The Basics About Research in the Fuchs Laboratory
Why Use Skin as a Model System for Study?
As basic scientists with an interest in applying our knowledge to human medicine, we chose skin as a model system, because skin epithelium is one of the few tissues of the body whose human and mouse stem cells (keratinocytes) can be maintained and propagated in culture. This feature has been exploited for nearly 3 decades in the successful treatment of burn patients with epidermis generated from cultured stem cells.
In addition, skin is at the body surface, making it readily accessible and particularly well-suited for mouse and human genetics. Our collaborative studies with the Mombaerts lab at Rockefeller have shown that hair follicle stem cell nuclei can be reprogrammed epigenetically by nuclear transfer, enabling us to clone mice. When coupled with recent successes in generating induced pluripotent stem cells (iPS cells) by genetic manipulation of skin cells, this raises the likelihood that skin stem cells will have additional uses for regenerative medicine in the future.
Thus, we study the molecular biology of how skin cells behave in vitro, and then exploit transgenic, gene knockout and more recently lentiviral knockdown technologies to test skin protein function in vivo. To explore how skin biology changes during wound-healing, we monitor keratinocyte migration in skin explant cultures. To explore how skin biology changes in mouse or human genetic skin disorders, we culture the stem cells from skin biopsies of affected individuals. Because no immortalization is necessary, normal skin cells can be studied, and the link to human genetic diseases, including cancers, is greatly facilitated.
See Creating a Knockout Mouse 
What kinds of questions does the laboratory address?
First, we'd like to know the properties of the multipotent skin stem cells that can differentiate to produce either epidermis or hair follicles. We devised novel methods to isolate these cells from mouse skin, and we employed microarray and RNAseq technology to determine their global patterns of gene expression. We've also begun to employ Chip-seq to determine how chromatin epigenetically changes and remodels as stem cells transition from a quiescent to activated to committed state. We are also using this information to explore how changes in gene expression and epigenetics arise as stem cells respond to various external stimuli, select a particular lineage and differentiate in normal tissue development, homeostasis and wound repair. We've learned that quiescent stem cells are in a Wnt-inhibited and BMP-rich environment and become activated upon directional Wnt signaling and inhibition of BMP signaling. We've begun to dissect the downstream targets of these pathways, and have shown that while Wnt inhibition represses stem cell fate specification, BMP signaling maintains quiescence by a mechanism that appears to involve the NFATc1 transcription factor and calcium signaling.
We'd like to know more about the molecular coordination of these and other signaling pathways that operate on these stem cells. We'd also like to elucidate the mesenchymal-epithelial cross-talk that coaxes stem cells to make the hair follicle in the embryo, and then again stimulates stem cells to regrow hair from this follicle in the adult. We've used transgenic mice, fluorescence-activated-cell sorting (FACS) and microarray analyses to isolate and transcriptionally profile these specialized mesenchymal cells. 
With this groundwork in place, we are now focusing on how the cross-talk elicits dramatic changes in transcription and in microRNA expression which translate into changes in proliferation, cell adhesion, cytoskeletal dynamics and cell polarity. The global question we are addressing is how stem cells become mobilized from their niches to form tissues, how stem cells know when to stop making tissue after wound-repair and how these processes are deregulated in aging and in cancer. The lab's extensive experience in skin biology coupled with strong expertise in the biochemistry and molecular biology of cytoskeletal-adhesion dynamics, as well as signaling and transcriptional regulation places us in a unique position to apply the requisite multifaceted approach in tacking these fascinating problems.
Finally, by defining the mechanisms involved in normal skin development, and using mouse genetics to explore loss of function mutations, we've linked our findings to human genetic skin disorders, whose etiology was previously unknown.
What kinds of approaches are taken in the Fuchs' lab?
Elaine's formal training is as a chemist, biochemist and cell biologist. Her lab's research utilizes molecular, cell and developmental biology as well as mouse and human genetics. Hence, while nearly all lab members use cell culture and transgenic/knockout mice as model systems to study skin, it's not surprising to find that there is a broad range of expertise and research approaches taken by individual lab members. Those in the lab who study skin stem cells and signaling employ approaches such as gene expression and promoter (ChIP-seq) profiling to study how stem cells alter their transcriptional program in response to changes in their microenvironment during development, differentiation and wound-healing. We combine array profiling with molecular approaches to study transcriptional regulation. We use lentiviral knockdowns and mouse genetics to explore the functional relevance of our findings. In addition, we cloned out the microRNAs that are differentially expressed during skin development. After demonstrating that miRs are globally important, we've now begun to dissect the functions of individual miRs. 
Others in the lab focus on cytoskeletal and adhesion dynamics in morphogenesis, and how these processes change in wound- healing and cancer. Postdocs and students in this area probe the regulation of actin, microtubule and intermediate filament dynamics during skin development and epithelial sheet formation, and cytoskeletal interactions with integrins and cadherins in adhesion. We've engineered transgenic mice expressing fluorescently labeled cytoskeletal and adhesive proteins and use videomicroscopy, whole embryo imaging, mouse genetics and biochemistry, molecular and cell biology to study changes in cytoskeletal dynamics and adhesion in living cells and tissues. Such approaches led us to our discovery that mammalian epidermal cells stratify and differentiate by using a mechanism found in worms and flies to orient their mitotic spindle and divide asymmetrically. Understanding the molecular mechanisms involved in asymmetric divisions in stem cells and in changes in cytoskeletal-adhesive dynamics in epidermal migration, wound repair and cancer are major efforts of this side of the lab's spectrum.
