182
c. Niehrs et al.
10.5 Perspective
BMP signalling plays a fundamental role during d/v patterning of mesoderm. Bmp-4 acts as a morphogen that provides positional information
to cells of the amphibian marginal zone and probably the ectoderm. It
appears that Bmp-2,-4 and -7 act together in this process which limits
loss-of-function genetic analysis carried out with individual members of
the family. Similar to the situation in Drosophila blastoderm, a system
of BMP antagonists emanating from the organizer provides a BMP-signaIling free zone and generates a gradient of BMP activity in the
vicinity. The shape of this gradient is probably crucial for the emerging
pattern and can be expected to be the subject to fine control. We know
very little about mechanisms that shape the BMP activity gradient, nor
has it yet been possible to visualize the gradient by any direct means. It
can be expected that the diffusion of both BMP proteins as well as BMP
antagonists is subject to control. We are only beginning to understand
how BMP positional information is converted into discrete cellular
responses, with Xvent homeobox genes being important components in
this process. It will be interesting to identify the promoter elements of
BMP target genes such as Xvents or myf-5 that regulate their distinct
expression domains at different signalling thresholds. Analysis of Smad
function has revealed that components of TGF-~ signalling pathways
are prime candidates for cancer genes. Hence, studying the mechanism
of BMP signalling has important implications for understanding cell
differentiation in development as well as in disease.
Acknowledgements. This work was supported by grant Ni 286/4-2 from the
Deutsche Forschungsgemeinschaft.
References
Aono A, Hazama M, Notoya K, Taketomi S, Yamasaki H, Tsukuda R, Sasaki S
and Fujisawa Y (1995) Potent ectopic bone-inducing activity of bone morphogenetic protein 417 heterodimer. Biochem Biophys Res Commun 2lO:
679-677
Arendt D, Niibler-Jung K (1994) Inversion of dorsoventral axis? Nature
371:26
c. Niehrs et al.
10.5 Perspective
BMP signalling plays a fundamental role during d/v patterning of mesoderm. Bmp-4 acts as a morphogen that provides positional information
to cells of the amphibian marginal zone and probably the ectoderm. It
appears that Bmp-2,-4 and -7 act together in this process which limits
loss-of-function genetic analysis carried out with individual members of
the family. Similar to the situation in Drosophila blastoderm, a system
of BMP antagonists emanating from the organizer provides a BMP-signaIling free zone and generates a gradient of BMP activity in the
vicinity. The shape of this gradient is probably crucial for the emerging
pattern and can be expected to be the subject to fine control. We know
very little about mechanisms that shape the BMP activity gradient, nor
has it yet been possible to visualize the gradient by any direct means. It
can be expected that the diffusion of both BMP proteins as well as BMP
antagonists is subject to control. We are only beginning to understand
how BMP positional information is converted into discrete cellular
responses, with Xvent homeobox genes being important components in
this process. It will be interesting to identify the promoter elements of
BMP target genes such as Xvents or myf-5 that regulate their distinct
expression domains at different signalling thresholds. Analysis of Smad
function has revealed that components of TGF-~ signalling pathways
are prime candidates for cancer genes. Hence, studying the mechanism
of BMP signalling has important implications for understanding cell
differentiation in development as well as in disease.
Acknowledgements. This work was supported by grant Ni 286/4-2 from the
Deutsche Forschungsgemeinschaft.
References
Aono A, Hazama M, Notoya K, Taketomi S, Yamasaki H, Tsukuda R, Sasaki S
and Fujisawa Y (1995) Potent ectopic bone-inducing activity of bone morphogenetic protein 417 heterodimer. Biochem Biophys Res Commun 2lO:
679-677
Arendt D, Niibler-Jung K (1994) Inversion of dorsoventral axis? Nature
371:26