Signaling Pathways Flashcards
list genes involved in development code for mRNAs
transcription factors
signaling molecules
receptor molecules
signal transduction pathways are established when ? and result in ?
when a ligand binds to a receptor
result in a signal being transmitted to the nucleus of responding cell
responding cell produces gene products that influence the developmental pathway of the cell
list signaling factor families as discussed in lecture
- transforming growth factor - beta superfamily
- fibroblast GF family
- hedgehog family
- Wnt family
activation of TGF - Beta1
occurs when the proregions are separated from the bioactive dimer
the bioactive dimer then can function as a signaling molecule
bone morphogenetic proteins are apart of what GF family?
TGF-b1
describe bone morphogenetic proteins
15 members
often inhibit other processes in the embryo
–bind to bioactive dimers to inhibit them
fibroblast GF family
22 members
regulation at memb of responding cells and w/ various parts of signal transduction machinery
hedgehog family
(related to drosophila)
include:
desert
indian
sonic hedgehog
Wnt family
18 members in mouse
related to drosophila
plays dif. roles in various animals but often interacts w/ parts of extracell matrix
cell surface receptors have _______ protein _______ activity and ?
intrinsic protein kinase activity
and utilize a 2nd messenger system
cell surface receptors include receptors for ?
fibroblast GFs
–tyrosine kinase
TGF-b1
serine/threonine kinase
examples of signaling pathways
delta-notch receptor tyrosine kinase hedgehog Wnt signaling MicroRNA retinol
components of delta-notch pathway
delta = signaling molecule notch = receptor on neighbor cell
activation of delta-notch pathway
delta proteolytic cleavage of notch intracell domain
intracell domain then complexes w/ deltex
complex enter nucleus
–binds to suppressor of hairless
notch-delta-suppressor complex binds enhancer of split
resultant inhibitory signal represses gene expression
define lateral inhibition
–type of signaling between a dominant cell and neighboring cells
describe what dominant cell means
refers to a cell in a population that begins to differentiate along a particular path
process of lateral inhibition
dominant cell expresses delta signaling
delta binds notch on neighbors
represses genes in neighboring cells – to stop neighbors from becoming what the dominant cell is
(ex. neurons)
receptor tyrosine kinase pathway can be utilized by ?
fibroblast GF family
and
TGF-b1 family
receptor tyrosine kinase – fibroblast GF family components and actions
FGF binds receptor tyrosine kinase
G protein is activated
(RAS, RAF, MAP kinase, ERK)
result = ERK translocates to nucleus and activates various transcription factors
receptor tyrosine kinase – TGF - b1 components and actions
TGF-b1 binds serine/threonine kinase receptor type II
receptor type II dimerizes w/ type I
activation of R-Smad and Co-Smad
receptor tyrosine kinase — TGF - b1 results
Smad dimer translocates to nucleus and binds to co-factors which can then bind to DNA regulatory factors
hedgehog pathway
sonic hedgehog protein
–complexes w/ cholesterol after being translated in sending cell (shh-c)
shh-c translocates to cell surface as product of dispersed gene
actions of shh-c
hedgehog pathway
inhibits the inhibitory actions of Patched on smoothened on the target cell
results of hedgehog pathway
uninhibited Smoothened signals the release of transcription Gli
from a complex on microtubules
Gli translocates to the nucleus and influences gene expression
in the absence of Wnt, _______ are bound to an intracellular ________ complex within the ______ cell
beta-catenins
destruction complex
w/in target cell
components of Wnt signaling pathway
Wnt molecule = ligand
–binds Frizzled on target
Frizzled interacts w/ intracell Disheveled
results of Wnt signaling
disheveled prevents degradation of b-catenins by destruction complex
b-catenins translocate to nucleus and activate transcription factors
define MiRNAs
microRNAs
small RNAs – noncoding RNAs that influence gene expression
2 major groups
groups of MiRNAs
- Piwi - interacting RNAs
piRNA - endogenous small interfering RNAs
endo-siRNAs
piRNAs
act during gametogenesis
–especially spermatogenesis
type of microRNA
endo-siRNAs
expressed in somatic tissues thru out development
type of microRNA
microRNA pathway – components and actions
refer to figure 4.17
**important to note DICER and Argonaute (AGO) protein
describe the microRNA pathway
miRNA precursor – hairpin loop so ds
DICER cleaves to ss
miRNA cannot act on mRNA until AGO binds creating the AGO/mi RNA complex
retinol pathway components
retinol = vit A = signal molecule
binds to extracell retinol-binding protein = RBP
retinol-RBP complex binds to memb RBP
retinol is released into cytoplasm and binds CRBP 1
retinol pathway actions
after a series of enzymatic transformations
retinoic acid is bound to CRABP1 and translocates to the nucleus
retinol pathway results
retinoic acid binds to dimer RXR-RAR
which binds to RARE
which activates transcription
