Mid 1: Lec 2

Question 1

Hh vertabrate homologues

Answer 1

desert, indian, sonic

Question 2

SHh pathway functions

Answer 2

Cell differentiation in embryonic development:

Finger/flipper/wing development, bilateral symmetry, brain, lungs, skeleton, muscle, GI tract

Question 3

Cyclopamine

Answer 3

Interrupts SHh pathway and results in cyclops sheep when eaten during gestation

Question 4

SHh canonical path

Answer 4

SHh signalling molecule is autocleaved, binds to Patched (Ptc1) receptor, reverses inhibitory effect of Ptc1 on Smoothened (Smo), activation of GLI TFs, gene expression (including Gli1 and Ptch1)

Question 5

Uncontrolled activation of SHh

Answer 5

Cancer

Question 6

Non-canonical Hh pathways: defining traits and types

Answer 6

-Non embryonic
-Gli independent:
Smo independent and
Smo dependent

-Type I: Hh prevents apoptosis
-Type II: Hh involved in cytoskeletal rearrangement

Question 7

Hh ligand biogenesis and forms
-what type of cells is it synthed in

Answer 7

-synthesized in stem cells of zone of polarizing activity (mesenchymal) and autocleaved into HH-N

Types:
-HH-N modified w/ cholesterol (By SCUBA)
-HH-N soluble multimer
-Lipoprotein w/ multiple HH-N
-Exovescicle with multiple HH-N

Question 8

Purpose of having multiple Hh forms

Answer 8

Different forms are degraded at different rates. This allows Hh to take part in autocrine, paracrine, and endocrine signalling