Expression ofMsx genes in regenerating and developing limbs of axolotl

Abstract

Msx genes, homeobox‐containing genes, have been isolated as homologues of the Drosophila msh gene and are thought to play important roles in the development of chick or mouse limb buds. We isolated two Msx genes, Msx1 and Msx2, from regenerating blastemas of axolotl limbs and examined their expression patterns using Northern blot and whole mount in situ hybridization during regeneration and development. Northern blot analysis revealed that the expression level of both Msx genes increased during limb regeneration. The Msx2 expression level increased in the blastema at the early bud stage, and Msx1 expression level increased at the late bud stage. Whole mount in situ hybridization revealed that Msx2 was expressed in the distal mesenchyme and Msx1 in the entire mesenchyme of the blastema at the late bud stage. In the developing limb bud, Msx1 was expressed in the entire mesenchyme, while Msx2 was expressed in the distal and peripheral mesenchyme. The expression patterns of Msx genes in the blastemas and limb buds of the axolotl were different from those reported for chick or mouse limb buds. These expression patterns of axolotl Msx genes are discussed in relation to the blastema or limb bud morphology and their possible roles in limb patterning. J. Exp. Zool. 282:703–714, 1998. © 1998 Wiley‐Liss, Inc.

Inhibition of zebrafish fin regeneration using in vivo electroporation of morpholinos against fgfr1 and msxb

“…Msxb was chosen as msx orthologs have been demonstrated to be expressed during regeneration in many different species (Akimenko et al, 1995;Crews et al, 1995;Reginelli et al, 1995;Simon et al, 1995;Carlson et al, 1998;Koshiba et al, 1998;Heber-Katz, 1999;Nechiporuk and Keating, 2002;Poss et al, 2002a,b) and there are data supporting a crucial functional role in regeneration in other vertebrates (Odelberg et al, 2000;Beck et al, 2003;Han et al, 2003).…”

“…Our second knock-down experiment utilized Msxb, as msx genes have been postulated to play a role in regeneration due to their specialized expression patterns during newt and axolotl limb regeneration (Crews et al, 1995;Simon et al, 1995;Carlson et al, 1998;Koshiba et al, 1998), murine digit tip regeneration (Reginelli et al, 1995;Han et al, 2003), murine ear punch healing (Heber-Katz, 1999), and zebrafish heart (Raya et al, 2003) and caudal fin regeneration (Akimenko et al, 1995;Nechiporuk and Keating, 2002;Poss et al, 2002a;Kawakami et al, 2004). There is also some correlative evidence for functional roles for Msx proteins in regeneration.…”

Looking proximally and distally: 100 years of limb regeneration and beyond

“…Stemness genes up-regulated during blastema formation are msx1 (Crews et al, 1995;Koshiba et al, 1998;Schnapp and Tanaka, 2005), nrad (Shimizu-Nishikawa et al, 2001), rfrng and notch (Cadinouche et al, 1999). Msx1 inhibits myogenesis (Song et al, 1992) and its forced expression in mouse C2C12 myotubes causes cellularization and reduced expression of muscle regulatory proteins ).…”

The molecular basis of amphibian limb regeneration: integrating the old with the new

“…41 The ability of Msx-1 to induce this response in vitro is consistent with other lines of evidence indicating that Msx transcription factors are important for regeneration in vivo in amphibians as well as in mammals. 16,[43][44][45][46][47] An extract of regenerating limb blastemas also induces formation of proliferative mononucleate cells from c2c12 myotubes in vitro, 48 indicating the presence of blastema factor(s) involved in the control of the differentiated state in a multipotent mesenchymal stem cell population. Given that Msx-1 is known to be causally linked to fragmentation, 41 this may indicate that there are factors in blastemas that regulate Msx expression.…”