New Three-Finger Protein from Starfish Asteria rubens Shares Structure and Pharmacology with Human Brain Neuromodulator Lynx2

Abstract

Three-finger proteins (TFPs) are small proteins with characteristic three-finger β-structural fold stabilized by the system of conserved disulfide bonds. These proteins have been found in organisms from different taxonomic groups and perform various important regulatory functions or act as components of snake venoms. Recently, four TFPs (Lystars 1–4) with unknown function were identified in the coelomic fluid proteome of starfish A. rubens. Here we analyzed the genomes of A. rubens and A. planci starfishes and predicted additional five and six proteins containing three-finger domains, respectively. One of them, named Lystar5, is expressed in A. rubens coelomocytes and has sequence homology to the human brain neuromodulator Lynx2. The three-finger structure of Lystar5 close to the structure of Lynx2 was confirmed by NMR. Similar to Lynx2, Lystar5 negatively modulated α4β2 nicotinic acetylcholine receptors (nAChRs) expressed in X. laevis oocytes. Incubation with Lystar5 decreased the expression of acetylcholine esterase and α4 and α7 nAChR subunits in the hippocampal neurons. In summary, for the first time we reported modulator of the cholinergic system in starfish.

Orientational Preferences of GPI-Anchored Ly6/uPAR Proteins

“…Ly6/uPAR proteins are valuable players in the physiology of animals, including humans [1][2][3]. They have been found in Echinodermata [4,5], Platyhelminthes [6], Arthropoda [7], and Chordata [1]. The name of the Ly6/uPAR superfamily comes from two representatives: lymphocyte antigen-6 (Ly6) [8] and urokinase-type plasminogen activator receptor (uPAR, also called PLAUR) [9].…”

Morphological and Physiological Aspects of Mutable Collagenous Tissue at the Autotomy Plane of the Starfish Asterias rubens L. (Echinodermata, Asteroidea): An Echinoderm Paradigm

“…However, they have provided evidence that tonic activity in a neural pathway that includes muscarinic receptors maintains a baseline level of stiffness in the dermal collagenous tissue. This is a further indication of the importance of cholinergic regulation of effector systems in A. rubens [ 77 ]. It is intriguing that atropine, by itself, stiffens the mutable capsular ligament (catch apparatus) of the spine joint of a sea-urchin [ 78 ], which is the opposite of its effect on the dermal collagenous tissue of asteriid starfish and, assuming that this action is receptor-mediated, implies that a cholinergic pathway could be responsible for tonic inhibition of stiffening in this ligament.…”