March 10, 2011

Think of the first time you kissed your partner…I’m sure it led to piloerection. Nerds, stop the giggling…I’m talking about goosebumps! The stunning image above is from a paper describing the relationship between hair follicles and the muscles that cause goosebumps.

We have epidermal stem cells in our hair follicles in a region called the bulge. The cells in the bulge are closely associated with the arrector pili muscle (APM), which is the muscle responsible for causing goosebumps. A recent study describes how bulge cells deposit a protein called nephronectin into the underlying basement membrane, and this provides a niche for APM differentiation during hair follicle development. Image above shows hair follicles (blue) and smooth muscle proteins found in the APM (red, green). The white brackets show groups of hair follicles that share APMs.

Fujiwara, H., Ferreira, M., Donati, G., Marciano, D., Linton, J., Sato, Y., Hartner, A., Sekiguchi, K., Reichardt, L., & Watt, F. (2011). The Basement Membrane of Hair Follicle Stem Cells Is a Muscle Cell Niche Cell, 144 (4), 577-589 DOI: 10.1016/j.cell.2011.01.014
Copyright ©2011 Elsevier Ltd. All rights reserved.

January 20, 2011

Not all neurons are created equally…today’s image is from a paper describing a pathway that regulates the differentiation of specialized neurons in the fruit fly Drosophila.

During development, cells are instructed to differentiate into specialized cell types. Although a lot of the signals that participate in this process a known, the exact mechanism for each cell type is not. A recent paper describes the differentiation of Drosophila mechanosensory neurons, which have specialized dendrites with cilia that help mediate sensory perception. The results in this paper show how proneural factors lead to downstream signals that direct the differentiation of these specialized neurons and their ciliary dendrites. Image above shows five of these mechanosensory neurons.

Cachero, S., Simpson, T., zur Lage, P., Ma, L., Newton, F., Holohan, E., Armstrong, J., & Jarman, A. (2011). The Gene Regulatory Cascade Linking Proneural Specification with Differentiation in Drosophila Sensory Neurons PLoS Biology, 9 (1) DOI: 10.1371/journal.pbio.1000568

July 5, 2010

During development of different tissues, there are pools of progenitor cells from which different cell types are formed. The mechanisms regulating how cell fate is determined are not completely understood, but a paper earlier this year helps to clarify this process in the developing retina. The authors identify a role for Blimp1, a transcription factor, in regulating the cell fate decision of the progenitor cells. Image shows retinal tissue from mice with (left) and without (right) Blimp1, after the cells have undergone differentiation into the different cell types. Without Blimp1, retinas had a thinner outer layer (bracket) and a thicker inner layer, as well as incorrect numbers of certain cells (red cells).

Reference: Joseph A. Brzezinski IV, Deepak A. Lamba and Thomas A. Reh, 2010. Development: 137, 619-629. doi: 10.1242/dev.043968. Adapted with permission by Development. Paper can be found here.

April 19, 2010

During development, cells must differentiate into specific types. This process was understood for many years to be an irreversible event, yet recent papers have challenged this idea. In one paper, researchers have been able to convert fibroblasts into neurons by expressing a specific set of genes. Image above shows these induced neuronal cells, only a few days after they started out as fibroblasts.

Reference: Thomas Vierbuchen, Austin Ostermeier, Zhiping P. Pang, Yuko Kokubu, Thomas C. Südhof, and Marius Wernig. Adapted by permission from Macmillan Publishers Ltd: Nature 463, 1035-1041, copyright 2010. Paper can be found here.