This document summarizes the TGF-β/SMAD signaling pathway. It discusses that TGF-β binds to receptors that phosphorylate and activate SMAD transcription factors. There are three classes of SMAD proteins: receptor-regulated SMADs, common-mediator SMAD4, and inhibitory SMADs. The TGF-β signaling pathway regulates processes like proliferation, differentiation, and fibrosis. Defects can cause cancer or kidney disease. TGF-β signaling is involved in development, ischemia/reperfusion injury, atherosclerosis, and treatment of diseases can target this pathway. The document provides an overview of the key components and functions of the TGF-β/SMAD signaling pathway and its role in

1. Edited by
student
Hassanein Hadi Ali

2. TGFb / SMAD pathway
Function
Role in disease
Role in treament

3. WHAT IS TGF?
• It is transforming growth factor or tumor growth factor.
• There are two types, TGF-α and TGF-β
• TGF-α is a single growth factor which is upregulated in some
human cancers. It is produced in macrophages, brain cells and
keratinocytes (basal cells in epidermis) and induces epithelial
development.
• TGF-β is a diverse family of growth factor. Many different
members and subfamilies are within it. TGF-β is a protein that
controls proliferation, cellular differentiation,which plays a role
in cancer, bronchial asthma, heart disease, bone growth,
mesoderm formation.

4. TGFβ Receptors
• Three types: Types RI, RII, and RIII
• Activation of these receptors cause in phosphorylate and results
in the activation of transcription factors. The type I and II receptors
contain serine–threonine protein kinases in their intracellular
domains that initiate intracellular signaling by phosphorylating
several transcription factors known as Smads.
Nomenclature of SMAD
The SMAD proteins are homologs (derived from the Sma and MAD
gene homologues in Caenorhabditis elegans and Drosophila
melanogaster proteins).

5. .
0Introduction
SMADS are phylogenetic old proteins, which are mediating
intracellular signaling of the large group of soluble TGFβ ligands,
containing transforming growth factor βs (TGFβs), bone
morphogenetic proteins (BMPs), growth and differentiation factors
(GDFs), Muller a n inhibitory factors (MISs), activins and inhibins.
Genes in the SMAD family provide instructions for producing
proteins that help regulate the activity of genes as well as cell growth
and division , which transmits signals from the outside of the cell to
the nucleus.

6. There are three classes of SMAD:
The receptor-regulated SMADs (R-SMAD) which include SMAD1,
SMAD2, SMAD3,
SMAD5, SMAD8 and SMAD9
The common-mediator SMAD (co-SMAD) which includes only
SMAD4, which
interacts with R-SMADs to participate in signaling
The antagonistic or inhibitory SMADS (I-SMAD) which include
SMAD6 and SMAD7,
which block the activation of R-SMADs and Co-SMADs.

7. TGF-β activation
Transforming growth factor beta-1 (TGF-β1) is an important
molecule promoting fibrosis in the liver, lung, kidney, pancreas, and
other organs . It has been shown that it may also play an important
role in the process of cardiac fibrosis, inflammation, and tissue
remodeling organs. Some currently known factors which activates
TGF-β are Protease, Integrins, PH and oxygen reactive species
(ROS).
Disruption of these activating factors can leads to unregulated TGF-
β signaling levels that may cause several complications including
inflammation, fibrosis, cancer .

9. TGFβ SIGNALING PATHWAY activation
A general mechanism for TGF-β signaling is TGF-β binds either to
type III receptors, which then present TGF-β to type II receptors, or
directly to type II receptors. Once activated by TGF-β, type II
receptors recruit, bind, and trans phosphorylate type I receptors
• TGF-β signaling pathway begins with a TGF-β dimer binding to
Type II TGF-β receptor at cell surface.
• TGF-β dimer induce formation of complex between typeII and type
I TGF-β receptors, both of which are transmembrane
serine/threonine kinases.
• Once TGF-β dimer binds to type II receptor and activates type I
receptor.
• The activated type I receptor phosphorelates a receptor regulated
Smad (R-smad) which then dimerizes with a Co-smad.
• The smad dimer translocates into the nucleus and with a DNA
binding partner activates transcription of target genes.

12. Activation of Smads causes their translocation from the cytoplasm
to the nucleus where they function to control gene expression. To
date, 10 Smad proteins have been identified (Smads 1 through 10).
Smad2 and Smad3 are phosphorylated by activated type I TGF-β
receptors. Smad4 is a common partner for all of the receptor-
activated Smads. Smad6 and Smad7 block the phosphorylation of
Smad2 or Smad3, thus inhibiting TGF-β signaling.
Dephosphorylation of the Smads within the nucleus results in their
translocation to the cytoplasm.

14. Role of inhibitory SMADs
There are two other SMADs which complete the SMAD family, the
inhibitory SMADs (I-SMADS), SMAD6 and SMAD7. They play a key
role in the regulation of TGF beta signaling and are involved in
negative feedback. SMAD7 competes with other R-SMADs with the
type I receptor and prevents their phosphorylation . It resides in the
nucleus and upon TGF beta receptor activation translocate to the
cytoplasm where it binds the type I receptor. SMAD6 binds SMAD4
preventing the binding of other R-SMADs with the co SMAD. The
levels of I-SMAD increase with TGF beta signaling.

16. Role tgfb in ageing
TGFβ signaling increases after brain infarct in aged individuals,TGFβ-
Smad3,2 is involved in many protective functions of microglia, and
shows major changes with aging. The activation of Smad3,2 pathway i
inhibited that increased TGFβ levels shifts the regulatory signaling
towards a dysregulated inflammatory activation, potentially leading to
the impairment of protective response, development of an increased
cytotoxicity and to neurodegenerative changes. Thus, increased
neuroinflammation, Which linked to neuronal damage, cognitive
impairment, and an increased susceptibility to neurodegenerative
diseases, such as AD alizhemer disease.

17. TGF-B/Smad signaling in kidney disease,bone
Dysregulation of TGF-B/Smad signaling is a possible pathogenic
mechanism of chronic kidney disease.TGF-B1 signal is transduced
by the R-Smads Smad2 and Smad3, both of which are found to be
overexpressed in diseased kidneys. Smad3 knockout mice display
reduced progression of renal fibrosis.Conversely, inhibiting Smad2
in kidney cells (full Smad2 knockouts are embryonic lethal) actually
leads to more severe fibrosis, suggesting that Smad2 works
antagonistically to Smad3 in the progression of renal fibrosis.Also
used anti-renal fibrosis effect of asperulosidic acid via
TGFβ1/smad2/smad3 and NF-κB signaling pathways in a rat model
of unilateral ureteral obstruction to prevent renal I/R injury.

18. The central role of TGF-β1 on EMT(Epithelial-mesenchymal
transition) and renal fibrosis has been confirmed by many
experiments which indicated the ability of TGF-β1 blockade with
decorin, neutralizing TGF-β antibody or anti-sense oligonucleotides
to attenuate renal fibrosis . Angiotensin II has been demonstrated to
raise expression of TGF-β1 and its receptors.TGF-β1 was known as an
ant inflammation cytokine. It produced anti-inflammatory effects
through inhibition of mutagenesis and cytokine responses in
glomerular cells and inhibiting infiltrating cells.

19. Transforming growth factor-β (TGF-β1) knockout mice showed
multi-organ inflammation and TGF-β1 deficient or deletion of
TGF-β1 mice exhibited lethal inflammation that die within three
weeks and cause autoimmune diseases. Increases or decreases in
the production of TGF-β have been linked to numerous disease
states, including atherosclerosis and fibrotic disease of the kidney.
Numerous studies in animals investigating the role of insufficient
TGF-β activity in disease have suggested that exogenous TGF-β
may promote the healing of fractures, bone defects, and both acute
and chronic wounds. In addition, TGF-β3 prevents chemotherapy-
and radiation-induced mucositis.

20. Role of Smad in cancer
Defects in Smad signaling can result in TGF-B resistance, causing
dysregulation of cell growth, which implicated in many cancer
types, including pancreatic, colon, breast, lung, and prostate cancer.
Smad4 is commonly mutated in human cancers, pancreatic and
colon cancer. TGF-β is a potent inhibitor of cell proliferation. It
arrests the cell cycle. This tumor-suppressive effect is eradicated in
many cancers by inactivation or loss of TGF-β pathway components.
In most human pancreatic cancers, adeletion to the Smad 4 gene
occurs. The Smad 4 protein is not produced (or is nonfunctional),
and proteins that inhibit cell proliferation upon stimulation by
TGFβ are not synthesized
T
.

22. Stimulation of angiogenesis may be another mechanism by which
TGF-β stimulates the growth of late-stage tumors. TGF-β, which is
produced by all leukocytes, promotes their differentiation and
inhibits their proliferation and activation. Smad3-deficient mice
develop chronic mucosal infections due to impairment of T-cell
activation and mucosal immunity.Choriocarcinoma tumor cells are
TGF-B signaling resistant, as well as lacking Smad3 expression.
Studies show that reintroducing Smad3 into choriocarcinoma cells
is sufficient to increase TIMP-1 (tissue inhibitor of metalloprotease-
1) levels, a mediator of TGF-B’s anti-invasive effect, and thus restore
TGF-B signaling..

23. Role of TGF-β in Atherosclerosis
TGF-β inhibits the proliferation and migration of smooth-muscle
and endothelial cells. Apolipoprotein A, a homologue of
plasminogen, is an independent risk factor for cardiovascular
disease when expressed at high levels. In mice, the expression of
apolipoprotein A inhibits proteolytic activation of TGF-β, thereby
promoting the proliferation of smooth-muscle cells and the
subsequent development of fatty lesions. Conversely, treatment of
mice with the antiestrogen tamoxifen increases serum TGF-β1 levels
and suppresses the formation of lipid lesions in the aorta.
These studies suggest that TGF-β can function as an inhibitor of
atherosclerosis.

24. Consistent with this hypothesis are the findings that serum levels of
TGF-β are low in patients with atherosclerosis and that tamoxifen
may mediate its cardioprotective effects by increasing serum TGF-β
levels.
. A large number of studies have shown that telmisartan can
attenuate cardiac fibrosis through acting on angiotensin II 1 receptor
(AT1R), and TGF-β 1/Smad signaling molecule is an important
pathway to achieve this effect that have as the function of anti-
cardiac fibrosis. Therefore, this study provides a new therapeutic
target for ACS

25. Stevioside, a natural glycoside compound, has many beneficial
biological activities. The results showed that after the
administration of stevioside, the myocardial hydroxyproline,
collagen accumulation, transforming growth factor-β1 (TGF-β1),
nuclear factor kappa B p65 (NF-κB p65), Smad2/3, and P-Smad2/3
were decreased, while the glutathione peroxidase and superoxide
dismutase levels in serum and myocardial tissues and Smad7 were
increased.

26. Role of TGF-β in ischemia/reperfusion
Previous studies have shown that up-regulation of transforming
growth factor β1 results in neuroprotective effects. Levels of
SMAD2/3 mRNA were up-regulated in the ischemic penumbra 6
hours after cerebral ischemia/reperfusion, reached a peak after 72
hours and were then decreased at 7 days. Phosphorylated SMAD2/3
protein levels were consistent with the mRNA levels. This study
aimed to observe SMAD2 and SMAD3 expression in the brain of a
cerebral ischemia/reperfusion rat model, explore the effects of
SMAD2 and SMAD3 on inflammation and apoptosis after
infarction. These findings indicate that SMAD3 exhibits
neuroprotective effects on the brain after ischemia/reperfusion
through anti-inflammatory and anti-apoptotic pathways.

27. Role of TGF-β in Development
Mice lacking TGF-β2 have cardiac, lung, craniofacial, and urogenital
defects, and mice lacking TGF-β3 have cleft palates. Polymorphisms
in the gene for TGF-β3 have been linked to the development of cleft
palate in, maternal tobacco use and alcohol consumption —
suggesting an important role for TGF-β3 in the development of this
disorder in humans.
Implications for the Treatment of Human Diseases
The role of TGF-β in human diseases encompasses two major
themes: one involving increased TGF-β activity, as occurs in patients
with fibrosis and progressive cancers, and a second involving
decreased TGF-β activity, as occurs in early tumorigenesis,
developmental defects, and atherosclerosis.
.

28. Implications for the Diagnosis and Prognosis of Human
Diseases
The levels of TGF-β in serum and of TGF-β mRNA in tissue can be
measured and used as diagnostic or prognostic markers for human
disease. High levels of TGF-β1 mRNA in tissue are associated with
invasive prostate cancer,colorectal cancer, and chronic viral hepatitis
and with decreased survival in patients with gastric cancer.Finally,
early increases in serum TGF-β2 levels predict a clinical response to
tamoxifen in patients with breast cancer. Polymorphisms in the gene
for TGF-β1 that appear to determine the production of TGF-β1 may
also be useful in predicting susceptibility to certain diseases.
Polymorphisms leading to increased TGF- β1 production have been
linked to fibrosis and hypertension and polymorphisms leading to
decreased TGF-β1 production have been
.linked to osteoporosis

29. Approach therapy for disease by TGFb
In humans, the success of angiotensin-converting–enzyme
inhibitors in treating diabetic nephropathy, interferon alfa in
treating hepatic fibrosis, azathioprine and prednisone in treating
autoimmune hepatitis, and cyclosporine or interferon gamma-1b in
treating pulmonary fibrosis is in part due to the ability of these
drugs and cytokines to reduce serum levels of TGF-β. In fact, the
efficacy of angiotensin-converting–enzyme inhibitors in
maintaining renal function and of interferon alfa in treating
hepatic fibrosis directly correlates with decreases in serum TGF-β
levels.

30. Catalpol, one of the main active ingredients isolated from
Rehmannia glutinosa, was possess anticancer activity. In
conclusion, these findings indicated that catalpol inhibits TGF‐β1 in
human NSCLC through the inactivation of Smad2/3 and NF‐κB
signaling pathways. Thus, catalpol may be a promising agent for the
treatment of NSCLCcells(Non-small-cell lung carcinoma ). The
results indicated that arsenic activates the TGF-β/Smad pathway
and induced fibrosis. The mechanism is related to the up-regulation
of NADPH oxidase and ROS accumulation. However, high-dose
arsenic exposure may inhibit this pathway.

31. preclinical Evaluation of AZ12601011 and AZ12799734,that inhibitors
of Transforming Growth Factor β Superfamily Type 1 receptors.
PDZK1-interacting protein 1 (PDZK1IP1) traps or interact Smad4
protein and suppresses transforming growth factor-β (TGF-β)
signaling, PDZK1IP1 gain-of-function decreased tumor size and
increased survival rates. Methyl ferulic acid attenuates liver fibrosis
and hepatic stellate cell activation by inhibiting the TGF-β1/smad.

32. Salvianolic acid A can alleviate the renal damage in CRF rats through
anti-oxidant stress, down-regulation of TGF-β1 signaling pathway
and up-regulation of(Bone Morphogenetic Protein 7) BMP-7/Smad6
signaling pathway. Silymarin ameliorates diabetic cardiomyopathy
via inhibiting TGF‐β1/Smadsignaling, suggesting that silymarin may
be a potential target for DCM treatment. .

33. Refrences
New england of medicine journal
Pubmed
Google schooler

34. Thank you