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Aberrant expression of Pax-2 in Danforth's short tail (Sd) mice
1Laboratory of Mammalian Genes and Development, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
Abstract:
The pattern of Pax-2 expression was studied in Danforth's short tail homozygous mice using Pax-2-specific antibodies. Because these mice lack a notochord in caudal regions, the floor plate of the spinal cord is not induced and posterior mesoderm-derived structures are also affected. The expression of Pax-2 during neural differentiation in the spinal cord was normal in anterior sections, but ectopic expression in the ventral half of the basal plate was observed in regions lacking the floor plate. The data support the hypothesis that Pax-2 expression domains are influenced by signals emanating from the floor plate and that Pax-2 functions during the dorsal-ventral patterning of the spinal cord. In the developing excretory system, Pax-2 expression was normal in the anterior structures, such as the mesonephros, and in the mesonephric duct. However, Pax-2 was not expressed in the uninduced metanephric mesenchyme. Thus, activation of Pax-2 in the mesenchyme is an early response to inductive signals emanating from the ureter. The Danforth's short tail mutation is a useful model for the study of developmentally regulated genes that are under the influence of the notochord or floor plate.
Insights
Pax-2 gene expression is crucial for spinal cord and kidney development. Floor plate signals influence Pax-2, impacting dorsal-ventral patterning and excretory system formation in mice.
Area of Science:
- Developmental biology
- Genetics
- Neuroscience
Background:
- Pax-2 is a transcription factor vital for kidney and spinal cord development.
- Danforth's short tail (Sd) mice lack a notochord, affecting floor plate induction and downstream gene expression.
- Understanding Pax-2 regulation provides insights into developmental signaling pathways.
Purpose of the Study:
- To investigate the role of floor plate signals in regulating Pax-2 expression during spinal cord development.
- To examine Pax-2 expression patterns in the developing excretory system of Sd mice.
- To elucidate the influence of the notochord/floor plate on Pax-2 function in development.
Main Methods:
- Utilized Pax-2-specific antibodies for immunohistochemical analysis in homozygous Danforth's short tail mice.
- Examined Pax-2 expression in both the spinal cord and developing excretory system.
- Correlated Pax-2 expression patterns with the presence or absence of notochord and floor plate structures.
Main Results:
- Normal Pax-2 expression in anterior spinal cord sections, but ectopic expression in the ventral basal plate of regions lacking floor plate.
- Pax-2 expression was normal in anterior excretory system structures (mesonephros, mesonephric duct).
- Pax-2 was not expressed in uninduced metanephric mesenchyme, indicating delayed activation by ureter signals.
Conclusions:
- Pax-2 expression domains are significantly influenced by floor plate-derived signals.
- Pax-2 plays a role in the dorsal-ventral patterning of the spinal cord.
- Activation of Pax-2 in metanephric mesenchyme is an early response to inductive signals from the ureter, highlighting its importance in kidney development.