The cystic fibrosis transmembrane conductance regulator (CFTR) is a unique member of the ATP-binding cassette (ABC) transporter superfamily that forms a Cl(-) channel with complex regulation. CFTR is composed of five domains: two membrane-spanning domains (MSDs), two nucleotide-binding domains (NBDs) and a unique regulatory domain (RD). The MSDs assemble to form a low conductance (6-10 pS) anion-selective pore with deep intracellular and shallow extracellular vestibules separated by a selectivity filter. The NBDs form a head-to-tail dimer with two ATP-binding sites (termed sites 1 and 2) located at the dimer interface. Anion flow through CFTR is gated by the interaction of ATP with sites 1 and 2 powering cycles of NBD dimer association and dissociation and hence, conformational changes in the MSDs that open and close the channel pore. The RD is an unstructured domain with multiple consensus phosphorylation sites, phosphorylation of which stimulates CFTR function by enhancing the interaction of ATP with the NBDs. Tight spatial and temporal control of CFTR activity is achieved by macromolecular signalling complexes in which scaffolding proteins colocalise CFTR and plasma membrane receptors with protein kinases and phosphatases. Moreover, a macromolecular complex composed of CFTR and metabolic enzymes (a CFTR metabolon) permits CFTR activity to be coupled tightly to metabolic pathways within cells so that CFTR inhibition conserves vital energy stores. CFTR is expressed in epithelial tissues throughout the body, lining ducts and tubes. It functions to control the quantity and composition of epithelial secretions by driving either the absorption or secretion of salt and water. Of note, in the respiratory airways CFTR plays an additional important role in host defence. Malfunction of CFTR disrupts transepithelial ion transport leading to a wide spectrum of human disease.
Cystic Fibrosis Transmembrane Conductance Regulator ; physiology ; Epithelium ; physiology ; Humans ; Ion Transport ; Phosphorylation ; Protein Interaction Domains and Motifs

Animals ; Humans ; Models, Biological ; Oxidative Stress ; genetics ; physiology ; Phosphorylation ; Protein Kinase C ; genetics ; metabolism ; physiology ; Signal Transduction ; genetics ; physiology

The purpose of this study is to reveal the role of Girdin in regulating the aggregation of actin filaments by studying the relationship between PKB/Akt and Girdin. First we used Scansite software (http://scansite.mit.edu) to predict relevant target sites of PKB/Akt on mouse Girdin. To gain insight into the role of phosphorylation of Girdin by PKB/Akt, we assessed the location of phosphorylated Girdin in fertilized eggs by staining with anti-P-Girdin 1 417 Ab. We detected a distinct increase in the fluorescence signal of F-actin and P-Girdin 1 417 after microinjection of Akt WT and myr-Akt. The addition of myr-Akt induced phosphorylation of Girdin in mouse fertilized eggs. In addition, siRNA-mediated Akt-knockdown blocked phosphorylation of Girdin. The distribution of actin filaments was obviously scattered. These results strongly suggest that PKB/Akt could directly phosphorylate Girdin on Ser1 417 and promote its function in mouse fertilized eggs.
Actins ; physiology ; Animals ; Mice ; Microfilament Proteins ; physiology ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; physiology ; RNA, Small Interfering ; Vesicular Transport Proteins ; physiology ; Zygote

Humans ; Hypoxia-Ischemia, Brain ; etiology ; Infant, Newborn ; Phosphorylation ; Protein Phosphatase 2 ; physiology ; Receptors, N-Methyl-D-Aspartate ; chemistry ; physiology

Sperm must be capacitated before sperm-ovum fusion. Capacitation was once considered as hyperactivation. But now many investigators thought that capacitation wasn't equal to hyperactivation, and that sperm hyperactivation might be a moiety of capacitation or the result of capacitation. In the present, the methods used to study sperm capacitation include fertilization in vitro, induction of sperm acrosome reaction, FITC-labeled chlortetracycline and plant hemoagglutinin. The studies on sperm capacitation in vitro mainly focused on the inductive substances of sperm capacitation and subsequent results analysis. It could lay foundation for the manifestation of molecular mechanism of sperm capacitation and destination of sperm capacitation in molecular levels.
Adenylyl Cyclases ; physiology ; Bicarbonates ; metabolism ; Calcium ; metabolism ; Humans ; Male ; Phosphorylation ; Sperm Capacitation ; drug effects ; physiology ; Sperm Motility

Homoeostasis depends on the close connection and intimate molecular exchange between extracellular, intracellular and intercellular networks. Intercellular communication is largely mediated by gap junctions (GJs), a type of specialized membrane contact composed of variable number of channels that enable direct communication between cells by allowing small molecules to pass directly into the cytoplasm of neighbouring cells. Although considerable evidence indicates that gap junctions contribute to the functions of many organs, such as the bone, intestine, kidney, heart, brain and nerve, less is known about their role in oral development and disease. In this review, the current progress in understanding the background of connexins and the functions of gap junctions in oral development and diseases is discussed. The homoeostasis of tooth and periodontal tissues, normal tooth and maxillofacial development, saliva secretion and the integrity of the oral mucosa depend on the proper function of gap junctions. Knowledge of this pattern of cell-cell communication is required for a better understanding of oral diseases. With the ever-increasing understanding of connexins in oral diseases, therapeutic strategies could be developed to target these membrane channels in various oral diseases and maxillofacial dysplasia.
Bone and Bones ; Cell Communication ; Connexins ; metabolism ; physiology ; Gap Junctions ; metabolism ; pathology ; Homeostasis ; physiology ; Humans ; Mouth Diseases ; Phosphorylation

Acetylation ; Animals ; Humans ; Phosphorylation ; Tumor Suppressor Protein p53 ; chemistry ; genetics ; metabolism ; physiology

OBJECTIVETo explore the mechanisms involved in Staphylococcus aureus (S. aureus) invading human monocytic U937 cells.

METHODSS. aureus were added to U937 cells at multiplicity of infections (MOI) of 20:1 for 0, 15, 30, 60, and 90 minutes, respectively. Cell apoptosis was analyzed with Hoechst 33258 staining and Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) flow cytometry analysis. Akt and nuclear factor-kappaB (NF-kappaB) activities were detected by Western blotting.

RESULTSInfection of U937 cells with S. aureus induced rapid cell death in a time-dependent manner, and the cells displayed characteristic features of apoptosis. S. aureus-induced apoptosis was associated with a prominent downregulation of activated (phosphorylated) Akt and NF-kappaB. The inhibition of phosphorylated Akt by LY294002 led to the inhibition of NF-kappaB in a dose-dependent manner. Inhibition of Akt with LY294002 caused further increase in apoptosis of U937 cells.

CONCLUSIONSS. aureus can stimulate the apoptosis of U937 cells. S. aureus induces apoptosis of U937 cells by inhibiting Akt-regulated NF-kappaB.

Apoptosis ; Chromones ; pharmacology ; Humans ; Morpholines ; pharmacology ; NF-kappa B ; physiology ; Phosphatidylinositol 3-Kinases ; physiology ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; antagonists & inhibitors ; physiology ; Staphylococcus aureus ; pathogenicity ; U937 Cells

OBJECTIVETo investigate the mechanism of hepatocytic insulin signal transduction defects in severely scalded rats, so as to clarify the molecular basis of postburn insulin resistance.

METHODSWistar rats inflicted by 30% III degree scalding on the back were employed as the model. The rat hepatocytic insulin receptor was partially purified by wheat-germ agglutinin (WGA)-sepharose 4B affinity chromatography. The change of receptor tyrosine protein kinase (TPK) activity, the receptor beta-subunit autophosphorylation and the hepatocytic insulin receptor binding behavior of scalded rats during early stage of scalding were observed by means of insulin receptor binding test, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) autoradiography of phosphorylation of insulin receptor and phosphorylation of exogenous substrate.

RESULTSThere exhibited no evident changes of hepatocytic insulin receptor maximal binding capacity and affinity at 3 postburn days (PBDs) in scalded rats. The autophosphorylation capacity of the receptor beta-subunit decreased significantly. And the receptor TPK activity decreased obviously and its reaction to insulin stimulation decreased markedly.

CONCLUSIONThe defects of the insulin receptor signal transduction in hepatocyte leading to the post-receptor defects of insulin biological effects might be molecular mechanism of postburn insulin resistance.

Animals ; Burns ; metabolism ; pathology ; physiopathology ; Disease Models, Animal ; Hepatocytes ; metabolism ; Insulin ; physiology ; Insulin Resistance ; physiology ; Phosphorylation ; Rats ; Rats, Wistar ; Receptor, Insulin ; metabolism ; Signal Transduction ; physiology

LFA-1 and ICAM-1 mediate a bi-directional signaling across the cell membrane which is essential for biological functions of lymphocyte, including exudation, activation, adhesion, immunosurveillance as well as immuno-logical synapse formation. The signal transducing is a dynamic process and dependent on the binding capacity between LFA-1 and ICAM-1. The affinity and the avidity of LFA-1 are two major regulation forms in this process. Phosphorylation of LFA-1 and cytoskeleton protein talin 1 play a critical role in signal transducing. In biology of lymphocyte, LFA-1 and ICAM-1 interaction forms the co-stimulatory signal to promote activation, proliferation and division. In this article the regulation of binding capacity between LFA-1 and ICAM-1, the regulation of LFA-1 subunit phosphorylation, the role of talin1 in signaling transduction of LFA-1 and ICAM-1, the synergic stimulatory signaling of LPA-1 and ICAM-1 were reviewed.
Humans ; Intercellular Adhesion Molecule-1 ; metabolism ; physiology ; Ligands ; Lymphocyte Function-Associated Antigen-1 ; metabolism ; physiology ; Lymphocytes ; cytology ; immunology ; metabolism ; Phosphorylation ; Signal Transduction ; physiology ; Talin ; metabolism