DEVELOPMENTAL BIOLOGY: A Loss of Flexibility With Age

 
Beverly A. Purnell

As a cell transitions from an undifferentiated state to a differentiated cell type, its gene expression profile changes, which in part reflects physical changes in chromatin structure. In a complementary approach, Pajerowski et al. have examined the macroscopic properties of the nucleus during differentiation. Aspiration with a micropipette revealed that the nuclei of pluripotent human embryonic stem cells could be deformed relatively easily; however, as the cells differentiated, the nuclei became stiffer. Hematopoietic stem cells (from bone marrow) were able to differentiate into fewer cell types than embryonic stem cells and, similarly, showed an intermediate level of deformability. Progression toward the differentiated state was accompanied by an increase in the filamentous protein lamin A/C and greater condensation of chromatin. When lamin A/C was knocked down in epithelial cells, their flow behavior resembled that of hematopoietic stem cells. Further analysis showed that the fluid character of the nucleus is determined primarily by chromatin but that the degree of nuclear deformability is set by the lamina. Variations in the physical plasticity of the nucleus may be important for allowing less differentiated cells to move through tissues. — BAP

Proc. Natl. Acad. Sci. U.S.A. 104, 15619 (2007).

Advertisements
This entry was posted in Science. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s