Biomedical Engineering Reference
In-Depth Information
interesting and related observation is that cell rearrangements in the pupal
wing lead to changes in the anatomical orientation of
fz/stan
signaling
(
Aigouy et al., 2011
).
Mutations in
fz/stan
pathway genes have also been found to alter the pat-
tern of dendrites and axons in some Drosophila neurons (
Matsubara,
Horiuchi, Shimono, Usui, & Uemura, 2011; Mrkusich, Flanagan, &
Whitington, 2011
). In both cases, it remains to be established as to how
much of the pathway is conserved in different tissues. A similar very wide
range of cell types have been found to utilize
fz
pathway homologs in
vertebrates (
Goodrich & Strutt, 2011; Wang & Nathans, 2007
).
2.5. PCP that is not fz/stan pathway dependent
There are also several interesting cases of PCP in Drosophila that are not
dependent on the
fz/stan
pathway, the most notable being the polarized cell
rearrangements that mediate germ band elongation (
Bertet, Sulak, & Lecuit,
2004; Zallen, 2007; Zallen & Wieschaus, 2004
) and the polarized actin
cytoskeleton seen in the follicle cells of developing egg chambers
(
Bateman, Reddy, Saito, & Van Vactor, 2001; Frydman & Spradling,
2001
). Interestingly, the
fat2
gene is required for actin polarization in
follicle cells (
Viktorinova, Konig, Schlichting, & Dahmann, 2009
).
3. PCP GENES
3.1. Early studies on the fz/stan pathway
Several of the genes of the
fz/stan
pathway were discovered long ago and
were used as markers in classical genetic experiments (see
Table 1.1
). These
include
fz
,
prickle
(
pk
),
disheveled
(
dsh
),
inturned
(
in
), and
multiple wing hairs
(
mwh
). Other
fz/stan
pathway genes were discovered in screens designed
to identify new PCP genes. These include s
tan
(also known as
flamingo
)
(
Chae et al., 1999; Usui et al., 1999
),
Van Gogh
(
Vang
) (also known as
strabismus
)(
Taylor et al., 1998; Wolff & Rubin, 1998
), and
fritz
(
frtz
)
(
Collier et al., 2005
). (Note: in this review, I use the primary FlyBase
name for all Drosophila genes.) The first detailed study on the function of
these genes in PCP was published about 30 years ago by
Gubb and
Garcia-Bellido (1982)
. Several important conclusions came from this
work. One was that the mutant hair polarity patterns seen on wings were
not random. Rather, the mutant pattern was stereotypic. Thus, cells in
the anterior region of an
fz
mutant wing routinely point more anteriorly
