EM localization of chromaffin cell ATPase

Author(s):  
V. Kriho ◽  
G. D. Pappas

During exocytosis of the chromaffin granules, ATP is released. ATP can then be hydrolyzed by the ecto-ATPases of the plasma membrane to provide adenosine for reuptake or for activation of P1 purinoceptors. Chromaffin granule membranes also possess ATPase activity. This activity is linked to the uptake of catecholamines from the cytoplasm into the membrane-bound granule compartment.In this report we combine EM cytochemistry and immunogold labelling to provide further evidence for the presence of ATPase on both the plasma membrane and granule membranes of bovine chromaffin cells in culture.

Author(s):  
V. Kriho ◽  
G. D. Pappas ◽  
R. P. Becker

Exocytotic granules of bovine chromaffin cells contain both catecholamines and ATP. Upon stimulation, the granule contents are discharged into the extracellular space. Catecholamines are eventually hydrolyzed. The resultant choline is then taken up by the cell for recycling. The fate of the extracellular ATP has not been determined. Ecto-ATPase activity has been localized at the plasma membrane of the chromaffin cell in the adrenal gland. This ATPase activity may play a role in the local metabolism of the released ATP.Our present study further investigates this ecto-ATPase activity, using biochemistry and EM cytochemistry, on isolated, intact bovine chromaffin cells. Our biochemical results are seen in the histogram of Fig. 1. ATPase assays show considerable ATPase activity when both Ca++ and Mg++ are present in physiological concentrations in the incubating solution. Even when Ca++ is omitted from the incubating solution, a great deal of ecto-ATPase activity is still demonstrated. Omitting Mg++ from the medium, however, reduced the level of ATPase activity by 91%.


2018 ◽  
Vol 151 (2) ◽  
pp. 118-130 ◽  
Author(s):  
Prabhodh S. Abbineni ◽  
Mary A. Bittner ◽  
Daniel Axelrod ◽  
Ronald W. Holz

Upon fusion of the secretory granule with the plasma membrane, small molecules are discharged through the immediately formed narrow fusion pore, but protein discharge awaits pore expansion. Recently, fusion pore expansion was found to be regulated by tissue plasminogen activator (tPA), a protein present within the lumen of chromaffin granules in a subpopulation of chromaffin cells. Here, we further examined the influence of other lumenal proteins on fusion pore expansion, especially chromogranin A (CgA), the major and ubiquitous lumenal protein in chromaffin granules. Polarized TIRF microscopy demonstrated that the fusion pore curvature of granules containing CgA-EGFP was long lived, with curvature lifetimes comparable to those of tPA-EGFP–containing granules. This was surprising because fusion pore curvature durations of granules containing exogenous neuropeptide Y-EGFP (NPY-EGFP) are significantly shorter (80% lasting <1 s) than those containing CgA-EGFP, despite the anticipated expression of endogenous CgA. However, quantitative immunocytochemistry revealed that transiently expressed lumenal proteins, including NPY-EGFP, caused a down-regulation of endogenously expressed proteins, including CgA. Fusion pore curvature durations in nontransfected cells were significantly longer than those of granules containing overexpressed NPY but shorter than those associated with granules containing overexpressed tPA, CgA, or chromogranin B. Introduction of CgA to NPY-EGFP granules by coexpression converted the fusion pore from being transient to being longer lived, comparable to that found in nontransfected cells. These findings demonstrate that several endogenous chromaffin granule lumenal proteins are regulators of fusion pore expansion and that alteration of chromaffin granule contents affects fusion pore lifetimes. Importantly, the results indicate a new role for CgA. In addition to functioning as a prohormone, CgA plays an important role in controlling fusion pore expansion.


1991 ◽  
Vol 39 (11) ◽  
pp. 1485-1493 ◽  
Author(s):  
T Fujimoto ◽  
K Lee ◽  
S Miwa ◽  
K Ogawa

We raised antibodies to brain fodrin and erythrocyte ankyrin and examined the distribution of the antigens in cultured bovine chromaffin cells by immunocytochemical techniques. Immunofluorescence microscopy of whole cells showed intense labeling for both proteins, but fine localization could not be determined. In contrast, in cell specimens mechanically unroofed before fixation, the distribution of the two proteins revealed an apparent difference in the ventral plasma membrane: immunofluorescence for fodrin was dense and mostly even, whereas that for ankyrin appeared as scattered dots. Immunogold electron microscopy of the unroofed cells showed that labeling for fodrin was localized in a network of thin filaments, the diameter of which was 2-3 nm at the thinnest portion. Ankyrin labeling was mostly associated with filaments 5-10 nm in diameter. Notably, labeling for both fodrin and ankyrin was found over the coated membrane. The present results indicate that fodrin and ankyrin in the chromaffin cell do not constitute a submembranous network as spectrin and ankyrin do in the erythrocyte; whereas fodrin is closely associated with the plasma membrane, ankyrin is mostly linked to the cytoskeleton. The existence of both proteins in the coated region implies that they are functionally related to exocytosis and/or to ensuing membrane retrieval in the chromaffin cell.


1986 ◽  
Vol 102 (2) ◽  
pp. 510-515 ◽  
Author(s):  
A Patzak ◽  
H Winkler

The exocytotic exposure and retrieval of an antigen of chromaffin granule membranes were studied with chromaffin cells isolated from bovine adrenal medulla. Cells were incubated with an antiserum against glycoprotein III followed by fluorescein- or gold-labeled anti-IgG. Immunofluorescence on the cell surface was present in a patchy distribution irrespective of whether bivalent antibodies or Fab fragments were used. During subsequent incubation these fluorescent membrane patches were internalized within 45 min. At the ultrastructural level immunogold-labeled patches were present on the surface of stimulated cells. During incubation (5 min to 6 h) these immunolabeled membrane patches became coated, giving rise to coated vesicles and finally to smooth vesicles. These latter vesicles were found spread throughout the cytoplasm including the Golgi region, but Golgi stacks did not become labeled. Part of the immunolabel was transferred to multivesicular bodies, which probably represent a lysosomal pathway. 30 min after incubation immunolabel was also found in electron-dense vesicles apparently representing newly formed chromaffin granules. After 6 h of incubation immunolabel was found in vesicles indistinguishable from mature chromaffin granules. These results provide direct evidence that after exocytosis membranes of chromaffin granules are selectively retrieved from the plasma membrane and are partly recycled to newly formed chromaffin granules, providing a shuttle service from the Golgi region to the plasma membrane.


1992 ◽  
Vol 1 (1) ◽  
pp. 33-41 ◽  
Author(s):  
John D. Ortega ◽  
Jacqueline Sagen ◽  
George D. Pappas

Xenogeneic donors, a largely untapped resource, would solve many of the problems associated with the limited availability of human donor tissue for neural transplantation. Previous work in our laboratory has revealed that xenografts of isolated bovine chromaffin cells survive transplantation into the periaqueductal gray (PAG) of immunosuppressed adult rats. Electron microscopic analysis reveals that graft sites contain healthy chromaffin cells, but do not contain host immune cells typical of graft rejection. The aim of the current study was to assess the necessary conditions for long-term survival of bovine chromaffin cell xenografts in the central nervous system (CNS). In particular, the need for short-course vs. permanent immunosuppressive therapy with cyclosporine A (CsA) for the long-term survival of grafted bovine chromaffin cells was addressed. Grafts from animals receiving continuous CsA treatment for either 3, 6, or 12 wk contained large clumps of dopamines-β-hydroxylase (DBH) positive cells in contrast to the few surviving cells observed in nonimmunosuppressed animals. In addition, grafts from animals that had CsA treatment terminated at 3 or 6 wk contained similarly large clumps of DBH-positive cells. Furthermore, short-term immunosuppression (3 wk) appeared to enhance the long-term survival of grafted cells, since clumps of DBH staining cells could still be positively identified in the host PAG at least 1 yr after transplantation. Complete rejection of graft tissue depends on several factors, such as blood–brain barrier integrity, the presence of major histocompatability complex (MHC) antigens in either the host or graft, and the status of the host immune system. By using a suspension of isolated bovine chromaffin cells, potential MHC antigen presenting cells, such as endothelial cells, are eliminated. In addition, CsA treatment may negate the immunologic consequences of increased blood–brain barrier permeability following surgical trauma by attenuating the host cell mediated response. In summary, long-term survival of isolated chromaffin cell xenografts in the rat CNS may be attained by a short-term course of CsA.


1997 ◽  
Vol 272 (2) ◽  
pp. C476-C484 ◽  
Author(s):  
R. B. Lomax ◽  
P. Michelena ◽  
L. Nunez ◽  
J. Garcia-Sancho ◽  
A. G. Garcia ◽  
...  

In this study, we investigated the contribution of different subtypes of voltage-dependent Ca2+ channels to changes in cytosolic free Ca2+ ([Ca2+]i) and secretion in noradrenergic and adrenergic bovine chromaffin cells. In single immunocytochemically identified chromaffin cells, [Ca2+]i increased transiently during high K+ depolarization. Furnidipine and BAY K 8644, L-type Ca2+ channel blocker and activator, respectively, affected the [Ca2+]i rise more in noradrenergic than in adrenergic cells. In contrast, the Q-type Ca2+ channel blocker omega-conotoxin MVIIC inhibited the [Ca2+]i rise more in adrenergic cells. omega-Agatoxin IVA (30 nM), which blocks P-type Ca2+ channels, had little effect on the [Ca2+]i signal. The N-type Ca2+ channel blocker omega-conotoxin GVIA similarly inhibited the [Ca2+]i rise in both cell types. The effects of furnidipine, BAY K 8644, and omega-conotoxin MVIIC on K+-evoked norepinephrine and epinephrine release paralleled those effects on [Ca2+]i signals. However, omega-conotoxin GVIA and 30 nM omega-agatoxin IVA did not affect the secretion of either amine. The data suggest that, in the bovine adrenal medulla, the release of epinephrine and norepinephrine are preferentially controlled by Q- and L-type Ca2+ channels, respectively. P- and N-type Ca2+ channels do not seem to control the secretion of either catecholamine.


FEBS Letters ◽  
1980 ◽  
Vol 114 (1) ◽  
pp. 45-47 ◽  
Author(s):  
S. Vijayasarathy ◽  
S. Shivaji ◽  
P. Balaram

2001 ◽  
Vol 153 (1) ◽  
pp. 177-190 ◽  
Author(s):  
Laura M. Johns ◽  
Edwin S. Levitan ◽  
Eric A. Shelden ◽  
Ronald W. Holz ◽  
Daniel Axelrod

We used total internal reflection fluorescence microscopy to study quantitatively the motion and distribution of secretory granules near the plasma membrane (PM) of living bovine chromaffin cells. Within the ∼300-nm region measurably illuminated by the evanescent field resulting from total internal reflection, granules are preferentially concentrated close to the PM. Granule motion normal to the substrate (the z direction) is much slower than would be expected from free Brownian motion, is strongly restricted over tens of nanometer distances, and tends to reverse directions within 0.5 s. The z-direction diffusion coefficients of granules decrease continuously by two orders of magnitude within less than a granule diameter of the PM as granules approach the PM. These analyses suggest that a system of tethers or a heterogeneous matrix severely limits granule motion in the immediate vicinity of the PM. Transient expression of the light chains of tetanus toxin and botulinum toxin A did not disrupt the restricted motion of granules near the PM, indicating that SNARE proteins SNAP-25 and VAMP are not necessary for the decreased mobility. However, the lack of functional SNAREs on the plasma or granule membranes in such cells reduces the time that some granules spend immediately adjacent to the PM.


Neuroscience ◽  
2004 ◽  
Vol 128 (1) ◽  
pp. 99-109 ◽  
Author(s):  
A. Benavides ◽  
S. Calvo ◽  
D. Tornero ◽  
C. González-GarcÍa ◽  
V. Ceña

Sign in / Sign up

Export Citation Format

Share Document