Subcellular distribution of Ca2+ pumping sites in human neutrophils.

Krause, Karl‐Heinz; Lew, P D

doi:10.1172/jci113035

Cited by 59 publications

(29 citation statements)

References 66 publications

(42 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The effect of 1,4,5-IP3 on the exchanger also appears to be quite specific, because neither 1,3,4,5-IP4, 1,3,4,-IP3, nor 4,5-IP2 affected the ability of the exchanger to transport Ca". Our conclusion that 1,4,5-IP3 may regulate cytosolic Ca++ by interacting with plasma membrane Na+-Ca++ exchanger, is consistent with recent observations in human neutrophils, rat hepatocytes, bovine adrenal cortex, and parotid acinar cells, where receptors for 1,4,5-IP3 located at or near the plasma membrane were isolated (32)(33)(34)(35)(36).…”

Section: Discussionsupporting

confidence: 91%

Inositol 1,4,5-trisphosphate may regulate rat brain Cai++ by inhibiting membrane bound Na(+)-Ca++ exchanger.

Fraser

Sarnacki²

1990

J. Clin. Invest.

View full text Add to dashboard Cite

The role of inositol 1,4,5-trisphosphate (1,4,5-IP3) in regulating cytosolic Ca" by stimulating Ca++ release from intracellular organelles is well established. However, other modes of intracellular Ca++ regulation by 1,4,5-IP3 have not been determined. To determine if 1,4,5-IP3 may regulate cell cytosolic Ca++ by acting on plasma membrane bound Na+-Ca++ exchanger, we investigated Ca++ transport in synaptosomes using 45Ca++ as tracer. In the presence of either an inhibitor of voltage gated Na+ channels (tetrodotoxin) or the K+ ionophore (valinomycin), Ca++ uptake was significantly inhibited (P < 0.05) by 1,4,5-IP3 in a concentration dependent manner, with half-maximal inhibition occurring at submicromolar concentrations between 10-9 M and 10-10 M 1,4,5-IP3. Similarly, Ca++ efilux by the exchanger was significantly inhibited 40% by 1,4,5-IP3. The inhibitory effect of 1,4,5-IP3 on the Na+-Ca++ exchanger was observed in the presence of Ca++ channel blockers, and in vesicles pretreated with caffeine to deplete the 1,4,5-IP3-sensitive stores of Ca++. These results suggest that during signal transduction in brain, 1,4,5-IP3 may increase cytosolic [Ca"]I in part by inhibiting the Na+-Ca++ exchanger and thus, Ca++ efflux from cell. (J. Clin. Invest. 1990.

show abstract

Section: Discussionsupporting

confidence: 91%

Inositol 1,4,5-trisphosphate may regulate rat brain Cai++ by inhibiting membrane bound Na(+)-Ca++ exchanger.

Fraser

Sarnacki²

1990

J. Clin. Invest.

View full text Add to dashboard Cite

show abstract

“…Rab6p has been found to be associated with the surface of Golgi cisternae, probably medial and trans, in a wide variety of animal cells (28). Rab lAp and rab6p are probably associated to the Golgi apparatus in human neutrophils since Golgi membranes were present in the membrane fraction obtained by centrifugation on Percoll gradient (37) as demonstrated by galactosyl transferase (a specific Golgi marker) immunoreactivity using an antiserum kindly provided by E. Berger (Zurich, Switzerland; data not shown). Similarly, in U937 cells induced to differentiate with PMA, rab6p was immunofluorescently detected in the Golgi area (unpublished data).…”

Section: Resultsmentioning

confidence: 97%

Increase in the expression of a family of small guanosine triphosphate-binding proteins, rab proteins, during induced phagocyte differentiation.

Maridonneau‐Parini¹,

Yang²,

Bornens³

et al. 1991

J. Clin. Invest.

View full text Add to dashboard Cite

Rab is a newly identified family of small G-proteins that share 35-70% homology with the yeast Sec4p and Yptlp involved in the regulation of the secretory pathway. Mature phagocytes display functions requiring organized intracellular traffic and, for this reason, we questioned whether phagocyte differentiation could correlate with the increased expression of rab proteins. Rabbit antisera raised against the recombinant proteins rablAp, 2p, 4p, and 6p were able to detect the corresponding proteins in the human monoblast leukemic cell line U937. When these cells were induced to differentiate into monocyte/ macrophage-like cells displaying functional characteristics of a normal phagocyte, rablAp, 2p, 4p, and 6p were increased and this correlated with an increase in the rab transcripts. Using a rab5 probe, we also observed an increased expression of the rab5 gene in differentiated cells. Similarly, differentiation of the human leukemic myeloblast HL60 cell line along either monocyte or granulocyte pathways induced an increased expression of the rab proteins. Rab proteins were also detected in human neutrophils and in guinea pig alveolar macrophages. As degranulation is one of the phagocyte functions acquired in the late stage of differentiation, we investigated whether rab proteins would be involved in this process. Although rab proteins were tightly membrane bound, none of them was detected in the specific or azurophil granules purified from human neutrophils. The increased expression of rab proteins in mature phagocytes suggests that they may promote functions highly developed in these cells. (J. Clin. Invest. 1991. 87:901-907.)

show abstract

“…However, this seems unlikely in neutrophils because they are virtually devoid of endoplasmic reticulum (22). Subcellular fractionation studies in neutrophils and HL-60 cells revealed that the Ca 2+ -pumping, Ins 1,4,5-P 3 -responsive organelle could be separated from endoplasmic reticulum, mitochondria, golgi apparatus and other known organelles (23,24). The Ca 2+ -pumping activity and Ins 1,4,5-P 3 -induced Ca 2+ -release activity copurified with a 60 kDa Ca 2+ -binding protein that showed biochemical similarities and immunological cross-reactivity with calsequestrin from muscle sarcoplasmic reticulum (24).…”

Section: Introductionmentioning

confidence: 98%