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Signals from primary mesenchyme cells regulate endoderm differentiation in the sea urchin embryo

Mayuko Hamada1, Masato Kiyomoto

  • 1Tateyama Marine Laboratory, Ochanomizu University, Kou-yatsu 11, Tateyama, Chiba 294-0301, Japan.

Development, Growth & Differentiation
|September 3, 2003
PubMed

Insights

Primary mesenchyme cells (PMC) are crucial for timely sea urchin gut development. Their presence promotes gut differentiation, a role distinct from their previously known suppressive signaling.

Area of Science:

  • Developmental biology
  • Marine biology
  • Cell signaling

Background:

  • Primary mesenchyme cells (PMC) in sea urchin embryos originate from micromeres.
  • PMCs are known to influence skeletogenesis and have a previously identified suppressive role on secondary mesenchyme cell (SMC) differentiation.
  • The precise role of PMCs in endoderm development, specifically gut differentiation, remains incompletely understood.

Purpose of the Study:

  • To investigate the role of primary mesenchyme cells (PMCs) in the timing and process of sea urchin gut differentiation.
  • To determine if the signaling mechanism by which PMCs influence gut differentiation is related to their known suppressive effect on SMCs.

Main Methods:

  • Experimental manipulation involving PMC ablation (removal) and transplantation in sea urchin embryos.
  • Observation and analysis of gut constriction formation and endoderm-specific alkaline phosphatase expression.
  • Assessment of the timing of gut differentiation competence relative to PMC signaling periods.

Main Results:

  • Deletion of PMCs significantly delayed gut constriction formation and the expression of endoderm-specific alkaline phosphatase.
  • PMC signaling for gut differentiation and SMC conversion occurred during the same gastrulation period, but endoderm retained competence later.
  • SMC conversion did not delay gut differentiation, and SMCs were not found to mediate the PMC signal to the endoderm.

Conclusions:

  • The presence of primary mesenchyme cells (PMCs) is essential for the timely differentiation of the sea urchin gut, likely through a promotive signal.
  • This promotive role in gut differentiation represents a novel function of PMCs, independent of their previously described suppressive signaling on secondary mesenchyme cells (SMCs).
  • The findings highlight a distinct developmental pathway regulated by PMCs, impacting endodermal tissue formation.

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