Cell to Cell Communication Flashcards

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1
Q

how do cells and tissues “know” how to develop

A

induction and competence

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2
Q
  • proteins made by a cell or group of cells that alter the behavior and differentiation of adjacent
  • inter- and intracellular signals
A

paracrine factors

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3
Q

response to signals at the molecular level

A

signal transduction/ signal transduction cascades

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4
Q

communication between cells requires (2)

A
  • ligand
  • receptor protein
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5
Q

the signaling molecule

A

ligand

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6
Q

the molecule to which the receptor binds; maybe on the plasma membrane or within the cell

A

receptor protein

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7
Q

types of cell signaling (4) - depending on how far

  1. ________: cell targets itself
  2. ________: short distance
  3. ________: long distance
    4: ________: gap junction
A
  1. autocrine signaling
  2. paracrine signaling
  3. endocrine signaling
  4. juxtacrine/direct signaling
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8
Q

Types of binding
1. ________ - identical receptor or adhesion molecule
2. ________- different receptor or adhesion molecule

A
  1. homophilic
  2. heterophilic
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9
Q

Types of receptors (2)

  1. __________: within the cell (cytoplasm) and respond to hydrophobic ligand molecules (ex: steroid hormones)
  2. __________: integral proteins (at membrane) that bind to external signaling molecules and perform signal transduction. hydrophilic ligand molecules
A
  1. Internal receptor (intracellular or cytoplasmic receptors)
  2. Cell-surface receptors (transmembrane receptor)
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10
Q

Receptor types (3 subclasses of cell-surface receptors)

  1. __________: ion channel that opens in response to a ligand (ex: Na channel)
  2. __________: receptor is an enzyme that is activated by the ligand
  3. _________: a G-protein (bound to GTP) assists in transmitting the signal
A
  1. channel linked receptors
  2. enzymatic receptors
  3. G protein-coupled receptor
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11
Q

Three stages of signal transduction

  1. _________ of extracellular signal
  2. ________ of signal from outside of cell to inside of cell-often multi stepped
  3. __________. Is initiated and/or occurs entirely within receiving cell
A
  1. reception
  2. transduction
  3. cellular response
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12
Q
  • interaction at close range between two or more cell tissues with different histories and properties
  • has two parts:
A
  1. induction
    • inducer
    • responder
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13
Q

tissue that produces signal that changes the cellular behavior of the other tissue

A

inducer

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14
Q

tissue being induced; the target tissue

A

responder

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15
Q
  • the ability of a cell or tissue to respond to a specific inductive signal (Waddington 1940)
  • actively acquired (and can also be transient)
A

competence

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16
Q

Induction - Vertebrate Eye Development

  1. ______ are outgrowings of the brain which make contact with the ___________ and this contact induces changes necessary for futher development of the eye
  2. _____________ ( tissue thickening) induced in head ectoderm by close contact with neural (brain) tissue.
  3. The developing lens then induces brain to form the ________ (will develop into the pigmented retina and neural retina).
A
  1. optic vesicles, surface ectoderm
  2. lens placode
  3. optic cup
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17
Q

needed for normal induction of lens (2)

A
  • presence of optical vesicle
  • ectodermal competence
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18
Q

Factors that enable a cell or tissue to respond to an inductive signal. These can be actively acquired and may be transient.

A

Competence factor

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19
Q

**Competence factor **

  • is a competence factor for lens inductions
  • its expressed in the head ectoderm, but not in other regions of surface ectoderm.
  • is needed for the surface ectoderm to respond to the inductive signal from the optic vesicles; the inducing tissue does not need it
A

Pax6

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20
Q

When Pax6 is not wild-type and is a mutant, which is the defective component- the optic vesicle or the surface ectoderm?

A

surface ectoderm

21
Q

Studies in amphibians suggest that the first inducers maybe the ___________ and ___________________ that underlie the lens-forming ectoderm during the early and mid-gastrula stages.

A

pharyngeal endoderm and heart-forming mesoderm

22
Q

There is no single inducer of the lens.

Optical vesicle inducers: (2)

A
  1. BMP4 (bone morphogenic protein 4)
  2. Fgf8 (fibrobast growth factor 8)
23
Q

induces Sox2 and Sox3 transcription factos

A

BMP4 (bone morphogenic protein 4)

24
Q

induces L-maf transcription factor

A

Fgf8 (fibrobast growth factor 8)

25
Q

The combination of ______, ______, ______and ______ in the ectoderm ensures the production of the lens and the activation of lens-specific genes such as ________.

A

Pax6, Sox2, Sox3 and L-maf
crystallin

26
Q

EFFECTS OF MULTIPLE INDUCERS (2)

A
  1. Sequential and Additive
  2. Reciprocal and Sequential Inductive Events
27
Q

example of Sequential and Additive (Inducers in Frog Lens Development)
First Inducer: (2)
Second Inducer: (1)

A

Pharyngeal Endoderm and Heart-Forming Mesoderm
Anterior Neural Plate

28
Q

example of Reciprocal and Sequential Inductive Events

A

Vertebrate Eye Development

29
Q

Inductive interactions

  • ____________ plays an instructive role (as the inducing tissue)
  • initiates gene activity in ________ cells
A
  • mesenchyme
  • epithelial
30
Q

The lens placode __________ by inducing the optic vesicle before the lens forms its characteristics fibers.

A

reciprocrates

31
Q

How do these interactions work?

  • _________ - a signal from the inducer is required for initiation new gene expression. Without the inducer, the cell is not capable of differentiating.
  • _________ -the tissue has already been specified, but requires an environmental change that allows expression of the differentiated tissues traits. (ex: many tissues need a solid substrate containing fibronectin in order to develop.)
A
  • instructive interaction
  • permissive interaction
32
Q

All organs consist of an epithelium and an associated mesenchyme. Many inductions involve interactions between epithelia and mesenchyme.

___________
- sheets or tubes of connected cells
- originate from any germ layer

_________
- loosely packed, unconnected cells
- derived from mesoderm or neural crest

A

epithelia
mesenchyme

33
Q

Two types of specificity of induction

______ - source of mesenchyme (inducing tissue) determines the structure of the epithelial derivative; skin epithelium and mesenchyme

______ - epithelial response is limited to genomic capability (ex. _____ - a single organism that’s made up of cells from two or more individuals (2 sets of DNA))

A

regional specificity
genomic specificity - (ex: chimeras)

34
Q

_________: The Inducer Molecules

_____________- signaling molecules (proteins) produced by one cell (tissue) and distributed via diffusion to a localized areal often act as inducers

A

Paracrine Factors

Paracrine Factors / Growth and Differentiation Factors (GDF)

35
Q

Paracrine Factor Families (4)

A
  1. Fibroblast growth factor (FGF)
  2. Hedgehog family
  3. Wingless family (Wnt)
  4. TGF-β superfamily (Transforming growth factor)
    - TGF-β family
    - Activin family
    - Bone morphogenic proteins (BMPs)
    - Vg1 family
36
Q

Cell-Cell Communication

  • A cell’s response to a signal often involves activating or inactivating proteins.
  • ______ is a common way to change the activity of a protein
    1. _________- an enzyme that adds a phosphate to a protein
    2. ________- an zyme that removes a phosphate from protein
A
  • Phosphorylation
    1. protein kinase
    2. phosphatase
37
Q

Signal Transduction Pathways

A
  1. RTK Pathway - Generic
  2. JAK-STAT Pathway
  3. Hedgehog pathway
  4. Wnt signaling pathway/Beta-catenin pathway
    5.The Notch pathway
38
Q
  • active during development
  • repressed/silenced in adult
  • cause tumor formation when inappropriately activated
    = mutation (e.g. constitutive activation)
    > many cancers have mutated ______

Give 4 examples of this in RTK Pathway.

A

proto-oncogenes (onco = cancer)
1. RAS
2. RAF
3. MEK
4. ERK

39
Q

The _____________ is critical in numerous developmental processes. In the migrating neural crest cells of humans and mice, the pathway is important in activation the ________________ to produce pigment cells (melanoblast cells, pigmented retina).

A

micropthalmia transcription factor (Mitf)

40
Q

In JAK-STAT pathway
> _______ - non-receptor tyrosine kinase
> _______ - family transcription factor

Note: STATs can be activated independently of JAKs
- RTK
- non receptor tyrosine kinases

A

Janus Kinase
Signal Transduction and Activation of Transcription

41
Q

______ pathway is very important in regulation of human fetal bone growth. Mutation -> severe forms of dwarfism

A

(JAK-) STAT pathway

42
Q

_________ pathway is extremely important in vertebrate limb and neural differentiation.

A

Hedgehog pathway

43
Q

One remarkable feature of Hedgehog signal transduction pathway is the importance of ______.

  1. It is critical for the catalytic cleavage of ________ protein. Only the AMINO TERMINAL PORTION is functional and secreted. It binds to the active N-terminus of the protein and allows this paracrine factor to diffuse over a range of a few hundred micrometer (cholesterol modification)
  2. The ________ protein that binds sonic hedgehog also needs cholesterol in order to function.
A

Cholesterol
1. Sonic hedgehog protein
2. Patched protein

44
Q

Vertebrates have at least three homologues of the Drosophila hedgehog gene (3)

  • ________ - sertoli cells of the testes
  • ________ - gut and cartilage
  • ________ - important in embryo development
A
  • desert hedgehog (dhh)
  • indian hedgehog (ihh)
  • sonic hedgehog (shh)
45
Q
  • their name is a fusion of the name of the Drosophila segment polarity gene _______ with the name of its vertebrate homologues, _________.
  • they are a family of cysteine-rich glycoproteins
  • ___ gene family
    • ____ genes characterized in vertebrates and invertebrate combined
      - ____ in human
  • Receptors: __________
    - _____ genes found in vertebrates
A

Wnt (Wingless-related integration site) Family
- wingless, integrated
- Wnt: 30, 19
- Frizzled gene family: 10

46
Q

The Wnt Signaling Pathway

  • ________: active in inducing the dorsal cells of the somites to become muscle and is involved in the specification of the midbrain cells
  • ________: critical in establishing the polarity of the insect and vertebrate limbs, promoting the proliferation of stem cells
  • _____ proteins play several roles in the development of the urogenital organs
  • ____ is necessary for kidney development and for female sex determination
A

Wnt1
Wnt proteins
Wnt proteins
Wnt4

47
Q

Wnt/Beta-catenin Pathway

__________ - targets Beta-catenin for degradation
__________ - prevents Beta-catenin from APC

A

APC (adenomatosis polyposis coli)
GSK-3 (Glycogen synthase kinase 30

48
Q

____ pathway

  • important in development and homeostasis
    > cellular proliferation, differentiation, and apoptosis
  • involved in development of sensosry hair cells and branched arterial networks
  • associated with tissue growth and cancer, and cell death and tumor suppression
  • 4 NOTCH receptors in Mammals: (4)
  • Ligands:
    > Jagged protein family (2)
    > Delta-like protein family (3)
A

Notch Signaling Pathway
- 4 NOTCH receptors in Mammals: (NOTCH1,NOTCH2…)
- Ligands:
> Jagged protein family (2): JAG1 and JAG2
> Delta-like protein family (3): DLL1, DLL3, and DLL4