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Stem Cells of the Developing and Adult Lung
APS Respiration Section
Claudette M. St. Croix and Barry R. Stripp
B.R. Stripp, J. Whitsett, B. Hogan, J.F. Engelhardt, S.D. Reynolds, T.Cheng
and Z. Borok
Despite considerable interest in the areas of lung development and in
remodeling of the adult lung following injury, there is little information
linking these two processes. In each case, multipotent cells contribute
either to establishment or regeneration of the airway epithelium. However,
mechanisms regulating lineage restriction, be they intrinsic or extrinsic,
remain controversial and may differ between development and repair in
adulthood. This symposium will include state-of-the-art presentations
outlining lineage specification and pattern formation signals that function
to modulate lung development as well as discussions of stem cells, their
supportive microenvironments, and the molecular mechanisms contributing to
their maintenance in the mature lung. Jeffery A. Whitsett will present
analysis of lineage specification in the developing foregut endoderm. These
studies indicate early lineage restriction of endodermal progenitors for the
peripheral epithelium. In contrast, Brigid L. Hogan will present analysis of
signal transduction pathways necessary for mesenchymal patterning of the
epithelial compartment along the proximal-distal axis. These studies suggest
that extrinsic factors regulate lineage restriction and patterning in the
developing lung. John F. Engelhardt will present characterization of stem
cells within the tracheal epithelium and identification of signal
transduction pathways necessary for establishment and maintenance of the
submucosal gland epithelium. Susan D. Reynolds will discuss niche
responsible for maintenance of adult stem cell populations. These studies
suggest that stem cells with similar molecular properties are maintained
within distinct microenvironments along the proximal distal axis of the
lung. Finally, Tao Cheng will discuss mechanisms regulating the balance
between stem cell maintenance and generation of progenitor cells within the
hematopoietic system. These studies indicate a critical role for the cycle
regulatory molecules p21, p17, and p18 in this process. It is anticipated
that this symposium will identify gaps in our knowledge of lineage
specification and the contribution that lineage restriction makes towards
lung homeostasis in heath and disease.
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