BMP signaling regulates the skeletal and connective tissue differentiation during caudal fin regeneration in sailfin molly (Poecilia latipinna)

Abstract

Caudal fin regeneration in sailfin molly, Poecilia latipinna (Lesueur 1821) involves an initial wound healing stage, followed by blastema that is formed of fast proliferating cells. In order to replicate the lost fin, correct differentiation of the blastemal cells into various tissues is the prime essence. Among the molecular signals governing proper differentiation of blastemal cells, members of the bone morphogenetic protein (BMP) family are crucial. Herein, we investigated the specific effects of inhibition of BMP signaling using LDN193189 on skeletal and connective tissue formation in the regenerating tail fin of P. latipinna during early differentiation phase. It was observed that BMP inhibition leads to reduction in the length of regeneration, which can be correlated with compromised proliferation of blastemal cells. Decreased expression of cell proliferation marker like pcna together with reduced BrdU positive cells consolidate the above observation. Further, histological analysis revealed stunted progression of skeletal tissues and this correlated with the reduced expression of sox9, runx2 and dlx5, Osc and Osn genes in response to BMP inhibition. Also, defective bone patterning was observed due to BMP inhibition, which was associated with diminished levels of shh, ptc-1, gli2 and other BMP ligands. Moreover, histochemical analysis revealed that collagen, one of the most prominent components of connective tissue, was formed below par in treated fin tissues which was subsequently confirmed by biochemical and transcript level analyses. Overall our results highlight the importance of the BMP pathway in proper differentiation of skeletal and connective tissues during the differentiation stage of regenerating caudal fin.

BMP signaling is required for amphioxus tail regeneration

“…In planarians, the bmp2/4-like and smad4-like genes are necessary for lateral regeneration (Reddien et al, 2007). Similarly, in fish, the BMP signaling pathway is required for caudal fin regeneration, and ectopic expression of the BMP signaling inhibitor Chordin can perturb the normal regeneration process (Smith et al, 2006;Thorimbert et al, 2015;Rajaram et al, 2017). In amphibians, BMP is involved in both tail and limb regeneration (Beck et al, 2006).…”

Variation in expression and activity pattern ofmmp2andmmp9on different time scales in the regenerating caudal fin ofPoecilia latipinna

“…Another teleost, the sailfin molly Poecilia latipinna (LeSeuer 1821) is endowed with a similar ability to regrow its severed or amputated caudal fin. Previous studies on P. latipinna have demonstrated its advantages over the use of D. rerio to study the mechanism of epimorphic regeneration primarily because of its inherent adaptability to the oriental laboratory conditions (Rajaram et al, ). A comparative account, focussing on the time line of caudal‐fin regeneration in both, D. rerio and P. latipinna has been published recently by Murawala et al .…”

No Correlation between Endo- and Exoskeletal Regenerative Capacities in Teleost Species

“…The dermal fin folds are useful during swimming, but due to their fine structure, they can get easily injured, therefore, the capacity to regenerate them has clear adaptive value. Exoskeletal regeneration has been described in many Actinopterygian species, (e.g., sturgeon (Acipenser oxyrinchus) [35], short-lived killifish (Nothobranchius furzeri) [36], sailfin molly (Poecilia latipinna) [37], mexican cavefish (Astyanax mexicanus) [38], medaka (Oryzias latipes) [39], loach (Paramisgurnus dabryanu) [40] and several others [41]), suggesting that this is an ancestral trait of ray-finned fishes.…”