Comparison of the insulin binding, uptake and endogeneous insulin content in long‐ and short‐term starvation in <i>Tetrahymena</i>

Csaba, G.; Kovács, P.; Pállinger, Éva

doi:10.1002/cbf.1399

Cited by 11 publications

(10 citation statements)

References 18 publications

(16 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…thermophila behavior responds in a specific and selective way to the addition of effectors (hormones, drugs) that would, at first glance, be expected to affect only cells of multicellular eukaryotes (39–41). It has been conjectured that these behaviors are mediated by ligand-receptor interactions (42).…”

Section: Discussionmentioning

confidence: 99%

Entry and Killing of Tetrahymena thermophila by Bacterially Produced Shiga Toxin

Stolfa

Koudelka

2013

mBio

View full text Add to dashboard Cite

Phage-encoded Shiga toxin (Stx) acts as a bacterial defense against the eukaryotic predator Tetrahymena thermophila. It is unknown how Stx enters Tetrahymena protozoa or how it kills them. Tetrahymena protozoa are phagocytotic; hence, Stx could gain entry to the cytoplasm through the oral apparatus or via endocytosis. We find that Stx2 can kill T. thermophila protozoa that lack an oral apparatus, indicating that Stx2 can enter these cells via endocytosis. As opposed to the lack of effect on mammalian phagocytes, Stx2 produced by bacteria encapsulated within phagocytotic vesicles is also capable of killing Tetrahymena. Addition of an excess of the carbohydrate binding subunits of Stx2 (StxB) and/or ricin (ricin B) blocks Stx2 cytotoxicity. Thus, regardless of whether Stx2 enters the cytoplasm by endocytosis or from the phagocytotic vesicle, this transport is mediated by a putative glycoconjugate receptor. Bacteriophage-mediated lysis of Stx-encoding bacteria is necessary for Stx toxicity in Tetrahymena; i.e., toxin released as a consequence of digestion of bacteria by Tetrahymena is harmless to the cell. This finding provides a rationale as to why the genes encoding Stx are found almost exclusively on bacteriophages; Stx must be released from the bacteria prior to the digestion of the cell, or it will not be able to exert its cytotoxic effect. It also suggests a reason why other bacterial exotoxins are also found only on temperate bacteriophages. Incubation of Tetrahymena with purified Stx2 decreases total protein synthesis. This finding indicates that, similar to mammalian cells, Stx2 kills Tetrahymena by inactivating its ribosomes.

show abstract

Section: Discussionmentioning

confidence: 99%

Entry and Killing of Tetrahymena thermophila by Bacterially Produced Shiga Toxin

Stolfa

Koudelka

2013

mBio

View full text Add to dashboard Cite

show abstract

“…endorphin and serotonin in 10 -18 M) [66,67] as well as the lysosomal protein degradation blocker, bacitracin [68]. Starvation also influences the insulin production, binding and uptake of the cells [69]. Higher concentrations (10 -3 -10 -5 M) of insulin down regulate the insulin receptors, while lower concentrations (10 -6 -10 -18 M) provoke hormonal imprinting [70].…”

Section: The Insulin Receptormentioning

confidence: 99%

“…Histidine, the basic amino acid and histamine similarly influence phagocytosis [163]. Presence of histamine or serotonin enormously decreases insulin binding [69]. Treatment with histamine or serotonin elevates EGF content of the cells [164].…”

Section: Biogenic Aminesmentioning

confidence: 99%

See 1 more Smart Citation

The hormonal system of the unicellular Tetrahymena: A review with evolutionary aspects

Csaba

2012

Acta Microbiologica Et Immunologica Hungarica

View full text Add to dashboard Cite

The unicellular ciliate, Tetrahymena has receptors for hormones of the higher ranked animals, these hormones (e.g. insulin, triiodothyronine, ACTH, histamine, etc.) are also produced by it and it has signal pathways and second messengers for signal transmission. These components are chemically and functionally very similar to that of mammalian ones. The exogenously given hormones regulate different functions, as movement, phagocytosis, chemotaxis, cell growth, secretion, excretion and the cells' own hormone production. The receptors are extremely sensitive, certain hormones are sensed (and response is provoked) at 10-21 M concentration, which makes likely that the function could work by the effect of hormones produced by the Tetrahymena itself. The signal reception is selective, it can differentiate between closely related hormones. The review is listing the hormones produced by the Tetrahymena, the receptors which can receive signals and the signal pathways and second messengers as well, as the known effects of mammalian hormones to the life functions of Tetrahymena. The possible and justified role of hormonal system in the Tetrahymena as a single cell and inside the Tetrahymena population, as a community is discussed. The unicellular hormonal system and mammalian endocrine system are compared and evolutionary conclusions are drawn.

show abstract

“…Osmotic, formaldehyde or thermal stress raised insulin binding, as also prolonged starvation (Csaba et al, , , ; Csaba and Pállinger, , ). These treatments also increased insulin production.…”

Section: Effects Of Insulin and Effects On Insulinmentioning

confidence: 99%

Insulin at a unicellular eukaryote level

Csaba

2013

Cell Biology International

View full text Add to dashboard Cite

The unicellular ciliate, Tetrahymena, has been the main model for studying the hormonal system of unicellular animals. Tetrahymena produce, store, secrete and take up insulin, the hormone being similar to that of mammals, both immunocytochemically and functionally. The plasma membrane and nuclear envelope of Tetrahymena have insulin receptors, which are structurally similar to the mammalian receptor, as it their binding capacity. The cell has also second messengers and signal pathways for insulin. Insulin influences the synthesis of other hormones. The first short encounter between the cell and insulin provokes the hormonal imprinting that alters the function of the cells and is transmitted to the progeny, and can persist for over 1,000 generations, in hormone binding, hormone content, phagocytosis, cell growth and movement. Insulin has a survival function in Tetrahymena and during stress insulin production and binding are elevated. Other protozoa also react to insulin, and the evolutionary aspects are discussed in this review since it is still not appreciated that the hormones are of great antiquity in the animal kingdom.

show abstract

Comparison of the insulin binding, uptake and endogeneous insulin content in long‐ and short‐term starvation in Tetrahymena

Cited by 11 publications

References 18 publications

Entry and Killing of Tetrahymena thermophila by Bacterially Produced Shiga Toxin

Entry and Killing of Tetrahymena thermophila by Bacterially Produced Shiga Toxin

The hormonal system of the unicellular Tetrahymena: A review with evolutionary aspects

Insulin at a unicellular eukaryote level

Contact Info

Product

Resources

About