrophil plasma membrane phospholipase D.
ADP-Ribosylation Factor 1 ; ADP-Ribosylation Factors* ; Brain* ; Cell Membrane ; Chromatography ; Cytosol* ; Fibrinogen ; Humans ; Membranes ; Neutrophils* ; Phospholipase D* ; Phospholipases*

OBJECTIVETo detect expression of mouse ARL-1 homologous proteins in mouse tissues, and analyze homology, genetic distance and phylogenetic relationship between human aldose reductase like-1 (ARL-1) and mouse homologous proteins.

METHODSHomology of mouse ARL-1 homologous proteins with human ARL-1 was analyzed by software Clustal X 1.8 using GenBank and Swiss-Prot database; genetic distance and phylogenetic relationship between mouse ARL-1 homologous proteins and human ARL-1 were analyzed by software Mega 2.0; mouse tissues were detected by Western blotting using polyclonal antibodies against ARL-1 protein from domestic rabbits.

RESULTSThe amino acid sequence of human ARL-1 was 83%, 82%, 81%, 79%, 70%, 51%, 50% and 45% identical to that of the Chinese hamster ovary reductase (CHO-Red), the mouse fibroblast growth factor-regulated protein (FR-1), rat aldose reductase-like protein (rARLP), the mouse vas deferens protein (MVDP), rat lens aldose reductase (LeAR), delta4-3-ketosteroid-5beta-reductase (5beta-Red), rat aldo-keto reductase protein c (RaK-c) and 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD). Among all the mouse ARL-1 homologous proteins, the genetic distance between CHO-Red and human ARL was the shortest (18.0%, P = 0.023), next was FR-1 (19.1%, P=0.023) and rARLP (19.9%, P = 0.025). From the phylogenetic tree, the protein whose relationship with human ARL-1 was the closest with CHO-Red, next was mouse FR-1, rARLP, MVDP and LeAR. Homologous proteins were found in mouse tissues including vas deferens, testis, bladder and uterus by Western blotting using polyclonal antibodies against ARL-1 protein from domestic rabbits.

CONCLUSIONSCHO-Red has the highest homology, the shortest genetic distance and the closest relationship with human ARL-1, next is FR-1, rARLP, MVDP. The major distribution of mouse ARL-1 homologous proteins is in vas deferens, testis, bladder and uterus, deducing they might be CHO-Red, FR-1, rARLP or MVDP

ADP-Ribosylation Factors ; biosynthesis ; genetics ; Aldehyde Reductase ; biosynthesis ; genetics ; Animals ; Cloning, Molecular ; Cricetinae ; Cricetulus ; Female ; Gene Expression ; Humans ; Male ; Membrane Proteins ; biosynthesis ; genetics ; Mice ; genetics ; Pregnancy ; Sequence Homology, Amino Acid

OBJECTIVETo investigate the effects of silencing ADP-ribosylation factor 6 (Arf6) on the proliferation, migration, and invasion of prostate cancer cell line PC-3 and the possible molecular mechanisms.

METHODSThree Arf6-specific small interfering RNA (siRNA) were transfected into cultured prostate cancer cell line PC-3. Arf6 expression was examined by real-time PCR and Western blotting. MTT assay, wound healing assay, and Transwell migration and invasion assay were used to observe the effect of Arf6 silencing on the proliferation, migration, and invasion ability of PC-3 cells. The levels of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), ERK1/2, p-AKT, AKT and Rac1 were detected by Western blotting.

RESULTSTransfection of siRNA-3 resulted in significantly decreased Arf6 mRNA and protein expression with inhibition rates of (91.88±3.13)% and (86.37±0.57)%, respectively. Arf6 silencing by siRNA-3 markedly suppressed the proliferation, migration and invasion of PC-3 cells and reduced the expression levels of p-ERK1/2 and Rac1.

CONCLUSIONSilencing of Arf6 efficiently inhibits the proliferation, migration, and invasion of PC-3 cells in vitro, and the underlying mechanisms may involve the down-regulation of p-ERK1/2 and Rac1.

ADP-Ribosylation Factors ; genetics ; metabolism ; Cell Line, Tumor ; Cell Movement ; Down-Regulation ; Humans ; Male ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Neoplasm Invasiveness ; Prostatic Neoplasms ; pathology ; RNA Interference ; RNA, Messenger ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; Real-Time Polymerase Chain Reaction ; Transfection ; Wound Healing ; rac1 GTP-Binding Protein ; metabolism

As glucose is known to induce insulin secretion in pancreatic beta cells, this study investigated the role of a phospholipase D (PLD)-related signaling pathway in insulin secretion caused by high glucose in the pancreatic beta-cell line MIN6N8. It was found that the PLD activity and PLD1 expression were both increased by high glucose (33.3 mM) treatment. The dominant negative PLD1 inhibited glucose-induced Beta2 expression, and glucose-induced insulin secretion was blocked by treatment with 1-butanol or PLD1-siRNA. These results suggest that high glucose increased insulin secretion through a PLD1-related pathway. High glucose induced the binding of Arf6 to PLD1. Pretreatment with brefeldin A (BFA), an Arf inhibitor, decreased the PLD activity as well as the insulin secretion. Furthermore, BFA blocked the glucose-induced mTOR and p70S6K activation, while mTOR inhibition with rapamycin attenuated the glucose induced Beta2 expression and insulin secretion. Thus, when taken together, PLD1 would appear to be an important regulator of glucose-induced insulin secretion through an Arf6/PLD1/mTOR/p70S6K/Beta2 pathway in MIN6N8 cells.
ADP-Ribosylation Factors/metabolism/physiology ; Animals ; Basic Helix-Loop-Helix Transcription Factors/metabolism/physiology ; Cells, Cultured ; Gene Expression Regulation, Enzymologic/drug effects ; Glucose/*pharmacology ; Insulin/*secretion ; Insulin-Secreting Cells/*drug effects/enzymology/metabolism/secretion ; Intracellular Signaling Peptides and Proteins/metabolism/physiology ; Mice ; Models, Biological ; Oligodeoxyribonucleotides, Antisense/pharmacology ; Phospholipase D/antagonists & inhibitors/genetics/metabolism/*physiology ; Protein-Serine-Threonine Kinases/metabolism/physiology ; Ribosomal Protein S6 Kinases, 70-kDa/metabolism/physiology ; Signal Transduction/drug effects/genetics