Flashing light signaling circuit in sponges: Endogenous light generation after tissue ablation in Suberites domuncula

• Published in: Journal of cellular biochemistry 2010-12, Vol.111 (6), p.1377-1389
• Main Authors: Wiens, Matthias, Wang, Xiaohong, Unger, Andreas, Schröder, Heinz C., Grebenjuk, Vladislav A., Pisignano, Dario, Jochum, Klaus P., Müller, Werner E.G.
• Format: Article
• Language: English
• Subjects: Animals; Blotting, Northern; Blotting, Western; cryptochrome; Cryptochromes - genetics; Cryptochromes - metabolism; Demospongiae; Hexactinellida; Immunohistochemistry; Light; light emission; light signaling circuit; luciferase; Luciferases - genetics; Luciferases - metabolism; Marine; Porifera; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction - physiology; SOX-related protein; sponges; Suberites - genetics; Suberites - metabolism; Suberites domuncula
• ISSN: 0730-2312; 1097-4644; 1097-4644
• DOI: 10.1002/jcb.22866

The skeleton of siliceous sponges (phylum Porifera: classes Demospongiae and Hexactinellida), composed of tightly interacting spicules that assemble to a genetically fixed scaffold, is formed of bio‐silica. This inorganic framework with the quality of quartz glass has been shown to operate as light waveguide in vitro and very likely has a similar function in vivo. Furthermore, the molecular toolkit for endogenous light generation (luciferase) and light/photon harvesting (cryptochrome) has been identified in the demosponge Suberites domuncula. These three components of a light signaling system, spicules—luciferase—cryptochrome, are concentrated in the surface layers (cortex) of the poriferan body. Specimens from which this cortex has been removed/ablated do not emit light. However, with regeneration and reconstitution of the cortex the animals re‐gain the capacity to flash light. This newly discovered characteristic of sponges to generate light prompted us to investigate the genetic basis for the endogenous light signaling system. As a potential transcription factor involved in the expression of luciferase and cryptochrome, a SOX‐related protein has been identified. In dark‐adapted animals or in tissue from below the cortex region, the medulla, no gene or protein expression of SOX‐related protein, luciferase, and cryptochrome could be detected. However, during the regeneration of the cortex, a stage‐specific expression pattern was recorded: SOX‐related protein > luciferase > cryptochrome. We conclude that a flashing light signaling circuit exists, which might control the retinoic acid‐induced differentiation of stem cells into pulsating and contracting sponge cells, that is, pinacocytes and myocytes. J. Cell. Biochem. 111: 1377–1389, 2010. © 2010 Wiley‐Liss, Inc.