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Cell-type-specific genes expressed late in Dictyostelium development show markedly different responses to 3'5' cyclic
A J Richards1, A J Corney, B D Hames
1Department of Biochemistry, University of Leeds, UK.
Abstract:
The maintenance of late gene expression by 3'5' cyclic AMP was re-examined using several newly isolated cell-type-specific genes. Expression of all the prespore-enriched genes ceased immediately upon disaggregation of developing cells and pre-existing mRNA was rapidly degraded. For most genes, cAMP had little or no effect either alone or in combination with conditioned medium factors. The expression of the non-cell-type-specific genes 7E and 2C also ceased upon cell disaggregation but cAMP triggered a full re-induction of expression although the timing of the response differed markedly between these two genes. In contrast to earlier interpretations, these data argue that for none of these late prespore genes is cAMP alone sufficient for the maintenance of expression. The responses of the two prestalk mRNAs examined were gene-specific. Prestalk 5D mRNA decayed slowly upon disaggregation and was partially stabilized by cAMP whereas prestalk 5G mRNA increased upon disaggregation and was inhibited by cAMP.
Insights
Cyclic AMP (cAMP) does not solely maintain late gene expression in developing cells. New data show cAMP is insufficient for prespore genes but differentially affects prestalk gene expression.
Area of Science:
- Molecular Biology
- Developmental Biology
- Cell Biology
Background:
- Late gene expression is crucial for cellular differentiation.
- The role of cyclic AMP (cAMP) in regulating gene expression during development has been previously studied.
- Understanding gene regulation is key to deciphering developmental processes.
Purpose of the Study:
- To re-examine the role of cAMP in maintaining late gene expression.
- To investigate the effects of cAMP on newly isolated cell-type-specific genes.
- To clarify the sufficiency of cAMP in gene expression regulation.
Main Methods:
- Utilized newly isolated cell-type-specific genes for analysis.
- Studied gene expression following cell disaggregation.
- Assessed the impact of cAMP and conditioned medium factors on mRNA levels.
Main Results:
- Expression of prespore-enriched genes ceased upon disaggregation and mRNA degraded rapidly.
- cAMP had minimal effect on most prespore genes, alone or with factors.
- Non-cell-type-specific genes 7E and 2C showed cAMP-induced re-expression, with differing kinetics.
- Prestalk 5D mRNA decayed slowly and was partially stabilized by cAMP.
- Prestalk 5G mRNA increased upon disaggregation and was inhibited by cAMP.
Conclusions:
- cAMP alone is insufficient for maintaining expression of the late prespore genes studied.
- Gene expression regulation by cAMP is complex and gene-specific.
- Cellular disaggregation significantly impacts gene expression, with varied responses to cAMP.