Dephosphorylation of MAP2D enhances its binding to vimentin in preovulatory ovarian granulosa cells.

Preovulatory granulosa cells express the low-molecular-mass MAP2D variant of microtubule-associated protein 2 (MAP2). Activation of the luteinizing hormone choriogonadotropin receptor by human choriogonadotropin (hCG) promotes dephosphorylation of MAP2D on Thr256 and Thr259. We sought to evaluate the association of MAP2D with the cytoskeleton, and the effect of hCG on this association.

Blau syndrome-associated Nod2 mutation alters expression of full-length NOD2 and limits responses to muramyl dipeptide in knock-in mice.

The biochemical mechanism by which mutations in nucleotide-binding oligomerization domain containing 2 (NOD2) cause Blau syndrome is unknown. Several studies have examined the effect of mutations associated with Blau syndrome in vitro, but none has looked at the implication of the mutations in vivo. To test the hypothesis that mutated NOD2 causes alterations in signaling pathways downstream of NOD2, we created a Nod2 knock-in mouse carrying the most common mutation seen in Blau syndrome, R314Q (corresponding to R334Q in humans).

Loss of R2D2 proteins ROPN1 and ROPN1L causes defects in murine sperm motility, phosphorylation, and fibrous sheath integrity.

The fibrous sheath (FS) is a flagellar cytoskeletal structure unique to sperm that surrounds the outer dense fibers and axoneme. Its primary components are A-kinase anchoring proteins (AKAPs) 3 and 4, which suggests that the FS affects flagellar beating via the scaffolding of signaling pathways necessary for motility. Sperm proteins ROPN1 and ROPN1L bind AKAP3.

PKA and GAB2 play central roles in the FSH signaling pathway to PI3K and AKT in ovarian granulosa cells.

Controlled maturation of ovarian follicles is necessary for fertility. Follicles are restrained at an immature stage until stimulated by FSH secreted by pituitary gonadotropes. FSH acts on granulosa cells within the immature follicle to inhibit apoptosis, promote proliferation, stimulate production of steroid and protein hormones, and induce ligand receptors and signaling intermediates.

α-Tocopherol (vitamin E) stimulates cyclic AMP production in human peripheral mononuclear cells and alters immune function.

α-Tocopherol, the most biologically active member of the vitamin E family of fat soluble compounds, exhibits both antioxidant and anti-inflammatory properties. However, its mechanisms of action are not fully understood. Here, we show that, unlike other antioxidants, α-tocopherol stimulates the production of cyclic adenosine monophosphate (cAMP).

Loss of ASP but not ROPN1 reduces mammalian ciliary motility.

Protein kinase A (PKA) signaling is targeted by interactions with A-kinase anchoring proteins (AKAPs) via a dimerization/docking domain on the regulatory (R) subunit of PKA. Four other mammalian proteins [AKAP-associated sperm protein (ASP), ropporin (ROPN1), sperm protein 17 (SP17) and calcium binding tyrosine-(Y)-phosphorylation regulated protein (CABYR)] share this highly conserved RII dimerization/docking (R2D2) domain. ASP and ROPN1 are 41% identical in sequence, interact with a variety of AKAPs in a manner similar to PKA, and are expressed in ciliated and flagellated human cells.

Retinoid-induced expression and activity of an immediate early tumor suppressor gene in vascular smooth muscle cells.

Retinoids are used clinically to treat a number of hyper-proliferative disorders and have been shown in experimental animals to attenuate vascular occlusive diseases, presumably through nuclear receptors bound to retinoic acid response elements (RARE) located in target genes. Here, we show that natural or synthetic retinoids rapidly induce mRNA and protein expression of a specific isoform of A-Kinase Anchoring Protein 12 (AKAP12β) in cultured smooth muscle cells (SMC) as well as the intact vessel wall. Expression kinetics and actinomycin D studies indicate Akap12β is a retinoid-induced, immediate-early gene.

AKAPs in lipid rafts are required for optimal antigen presentation by dendritic cells.

Dendritic cell (DC) maturation and antigen presentation are regulated by activation of protein kinase A (PKA) signaling pathways, through unknown mechanisms. We have recently shown that interfering with PKA signaling through the use of anchoring inhibitor peptides hinders antigen presentation and DC maturation. These experiments provide evidence that DC maturation and antigen presentation are regulated by A-kinase anchoring proteins (AKAPs).

Lipoic acid stimulates cAMP production via G protein-coupled receptor-dependent and -independent mechanisms.

Lipoic acid (LA) is a naturally occurring fatty acid that exhibits anti-oxidant and anti-inflammatory properties and is being pursued as a therapeutic for many diseases including multiple sclerosis, diabetic polyneuropathy and Alzheimer's disease. We previously reported on the novel finding that racemic LA (50:50 mixture of R-LA and S-LA) stimulates cAMP production, activates prostanoid EP2 and EP4 receptors and adenylyl cyclases (AC), and suppresses activation and cytotoxicity in NK cells. In this study, we present evidence that furthers our understanding of the mechanisms of action of LA.

Lipoic acid attenuates inflammation via cAMP and protein kinase A signaling.

Background: Abnormal regulation of the inflammatory response is an important component of diseases such as diabetes, Alzheimer's disease and multiple sclerosis (MS). Lipoic acid (LA) has been shown to have antioxidant and anti-inflammatory properties and is being pursued as a therapy for these diseases. We first reported that LA stimulates cAMP production via activation of G-protein coupled receptors and adenylyl cyclases.

Myeloid translocation gene 16b is a dual A-kinase anchoring protein that interacts selectively with plexins in a phospho-regulated manner.

The myeloid translocation gene (MTG) homologue Nervy associates with PlexinA on the plasma membrane, where it functions as an A-kinase anchoring protein (AKAP) to modulate plexin-mediated semaphorin signaling in Drosophila. Mammalian MTG16b is an AKAP found in immune cells where plexin-mediated semaphorin signaling regulates immune responses. This study provides the first evidence that MTG16b is a dual AKAP capable of binding plexins.

A-kinase anchoring in dendritic cells is required for antigen presentation.

Background: Dendritic cells (DC) are the most potent antigen presenting cells (APC) of the immune system. Prostaglandin E(2), cyclic AMP, and protein kinase A (PKA) have all been shown to regulate DC maturation and activity. In other cells, the ability of these molecules to convey their signals has been shown to be dependent on A-kinase anchoring proteins (AKAPs).

Lipoic acid stimulates cAMP production via the EP2 and EP4 prostanoid receptors and inhibits IFN gamma synthesis and cellular cytotoxicity in NK cells.

The antioxidant lipoic acid (LA) treats and prevents the animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE). In an effort to understand the therapeutic potential of LA in MS, we sought to define the cellular mechanisms that mediate the effects of LA on human natural killer (NK) cells, which are important in innate immunity as the first line of defense against invading pathogens and tumor cells. We discovered that LA stimulates cAMP production in NK cells in a dose-dependent manner.

Lipoic acid: a novel therapeutic approach for multiple sclerosis and other chronic inflammatory diseases of the CNS.

The naturally occurring antioxidant lipoic acid (LA) was first described as an essential cofactor for the conversion of pyruvate to Acetyl-CoA, a critical step in respiration. LA is now recognized as a compound that has many biological functions. Along with its reduced form dihydrolipoic acid (DHLA), LA reduces and recycles cellular antioxidants such as glutathione, and chelates zinc, copper and other transition metal ions in addition to heavy metals.

Protein kinase A RII-like (R2D2) proteins exhibit differential localization and AKAP interaction.

A-kinase anchoring proteins (AKAPs) bind to protein kinase A (PKA) via an amphipathic helix domain that interacts with a dimerization/docking domain on the regulatory (R) subunit of PKA. Four other mammalian proteins (ROPN1, ASP, SP17, and CABYR) also contain a highly conserved RII dimerization/docking (R2D2) domain, suggesting all four proteins may interact with all AKAPs in a manner similar to RII. All four of these proteins were originally detected in the flagellum of mammalian sperm.

Identification and characterization of RHOA-interacting proteins in bovine spermatozoa.

In somatic cells, RHOA mediates actin dynamics through a GNA13-mediated signaling cascade involving RHO kinase (ROCK), LIM kinase (LIMK), and cofilin. RHOA can be negatively regulated by protein kinase A (PRKA), and it interacts with members of the A-kinase anchoring (AKAP) family via intermediary proteins. In spermatozoa, actin polymerization precedes the acrosome reaction, which is necessary for normal fertility.

The role of protein kinase A and A-kinase anchoring proteins in modulating T-cell activation: progress and future directions.

Protein kinase A (PKA) is a broad-specificity serine/threonine protein kinase whose spatial and temporal regulation is maintained through interactions with A-kinase anchoring proteins (AKAPs). Subcellular localization of AKAPs through unique targeting domains provides a mechanism by which PKA can respond to localized microdomains of cyclic AMP (cAMP) and phosphorylate nearby substrates. For nearly 40 years, cAMP has been known to be a potent modulator of the immune system.

AKAP3 selectively binds PDE4A isoforms in bovine spermatozoa.

Cyclic AMP plays an important role in regulating sperm motility and acrosome reaction through activation of cAMP-dependent protein kinase A (PKA). Phosphodiesterases (PDEs) modulate the levels of cyclic nucleotides by catalyzing their degradation. Although PDE inhibitors specific to PDE1 and PDE4 are known to alter sperm motility and capacitation in humans, little is known about the role or subcellular distribution of PDEs in spermatozoa.

The role of protein kinase A anchoring via the RII alpha regulatory subunit in the murine immune system.

Intracellular cAMP may inhibit T cell activation and proliferation via activation of the cAMP-dependent protein kinase, PKA. PKA signaling is maintained through interactions of the regulatory subunit with A-kinase anchoring proteins (AKAPs). We demonstrated that T cells contain AKAPs and now ask whether PKA anchoring to AKAPs via the RIIalpha regulatory subunit is necessary for cAMP-mediated inhibition of T cell activation.

A-kinase anchoring proteins interact with phosphodiesterases in T lymphocyte cell lines.

The cAMP protein kinase A (PKA) pathway in T cells conveys an inhibitory signal to suppress inflammation. This study was performed to understand the mechanisms involved in cAMP-mediated signaling in T lymphocytes. A-kinase anchoring proteins (AKAPs) bind and target PKA to various subcellular locations.

Neuronal microtubule-associated protein 2D is a dual a-kinase anchoring protein expressed in rat ovarian granulosa cells.

A-kinase anchoring proteins (AKAPs) function to target protein kinase A (PKA) to specific locations within the cell. AKAPs are functionally identified by their ability to bind the type II regulatory subunits (RII) of PKA in an in vitro overlay assay. We previously showed that follicle-stimulating hormone (FSH) induces the expression of an 80-kDa AKAP (AKAP 80) in ovarian granulosa cells as they mature from a preantral to a preovulatory phenotype.

Expression and intracellular localization of protein phosphatases 2A and 2B, protein kinase a, A-Kinase anchoring protein (AKAP79), and binding of the regulatory (RII) subunit of protein kinase a to AKAP79 in human myometrium.

Objective: To determine the expression and intracellular localization of protein phosphatases 2A (PP2A) and 2B (PP2B), protein kinase A (PKA), and A-kinase anchoring protein (AKAP79), and expression of PKA (RII subunit) binding to AKAP79 in human postmenopausal and pregnant myometrium and to correlate their expressions to blood levels of estradiol, progesterone, and oxytocin.

Methods: Myometrial samples were taken from postmenopausal hysterectomy specimens (group 1, n = 5), from pregnant nonlaboring women (group 2, n = 7) and pregnant laboring women (group 3, n = 5) at cesarean. Western immunoblotting, immunohistochemical, and RII overlay assays were performed.

Follicle-stimulating hormone activates extracellular signal-regulated kinase but not extracellular signal-regulated kinase kinase through a 100-kDa phosphotyrosine phosphatase.

In this report we sought to elucidate the mechanism by which the follicle-stimulating hormone (FSH) receptor signals to promote activation of the p42/p44 extracellular signal-regulated protein kinases (ERKs) in granulosa cells. Results show that the ERK kinase MEK and upstream intermediates Raf-1, Ras, Src, and L-type Ca(2+) channels are already partially activated in vehicle-treated cells and that FSH does not further activate them. This tonic stimulatory pathway appears to be restrained at the level of ERK by a 100-kDa phosphotyrosine phosphatase that associates with ERK in vehicle-treated cells and promotes dephosphorylation of its regulatory Tyr residue, resulting in ERK inactivation.

Sperm PP1gamma2 is regulated by a homologue of the yeast protein phosphatase binding protein sds22.

Serine/threonine phosphatase PP1gamma2 is a testis-specific protein phosphatase isoform in spermatozoa. This enzyme appears to play a key role in motility initiation and stimulation. Catalytic activity of PP1gamma2 is higher in immotile compared with motile spermatozoa.

Identification and characterization of myeloid translocation gene 16b as a novel a kinase anchoring protein in T lymphocytes.

Increased levels of intracellular cAMP inhibit T cell activation and proliferation. One mechanism is via activation of the cAMP-dependent protein kinase (PKA). PKA is a broad specificity serine/threonine kinase whose fidelity in signaling is maintained through interactions with A kinase anchoring proteins (AKAPs).