Perturbation of the morphology of the trans-Golgi network following Brefeldin A treatment: redistribution of a TGN-specific integral membrane protein, TGN38

Brefeldin A (BFA) has a dramatic effect on the morphology of the Golgi apparatus and induces a rapid redistribution of Golgi proteins into the ER (Lippincott-Schwartz, J., L. C. Yuan, J. S. Bonifacino, and R. D. Klausner. 1989. Cell. 56:801-813). To date, no evidence that BFA affects the morphology of the trans-Golgi network (TGN) has been presented. We describe the results of experiments, using a polyclonal antiserum to a TGN specific integral membrane protein (TGN38) (Luzio, J.P., B. Brake, G. Banting, K. E. Howell, P. Braghetta, and K. K. Stanley. 1990. Biochem. J. 270:97-102), which demonstrate that incubation of cells with BFA does induce morphological changes to the TGN. However, rather than redistributing to the ER, the majority of the TGN collapses around the microtubule organizing center (MTOC). The effect of BFA upon the TGN is (a) independent of protein synthesis, (b) fully reversible (c) microtubule dependent (as shown in nocodazole-treated cells), and (d) relies upon the hydrolysis of GTP (as shown by performing experiments in the presence of GTP gamma S). ATP depletion reduces the ability of BFA to induce a redistribution of Golgi proteins into the ER; however, it has no effect upon the BFA-induced relocalizations of the TGN. These data confirm that the TGN is an organelle which is independent of the Golgi, and suggest a dynamic interaction between the TGN and microtubules which is centered around the MTOC.

TGN38/41 recycles between the cell surface and the TGN: brefeldin A affects its rate of return to the TGN

TGN38 and TGN41 are isoforms of an integral membrane protein (TGN38/41) that is predominantly localized to the trans-Golgi network (TGN) of normal rat kidney cells. Polyclonal antisera to TGN38/41 have been used to monitor its appearance at, and removal from, the surface of control and Brefeldin A (BFA)-treated cells. Antibodies that recognize the lumenal domain of TGN38/41 are capable of specific binding to the surface of both control and BFA-treated cells. In both control and BFA-treated cells internalized TGN38/41 is targeted to the TGN; however, there are differences in 1) the morphology of the intracellular structures through which TGN38/41 passes and 2) the kinetics of internalization. These data demonstrate that TGN38/41 cycles between the plasma membrane and the TGN in control and BFA-treated cells and suggest that recycling pathways between the plasma membrane and the TGN exist for predominantly TGN proteins as well as those that normally cycle to other intracellular compartments. They also demonstrate that addition of BFA not only alters the morphology and localization of the TGN but also the kinetics of endocytosis.

Vacuolar ATPase inactivation blocks recycling to the trans-Golgi network from the plasma membrane

TGN38/41 is an integral membrane protein which recycles between the trans-Golgi network (TGN) and the cell surface but is predominantly located in the TGN of rat (NRK) cells at steady state. As part of our studies on the mechanism and route of recycling between the TGN and the cell surface we have used chloroquine or Bafilomycin A1 to modulate the lumenal pH of endocytic organelles. The data we present demonstrate that inactivation of the proton pump which maintains the acidic environment within the lumen of endocytic organelles leads to an accumulation of TGN38/41 in early endosomes. These data confirm the observation that TGN38/41 recycles between the plasma membrane and the TGN and identifies a specific block in that recycling pathway.

Biologic characterization of ICI 200,880 and ICI 200,355, novel inhibitors of human neutrophil elastase

ICI 200,880 and its close structural analog, ICI 200,355, are representatives of a new chemical class of inhibitors of human neutrophil elastase (HNE). Both compounds are substituted tripeptide ketones, which demonstrated competitive kinetics versus HNE, with identical Ki values of 5.0 x 10(-10) M. The selectivity of ICI 200,880 for HNE versus a variety of enzymes ranged from 150-fold [relative to porcine pancreatic elastase (PPE)] to greater than 360,000-fold in favor of HNE. The compound effectively inhibited HNE-hydrolysis of bovine ligamentum nuchae elastin. In pharmacokinetic studies, ICI 200,880 and ICI 200,355 displayed long retention times when administered directly to the lung and were rapidly eliminated after intravenous administration. Pretreatment of hamsters with either inhibitor before intratracheal administration of HNE produced dose- and time-dependent inhibition of enzyme-induced increases in lung weight, total lavageable red cells, and total lavageable white cells. Aerosol administration of ICI 200,880 produced similar results. Subcutaneous administration of either 50 or 100 mumol/kg (twice/day) of ICI 200,880 for 14 or 28 days prevented the time-dependent increase in alveolar diameter produced by a single intratracheal dose of PPE when compound dosing was initiated 24 h after the enzyme. Treatment of hamsters with the same protocol and doses of ICI 200,880 for 8 wk prevented the destructive lesion induced by a single intratracheal dose of HNE. It is concluded that ICI 200,880 and ICI 200,355 have biochemical, pharmacokinetic, and pharmacologic profiles that make them useful therapeutic agents for understanding the role of HNE in various diseases. ICI 200,880 is presently being evaluated in humans.

Analysis of the co-localization of the insulin-responsive glucose transporter (GLUT4) and the trans Golgi network marker TGN38 within 3T3-L1 adipocytes

The exposure of isolated adipocytes to insulin results in an approximately 20-fold increase in the rate of glucose transport into the cell. This increase is mediated by the movement of a pool of intracellular vesicles containing the so-called insulin-responsive glucose transporter (GLUT4) to the cell surface. In the resting state, most of the GLUT4 molecules are sequestered inside the adipocyte in an as yet unidentified intracellular compartment. TGN38 is an integral membrane protein which has been shown to be predominantly localized to the trans Golgi network [Luzio, Brake, Banting, Howell, Braghetta and Stanley (1990) Biochem. J. 270, 97-102]. Here we investigate whether GLUT4 and TGN38 are co-localized in the murine 3T3-L1 adipocyte cell line. Immuno-adsorption of intracellular vesicles containing GLUT4 with an anti-peptide antibody specific for this isoform did not deplete the low-density microsomal fraction of TGN38 in these cells; moreover, no TGN38 was detected in the GLUT4-containing vesicles by immunoblotting with a TGN38-specific antiserum. Immuno-adsorption of TGN38-containing vesicles and subsequent analysis of the proteins in these vesicles revealed that a detectable amount of GLUT4 (5-10%) did co-localise with TGN38. The amount of GLUT4 in the TGN38-containing vesicles did not change in response to insulin. Immunofluorescence analysis of TGN38 and GLUT4 in these cells revealed markedly different staining patterns. Reversal of insulin-stimulated glucose transport and subsequent analysis of the TGN38-containing vesicles demonstrated that during the re-cycling of GLUT4 to the intracellular storage site there was no increase in the amount of GLUT4 co-localized with TGN38. Taken together, these results suggest that the trans Golgi network is not the major site of the intracellular GLUT4 pool within 3T3-L1 adipocytes.

Overexpression of TGN38/41 leads to mislocalisation of gamma-adaptin

TGN38 and TGN41 are isoforms of a monotopic integral membrane protein which recycles between the trans Golgi network (TGN) and the cell surface, but which, at steady state, is predominantly located in the TGN. Full-length and truncated versions of rat TGN38/41 have been expressed in monkey (COS) and human (Heb7a) cells under the control of the heavy metal inducible Metallothionein IIA promoter. This has allowed the regulated expression of TGN38/41 protein constructs to different levels in the transfected cells. These studies show that (i) controlled overexpression of TGN38/41 results in mislocalisation to parts of the endocytic pathway, (ii) a truncated version of TGN38/41, lacking the cytoplasmic domain, remains in the TGN, and (iii) there is a direct or indirect interaction between the cytoplasmic domain of TGN38/41 and gamma-adaptin.

Epitope mapping of two isoforms of a trans Golgi network specific integral membrane protein TGN38/41

TGN38/41 is an integral membrane protein predominantly located in the trans Golgi network (TGN) of rat (NRK) cells. We have used a cDNA expression system to map the epitopes recognised by a panel of antibodies raised to TGN38/41 as a preliminary step in the accurate identification of the region(s) of the molecule responsible for its correct intracellular location. These studies have confirmed the predicted topology of the molecule, and have identified a region in the cytoplasmic domain which is immunologically (and hence potentially functionally) conserved between species.

Identification, molecular characterization and immunolocalization of an isoform of the trans-Golgi-network (TGN)-specific integral membrane protein TGN38

TGN38 is an integral membrane protein previously shown to be predominantly localized to the trans-Golgi network (TGN) of cells by virtue of a signal contained within its cytoplasmic 'tail' [Luzio, Brake, Banting, Howell, Braghetta & Stanley (1990) Biochem. J. 270, 97-102]. We now (i) describe the isolation of cDNA clones encoding an isoform of TGN38, (ii) present the sequence of that isoform and (iii) describe the production and use of antibodies which specifically recognize the new isoform. This isoform, designated TGN41, is also predominantly localized to the TGN. The only sequence differences between the protein coding regions of cDNA clones encoding TGN38 and those encoding TGN41 occur within the region specifying the cytoplasmic tails of the two proteins. The TGN localization signal is shown to be within the sequence common to both proteins.

CD28 stimulates tyrosine phosphorylation, cellular redistribution and catalytic activity of the inositol lipid 5-phosphatase SHIP

The D-3 phosphoinositide lipids phosphatidylinositol 3,4, 5-trisphophate [PtdIns(3,4,5)P(3)] and phosphatidylinositol 3, 4-bisphosphate [PtdIns(3,4)P(2)] represent upstream components of a major signaling pathway that is strongly activated by the T cell costimulatory molecule CD28. A major route for degradation of PtdIns(3,4,5)P(3) (and hence, regulation of PtdIns(3,4,5)P(3)-driven effector pathways), involves its conversion to PtdIns(3,4)P(2) by the 145-kDa SH2-containing inositol (poly)phosphate 5-phosphatase (SHIP). In this study, we demonstrate using the murine T cell hybridoma DC27.1, that SHIP is strongly tyrosine phosphorylated after ligation of CD28 by either mAb or the natural ligand B7.1. Ligation of CD3 also stimulates SHIP tyrosine phosphorylation and an additive effect on tyrosine phosphorylation of SHIP is observed when both CD3 and CD28 are ligated. The tyrosine phosphorylation of SHIP in response to CD28 ligation correlates with a marked redistribution of SHIP from the cytosol to the plasma membrane, as well as an increase in the in vitro 5-phosphatase activity associated with SHIP immunoprecipitates derived from CD28-stimulated cells. However, we have been unable to detect a direct association between CD28 and SHIP, so the mechanisms by which CD28 exerts the observed effects on SHIP remain unclear. This is the first demonstration that SHIP is a biochemical target for CD28 and suggests that SHIP may be involved in the regulation of T cell activation.

Biochemical and pharmacological characterization of ICI 186,756: a novel, potent, and selective inhibitor of human neutrophil elastase

ICI 186,756 is a representative of a new chemical class of synthetic inhibitors of human neutrophil elastase (HNE). This compound demonstrated competitive inhibition of HNE with a Ki of 3.6 +/- 0.8 x 10(-9) mol/L. The selectivity of ICI 186,756 for HNE versus a variety of enzymes ranged from a minimum of 870-fold to greater than 640,000. The compound effectively inhibited hydrolysis of bovine ligamentum nuchae elastin by HNE. Pretreatment of hamsters with ICI 186,756 up to 2 h before intratracheal administration of HNE inhibited enzyme-induced increases in lung weight, total lavageable red cells, and total lavageable white cells measured 24 h after HNE administration. In contrast, similar lung effects produced by intratracheal administration of porcine pancreatic elastase (PPE) were not inhibited by ICI 186,756. Treatment of hamsters with 43 mumol/kg (sc) of ICI 186,756 for 14 or 28 days modulated the increases in alveolar diameter produced by both PPE and HNE, respectively. It is concluded that ICI 186,756 is a potent, competitive, and selective inhibitor of HNE that may be useful in understanding the role of this enzyme in animal models of various diseases. Furthermore, the maintenance or progression of emphysema-like lesions induced in hamsters by PPE do not appear to be due to the persistence of that enzyme within the lung.

Idiographic quality of life assessment before radical cystectomy

BACKGROUND

We sought to determine if idiographic, or self-defined, measures added to our understanding of patients with bladder cancer's quality of life (QOL) prior to radical cystectomy (RC). We tested whether idiographic measures increased prediction of global QOL beyond standard (nomothetic) measures of QOL components.

METHODS

We administered the European Organization for Research and Treatment of Cancer Quality of Life Questionnaires (QLQ)-C30 and QLQ-BLM30, and our own idiographic Quality of Life Appraisal Profile prior to RC. Idiographic measures included number of goal statements, distance from goal attainment, and ability to complete goal attainment activities. Multivariate linear regression was used to predict measures of global QOL and related constructs of life satisfaction and mental health.

RESULTS

Two hundred fiftheen patients reported a median of 8 (interquartile range [IQR] 6, 11) goals and half had an average goal attainment rating above 6.9 out of 10 (IQR 5.5, 8.2). On multivariable analysis, QLQ-C30 role functioning and QLQ-BLM30 future perspective explained 15.7% of the variability in preoperative global QOL. Including goal attainment and activity difficulty explained an additional 12% of global QOL variance. Smaller gains were seen on measures of global health, life satisfaction, mental health, and activity, suggesting that idiographic measures capture aspects of QOL distinct from health and functional status defined by nomothetic scales.

CONCLUSIONS

Idiographic assessment of QOL added to prediction of global QOL above and beyond health-related components measured using nomothetic instruments. This self-defined information may be valuable in communicating with cancer patients about their QOL. Copyright © 2015 John Wiley & Sons, Ltd.

Propensity-matched analysis of patient-reported outcomes for neoadjuvant chemotherapy prior to radical cystectomy

PURPOSE

To evaluate patient-reported outcomes (PROs) for bladder cancer patients undergoing neoadjuvant chemotherapy (NAC) prior to radical cystectomy (RC) using longitudinal data and propensity-matched scoring analyses.

METHODS

155 patients with muscle-invasive bladder cancer scheduled for RC completed the European Organization for Research and Treatment of Cancer questionnaires, EORTC QLQ-C30, EORTC QLQ-BLM30, Fear of Recurrence Scale, Mental Health Inventory and Satisfaction with Life Scale within 4 weeks of surgery. A propensity-matched analysis was performed comparing pre-surgery PROs among 101 patients who completed NAC versus 54 patients who did not receive NAC. We also compared PROs pre- and post-chemotherapy for 16 patients who had data available for both time points.

RESULTS

In propensity-matched analysis, NAC-treated patients reported better emotional and sexual function, mental health, urinary function and fewer financial concerns compared to those that did not receive NAC. Longitudinal analysis showed increases in fatigue, nausea and appetite loss following chemotherapy.

CONCLUSION

Propensity-matched analysis did not demonstrate a negative effect of NAC on PRO. Several positive associations of NAC were found in the propensity-matched analysis, possibly due to other confounding differences between the two groups or actual clinical benefit. Longitudinal analysis of a small number of patients found small to modest detrimental effects from NAC similar to toxicities previously reported. Our preliminary findings, along with known survival and toxicity data, should be considered in decision-making for NAC.