scholarly journals Dipeptidyl peptidase IV is sorted to the secretory granules in pancreatic islet A-cells.

1993 ◽  
Vol 41 (1) ◽  
pp. 81-88 ◽  
Author(s):  
M D Poulsen ◽  
G H Hansen ◽  
E Dabelsteen ◽  
P E Høyer ◽  
O Norén ◽  
...  
Keyword(s):  
Pancreatic Islet ◽  
Endocrine Cells ◽  
Polyclonal Antibodies ◽  
Secretory Granules ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase Iv ◽  
Second Primary ◽  
Double Labeling ◽  
A Cells ◽  
Granule Membrane

Dipeptidyl peptidase IV (DP IV:EC 3.4.14.5) was localized in endocrine cells of pig pancreas by immunohistochemical and enzyme histochemical methods. Immunolight microscopy with both monoclonal and polyclonal antibodies demonstrated DP IV immunoreactivity in cells located in the peripheral part of the islets of Langerhans. The antigen is enzymatically active, as shown by enzyme histochemical analysis with a synthetic DP IV substrate. By immunoelectron microscopy (immunogold labeling), the labeling of DP IV in the islets was associated with the secretory granules of the A-cells, as identified by double labeling using a monoclonal glucagon antibody as the second primary antibody. These results show that DP IV is sorted to secretory granules in the pig pancreatic islet A-cells. Furthermore, this secretory granule enzyme, as opposed to intestinal brush border DP IV, is suggested to be a soluble protein, since the gold particles appear all over the granules and are not specifically associated with the granule membrane.

Patterns of calcium localization in pancreatic endocrine cells

1976 ◽  
Vol 21 (1) ◽  
pp. 107-117
Author(s):  
M. Ravazzola ◽  
F. Malaisse-Lagae ◽  
M. Amherdt ◽  
A. Perrelet ◽  
W.J. Malaisse ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
Endocrine Cells ◽  
Secretory Granules ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Calcium Localization ◽  
A Cells ◽  
D Cells

Subcellular calcium localization in the dndocrine cells of rat pancreas was studied by the pyroantimonate precipitation technique. Calcium-containing electron-dense deposits in the endocrine cells were mostly found within secretory granules and along the plasma membrane, but their pattern of distribution in A-, B- and D-cells displayed qualitative and quantitative differences. In B-cells, numerous secretory granules contained deposits located in the halo surrounding the granule core. In A-cells, only few granules contained precipitates in their halo, whereas in D-cells, deposits were situated in the dense core of the secretory granules. Deposits along the plasma membrane occurred generally on the outer leaflet of the plasma membrane of B- and D-cells and on the inner leaflet of that of A-cells. In islets incubated at a high glucose concentration or in the presence of the calcium ionophore A23187, the number of beta granules containing precipitates was significantly increased. By contrast, only few deposits were observed in B-cells incubated in calcium-deprived medium enriched with EGTA. These findings indicate that: the pattern of calcium localization varies in different islet cell types; in B-cells the secretory granules represent one of the major stores of intracellular calcium; and that this store undergoes changes in conditions which alter insulin release.

Regulatory subunits of cyclic AMP-dependent protein kinase: presence in granules and secretion by exocrine and endocrine cells

1989 ◽  
Vol 93 (4) ◽  
pp. 675-681
Author(s):  
A.R. Hand ◽  
M.I. Mednieks
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Endocrine Cells ◽  
Polyclonal Antibodies ◽  
Secretory Granules ◽  
Regulatory Subunit ◽  
Secretory Cells ◽  
Dependent Protein Kinase ◽  
Regulatory Subunits ◽  
Dependent Protein

Cyclic AMP-dependent protein kinase (cAPK) is the intracellular mediator of signal transduction events involving the adenylate cyclase-cyclic AMP system. A monoclonal antibody (MAb BB1) to the type II regulatory subunit (RII) of cAPK was used in a post-embedding immunogold-labeling procedure to determine the ultrastructural localization of RII in several different secretory cells of the rat. Label was present in nuclei, especially over the heterochromatin, and in the cytoplasm, particularly in areas containing rough endoplasmic reticulum. Immunolabeled RII was also present in secretory granules of the parotid gland, exocrine and endocrine pancreas, seminal vesicle, anterior and intermediate pituitary, and intestinal endocrine cells. Photoaffinity labeling of parotid saliva, pancreatic and seminal fluids with the cyclic AMP analogue, 32P-labeled-8-azido-cyclic AMP, revealed the presence of cyclic AMP-binding proteins with electrophoretic mobilities similar to those of authentic cAPK regulatory subunits. These results confirm our previous observations on the localization of cAPK regulatory subunits in the rat parotid using polyclonal antibodies, and extend them to a number of other exocrine and endocrine cells. The apparent widespread occurrence of cAPK subunits in secretory granules and secretory fluids suggests that cAPK may be involved in specific intragranular regulatory and/or phosphorylation events, or that it has an unidentified extracellular function.

scholarly journals Dipeptidyl Peptidase IV Inhibitor MK-0626 Attenuates Pancreatic Islet Injury in Tacrolimus-Induced Diabetic Rats

PLoS ONE ◽  
2014 ◽  
Vol 9 (6) ◽  
pp. e100798 ◽  
Author(s):  
Long Jin ◽  
Sun Woo Lim ◽  
Kyoung Chan Doh ◽  
Shang Guo Piao ◽  
Jian Jin ◽  
...  
Keyword(s):  
Pancreatic Islet ◽  
Dipeptidyl Peptidase ◽  
Diabetic Rats ◽  
Dipeptidyl Peptidase Iv

scholarly journals Immunohistochemical Localization of Monoamine Oxidase Type B in Pancreatic Islets of the Rat

2005 ◽  
Vol 53 (9) ◽  
pp. 1149-1158 ◽  
Author(s):  
Yu-Hong Huang ◽  
Akio Ito ◽  
Ryohachi Arai
Keyword(s):  
B Cells ◽  
Monoamine Oxidase ◽  
Pancreatic Islets ◽  
Pancreatic Islet ◽  
Secretory Granules ◽  
Secretory Process ◽  
Type B ◽  
Electron Microscopic ◽  
Double Labeling ◽  
Outer Membranes

Monoamine oxidase (MAO) is regarded as a mitochondrial enzyme. This enzyme localizes on the outer membrane of mitochondria. There are two kinds of MAO isozymes, MAO type A (MAOA) and type B (MAOB). Previous studies have shown that MAOB activity is found in the pancreatic islets. This activity in the islets is increased by the fasting-induced decrease of plasma glucose level. Islet B cells contain monoamines in their secretory granules. These monoamines inhibit the secretion of insulin from the B cells. MAOB is active in degrading monoamines. Therefore, MAOB may influence the insulin-secretory process by regulating the stores of monoamines in the B cells. However, it has not been determined whether MAOB is localized on B cells or other cell types of the islets. In the present study, we used both double-labeling immunofluorescence histochemical and electron microscopic immunohistochemical methods to examine the subcellular localization of MAOB in rat pancreatic islets. MAOB was found in the mitochondrial outer membranes of glucagon-secreting cells (A cells), insulin-secreting cells (B cells), and some pancreatic polypeptide (PP)-secreting cells (PP cells), but no MAOB was found in somato-statin-secreting cells (D cells), nor in certain other PP cells. There were two kinds of mitochondria in pancreatic islet B cells: one contains MAOB on their outer membranes, but a substantial proportion of them lack this enzyme. Our findings indicate that pancreatic islet B cells contain MAOB on their mitochondrial outer membranes, and this enzyme may be involved in the regulation of monoamine levels and insulin secretion in the B cells.

scholarly journals Immunocytochemical Localization of Secretogranin III in the Anterior Lobe of Male Rat Pituitary Glands

2003 ◽  
Vol 51 (2) ◽  
pp. 227-238 ◽  
Author(s):  
Yuko Sakai ◽  
Masahiro Hosaka ◽  
Yoshiki Hira ◽  
Tatsuo Harumi ◽  
Yoshiyuki Ohsawa ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Secretory Granule ◽  
Endocrine Cells ◽  
Secretory Granules ◽  
Anterior Lobe ◽  
Male Rat ◽  
Secretory Proteins ◽  
Chromogranin B ◽  
Rat Pituitary ◽  
Granule Membrane

Secretogranin III (SgIII) is one of the acidic secretory proteins, designated as granins, which are specifically expressed in neuronal and endocrine cells. To clarify its precise distribution in the anterior lobe of the rat pituitary gland, we raised a polyclonal antiserum against rat SgIII for immunocytochemical analyses. By immunohistochemistry using semithin sections, positive signals for SgIII were detected intensely in mammotropes and thyrotropes, moderately in gonadotropes and corticotropes, but not in somatotropes. The distribution pattern of SgIII in the pituitary gland was similar to that of chromogranin B (CgB), also of the granin protein family, suggesting that the expressions of these two granins are regulated by common mechanisms. The localization of SgIII in endocrine cells was confirmed by immunoelectron microscopy. In particular, secretory granules of mammotropes and thyrotropes were densely and preferentially co-labeled for SgIII and CgB in their periphery. Moreover, positive signals for SgIII were occasionally found in cells containing both prolactin and TSH in secretory granules. These lines of evidence suggest that SgIII and CgB are closely associated with the secretory granule membrane and that this membrane association might contribute to gathering and anchoring of other soluble constituents to the secretory granule membrane.

scholarly journals Platelet alpha-granule and plasma membrane share two new components: CD9 and PECAM-1

Blood ◽  
1994 ◽  
Vol 84 (6) ◽  
pp. 1722-1730 ◽  
Author(s):  
EM Cramer ◽  
G Berger ◽  
MC Berndt
Keyword(s):  
Plasma Membrane ◽  
Polyclonal Antibodies ◽  
Present Report ◽  
Cross Reactivity ◽  
Membrane Receptors ◽  
Type I ◽  
Double Labeling ◽  
Platelet Surface ◽  
Platelet Receptor ◽  
Granule Membrane

CD9 (p24) and PECAM1 (CD31) antigens are well-defined components of the platelet plasma membrane. Both are integral glycoproteins (GPs) implicated in the adhesive and aggregative properties of human platelets. In the present report, we have investigated their subcellular localization using immunoelectron microscopy. The monospecificity of the two polyclonal antibodies used was confirmed by immunoblotting. On normal resting platelets, immunolabeling for CD9 and PECAM1 was found lining the plasma membrane and the luminal face of the open canalicular system. Some labeling was also consistently found on the alpha-granule limiting membrane. This was confirmed by double labeling experiments in which fibrinogen and von Willebrand factor (vWF) were used as alpha-granule markers. CD9 and PECAM-1 were found lining the membrane of the same granules that contained fibrinogen and vWF in their matrix. CD9 and PECAM-1 thus appear to have an intracellular distribution identical to GPIIb-IIIa, a major aggregation platelet receptor. To rule out a cross-reactivity of the two polyclonal antibodies with GPIIb/IIIa, we studied PECAM1 and CD9 expression on the platelets from a patient with type I Glanzmann's thrombasthenia whose platelets are devoid of GPIIb/IIIa. The same pattern of labeling was observed for both antigens as for normal platelets. Normal platelets were further observed after stimulation by agonists that either fail to induce (ADP) or induce granule secretion (thrombin). After treatment with ADP, platelets changed shape and centralized their granules; the plasma membrane immunolabeling remained unchanged; and gold particles were still found decorating the periphery of the centralized alpha- granules. After thrombin treatment, alpha-granules fused with the platelet membrane and secretion occurred. A significant increase of labeling was then observed on the platelet surface. From these results we conclude that the alpha-granule membrane contains two additional receptors in common with the plasma membrane. This suggests that alpha- granule membrane receptors may originate from a dual mechanism: direct targeting from the Golgi complex in megakaryocytes (for alpha-granule- specific receptors such as P-selectin) or by endocytosis from the plasma membrane (for proteins distributed in the two compartments).

scholarly journals Dipeptidyl Peptidase IV Inhibitor MK-0626 Attenuates Pancreatic Islet Injury in Tacrolimus-Induced Diabetic Rats

2014 ◽  
Vol 33 (2) ◽  
pp. A6-A7
Author(s):  
Sun Woo Lim ◽  
Jin Long ◽  
Doh Kyoung Chan ◽  
Jin Jian ◽  
Piao Shang Guo ◽  
...  
Keyword(s):  
Pancreatic Islet ◽  
Dipeptidyl Peptidase ◽  
Diabetic Rats ◽  
Dipeptidyl Peptidase Iv
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