B1. In the developing cerebellum, Sonlo Hedgehog (Shh) is the mltogen for neural
ID: 268615 • Letter: B
Question
B1. In the developing cerebellum, Sonlo Hedgehog (Shh) is the mltogen for neural precursor cells. Shh binds to Its receptor PATCHED at the surface of neural preaursor celis to activate the Hedgehog pethway, Which mutations In Hedgehog pathway loads to childhood brain tumor medulloblastoma? a) Loss-of-function mutations in Patched c) d) Galn-of-function mutations in Patched Loss-of-function mutations in Gli transcription regulator B2. If you are designing a pathway specfic inhibitor to cure medulloblastoma, what signaling transducers in the Hedgehog pathway should you target? a) PATCHED b) SMOOTHENED c) SUFU d) Sonic Hedgehog (Shh) B3. In breast cancer, the proto-oncogene receptor Her2 (a receptor tyrosine kinase) undergoes a Val Gin mutation in its transmembrane domain that results in the conversion of Her2 into an oncogene. This results in: a) Evasion of apoptosis b) Sustained Angiogenesis c) Tissue invasion and metastasis d) Self-sufficiency in growth signals B4. The mutated Her2 activates the PI3 Kinase-Akt signaling pathway. This results in: a) Evasion of apoptosis b) Sustained Angiogenesis c) Tissue invasion and metastasis d) Self-sufficiency in growth signals B5. Mutated Her2 overexpression is associated with high VEGE (Vascular Endothelial Growth Factor) levels in human breast cancer cells. This results in: a) Evasion of apoptosis b) Sustained Angiogenesis c) Tissue invasion and metastasis d) Self-sufficiency in growth signalsExplanation / Answer
PATCHED is a tumor suppresor gene. PATCHED gene regulates another protein called SMOOTHENED. If Sonic Hedgehog binds to PATCHED, SMOOTHENED will be released and this will increase cell proliferation.
Thus
B1. a loss of function mutation in PATCHED will drive meduoblastomas.
B2. SMOOTHENED
as mutation of smoothened can results in inhibition of cell proliferationd and inhibition of Shh pathway. Thus if we block the SMOOTHENED, the downstream signalling cascade will also be blocked.
B3. Evasion of apoptosis.
B4. Tissue invasion and metastasis
B5. sustained angiogenesis
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