Jacques Emile Dumont

Microinjection of catalytic subunit of cyclic AMP-dependent protein kinases triggers acute morphological changes in thyroid epithelial cells

In dog thyroid epithelial cells in primary culture, thyrotropin acting through cyclic AMP induced rapid morphological changes associated with complete disruption of actin containing stress fibers. This modification preceded cell retraction and rounding up. These morphological effects were also induced by glass capillary microinjection of purified catalytic subunit of cAMP‐dependent protein kinase. This provides the first direct evidence in intact cells that catalytic subunit, which is released upon activation of cAMP‐dependent protein kinases, is responsible for cAMP‐dependent morphological transformation.

Cloning and Sequencing of a New Calmodulin Related Calcium-Binding Protein Controlled by Cyclic AMP Dependent Phosphorylation in the Thyroid: Calcyphosine

The thyroid cell, as many other cells, is subjected to controls through the cyclic AMP, the calcium-phosphatidylinositol and the growth factor receptors tyrosine protein kinases cascades. In the study of the proteins whose synthesis and postranslational covalent modifications are modulated by these cascades, we identified on two-dimensional gel electrophoresis a protein belonging to the calmodulin superfamily, which is phosphorylated in response to cyclic AMP, which binds calcium and which is synthesized in differentiating conditions: calcyphosine (Lefort et al. 1989). In this short review, we summarize recent data on the identification, cloning, sequencing, and properties of calcyphosine.