Post on 16-Aug-2015
TRANSCRIPTION FACTORS IMPACT CEREBRAL ANEURYSMS
The activity of transcription factors Ets-1 and NF-κB impacts the progression of cerebral
aneurysm rupture
Sallie Ferren and William Heinrich
Florida State College at Jacksonville
Biomedical Degree Capstone
Spring 2015
IDS 4936
DR. Lanh Bloodworth
A course assignment presented to the Department of Biomedical Sciences in partial fulfillment
of the requirements for the Bachelor of Science Degree, Florida State College at Jacksonville
Date
April 24, 2015
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TRANSCRIPTION FACTORS IMPACT CEREBRAL ANEURYSMS
Abstract
Cerebral Aneurysms (CAs) are common cerebrovascular pathologies that typically form
at the bifurcations of cerebral arteries and are a leading cause of stroke death. Studies have
shown that inflammation plays a key role in the development and progression of ruptures. NF-
κB, a chemical mediator stimulating apoptosis and Ets-1 are transcription factors
responsible for the regulation of inflammatory genes during aneurysm formation. The
downstream target Ets-1 in CA development was identified by chromatin immunoprecipitation
analysis and revealed that Ets-1 transactivated MCP-1 in the walls of cerebral aneurysms. Recent
studies have been conducted using a synthesized decoy, oligodeoxynucleotide (ODN), which
synergistically represses the molecular mediators by binding to NF-κB and Ets-1. This
inhibits response showing significant size in reduction and disruption of the internal elastic
lamina. Our study will determine if a decrease in inflammation in VSMC should lead to the
inhibition of CA development. Therefore, if regulation of the expression of Ets-1 and NF-
κB is controlled, then vascular endothelial growth and angiogenesis should be regulated.
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Introduction
General Background
A cerebral aneurysm is a weak or think spot on a blood vessel in the brain that creates a
bulge in the blood vessel and fills with blood (National Institute of Neurological Disorders and
Stroke, 2015) and can occur in anyone, at any age, although CA are more prevalent in adults and
slightly more common in women. It is estimated that 2.3% of the Western population have
intracranial aneurysms, with over 30,000 diagnosed every year. If a cerebral aneurysm develops,
this could eventually lead to pressure on a nerve or surrounding brain tissue. The incidence of
reported ruptured aneurysm is about 10 in every 100,000 persons per year most commonly in
people between ages 30 and 60 years. Possible risk factors for rupture include hypertension,
alcohol abuse, drug abuse (particularly cocaine), and smoking. In addition, the condition and size
of the aneurysm affects the risk of rupture.
An unruptured aneurysm may go unnoticed throughout a person’s lifetime. A burst
aneurysm may be fatal or could lead to hemorrhagic stroke, or vasospasm, which is the leading
cause of disability or death following a burst aneurysm, other problems may occur. Once the
aneurysm has burst, it may bleed into the brain and additional aneurysms may also occur. More
commonly, rupture may cause a subarachnoid hemorrhage, or bleeding into the space between
the skull bone and the brain. It is estimated that approximately forty percent of individuals whose
aneurysm has ruptured do not survive the first twenty-four hours and another twenty five percent
die from complications within six months of the burst. As previously explained, aneurysms can
be fetal or lead to a host of complications, approximately 12% of patients die before they can be
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treated. This paper will discuss how NF-κB and Ets-1 are transcription factors that are
important mediators in the development of cerebral aneurysms and if the expression of NF-
κB and Ets-1 are inhibited, there should be a decrease in the incidence of cerebral
aneurysm formation and rupture. Therefore, determining the molecular cause of CAs is very
important so that further research and more effective diagnosis and treatment methods can be
discovered.
Previous research studies
Research studies in molecular biology using human samples and rats have pointed out
that inflammation is key in the leading development of cerebral aneurysms. These studies have
described the most recent understanding of the inflammation pathways from initiation to rupture
of CAs. Transcription factors such as NF-κB and Ets-1 have proven to lead to
inflammatory chemicals that signal the accumulation of macrophages in vascular smooth muscle
cells in the arteries of humans and rats leading to endothelial dysfunction and pathological
remodeling changes to the vascular walls (Kataoka, 2015).
Pathophysiology and Etiology
In a broad, general spectrum of the pathophysiology of cerebral aneurysms, CAs may be
more prevalent in people with certain genetic diseases. The embryological develop of connective
tissue is linked to mesenchyme and may lead to CAs in these people. Moreover, high blood
pressure, infection in the arterial wall, tumors in the head and neck, and atherosclerosis has also
been linked to cause cerebral aneurysms (National Institute of Neurological Disorders and
Stroke, 2015).
This paper will include an analysis that will be specific on molecular and cellular causes
of cerebral aneurysm, based around NF-κB and Ets-1 general transcription factors that
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regulate inflammation in vascular smooth muscle cells. We will explain the Proto-oncogene E26
transformation-specific-1 (Ets-1) not only plays a crucial role in reciprocal regulation of
inflammatory and anti-inflammatory responses but also in the regulation of a wide variety of
biological processes such as cellular growth (Grenningloh, Kang, & Ho, 2005). The Ets
transcription family is involved in direct gene expression and binds to specific promoters and
enhancers, allowing assembly to occur of components for transcription. The Ets domain is a
helix-turn-helix binding protein responsible for the recognition of a specific sequence called 5′-
GGA (A/T)-3′ (Sharrocks, A., Brown, A., Ling, Y., & Yates, P., 1997). In addition to the role as
a binding protein, protein-protein interactions also occur and have been identified as either a
transcriptional activator or repressor and are regulated by signal transduction pathways. An
important function of Ets domain transcription factor is to regulate hematopoiesis, the production
of red blood cells, in adults.
MCP-1, or monocyte chemoattractant protein-1, a member of the C-C chemokine
subfamily, was originally identified for its potent chemotactic activity toward monocytes
(Feinberg, 2004). Monocyte chemoattractant protein-1 (MCP-1) led to the enlargement of
VSMC and development of cerebral aneurysms through the recruitment of monocytes or
macrophages in the walls of CA. There is a secretion of proteinases such as metalloproteinase
(MMP)-2, -9 and cysteine cathepsins, causing degeneration of the walls surrounding the cerebral
aneurysm (Aoki et al., 2010). Levels of MMP were found to be higher in patients with ruptured
CAs versus patients with unruptured CAs (Chalouhi, 2012).
In the inflammatory process, macrophages have three major functions, antigen
presentation, followed by phagocytosis, and then production of various chemical mediators of
inflammation including cytokines and growth factors. This is important in the development of
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cerebral aneurysms as macrophages play a key role in the synthesis due to the Ets-1 transcription
factor. Expression of Ets genes is associated with mesenchymal-epithelial interactions and
changes in extracellular matrix proteins that contribute to tissue remodeling and integrity
(Maroulakou & Bowe, 2000).
A higher prevalence of CAs in women is thought to be due to decrease in estrogen level after
menopause. Estrogen protects several components within the artery wall and inhibits the activity
of TNF- that protects against inflammation of the blood vessels, which, can lead to aneurysms
(Francis, Tu, Qian, & Avolio, 2013). In humans, Ets-1 is expressed in high levels in proliferating
vascular endothelial cells of an embryo and in the blood vessels of an adult during angiogenesis,
or the formation of blood vessels from existing vasculature (Maroulakou & Bowe, 2000).
Treatments
When an unruptured aneurysm is detected, the decision to treat can be complicated
because usually only 1-2% eventually ruptures but the mortality rate within the first month after
a rupture is about 50% (Francis et al., 2013). Treatment sometimes involves complications,
therefore it is mainly recommended for larger or oddly shaped unruptured CAs or if they are
causing symptoms in the patient (NINDS, 2015). Morbidity and mortality are associated with
CA despite clinical advances in diagnosis and therapy. Currently there are only invasive
treatment modalities such as microsurgical clipping and endovascular coiling. Endovascular
coiling has showed a better clinical outcome when compared to microsurgical clipping especially
when using biologically active coated coils (Hudson, Hoyne, & Hasan, 2013). Liquid embolic
materials, such as Onyx HD500 have also been used as treatment but are mostly effective at only
treating smaller CAs. All of the aforementioned interventions have procedural complication rates
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and, thus, illustrate the need for noninvasive alternatives and a clearer understanding of the
pathophysiology of CAs (Hudson et al., 2013).
Future Treatments
An independent study performed by Hasan and colleagues for Mayo Clinic on subjects
enrolled in the International Study of Unruptured Intracranial Aneurysms (ISUIA) found that
patients who used aspirin 3x weekly to daily had an occurrence rate (OR) for hemorrhage 60%
less when compared to the reference group who did not use aspirin or used it ‘< once a month.
This data suggest that a low dose of acetylsalicylic acid may attenuate inflammation in CA and
histologically showed a decrease in macrophage and pro-inflammatory molecule expression
(Hudson et al., 2013).
According to Hudson et al., 2013 diagnostic imaging has been used at a cellular level to
identify macrophages as a biomarker for inflammation. Human patients were injected with
ferumoxytol and then imaged with T2-MRI to show the macrophages localizing in the wall of
cerebral aneurysms. Ferumoxytol is an ultra-small super-paramagnetic iron oxide, until recently
used as an iron replacement but now as an intravenous contrast for Magnetic Resonance Imaging
(MRI) to demonstrate signal enhancement or loss (Bashir, Bhatti, Marin, & Nelson, 2014). This
will be crucial in diagnosing and preventing CA ruptures.
The activated DNA binding form of transcription factor NF-κB with MCP-1 and
Vascular Cell Adhesion Molecule-1 (VCAM-1) showed a molecular basis which caused
activation of macrophages during CA inflammation (Hudson et al., 2013). A recent study by
Aoki et al, 2010 showed an overexpression of NF-κB in the CA wall of rats and created
mice that were NF-κB deficient and saw a reduction in macrophage recruitment, MCP-1,
and VCAM-1 mRNA, and overall size.
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In another experiment, Aoki et al, 2010 performed a synthesized decoy
oligodeoxynucleotide (ODN) that was used to bind and inhibit NF-κB. They found a
significant reduction in CAs when decoy ODN was administered after one week of induction.
When used simultaneously for both NF-κB and Ets-1, they produce a synergistic effect
that represses molecular mediators of inflammation while promoting collagen biosynthesis
(Hudson et al., 2013).
Another area of interest for possible treatment of CAs is statins due to their inhibitory
action on NF-κB and beneficial results for vascular disease. One study by Aoki et al.,
2010 found that in rats, after administrating an oral dose one month after CA induction, there
was a decrease in expression of inflammatory mediators MMP-1 and MMP-9. Another study
found that lower doses attenuated CA progression but that higher doses promoted CA growth
and rupture. Furthermore, a study done by an independent hospital based control group found
that there was actually an inverse relationship between statins and CAs (Hudson et al., 2013).
Materials and Methods
To determine if there will be a decrease in the incidence of cerebral aneurysm formation
and rupture by controlling the expression of NF-κB and Ets-1, an article by Aoki et al.,
2010 was reviewed. Aoki et al., 2012 extended their previous findings by examining the
regressive effect of decoy ODN, which simultaneously inhibit NF-κB and Ets-1 in the
development of CAs. They performed several experiments on 7 week-old rats as described
below, using numerous techniques at Kyoto University School of Medicine and Osaka
University School of Medicine.
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CAs were introduced into rat cerebral walls, after CA induction, the animals were perfused
transcardially with 4% paraformaldehyde and the anterior cerebral artery/olfactory artery
(ACA/OA) bifurcation was subjected to fluorescence immunohistochemistry among other tests
using several antibodies. The number of SMA (smooth muscle -actin), CD68 or CD31 were
identified and calculated for Ets-1 double positive cells.
To detect specific proteins, a Western Blotting technique was used, the ACA/OA
bifurcation was homogenized and dissolved into samples. Electrophoresis was ran, the
membranes were then incubated with primary antibodies and then incubated again with
secondary antibodies. A quantitative (real-time) Polymerase Chain Reaction (qPCR) was also
used to analyze RNA from the whole circle of Willis (anastomotic system of arteries at the base
of the brain that provides communication between blood supply of forebrain and hindbrain) then
converted into cDNA from dead rats to amplify and simultaneously detect MCP-1 expression.
For quantification, a second-derivative was used for cross-point determination.
Next, nuclear protein was extracted from a whole circle of Willis using electrophoretic
mobility shift assay (EMSA) with a biotin 3 oligonucleotides containing c-Ets-binding
consensus sequence and then followed by an anti-Ets-1 super-shift assay. Then, Chromatin
Immunoprecipitation (CHIP) was carried out after homogenization, cell lysis, and sonication
using anti-Ets-1 antibodies. Prior to this, a whole circle of Willis, with or without CA induction
was dissected and cross-linked by formaldehyde, then PCR was then carried out using primers or
rat MCP-1 and -9.
In a decoy ODNs treatment, Ets was synthesized along with scrambled decoy ODNs to
serve as a control. Ets or the scrambled decoy ODNs was then injected into the cisterna magna
every two weeks under general anesthesia. After 1 month, the ACA/OA bifurcation was stripped
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and observed using Elastica van Gieson (EvG) staining and macrophage accumulation was
assessed. Lastly, Immunohistochemistry was conducted with human CA samples retrieved from
neck clippings of un-ruptured CAs; the middle cerebral artery from an autopsy was used as a
control. Samples were fixed and then double stained to determine if Ets-1 was expressed in
human CA walls.
Results
Aoki et al., 2010 results showed in the immunohistochemistry test that Ets-1 was
expressed in the CA walls 1 month after induction but was barely present in the control cerebral
arterial walls. The result for the western blotting showed an increase in Ets-1 expression 1 month
after CA induction and was reduced from 1 to 3 months. The results for the EMSA produced a
band specific to the Ets family; this was later eliminated due to competition with
oligonucleotides. In the CHIP assay performed on the MCP-1 promoter with anti-Ets-1
polyclonal antibody showed MCP-1 binding site at -102 an increase from 1 month to 3 months,
conversely the -832 binding site for Ets showed a decrease from 1 month to 3 months and no
band was detected for the MMP-9 promoter. The ets decoy ODN-treated group compared to the
scrambled decoy ODN-treated group was significantly different, Ets decoy ODN inhibited DNA
binding activity. The qPCR analysis showed the MCP-1 expression increased in the scrambled
decoy ODN while the ets decoy ODN was significantly inhibited. This preserved the MCP-1
expression in endothelial cells after the ets decoy ODN treatment while inhibiting macrophage
infiltration in CA walls. In the immunohistochemistry for human samples, Ets-1 was found
generously in CA walls along with SMA and MCP-1 but rarely in the middle cerebral artery of
the control group.
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Feinberg et al., 2004 explains that several lines of evidence suggest a critical role for
MCP-1 in vascular disease. Studies have also demonstrated a reduction in atherosclerotic lesion
formation in mice deficient in MCP-1 or its chemokine receptor (CCR2) in atherosclerotic-prone
mice as explained. The information supported by Feinberg et al., 2004 also suggests
macrophage-specific overexpression of MCP-1 resulted in the increased development of vascular
lesion size and infiltration of macrophages in atherosclerosis-prone mice. In several animal
models, blockade of MCP-1 or deficiency of CCR2 decreased neointimal hyperplasia after
arterial injury. A link was discovered between macrophages and lymphocytes, which infiltrate
the aneurysm wall leading to the presence of the development of a cerebral aneurysm (Jayaraman
et al., 2008).
Another study conducted by Chyatte, Bruno, & Desai, 1999 discovered there was an
increased level of macrophages, T-lymphocytes, and cell adhesion molecule-1 in aneurysm
vascular tissue, but rarely in the control tissue. Feinberg et al., 2004 stated that in a previous
research that cytokines are a major chemical mediator in inflammation by activation of MCP-1
that occurs primarily at the level of transcription. This supports that Ets-1 inhibition from
binding may inhibit inflammation in the brain and therefore, less cerebral aneurysms will
development.
Studies also demonstrate that MCP-1 is a downstream gene of Ets-1 during CA
development. This study used Ets decoy ODNs which inhibited MCP-1 expression and shown a
significant difference in the media. MCP-1 was expressed at a high level in epithelial cells
especially at the early phase of CA formation. The Ets decoy ODN treatment did not abolish
MCP-1 expression in endothelial cells. Therefore, this suggests that different role between NF-
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κB and Ets-1 in transcriptional regulation of MCP-1 in CA walls. Ets decoy ODN
treatment resulted in suppression of CA enlargement without affecting systemic blood pressure.
According to Chalouhi et al., 2012 one study histologically compared 42 ruptured CAs
with 24 unruptured CAs and confirmed the infiltration of macrophages in the vessel walls
associated with aneurysm ruptures, apoptosis, and VSMC proliferation. While another
histological study compared 44 ruptured and 27 unruptured and found significantly more
endothelial damage, structural changes, and inflammatory cell invasion in the ruptured CAs.
Discussion
Ets-1 is involved in the regulation of vascular inflammation and remodeling in various
vascular diseases, but has been considered in the development of cerebral aneurysms (Aoki et
al., 2010). The main experiment by Aoki et al., 2010 used fluorescence immunohistochemistry
with different animal antibodies, Western Blotting, qPCR, and (EMSA) with a biotin 3
oligonucleotides containing c-Ets-binding consensus sequence and then followed by an anti-Ets-
1 super-shift assay.
Aoki et al., 2010 demonstrated in their research on Ets-1 that immunochemistry showed
that Ets-1 expression in media of CA walls at one month after the induction of a CA, while Ets-1
was barely expressed in the control arterial walls used. Treatment with Ets decoy
oligodeoxynucleotides resulted in the prevention of CA development, upregulation of MCP-1
expression and increase in macrophage accumulation in CA walls
The study showed that Ets-1 regulates expression of vascular endothelial growth factor,
regulating angiogenesis. Also, Ets-1 is highly expressed in VSMC derived from human
atherosclerotic plaques and in VSMC in the rat carotid artery after balloon injury (Aoki et al.,
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2010). Deficient mice showed a marked reduction in vascular remodeling in response to a
systemic administration of angiotensin II. With decreased vascular remodeling, this could lead to
an increase risk of developing cerebral aneurysms based on that the vascular smooth muscle cells
in the area become weaker (Aoki et al., 2010). Results also demonstrated in this study that
transactivation of Ets-1 induces the expression of platelet derived growth factor, thus promoting
VSMC proliferation. An increased expression and activation of Ets-1 in VSMCs in CA walls
strongly suggest the contribution of Ets-1 to vascular inflammation and remodeling occurring in
CA walls. This team hypothesized that pro-inflammatory cell types are the prime source of TNF-
alpha that initiate damage to endothelium, Smooth Muscle Cells (SMC) and Internal Elastic
Lamina (IEL). This supports that inflammation is a source of the development of cerebral
aneurysms, though a link between the Ets-1 transcription factors was not found in this study.
This study does support that inflammation is a primary cause of cerebral aneurysm development
however inflammation is triggered by stimulating the binding of Ets-1 to a sequence of DNA,
triggering the process of synthesizing various chemical mediators, like macrophages.
Ets-1 was expressed in the CA wall, although a small amount of Ets-1 was expressed in
the adjacent arterial wall. Ets-1 expression was reduced from 1 to 3 of CA induction. In western
blotting, Ets-1 expression was significantly upregulated one month after CA induction.
With the correlation of findings in this review between Ets-1 and its’ role in inflammation, it
can be determined that if Ets-1 is regulated, then inflammation can be controlled, leading to
decrease in the formation of CAs.
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Conclusion
In review of this analysis, an investigation of the molecular causes of the formation of
cerebral aneurysms was completed. NF-κB and Ets-1 is considered prime transcription
factors mediating transcription and therefore, protein synthesis and/or other mechanisms to
signal inflammation response. This leads to the accumulation of inflammatory chemicals,
including macrophages within SMVC of the arteries within the brain. Results have shown that
there is probable cause that these chemical mediators lead to inflammation in the muscle with
macrophages involvement and therefore, a cerebral aneurysm. They have also shown that by
inhibiting these transcription factors, which play a crucial role in CA development, we can
inhibit their expression and therefore control and possibly prevent CAs (Aoki et al., 2007). More
conclusive studies need to be completed to determine if other means or variables will control
cerebral aneurysms as well. Therefore, with the medical advances used today and with the
studies that show promising results for CAs, such as treatment with Ets decoy ODN; soon there
should be an alternative noninvasive medical treatment for management and preventions of CAs.
Future Perspective
Further studies should be completed using Ets decoy ODN to inhibit the development and
progression of cerebral aneurysms in rat and human vascular smooth muscle cells. A larger
sample size will further indicate accurate results to depict the usefulness of this approach.
Furthermore, different species of animal should be examined in addition to rats to instill that
inhibition of Ets transcription factor through the use of Ets ODN decoys actually
inhibits/decreases the development of cerebral aneurysms. Also, a better understanding of the
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exact mechanisms in the inflammation processes leading to CA ruptures will aid in the
development of more noninvasive treatments and possibly prevention.
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References
Akoi, T., Kataoka, H., Nishimura, M., Ishibashi, R., Morishita, R., & Miyamoto, S. (2010). Ets-1
promotes the progression of cerebral aneurysm by inducing the expression of MCP-1 in
vascular smooth muscle cells. Gene Therapy. 17(9), 1117-1123; doi: 10.1038/gt.2010.60
Akoi, T., Kataoka, H., Nishimura, M., Ishibashi, R., Morishita, R., & Miyamoto, S. (2012).
Regression of intracranial aneurysms by simultaneous inhibition of nuclear factor-κB and
Ets with chimeric decoy oligodeoxynucleotide treatment. Neurosurgery. 70(6), 1534-43;
doi: 10.1227/NEU.0b013e318246a390.
Akoi, T., Kataoka, H., Shimamura, M. Nakagami, H., Wakayama, K., Moriwaki, T., Ishibashi,
R., Nozaki, K., Morishita, R., & Hashimoto, N. (2007). NF-kB is key mediator of
cerebral aneurysm formation. American Heart Association. Retrieved from
http://circ.ahajournals.org/content/116/24/2830.short
Bashir, M., Bhatti, J., Marin, D., & Nelson, R. (2014). Emerging applications for ferumoxytol as
a contrast agent in MRI. Journal of Magnetic Resonance Imaging. 41(4), 884-889; doi:
10.1002/jmri/24651
Chalouhi, N., Ali, M., Jabbour, P., Tjoumakaris, S., Gonzalez, F., Rosenwasser, R., Koch, W., &
Dumont, A. (2012). Biology of intracranial aneurysms: role of inflammation. Journal of
Cerebral Blood Flow & Metabolism. 32, 1659-1676; doi: 10.1038/jcbfm.2012.84
Chyatte, D., Bruno, G., Desai, S., & Todor, D. (1999). Inflammation and intracranial aneurysms.
Neurosurgery. 45(5). Retrieved 13 March, 2015 from
http://www.ncbi.nlm.nih.gov/pubmed/10549930
16
TRANSCRIPTION FACTORS IMPACT CEREBRAL ANEURYSMS
Hasan, D. & Mayo Clinic (2011). Research from Mayo Clinic has provided new information
about aneurysms. Academic OneFile. Retrieved from
http://db08.linccweb.org/login?url=http://go.galegroup.com.db08.linccweb.org/ps/i.do?
id=GALE
%7CA275801830&v=2.1&u=lincclin_fccj&it=r&p=AONE&sw=w&asid=8a66625a5e08
dd4c02c8acc7319e2ff7
Francis, S., Tu, J., Qian, Y., & Avolio, A. (2013). A combination of genetic, molecular and
haemodynamic risk factor contributes to the formation, enlargement, and rupture of brain
aneurysms. Journal of Clinical Neuroscience. 20(7), 912-918;
doi:10.1016/j.jocn.2012.12.003
Feinberg, M., Shimizu, K., Lebedeva, M., Haspel, R., Takayama, K., Chen, Z., Frederick, J.,
Wang, X., Simon, D., Libby, P., Mitchell, R., & Jain, M. (2004). Essential role for Smad3
in regulating MCP-1 expression and vascular inflammation. Circulation Research
Journal. 94, 601-608. doi: http://dx.doi.org/10.1182/blood-2006-07-036400
Grenningloh, R., Kang, B., & Ho, I. (2005). Ets-1, a functional cofactor of T-bet, is essential for
Th1 inflammatory responses. The Journal of Experimental Medicine. 201(4), 615-626;
doi:10.1048/jem.20041330
Hudson, J., Hoyne, D., & Hasan, D. (2013). Inflammation and human cerebral aneurysms:
current and future treatment prospects. Future Neurology. 8.6, 663. Retrieved from
http://dx.doi.org.db08.linccweb.org/10.2217/fnl.13.40
Jayaraman, T., Paget, A., Shin, Y., Mayer, J., Chaundhry, H., Nijmi, Y., Silane, M., Berenstein,
A. (2008). TNF-alpha-mediated inflammation in cerebral aneurysms: a potential link to
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TRANSCRIPTION FACTORS IMPACT CEREBRAL ANEURYSMS
growth and rupture. Vascular Health Risk Management. 4(4), 805-817; doi:
10.1161/STROKEAHA.113.002390
Kataoka, H. (2015). Molecular mechanisms of the formation and progression of intracranial
aneurysms. Neurol Med Chir. 55, 214-229; doi: 10.2176/nmc.ra.2014-0337
Maroulakou, I. & Bowe, D. (2000). Expression and function of Ets transcription factors in
mammalian development: a regulatory network. Oncogene. 19, 6432-6442. Retrieved
from http://www.ncbi.nlm.nih.gov/pubmed/11175359
National Institute of Neurological Disorders and Stroke (NINDS). (2015). Cerebral aneurysms
information page. Retrieved from
http://www.ninds.nih.gov/disorders/cerebral_aneurysm/cerebral_aneurysms.htm
Sharrocks, A., Brown, A., Ling, Y., & Yates, P. (1997). The ETS-domain transcription factor
family. The International Journal of Biochemistry and Cell Biology. 29(12). doi:
10.1016/S1357-2725(97)00086-1
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