CST Guide:

Section I: Research Areas
chapter 06: Development and differentiation
YAP localizes to
the nucleus in low
confluence cells, but
is translocated to the
cytoplasm during
high confluence
(contact inhibition).
Hippo Signaling
Hippo signaling is an evolutionarily conserved pathway that plays a critical role in development by
regulating cell proliferation, apoptosis, and stem cell self-renewal. Activation of the Hippo pathway
(e.g., by cell-cell contact) suppresses cell proliferation by initiating a signaling cascade that results in
phosphorylation, cytoplasmic retention, and proteasomal degradation of the transcriptional co-activators
YAP and TAZ, thereby preventing the transcription of genes that promote proliferation.
A B C
Notch Signaling
The Notch pathway is a contact-dependent signaling cascade mediated by the Notch receptor on the
receiving cell and the Delta-like and Jagged ligands on the signal-sending cell. Receptor-ligand binding
results in a series of cleavages to the Notch receptor, culminating in release of the Notch intracellular
domain (NICD) by γ-secretase. The NICD translocates to the nucleus where it interacts with RBPSUH
and Mastermind-like (MAML) proteins to regulate transcription of target genes that mediate cell fate
decisions in neuronal, cardiac, immune, and endocrine development.
Hedgehog Signaling
The evolutionarily conserved Hedgehog (Hh) pathway plays a critical role in a time and positiondependent
fashion during development. Hedgehog ligands (Sonic, Desert, and Indian Hedgehog) act as
classic morphogens, whose concentration gradient promotes specific developmental outcomes at distinct
concentration thresholds. Hedgehog signaling occurs when a hedgehog family ligand binds to the
receptor Patched (PTCH), releasing Smoothened (SMO) from suppression and allowing it to translocate to
primary cilium. Once there, SMO signals through G proteins, ultimately leading to nuclear translocation
of GLI zinc finger transcription factors. Hedgehog signaling is instrumental early in embryogenesis,
orchestrating neural plate patterning and ventral polarity of the neural tube, and anterior-posterior axis
patterning (e.g. during limb formation). Defects in Hh signaling are the most common cause of midline
birth defects, resulting in disorders such as holoprosencephaly, which is characterized by incomplete
separation of the forebrain hemispheres and their derivatives. The Hedgehog pathway has also been
shown to play a role in maintenance of adult stem cells, particularly neural progenitors and hematopoietic
stem cells.
YAP (D8H1X) XP ® Rabbit mAb #14074: Confocal IF analysis of low confluence MCF 10A cells (A), high confluence MCF 10A (B), and
YAP-negative RL-7 cells (C) using #14074 (green). Blue pseudocolor in lower images = DRAQ5 ® #4084 (fluorescent DNA dye). Increased
nuclear localization of YAP protein is seen in low confluence (proliferating) cells.
TGF-β/BMP Signaling
Transforming growth factor-β (TGF-β) superfamily signaling plays a critical role in the regulation of cell
proliferation, differentiation, developmental patterning and morphogenesis, and disease pathogenesis.
In the canonical TGF-β signaling pathway, ligand binding to one of the three types of TGF-β receptors
results in receptor activation and phosphorylation of the Smad2/3 or Smad1/5/9 effector proteins.
These phosphorylated Smads dimerize with the co-activating Smad4 and translocate to the nucleus,
where they stimulate transcription of target genes. TGF-β receptors can also signal through noncanonical
(Smad-independent) pathways that promote cytoskeletal rearrangement and adhesion through
activation of RhoA, Rac/cdc42, and PI3K pathways.
BMP2 treatment results in phosphorylation
of Smad1/5 at Ser463/465.
Phospho-Smad1 (Ser463/465)/Smad5 (Ser463/465)/Smad9 (Ser465/467)
(D5B10) Rabbit mAb #13820: WB analysis of extracts from Hep G2 or MEF cells,
untreated (-) or treated with Human BMP2 #4697 (50 ng/ml, 30 min; +), using
#13820 (upper) and Smad1 (D59D7) XP ® Rabbit mAb #6944 (lower).
Lanes
1. Hep G2
2. MEF
kDa
140
100
80
60
50
40
30
20
140
100
80
60
50
40
30
1 2
Phospho-Smad1
(Ser463/465)/
Smad5 (Ser463/465)/
Smad9 (Ser465/467)
Smad1
Development and Cancer
Ectopic activation or dysregulation of embryonic signaling pathways is recognized as an important
contributor to tumorigenesis in many contexts. For example, constitutive activation of the Hedgehog
pathway by mutations in PTCH or SMO are strongly linked to basal cell carcinoma and medulloblastoma.
Likewise, mutations in components of the Wnt signaling pathway, which can lead to increased stability
and transcriptional activity of β-catenin, are directly associated with colorectal, gastric, hepatocellular,
ovarian, breast, and prostrate cancers. In Hippo signaling, the central pathway mediators, YAP and
TAZ, function as oncogenes, and amplification of YAP has been associated with a variety of tumors
including hepatocellular, lung, colorectal, breast, and liver carcinomas. The TGF-β signaling pathway
is recognized as a potentially important driver of cancer metastasis, through its ability to regulate the
process of epithelial-mesenchymal transition (EMT).
Cancer stem cells (CSC) are a rare sub-population of tumorigenic cells found within tumors that (like
normal stem cells) are multipotent and self-renewing. These cells posses tumor-initiating potential and
can differentiate into all the other cell types that compose the bulk of the tumor. Cell surface markers
can distinguish CSCs from differentiated cancer cells in many tumor types and be used to purify subpopulations
of CSCs. These include CD133, CD44, CD24, ALDH1, and EpCAM, among others.
Select Reviews
Addis, R.C. and Epstein, J.A. (2013) Nat. Med. 19, 829−836. • Ader, M. and Tanaka, E.M. (2014) Curr. Opin. Cell Biol. 31C,
23−28. • Gieseck, R.L. 3rd, Colquhoun, J., and Hannan, N.R. (2014) Biochim. Biophys. Acta. Jun 2 [Epub ahead of print] •
Ingham, P.W. and McMahon, A.P. (2001) Genes and Dev. 15, 3059−3087. • Isobe, K.I., Cheng, Z., Nishio, N. et al. (2014) Nat.
Biotechnol. 31, 411−421. • Itoh, F., Watabe, T., and Miyazono, K. (2014) Semin. Cell Dev. Biol. 32C, 98−106. • Jamieson,
C., Sharma, M., and Henderson, B.R. (2014) Semin. Cancer Biol. 27C, 20−29. • Jiang, J. and Hui, C-C. (2008) Developmental
Cell 15, 801−812. • Jopling, C., Boue, S., and Izpisua Belmonte, J.C. (2011) Nat. Rev. Mol. Cell Biol. 12, 79−89. • Kreso,
A. and Dickemail, J.E. (2014) Cell Stem Cell 14, 275–291. • Lien, W.H. and Fuchs, E. (2014) Genes Dev. 28, 1517−1532. •
Ntziachristos, P., Lim, J.S., Sage, J., et al. (2014) Cancer Cell 25, 318−334. • Robbins, D.J., Fei, D.L., and Riobo, N.A. (2012)
Sci. Signal. 5, re6. • Sánchez, A.A. and Yamanaka, S. (2014) Cell 157, 110−119. • Sarkar, A. and Hochedlinger, K. (2013)
Cell Stem Cell 12, 15−30. • Torres-Padilla, M.E. and Chambers, I. (2014) Development 141, 2173−2181. • Varelas, X.
(2014) Development 141, 1614−1626.
Elevated levels of
β-catenin are found in
colon carcinoma.
β-Catenin (D10A8) XP ® Rabbit mAb
#8480: IHC analysis of paraffin-embedded
human colon carcinoma using #8480.
Amplification of YAP is
associated with breast
adenocarcinoma.
20
– +
– +
Human BMP2
Cancer Research
Please visit our website to learn more about the scientific tools and educational resources we have online for cancer
signaling and proteomic analysis, including discussion of key disease drivers. www.cellsignal.com/cancerguide
YAP (D8H1X) XP ® Rabbit mAb #14074:
IHC analysis of paraffin-embedded human
breast adenocarcinoma using #14074.
156 For Research Use Only. Not For Use in Diagnostic Procedures. See pages 302 & 303 for Pathway Diagrams, Application, and Reactivity keys.
www.cellsignal.com/cstdevelopment
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