Effect of vasoactive peptides on Tetrahymena. chemotactic properties of endothelins (ET-1, ET-2, ET-3, fragment 11-21 of ET-1 and big endothelin-1): a short-term inducible signalling mechanism of chemotaxis.
The unicellular Tetrahymena is a sensitive model for the study of chemotaxis induced by endothelins. In short-term chemotactic responses, ET-2 and ET-3 were chemorepellent, compared to the referent control (culture medium) and chemoattractant, ET-1. These differences suggest that the change of some aromatic residues in the loop region (residues 5-9) of the ET-1 abrogates its chemoattractant character. The response of Tetrahymena is highly selective, since substitution of two amino acids are enough to cause this alteration in (behavioural) response. Such a change seems to be more important than the loss of the entire first 10 amino acids (in ET-1 fragment 11-21), since after this it acquires some chemoattractive effect of ET-1. Selection with ET-3 rigorously stimulated the cell's responsiveness to the medium, this ability was abolished by the repeated ET-3 treatment. Big endothelin-1 was repellent in all concentrations. These experiments demonstrate the very sensitive discriminating capacity of chemotactic responsiveness at a low level of phylogeny. Chemotactic selection with endothelins underlines the possibility that there may be separate mechanisms responsible for the short-term chemotactic responses and the long-lasting effects of chemotactic selection.
Köhidai
L
L
Department of Genetics, Cell and Immunobiology, Semmelweis University,Budapest, Hungary.
Tóth
K
K
Ruskoaho
H
H
Csaba
G
G
D000818:Animals; D002633:Chemotaxis / Q000187:drug effects* / Q000502:physiology; D019332:Endothelin-1 / Q000494:pharmacology* / Q000502:physiology; D019333:Endothelin-2 / Q000494:pharmacology* / Q000502:physiology; D019334:Endothelin-3 / Q000494:pharmacology* / Q000502:physiology; D016232:Endothelins / Q000494:pharmacology* / Q000502:physiology; D010446:Peptide Fragments / Q000494:pharmacology; D011498:Protein Precursors / Q000494:pharmacology* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013768:Tetrahymena / Q000187:drug effects / Q000502:physiology*
D019332:Endothelin-1; D019333:Endothelin-2; D019334:Endothelin-3; D016232:Endothelins; D010446:Peptide Fragments; D011498:Protein Precursors