Last minute must knows

Which TFs can FGF activate?

• Mapk/ERK - FOS - ETS - cell proliferation

• Akt - FOXO - cell survival

• Calcineurin - NFAT - cell motility

Which signals define paraxial mesoderm?

Tbx6 and brachyury

Which signals define a chondrocyte?

sox5, 6, 9 and Runx2

Which signal mediates condensation of mesenchymal cells in chondrogenesis? Which signal then defines chondro vs osteo fates?

sox9

no wnt vs wnt

Which signals define an osteocyte?

Rnx2, osterix

What induces Tbx20 and what does it induce?

notch

nppa - chamber program

Positive feedback loop with Hh

Gli1 which can’t be proteolysed

What do different BMP family members and Shh levels induce the expression of in the neural tube?

pax6 is most dorsally expressed, pax7 then nikx6.1 is most ventral

How many somites do humans, chicks, mice and zebrafish have?

The human embryo has 38-45 somites, while the chick has 55 , the mouse 65, and the zebrafish 33

How many vertebrae do humans have when born vs by adulthood?

33 vs 24 and 9 fused ones

How is the determination front maintained?

strict boundaries maintained by:

FGF inhibits raldh2 used in ra synthesis

FGF = cyp26 = degradation of RA

erk involved in border between fgf and ra (fgf = erk, ra blocks erk)

What is a boundary cell in somitogenesis?

Boundary cells in somitogenesis are a specific cohort of cells at the border of the presomitic mesoderm (PSM) that undergo a mesenchymal-to-epithelial transition (MET). They form a stable, cohesive epithelial ring that physically separates and demarcates individual somites, the embryonic blocks that later develop into vertebrae and ribs.

What signals expand muscle masses dorsally and ventrally?

meox2, pax3, six1/4

What is required for c-met expression? what binds this receptor allowing migration of MPCs?

pax3

HGF/SF (hepatocyte growth factor/scatter factor)

Which delta/notch are expressed in anterior vs posterior somite?

anterior: delta3 and notch2 → mesp2

posterior: notch1 delta 1

Genes like Goosecoid (Gsc) are only transcriptionally activated in the presence of which ligand?

via BOTH a Nodal downstream effector (Smad2/4) and a Wnt/beta catenin downstream effector (TCF)

State a technique for lineage tracing

lacz enhancer with enhancer of interest + x gal = blue substrate

TGF-beta-like family activates what?

tgf-beta and nodal - smad2/3 + co-smad4

BMP-like family activates what?

smad1/5/8 and co-smad4

non-canonical smad signalling

p38, JNK, Ras-Erk, PI3K-Akt, GTPases

What does SH2 domain of EC proteins binding RTKs recognise on the RTK? What does the SH3 domain allow?

phosphotyrosine within short phosphopeptide - phosphotyrosine, glutamic acid x 2 and isoleucine

allows protein-protein interactions

BMP antagonists

noggin, chordin, follistatin

How does follistatin work?

binds BMP and inhibits activation of receptor

What are 3 ways of managing Smoothened signalling?

relocation, accumulation, phosphorylation

How does chordin work?

EC trap for BMP inhibiting binding

Explain the Warburg effect

metabolic alteration where cancer cells consume vast amounts of glucose and convert it into lactate, even when oxygen is abundant ie aerobic glycolysis, it fuels rapid tumour growth + provides for cell division

How does noggin work?

EC molecular trap, sequestering and blocking interaction with receptor

Wnt antagonists

dickkopf, cerberus

Which transcription factor is the target of wnt/beta catenin?

T-cell factor ie TCF

What is characteristic of Pax3/7 genes? What do Pax1/9 share with these gene?

homeodomain specifies pax3/7

both contain the n terminal paired domain that binds dna and the octapeptide that binds co-repressors

Which is the only dimerised RTK?

insulin receptor

What defines ureteric bud epithelium?

FGF9 and RA

What defines lateral hypaxial muscles vs medial epaxial muscles?

Wnt and low Shh // Wnt7a and BMP (which inhibits Shh)

What defines metanephric mesenchyme?

wnt

Which signals define dermomyotome vs sclerotome?

wnt from surface ectoderm and dorsal neural tube = Pax3/7 vs Shh from floor plate and notochord = Pax1/9

What does lateral plate mesoderm give rise to?

circulatory system, extra-embryonic structures, pelvis and limb bones

Gap gene example

knirps

Pair rule gene example

paired

Segment polarity gene

gooseberry

Which pathway requires dual phosphorylation and why?

Raf/Mek/Mapk as a safety mechanism to avoid constitutive activity and cancers

Which signals are involved in kidney formation?

Pax2,8 , Lim1, FGF9, RA, Wnt, GDNF, Wnt11, Six2, Notch

Describe the pathway through which En could activate omb, sal

En → Hh → Dpp → Tkv/Pnt → mad → omb/sal

What makes up the Wnt/Wg destruction complex?

APC, Axin, CK1, GSK3, Dsh, Slimb all bind frizzled

What makes up the Hh destruction complex?

Cos2 scaffold protein + fused kinase + CKI + PKA + GSK3 kinases + Slimb

Which modifications does Wnt undergo, making it hydrophobic and membrane tethered?

lipid modificcations - palmitate + palmitolate (palmitoleoylation) makes it hydrophobic and allows it to bind its chaperone protein wntless, bringing it from ER to PM for release

Which modifications does Hh undergo, making it hydrophobic and membrane tethered?

lipid modifications - palmitate and cholesterol added following autoproteolytic cleavage, allows to bind to Scube and Dispatched

Non canonical wnt

planar cell polarity / convergent extension

What is planar cell polarity?

collective alignment of cellular structures along an axis perpendicular to the apical-basal axis eg uniform orientation of hairs on drosophila wing or stereocilia in vertebrate ear

Non canonical Hh

aerobic glycolysis = higher levels of lactate and lower of glucose = weight loss and muscle cramps

What does Ci stand for? What is its analogue in vertebrates?

Cubitus interruptus

Gli1, 2, 3 (glioma-associated oncogene)

What is Dpp analogue in vertebrates?

TGF-beta

How does patched inhibit smoothened?

depletes cholesterol in plasma membrane

What makes the segmentation clock tick ?

time lag in feedback response where Notch activation downregulates its own ligand

Function of dally like protein (dlp)

acts as a HSPG reservoir that helps hand over ligands like wnt

Aim of Heidelberg screen by Nusslein-Volhard and Wieschaus

identify all genes required for the development and patterning of the larval cuticle - saturation mutagenesis screen designed to find mutations that altered segments and structures of fly external skeleton using alkylating agents eg ENU and EMS

Define endo-reduplication

process in which DNA replication occurs without cytokinesis (cell division) = many copies of genome for high-volume transcription

Explain what a cuticle prep is

What organism does cHairy1 belong to?

chicks

What organism does Hes belong to?

mouse and humans

What organism does Her belong to ?

zebrafish

What does surface ectoderm and dorsal neural tube expression of Wnt pattern?

dermomyotome through Pax3/7 and MyoD expression

Do short or long germ band insects function in a similar manner to vertebrates ie with a segmentation clock?

short eg Tribolium beetle // long like drosophila (entire body plan patterned at once during blastoderm stage)

Transitioning from syncytial blastoderm to cellular blastoderm, what happens 3 hrs post fertilisation?

membranes form around each individual nucleus at the periphery - cellularisation involves invagination of PM to enclose each nucleus = single layer of cells

Which organism is used to represent short germ band insect machinery?

Tribolium beetle

What patterns the neural tube as dorsal?

BMP and TGF-beta from ectoderm = dorsal sensory interneurons

What is canonical BMP signalling?

smad

What techniques reveal the expression of individual genes vs all genes in a biological sample?

in situ hybridisation and reporter gene constructs

RNA-seq analysis

In what organisms are reverse genetics done?

mice

In what organisms are forward genetics done?

flies and c elegans

restricted diffusion

regulated movement of morphogens (signaling molecules) across extracellular spaces to form precise concentration gradients

Myogenin KO

die shortly after birth from diaphragm defect

Myod // Myf5 KO

viable with no defects, increased myf5 during embryogenesis compensating for myod with slight delay in limb muscle development + deficit in muscle regeneration in adult mice // viable with no defects, delay in myotome formation until the onset of myod

Pax3 KO

splotch mouse

Pax1 KO

mice are viable. Have abnormalities in the vertebral column, the sternum and the scapula

Pax9 KO

mice die shortly after birth. Have abnormal craniofacial, visceral and limb skeletogenesis.

Pax 1/9

mice completely lack derivatives of medial sclerotome: vertebral bodies, intervertebral discs, proximal ribs. Pax1 or Pax9 is required for medial sclerotome development.

2 modes of ossification

intramembranous ossification and endochondral ossification

early vs late organiser

bmp and wnt antagonists vs just bmp antagonists

AP vs DV neural plate gradients

wnt (high in P) vs bmp (high in V)