Polyamine Triggering of Exocytosis in Paramecium Involves an Extracellular Ca 2+ /(Polyvalent Cation)-Sensing Receptor, Subplasmalemmal Ca-Store Mobilization and Store-Operated Ca 2+ -Influx via Unspecific Cation Channels

Klauke, Norbert; Blanchard, Marie-Pierre; Plattner, Helmut

doi:10.1007/s002320001039

Cited by 43 publications

(62 citation statements)

References 98 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Bearing in mind the considerable ambiguity of pharmacological tools in work with ciliated protozoans (77), we rather reanalyzed the effects of different trigger agents previously used, among them polyamines (49,74,78) and the permeable RyR agonists, 4-CmC and caffeine, which all normally produce trichocyst exocytosis in parallel to SOC-type Ca 2ϩ signaling (46)(47)(48).…”

Section: Discussionmentioning

confidence: 99%

“…Each cell possesses up to 1,000 trichocysts attached to the cell membrane. Their contents can be extruded synchronously in response to natural stimuli, i.e., predators (34, as confirmed by Knoll et al [49]), to artificial polyamine secretagogues such as aminoethyldextran (AED) (78), to caffeine (48) or to the ryanodine substitute, 4-chloro-meta-cresol (4-CmC) (46). Their expulsion strictly depends on Ca 2ϩ (10) and is accompanied by an increase of intracellular [Ca 2ϩ ] i (24,47).…”

Section: Camentioning

confidence: 94%

“…Their expulsion strictly depends on Ca 2ϩ (10) and is accompanied by an increase of intracellular [Ca 2ϩ ] i (24,47). This Ca 2ϩ signal originates from rapid mobilization of cortical stores, the alveolar sacs (33,64,74), superimposed by Ca 2ϩ influx (46,72). It thus represents a SOC-type mechanism (SOC, store-operated Ca 2ϩ entry) known from mammalian systems (81).…”

Section: Camentioning

confidence: 99%

“…They possess a SERCA-type pump located at the membrane facing the cell center (36,37) and a luminal high-capacity/lowaffinity CaBP of the calsequestrin type (73). Thus far, Ca 2ϩ release channels of these stores were identified only indirectly as cells respond by exocytosis to the RyR activators caffeine (54,48) and 4-CmC (46). However, an involvement of conserved RyRs has remained questionable as ryanodine is not able to activate Ca 2ϩ release from alveolar sacs, as is the case with IP 3 (54).…”

Section: Camentioning

confidence: 99%

“…Clearly, CRC-IV-1 silencing results in a significant reduction of Ca 2ϩ releasable from stores compared to controls (pPD-GFP). Since former studies had shown that the ryanodine receptor activators, 4-CmC and caffeine, activate Ca 2ϩ release from alveolar sacs (46,48), we also applied these drugs to mock-treated and to CRC-IV-1-silenced cells. As shown in Fig.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Ladenburger¹,

Sehring²,

Korn³

et al. 2009

Molecular and Cellular Biology

121

View full text Add to dashboard Cite

A database search of the Paramecium genome reveals 34 genes related to Ca 2؉ -release channels of the inositol-1,4,5-trisphosphate (IP 3 ) or ryanodine receptor type (IP 3 R, RyR). Phylogenetic analyses show that these Ca 2؉ release channels (CRCs) can be subdivided into six groups (Paramecium tetraurelia CRC-I to CRC-VI), each one with features in part reminiscent of IP 3 Rs and RyRs. We characterize here the P. tetraurelia CRC-IV-1 gene family, whose relationship to IP 3 Rs and RyRs is restricted to their C-terminal channel domain. CRC-IV-1 channels localize to cortical Ca 2؉ stores (alveolar sacs) and also to the endoplasmic reticulum. This is in contrast to a recently described true IP 3 channel, a group II member (P. tetraurelia IP 3 R N -1), found associated with the contractile vacuole system. Silencing of either one of these CRCs results in reduced exocytosis of dense core vesicles (trichocysts), although for different reasons. Knockdown of P. tetraurelia IP 3 R N affects trichocyst biogenesis, while CRC-IV-1 channels are involved in signal transduction since silenced cells show an impaired release of Ca 2؉ from cortical stores in response to exocytotic stimuli. Our discovery of a range of CRCs in Paramecium indicates that protozoans already have evolved multiple ways for the use of Ca 2؉ as signaling molecule.Ca 2ϩ is an important component of cell activity in all organisms, from protozoa to mammals. Thereby Ca 2ϩ may originate from the outside medium and/or from internal stores (7, 18). Ca 2ϩ release from internal stores is mediated by various Ca 2ϩ release channels (CRCs), of which the inositol-1,4,5-trisphosphate receptor (IP 3 R) and ryanodine receptor (RyR) families have been studied most extensively (8,9,29,63 (14). IP 3 generates and maintains a Ca 2ϩ gradient in the hyphal tip of Neurospora crassa and the IP 3 -sensitive channels have been reconstituted and characterized with the planar bilayer method (87). In summary, these publications suggest that IP 3 -dependent signaling pathways are conserved among unicellular organisms, including protozoa.Despite these data, the molecular characterization of IP 3 or ryanodine receptors in low eukaryotes is currently a challenge since the identification of orthologues has not been possible thus far, probably because of evolutionary sequence divergence (66). Traynor et al. (96) identified an IP 3 receptor-like protein, IplA, in Dictyostelium discoideum, which possesses regions related to IP 3 R sequences, but thus far no evidence for IP 3 interaction exists. We have recently described an IP 3 R in the ciliated protozoa Paramecium tetraurelia (referred to here as P. tetraurelia IP 3 R N ) (53), with features characteristic of mammalian IP 3 Rs in terms of topology and ability for IP 3 binding. The expression level of P. tetraurelia IP 3 R N is modulated by extracellular Ca 2ϩ concentrations ([Ca 2ϩ ] o ) and immunofluorescence studies reveal an unexpected localization to the contractile vacuole complex (CVC), the major organelle involved in osmoregulation...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Camentioning

confidence: 94%

Section: Camentioning

confidence: 99%

Section: Camentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Ladenburger¹,

Sehring²,

Korn³

et al. 2009

Molecular and Cellular Biology

121

View full text Add to dashboard Cite

show abstract

My favorite cell—Paramecium

Plattner

2002

BioEssays

View full text Add to dashboard Cite

A Paramecium cell has a stereotypically patterned surface , with regularly arranged cilia, dense-core secretory vesicles and subplasmalemmal calcium stores. Less strikingly, there is also a patterning of molecules; for instance, some ion channels are restricted to certain regions of the cell surface. This design may explain very effective and selective responses, such as that to Ca 2 + upon stimulation. It enables the cell to respond to a Ca 2 + signal precisely secretion (exocytosis) or by changing its ciliary activity. These responses depend on the location and/or type of signal, even though these two target structures co-exist side-by-side, and normally only limited overlap occurs between the different functions. Furthermore, the patterning of exocytotic sites and the possibility of synchronous exocytosis induction in the sub-second time range have considerably facilitated analyses, and thus led to new concepts of exocytotic membrane fusion. It has been possible to dissect complicated events like overlapping Ca 2 + fluxes produced from external sources and from internal stores. Since molecular genetic approaches have become available for Paramecium, many different gene products have been identified only some of which are known from "higher" eUkaryotes. Although a variety of basic cellular functions are briefly addressed to demonstrate the uniqueness of this unicellular organism, this article focuses on exocy-tosis regulation. BioEssays 24:649-658, 2002.

show abstract

Crystal structure analysis of the exocytosis-sensitive phosphoprotein, pp63/parafusin (phosphoglucomutase), from Paramecium reveals significant conformational variability 1 1Edited by D. Rees

Müller

Diederichs

Breed

et al. 2002

Journal of Molecular Biology

View full text Add to dashboard Cite

During exocytosis of dense-core secretory vesicles (trichocysts) in Paramecium, the protein pp63/parafusin (pp63/pf) is transiently dephosphorylated. We report here the structures of two crystal forms of one isoform of this protein which has a high degree of homology with rabbit phosphoglucomutase, whose structure has been reported. As expected, both proteins possess highly similar structures, showing the same four domains forming two lobes with an active-site crevice in between. The two X-ray structures that we report here were determined after crystallization in the presence of sulfate and tartrate, and show the lobes arranged as a closed and an open conformation, respectively. While both conformations possess a bound divalent cation, only the closed (sulfatebound) conformation shows bound sulfate ions in the``phosphate-transfer site'' near the catalytic serine residue and in the``phosphate-binding site''.Comparison with the open form shows that the latter dianion is placed in the centre of three arginine residues, one contributed by subunit II and two by subunit IV, suggesting that it causes a contraction of the arginine triangle, which establishes the observed conformational closure of the lobes. It is therefore likely that the closed conformation forms only when a phosphoryl group is bound to the phosphate-binding site. The previously published structure of rabbit phosphoglucomutase is intermediate between these two conformers. Several of the known reversible phosphorylation sites of pp63/pf-1 are at positions critical for transition between the conformations and for binding of the ligands and thus give hints as to possible roles of pp63/pf-1 in the course of exocytosis.

show abstract

Polyamine Triggering of Exocytosis in Paramecium Involves an Extracellular Ca 2+ /(Polyvalent Cation)-Sensing Receptor, Subplasmalemmal Ca-Store Mobilization and Store-Operated Ca 2+ -Influx via Unspecific Cation Channels

Cited by 43 publications

References 98 publications

Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

My favorite cell—Paramecium

Crystal structure analysis of the exocytosis-sensitive phosphoprotein, pp63/parafusin (phosphoglucomutase), from Paramecium reveals significant conformational variability 1 1Edited by D. Rees

Contact Info

Product

Resources

About

Polyamine Triggering of Exocytosis in Paramecium Involves an Extracellular Ca 2+ /(Polyvalent Cation)-Sensing Receptor, Subplasmalemmal Ca-Store Mobilization and Store-Operated Ca 2+ -Influx via Unspecific Cation Channels

Cited by 43 publications

References 98 publications

Novel Types of Ca2+ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Novel Types of Ca2+ Release Channels Participate in the Secretory Cycle of Paramecium Cells

My favorite cell—Paramecium

Crystal structure analysis of the exocytosis-sensitive phosphoprotein, pp63/parafusin (phosphoglucomutase), from Paramecium reveals significant conformational variability 1 1Edited by D. Rees

Contact Info

Product

Resources

About

Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells