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Richard A Anderson

Publications and source records attributed to Richard A Anderson.

At least 19 recordsLinked to original sources
PubMed2026

Lipid transfer proteins and PI4KIIα generate a phosphoinositide-linked proteome.

Phosphoinositide (PIPn) lipid second messengers in membranes regulate numerous cellular processes. In the cytosol, the phosphatidylinositol (PI) 3-kinase (PI3K)/Akt pathway is scaffolded on IQGAP1 to facilitate the activation of Akt by the synthesis of PI3,4,5P3. In the nucleus, PIPn signaling occurs in compartments separate from membranes by stably linking PIPns to nuclear proteins. While several of these proteins have been identified, understanding the extent and impact of protein-linked PIPn signaling warrants further investigation. The tumor suppressor p53, was shown in the companion paper to be regulated by PI transfer proteins (PITPs) and a PI 4-kinase (PI4KIIα), which are required to form p53-PIPn complexes that assemble a nuclear PI3K/Akt pathway. Here we report that class I PITPs (PITPα/β) and PI4KIIα initiate PIPn linkages to many different proteins. PITPα/β and PI4KIIα accumulate in the nucleoplasm in response to stress and are necessary to synthesize nuclear PIPns linked to proteins. These PITPα/β-dependent protein-PIPn complexes are detected by metabolically labeling cells with the PIPn precursor [3H]-myo-inositol and resist denaturation and SDS-PAGE, indicating that these protein-PIPn complexes represent a putative posttranslational modification. Proteomic and gene set enrichment analysis of proteins that are linked to PI4,5P2 reveals an emerging PIPn-linked proteome (PIPylome) regulated by PITPα/β and enriched in proteins that play key functional roles in metabolism, cell motility/division, and the DNA damage response. The PIPn-linked proteome represents a third messenger signaling paradigm distinct from the canonical membrane-localized pathway whereby linked PIPn messengers regulate protein function.

Phosphatidylinositols↗
PubMed2007

Green tea increases anti-inflammatory tristetraprolin and decreases pro-inflammatory tumor necrosis factor mRNA levels in rats.

BACKGROUND: Tristetraprolin (TTP/ZFP36) family proteins have anti-inflammatory activity by binding to and destabilizing pro-inflammatory mRNAs such as Tnf mRNA, and represent a potential therapeutic target for inflammation-related diseases. Tea has anti-inflammatory properties but the molecular mechanisms have not been completely elucidated. We hypothesized that TTP and/or its homologues might contribute to the beneficial effects of tea as an anti-inflammatory product. METHODS: Quantitative real-time PCR was used to investigate the effects of green tea (0, 1, and 2 g solid extract/kg diet) on the expression of Ttp family genes (Ttp/Tis11/Zfp36, Zfp36l1/Tis11b, Zfp36l2/Tis11d, Zfp36l3), pro-inflammatory genes (Tnf, Csf2/Gm-csf, Ptgs2/Cox2), and Elavl1/Hua/Hur and Vegf genes in liver and muscle of rats fed a high-fructose diet known to induce insulin resistance, oxidative stress, inflammation, and TNF-alpha levels. RESULTS: Ttp and Zfp36l1 mRNAs were the major forms in both liver and skeletal muscle. Ttp, Zfp36l1, and Zfp36l2 mRNA levels were more abundant in the liver than those in the muscle. Csf2/Gm-csf and Zfp36l3 mRNAs were undetectable in both tissues. Tea (1 g solid extract/kg diet) increased Ttp mRNA levels by 50-140% but Tnf mRNA levels decreased by 30% in both tissues, and Ptgs2/Cox2 mRNA levels decreased by 40% in the muscle. Tea (2 g solid extract/kg diet) increased Elavl1/Hua/Hur mRNA levels by 40% in the liver but did not affect any of the other mRNA levels in liver or muscle. CONCLUSION: These results show that tea can modulate Ttp mRNA levels in animals and suggest that a post-transcriptional mechanism through TTP could partially account for tea's anti-inflammatory properties. The results also suggest that drinking adequate amounts of green tea may play a role in the prevention of inflammation-related diseases.

Journal Article↗
PubMed2007

A diurnal variation in testicular hormone production is maintained following gonadotrophin suppression in normal men.

OBJECTIVE: A diurnal variation in serum testosterone in adult men is well recognized, but whether this occurs during exogenous testosterone administration and the degree to which it is endogenous to the testis is unclear. DESIGN: A clinical research centre investigation of testicular function in normal men. PATIENTS: Twenty normal men were recruited, 10 of whom were investigated during administration of testosterone with etonogestrel to suppress gonadotrophin secretion. MEASUREMENTS: Hourly blood samples were taken over 24 h for measurement of testosterone, inhibin B, LH, FSH and cortisol. Urinary excretion of testosterone and the testicular steroid epitestosterone was also measured. RESULTS: In the controls, a diurnal variation in serum testosterone and LH but not FSH was detected. The treated group had similar testosterone concentrations but showed no diurnal variation. Periodicity was also detected in inhibin B concentrations in 5 of the controls and in 9 of the treated group, who also showed synchrony not seen in the controls. Both groups showed diurnal variation in cortisol. Urinary testosterone excretion did not show a diurnal variation in either group, but this was apparent for epitestosterone with a morning peak in both groups despite the markedly lower excretion in the treated men. CONCLUSIONS: The diurnal variation of testosterone in normal men is due to a change in secretion rather than in clearance and is largely LH driven. An endogenous rhythm in both testicular steroidogenesis (epitestosterone) and Sertoli cell function (inhibin B) is also present.

Adult↗
PubMed2006

Stress-ING out: phosphoinositides mediate the cellular stress response.

Phosphoinositides regulate numerous cellular processes required for growth, proliferation, and motility. Whereas phosphoinositide signal transduction pathways within the cytosol have been well characterized, nuclear signaling pathways remain poorly understood. Accumulating experimental data have now started to uncover critical functions for nuclear phosphoinositides. In particular, phosphoinositides modulate the activity of the tumor suppressor protein ING2 in response to extracellular stress. These findings highlight a previously uncharacterized function for phosphoinositides and implicate their metabolism in signaling pathways critical for cell survival.

Animals↗
PubMed2006

Supervised membrane swimming: small G-protein lifeguards regulate PIPK signalling and monitor intracellular PtdIns(4,5)P2 pools.

Regulation of PIPK (phosphatidylinositol phosphate kinase) and PtdIns(4,5)P2 signalling by small G-proteins and their effectors is key to many biological functions. Through selective recruitment and activation of different PIPK isoforms, small G-proteins such as Rho, Rac and Cdc42 modulate actin dynamics and cytoskeleton-dependent cellular events in response to extracellular signalling. These activities affect a number of processes, including endocytosis, bacterial penetration into host cells and cytolytic granule-mediated targeted cell killing. Small G-proteins and their modulators are also regulated by phosphoinositides through translocation and conformational changes. Arf family small G-proteins act at multiple sites as regulators of membrane trafficking and actin cytoskeletal remodelling, and regulate a feedback loop comprising phospholipase D, phosphatidic acid, PIPKs and PtdIns(4,5)P2, contributing to enhancement of PtdIns(4,5)P2-mediated cellular events and receptor signalling. Na+, Kir (inwardly rectifying K+), Ca2+ and TRP (transient receptor potential) ion channels are regulated by small G-proteins and membrane pools of PtdIns(4,5)P2. Yeast phosphatidylinositol 4-phosphate 5-kinases Mss4 and Its3 are involved in resistance against disturbance of sphingolipid biosynthesis and maintenance of cell integrity through the synthesis of PtdIns(4,5)P2 and downstream signalling through the Rom2/Rho2 and Rgf1/Rho pathways. Here, we review models for regulated intracellular targeting of PIPKs by small G-proteins and other modulators in response to extracellular signalling. We also describe the spatial and temporal cross-regulation of PIPKs and small G-proteins that is critical for a number of cellular functions.

Animals↗
PubMed2006

Type Igamma661 phosphatidylinositol phosphate kinase directly interacts with AP2 and regulates endocytosis.

Clathrin-coated vesicles mediate sorting and intracellular transport of membrane-bound proteins. The formation of these coats is initiated by the assembly of adaptor proteins (AP), which specifically bind to membrane cargo proteins via recognition of endocytic sorting motifs. The lipid signaling molecule phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) is critical for this process, as it serves as both a targeting and regulatory factor. PI(4,5)P(2) is synthesized by type I phosphatidylinositol phosphate kinases (PIPKI). We have discovered a direct interaction between the mu2-subunit of the AP2 complex and PIPKIgamma661 via a yeast two-hybrid screen. This interaction was confirmed using both the mu2-subunit in glutathione S-transferase pulldowns and via coimmunoprecipitation of endogenous PIPKIgamma661 with the AP2 complex from HEK293 cells. The interaction is mediated, in vivo, by a tyrosine-based motif in the 26-amino acid tail of PIPKIgamma661. Because AP2 regulates endocytosis of transferrin receptor from the plasma membrane, we also examined a role for PIPKIgamma661 using a flow cytometry endocytosis assay. We observed that stable expression of wild type PIPKIgamma661 in Madin-Darby canine kidney cells enhanced transferrin uptake, whereas stable expression of kinase-dead PIPKIgamma661 had an inhibitory effect. Neither condition affected the overall cellular level of PI(4,5)P(2). RNA interference-based knockdown of PIPKIgamma661 in HeLa cells also had an inhibitory effect on transferrin endocytosis using the same assay system. Collectively, this evidence implies an important role for PIPKIgamma661 in the AP2-mediated endocytosis of transferrin.

Amino Acid Sequence↗
PubMed2006

Gonadotrope and thyrotrope development in the human and mouse anterior pituitary gland.

Genes and orthologous intrinsic and extrinsic factors critical for embryonic pituitary gonadotrope and thyrotrope cell differentiation have been identified mainly in rodents, but data on the human are very limited. In human fetal pituitaries examined between 14 and 19 weeks of gestation using immunofluorescent confocal microscopy, we found that most fetal gonadotropes expressed alpha-GSU, LHbeta, and FSHbeta gonadotropin subunits while almost no cells expressed alpha-GSU and LHbeta alone. Gonadotropes expressing alpha-GSU and FSHbeta only were detected in both male and female pituitaries, increasing in proportion to total gonadotropes in both males and females from 14 (approximately 4.5%) to 19 weeks (approximately 16.5%) with a peak in males of 45.5% compared with females of 16.5% at 17 weeks of gestation. When FSHbeta or LHbeta genes were expressed, gonadotropes were non-dividing. This profile of human fetal gonadotrope development differs from the current mouse model. Furthermore, while expression of alpha-GSU appears to be the lead protein in gonadotropes, in thyrotropes which ultimately express alpha-GSU with TSHbeta, we observed that most if not all thyrotropes were TSHbeta-positive but alpha-GSU-negative until around 19 weeks in human, and e15 in mouse, fetal pituitaries. Furthermore, the TSHbeta-only thyrotropes were dividing, and TSHbeta rather than alpha-GSU was the lead protein in thyrotrope development. Thus, while biologically active dimeric FSH and LH can be produced by the human fetal pituitary by 14 weeks, dimeric biologically active TSH will only be produced from around 17 weeks of gestation. The mechanism(s) responsible for the different molecular regulation of alpha-GSU gene expression in gonadotropes and thyrotropes in the developing human fetal pituitary now requires investigation.

Animals↗
PubMed2006

Direct effect of progestogen on gene expression in the testis during gonadotropin withdrawal and early suppression of spermatogenesis.

CONTEXT: Testicular production of steroids and gametes is under gonadotropin support, but there is little information as to the molecular mechanisms by which these are regulated in the human. The testicular response to gonadotropin withdrawal is important for the development of effective contraceptive methods. OBJECTIVE: Our objective was investigation of expression of genes in the normal human testis reflecting steroidogenesis, Sertoli cell function, and spermatogenesis after short-term gonadotropin withdrawal and the effects of activating testicular progesterone receptors. DESIGN AND SETTING: We conducted a randomized controlled trial at a research institute. PATIENTS: Thirty healthy men participated. INTERVENTIONS: Subjects were randomized to no treatment or gonadotropin suppression by GnRH antagonist (cetrorelix) with testosterone (CT group) or with additional administration of the gestogen desogestrel (CTD group) for 4 wk before testicular biopsy. Gene expression was quantified by RT-PCR. RESULTS: Both treatment groups showed similar suppression of gonadotropins and sperm production and markedly reduced expression of steroidogenic enzymes. Addition of progestogen in the CTD group resulted in reduced expression of 5alpha-reductase type 1 compared with both controls and the CT group. Inhibin-alpha and the spermatocyte marker acrosin-binding protein were significantly lower in the CTD but not CT groups, compared with controls, but did not differ between treated groups. Men who showed greater falls in sperm production also showed reduced expression of these three genes but not of the spermatid marker protamine 1. CONCLUSIONS: These data provide evidence for direct progestogenic effects on the testis and highlight steroid 5alpha-reduction and disruption of spermiation as important components of the testicular response to gonadotropin withdrawal.

3-Hydroxysteroid Dehydrogenases↗
PubMed2006

Movin' on up: the role of PtdIns(4,5)P(2) in cell migration.

Cell migration requires the coordination of many biochemical events, including cell-matrix contact turnover and cytoskeletal restructuring. Recent advances further implicate phosphatidylinositol(4,5)-bisphosphate [PtdIns(4,5)P(2)] in the control of these events. Many proteins that are crucial to the assembly of the migration machinery are regulated by PtdIns(4,5)P(2). Coordinated synthesis of PtdIns(4,5)P(2) at these sites is dependent on the precise targeting of the type I phosphatidylinositol phosphate kinases (PIPKs). Two PIPKI isoforms target to, and generate, PtdIns(4,5)P(2) at membrane ruffles and focal adhesions during cell migration. Here, we discuss our current understanding of PtdIns(4,5)P(2) in the regulation of cell responses to migratory stimuli and how the migrating cell controls PtdIns(4,5)P(2) availability.

Animals↗
PubMed2006

Nuclear PI(4,5)P(2): a new place for an old signal.

Over the last decades, evidence has accumulated suggesting that there is a distinct nuclear phosphatidylinositol pathway. One of the best examined nuclear lipid pathways is the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PI4,5P(2)) by PLC resulting in activation of nuclear PKC and production of inositol polyphosphates. However, there is a growing number of data that phosphoinositides are not only precursor for soluble inositol phosphates and diacylglycerol, instead they can act as second messengers themselves. They have been implicated to play a role in different important nuclear signaling events such as cell cycle progression, apoptosis, chromatin remodeling, transcriptional regulation and mRNA processing. This review focuses on the role of specifically PI4,5P(2) in the nucleus as a second messenger as well as a precursor for PI3,4,5P3, inositol polyphosphates and diacylglycerol.

Animals↗
PubMed2006

Nuclear phosphoinositide kinases and inositol phospholipids.

The presence of inositol phospholipids in the nuclei of mammalian cells has by now been well established, as has the presence of the enzymes responsible for their metabolism. However, our understanding of the role of these nuclear phosphoinositides in regulating cellular events has lagged far behind that for its cytosolic counterpart. It is clear, though, that the nuclear phosphoinositide pool is independent of the cytosolic pool and is, therefore, likely to be regulating a unique set of cellular events. As with its cytosolic phosphoinositides, many nuclear phosphoinositides and their metabolic enzymes are located at distinct sub-cellular structures. This arrangement spatially limits the production and activity of inositol phospholipids and is believed to be a major mechanism for regulating their function. Here, we will introduce the components of nuclear inositol phospholipid signal transduction and discuss how their spatial arrangement may dictate which nuclear functions they are modulating.

1-Phosphatidylinositol 4-Kinase↗
PubMed2006

Calculated free testosterone in men: comparison of four equations and with free androgen index.

BACKGROUND: Serum testosterone remains the most important investigation in the diagnosis of androgen deficiency in men. Most of the circulating testosterone is bound to albumin and sex hormone-binding globulin (SHBG), whereas free testosterone accounts for approximately 2% of total testosterone. Because direct measurement of free testosterone is impractical in routine practice, several equations are used to provide clinically useful estimates of free testosterone concentration. This study aimed to (1) obtain locally derived reference limits for total testosterone and calculated free testosterone (CFT) concentrations, and (2) critically evaluate the equations commonly used to estimate free testosterone. METHODS: Serum total testosterone, SHBG and albumin were assayed in morning blood samples obtained from 126 healthy men (aged 20-45 years) known to have normal semen analysis. CFT concentrations calculated using four published methods (i.e. the Sodergard, Nanjee-Wheeler, Vermeulen and Ly-Handelsman equations) were compared with one another and the free androgen index. RESULTS: Reference intervals for total testosterone and CFT by the Vermeulen equation were 9.4-31.0 nmol/L and 0.245-0.785 nmol/L (2.5-97.5 percentile), respectively. CFT values varied considerably with the four equations examined. Mean biases ranged from 5.8 to 56.0%; the Nanjee-Wheeler and Ly-Handelsman equations yielded positive and negative biases, respectively, against the other equations. Free androgen index was shown to correlate poorly with CFT (r2=0.21-0.46) and over-estimate the CFT at low SHBG concentrations. CONCLUSIONS: We have used various equations to derive reference ranges for CFT in healthy men aged 20-45 years. We suggest that CFT be incorporated into the investigation regimen for suspected hypogonadism when total testosterone results are equivocal.

Adult↗
PubMed2005

Burn-induced alterations of chromium and the glucose/insulin system in rats.

Our objective was to demonstrate a role of chromium (Cr) in response to severe burn. A third-degree burn involving 20% of total body surface was applied under anaesthesia in accord with ethical guidelines. Chromium concentrations in liver decreased progressively and were non-detectable on days 5 and 10 following injury. In quadriceps muscle, Cr concentrations increased 6h after injury and then declined significantly within the first day and remained at these levels the following 9 days. Urinary Cr losses were also increased. Changes in kidney, brain and serum Cr were not significant. Non-fasting glucose rose 6h after injury and then returned to levels measured before the burn. There was a significant rise in corticosterone reaching a maximum the first day after injury that was accompanied by significant increases in circulating insulin and glucagon that were maximal after 2 days. Changes in IGF-1 were not significant. In summary, changes in Cr concentrations were associated with an early hyperglycemia, hyperinsulinemia and increased secretion of stress hormones. These observations strongly suggest a mobilization and utilization of Cr following severe burn. Additional studies are needed to document that improved Cr status might lead to improved recovery following burn.

Animals↗
PubMed2005

Water-soluble polymeric polyphenols from cinnamon inhibit proliferation and alter cell cycle distribution patterns of hematologic tumor cell lines.

To explore possible anti-cancer properties of water-soluble, polymeric polyphenols from cinnamon, three myeloid cell lines (Jurkat, Wurzburg, and U937) were exposed to increasing concentrations of an aqueous extract prepared from cinnamon (CE) for 24 h. Cell growth and cell cycle distribution patterns responded in a dose-dependent manner to CE. That is, an increase in the percentage of cells distributed in G2/M was observed in all three cell lines as the amount of CE increased. At the highest dose of CE, the percentage of Wurzburg cells in G2/M was 1.5- and 2.0-fold higher than those observed for Jurkat and U937 cells, respectively. Wurzburg cells lack the CD45 phosphatase and may be more sensitive to imbalances in signaling through kinase/phosphatase networks that promote growth. The results suggest the potential of CE to interact with phosphorylation/dephosphorylation signaling activities to reduce cellular proliferation in tandem with a block at the G2/M phase of the cell cycle.

Cell Cycle↗
PubMed2005

Is atrial fibrillation an inflammatory disorder?

There is mounting evidence to support the influence of inflammation in the pathogenesis of atrial fibrillation (AF). Indeed, AF is associated with increased levels of known inflammatory markers, even after adjustment for confounding factors. The renin-angiotensin-aldosterone system (RAAS) appears to play a key role in this process. Atrial biopsies from patients with AF have also confirmed the presence of inflammation. Furthermore, there is preliminary evidence to support a number of drug therapies that have the potential to reduce the clinical burden of AF. In this review, we present an overview of the evidence supporting a link between inflammation and AF, and some of the drug therapies, such as the angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, steroids, fish oils, and vitamin C, that might be efficacious in the prevention of AF by modulating inflammatory pathways.

Ascorbic Acid↗
PubMed2005

A novel angiogenic role for prostaglandin F2alpha-FP receptor interaction in human endometrial adenocarcinomas.

Prostaglandins have been implicated in several neovascular diseases. In the present study, we found elevated FP receptor and vascular endothelial growth factor (VEGF) expression colocalized in glandular epithelial and vascular cells lining the blood vessels in endometrial adenocarcinomas. We investigated the signaling pathways activated by the FP receptor and their role in modulating VEGF expression in endometrial adenocarcinoma (Ishikawa) cells. Ishikawa cells were stably transfected with FP receptor cDNA in the sense or antisense orientations. Treatment of Ishikawa cells with prostaglandin F2alpha (PGF2alpha) rapidly induced transphosphorylation of the epidermal growth factor receptor (EGFR) and phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 via the FP receptor. Activation of EGFR-Ras-mitogen-activated protein kinase/ERK kinase (MEK) signaling via the FP receptor resulted in an increase in VEGF promoter activity, expression of VEGF mRNA, and secretion of VEGF protein. These effects of PGF2alpha on the FP receptor could be abolished by treatment of cells with a specific FP receptor antagonist, chemical inhibitors of c-Src, matrix metalloproteinase, and EGFR kinase or by inactivation of signaling with dominant-negative mutant isoforms of EGFR, Ras, or MEK or with small inhibitory RNA oligonucleotides targeted against the EGFR. Finally, we confirmed that PGF2alpha could potentiate angiogenesis in endometrial adenocarcinoma explants by transactivation of the EGFR and induction of VEGF mRNA expression.

Adenocarcinoma↗