Biomedical Engineering Reference
In-Depth Information
CHAPTER TWO
Asymmetric Protein Localization
in Planar Cell Polarity:
Mechanisms, Puzzles, and
Challenges
Ying Peng
*
, Jeffrey D. Axelrod
†
,1
*Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
†
Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
1
Corresponding author: e-mail address: jaxelrod@stanford.edu
Contents
1.
Introduction
34
2. Revisiting the Three-Tiered Hierarchy of PCP
35
2.1 Original three-tiered hierarchy model
35
2.2 Reasons to reconsider?
38
3. Asymmetric Protein Localization: A Hallmark of PCP
40
4. The Ways and Means to Planar Polarize a Cell: Mechanisms of Achieving Asymmetry
42
4.1 Required components as revealed by genetics
43
4.2 Domineering nonautonomy: How to talk to your neighbor
43
4.3 Autonomous choices: Focusing within a single cell
47
4.4 Building a unifying mechanism
49
Acknowledgments
50
References
50
Abstract
The polarization of epithelial cells along an axis orthogonal to their apical
-
basal axis is
increasingly recognized for roles in a variety of developmental events and physiological
functions. While now studied in many model organisms, mechanistic understanding is
rooted in intensive investigations of planar cell polarity (PCP) in
. Consensus
has emerged that two molecular modules, referred to here as the global and core mod-
ules, operate upstream of effector proteins to produce morphological PCP. Proteins of
the core module develop subcellular asymmetry, accumulating in two groups on
opposite sides of cells, consistent with proposed functions in producing cell polarity
and in communicating that polarity between neighboring cells. Less clear are the mo-
lecular and cell biological mechanisms underlying core module function in the gener-
ation and communication of subcellular asymmetry and the relationship between the
global and the core modules. In this review, we discuss these two unresolved questions,
highlighting important studies and potentially enlightening avenues for
Drosophila
further
