Signal transduction (cell to cell signaling)

Question 1

signals tell cell to…

Answer 1

• survive
• divide
• differentiate
• die

Question 2

steps of signal transduction

Answer 2

• signaling molecule bind to receptor (receotion)
• transduction (relay molecules)
• response OR termination
• ex: TF –> gene expression

Question 3

important transcription factors

Answer 3

• homeodomain-containing TF (Hox, Pax, Lim)
• helix loop helix TF
• zinc finger TF

Question 4

What are homeodomain containg TFs

Answer 4

• distinctive DNA binding sequence preferences
• contribute to specificity in target genes and diversity in function among homeodomain proteins

Question 5

example of homeodomain containing tf

Answer 5

• hexapeptide: Hox
• engrailed
• Paired: pax
• LIM

Question 6

What are Hox TF

Answer 6

• pattern the anterior posterior body axis playing crucial role in segment specific organogenesis
• normal temporo-spatial limb and organ development

Question 7

How are Hox TFs similar to combinatorial gene control

Answer 7

• diff hox genes control expression in diff segments
• order of genes in chromosome specifies order in time of their expression and where expressed spatially

Question 8

Describe loss of function Hox TFs

Answer 8

• if a segment is KOed, the expression will be taken over by another segment…
  ex: KO band of XIHbox1 expression… hindbrain will take over that area

Question 9

Pax TFs

Answer 9

• important for developmental steps… regional specification

Question 10

LIM TFs

Answer 10

• involved in tissue patterning and differentiation… specifically neural patterning (head development)

Question 11

Helix-loop-helix transcription factors

Answer 11

• basic helix-loop-helix: MyoD (muscle pattern .. master regulator TF)
• forkhead: FOX

Question 12

Zinc finger transcription factors

Answer 12

• zinc finger: sox, WT1, Kruppel

Question 13

sox

Answer 13

• works together with other Tf’s

Question 14

regulatory gene hierarchy

Answer 14

• cascade of gene expression (genes that encode TFs)
• gene products in each class control expression of genes in next class
• results in:
• stepwise organization of embryo… smaller and smaller regions until segmentation
• same gene function at different period of development or in diff organs

Question 15

Genes that guide development are..

Answer 15

• conserved
• earliest stages of human development occur under less rigid genetic control

Question 16

mutation of pax genes leads to…

Answer 16

• larger segments of regions

Question 17

mutation in pax gene

Answer 17

• larger segmented regions

Question 18

genetic hierarchy

Answer 18

• top to bottom
  maternal effect genes
  gap genes
  pair rule genes
  segment polarity genes
  homeotic genes

Question 19

one of the principal themes in contemporary cancer research is

Answer 19

• role of mutant forms of developmentally important genes in converting normal cells to tumor

Question 20

signaling molecules and pathways

Answer 20

• paracrine factors : diffusion of inducers from one cell to another
• matrix: matrix of one cell induces change in another
• contact : contact between inducing and responding cells

Question 21

paracrine factors

Answer 21

• fibroblast growth factors (FGF)
• related growth factors (EGF)
• TGF-B superfamily
• hedgehog
• Wnt (wingless)

Question 22

antagonists of paracrine factors

Answer 22

• noggin (BMP)
• chordin (BMP)

Question 23

FGF and TGF-B pathways

Answer 23

• know graph

Question 24

Growth factor to RTK

Answer 24

• GF -> RTK -> Ras -> MAPK cascade

Question 25

Describe FGF complexity

Answer 25

• same protein discovered in different contexts
• biologically can interact in different ways to do different things, despite being the same protein

Question 26

TGF-B to TGF-B/Smad signaling pathway

Answer 26

see graph

Question 27

hedgehog signaling pathway

Answer 27

• hedgehod inhibit patched
• patched inhibit smoothened
• smoothened activate Ci protein made activator (Gli)
• activates transcription

Question 28

Wnt signaling pathway

Answer 28

• see figure
• Wnt activate frizzle
• frizzle activate disheveled
• DSh inhibits GSK3
• GSK3 inhibit B-catenin
• B-catenin activate transcription

Question 29

Direct cell contact

Answer 29

• delta notch
• cadherin (homophilic)
• other cell-cell adhesion molecules

Question 30

delta-notch

Answer 30

• direct contact cell signaling
• communication
• controls cell differentiation processes during embryo/adult life…
• dysregulated in cancer
• lunatic fringe

Question 31

Where do you see delta-notch signaling

Answer 31

• gliogenesis
• left-right asymmetry determination
• somite function

Question 32

lunatic fringe

Answer 32

• acts in golgi to modify notch and alter notch’s ability to bind to its ligand Delta
• established anterior boundary of somites

Question 33

cell to cell adhesion molecules

Answer 33

• see figures

Question 34

extracellular matrix signaling moelcules and pathways

Answer 34

• integrin:
• principal receptors used by animal cells to bind to extracellular matrix
• heterodimers and
• function as transmembrane linkers between the extracellular matrix and actin cytoskeletion

Question 35

examples of how singlaing pathways are complex integrated cell processing pathways

Answer 35

• branch points for multiple responses
• cross talk; integration of multiple signals
• reciprocal communication/ induction