Lect. 11 - Signaling Pathways Flashcards Preview

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Flashcards in Lect. 11 - Signaling Pathways Deck (33):
1

how are signal transduction pathways established?

when a ligand (signaling molecule) binds to a receptor

2

result of signal transduction pathway

signal being transmitted to the nucleus of a responding cell - responding cell produces gene products that influence the developmental pathway of a cell

3

Transforming Growth Factor-beta Superfamily (TGF-B1)

disulfide linked dimer; consists of a large proregion and a bioactive region

4

what forms the dimer in TGF-B1

two bioactive regions after being cleaved from the proregion

5

what is the purpose of the proregion in TGF-B1 after begin cleaved?

they complex w/ the bioactive dimer to maintain it in a latent form

6

When does activation occur in TGF-B1?

when the proregions are separated from the bioactive dimer

7

what part of TGF-B1 functions as the signaling molecule?

bioactive dimer

8

bone morphogenic proteins

encompasses 15 members w/i TGF-B1 superfamily

9

what are the modes of action of the bone morphogenic proteins?

inhibit other processes in the embryo, often by being inhibited by other molecules; bind to bioactive dimers and prevent them from binding to receptors

10

Fibroblast Growth Factor Family number of members

22 members;

11

FGF family means of regulation

modification of interaction w/ heparan proteoglycans in receptor complex; regulation at membrane of responding cell via transmembrane proteins; regulation by molecules that complex w/ signal transduction machinery

12

Hedgehog Family

related to the segment polarity molecules in Drosophila; include desert, indian, sonic hedgehog

13

Wnt Family

includes 18 members in the mouse; related to segment polarity genes in drosophila; often interact w/ components of extracellular matrix; different roles in various vertebrate classes

14

cell surface receptors w/ intrinsic protein kinase activity

includes receptors for FGF (cytoplasmic domain possesses tyrosine kinase activity) and TGF-beta factors (cytoplasmic domain possesses serine/threonine kinase activity

15

in the delta-notch pathway, which signal molecule is on the dominant cell?

delta

16

in delta-notch pathways what is on the neighboring cell?

notch receptor

17

Delta-Notch pathway actions

proteolytic cleavage of notch in intracellular domain which then complexes w/ Deltex and enters nucleus; complex binds to suppressor of hairless; notch-deltex-suppressor of hairless complex binds to enhanver of split

18

what is the result signal from the delta notch pathway?

inhibitory signal represses gene expression

19

lateral inhibition

type of signaling b/w a dominant cell and neighboring cells; the dominant cell is the one that begins to differentiate along a particular path and expresses delta signaling on its membrane.

20

what happens in lateral inhibition after delta signaling molecule is expressed on the membrane of the dominant cell?

delta binds notch receptors on neighboring cells and represses genes in them (through delta-notch)

21

receptor tyrosine kinase pathway is used by what kind of signaling molecules?

FGF and TGF-beta

22

receptor tyrosine kinase pathway components and actions w/ FGF

FGF binds receptor tyrosine kinase; G protein activated (activates RAS, RAF, MAP kinase, and ERK); ERK translocates to nucleus and activates various TFs

23

receptor tyrosine kinase pathway components and actions w/ TGF-beta

Tgf-beta bind to serine/threonine kinase receptor type II which dimerizes w/ receptor type I (activates R-Smad and Co-Smad); Smad dimer translocates to nucleus and binds to co-factors which can then bind to regulatory factors

24

Hedgehog pathway

Shh + cholesterol then translocated to cell surface via Dispersed; it inhibited the inhibitory actions of Patched on Smoothened on target cell

25

In the hedgehog pathway, what is the result of getting an uninhibited smoothened?

it signals the release of transcription Gli from a compelx on microtubules and Gli translocates to the nucleus to influence gene expression

26

Wnt signaling pathway

Wnt binds to Frizzled on target cell; frizzled interacts w/ disheveled; disheveled prevents degradation of B-catenins by the destruction complex; b-catenins translocate to nucleus and activate Tfs

27

What is found in the absence of the Wnt?

beta-catenins are bound to an intracellular destruction complex w/i the target cell

28

miRNAs

small noncoding RNAs that influence gene expression

29

what are the two major groups of miRNAs

Piwi-interacting RNAs (piRNAs) and endogenous small interfering RNAs (endo-siRNAs)

30

piwi-interactingRNAs (piRNAs)

act during gametogenesis (esp. spermatogenesis)

31

endo-siRNAs

expressed in somatic tissues throughout development

32

miRNA pathway

double helical precursor w/ hairpin loop is cleaved by Dicer and the formed miRNA is complexed w/ an Argonaute (AGO) protein; complex cleaves target mRNA molecule inactivating it

33

retinol pathway

retinol binds RBP and complex binds to a membrane RBP; retinol is released and binds CRBP-1; RA is bound to CRABP-1 and translocated to nucleus; RA binds dimer RXR-RAR which binds RARE which activates transcription