Question

1.(a)The Wnt signal is involved in regulating the proliferation of many stem cell populations in humans. Wnt is an amino acid polymer. It binds to a cell surface receptor complex that includes the Frizzled receptor and the LRP receptor. When unbound the receptor is inactive. When the receptor is inactive a protein, beta-catenin, is bound by a cytoplasmic complex and destroyed. When the receptor is activated the recptor will bind a member of the cytoplasmic complex (Axin) and beta-catenin is not destroyed but is free in the cytoplasm. Free beta catenin will transport into the nucleus. In the nucleus the TCF protein binds to genes regulating proliferation. If beta-catenin is not in the nucleus, TCF is can not bind to beta-catenin and TCF will turn gene expression off. If beta-catenin is in the nucleus, TCF binds preferentially to beta-catenin and recruits RNA polymerase II to turn gene expression on.

Which of the following terms apply to the Wnt signal. Pick ALL that apply. there is more than one answer please

	A.	Wnt is a steroid hormone.
	B.	The readout (the effects) of Wnt signaling are physiologically fast.
	C.	Alterations in Wnt signaling can lead to cancer.
	D.	Wnt is a monoamine hormone
	E.	The readout (the effects) of
	F.	Wnt is a peptide hormone.
	G.	Wnt is involved in indirect signaling.
	H.	Wnt is involved in direct signaling.

Answer 1

The Wnt Signalling pathway is a type of Signal Transduction Pathway. The signals are transported through the cell surface receptors. Wnt signal can be divided into three branches Canonical, Planar cell polarity and Wnt/ Ca2+. The terms that apply to the Wnt signal are:

C. Alterations in Wnt signaling can lead to cancer:

Studies confirming that Canonical pathway is involoved in the formation of tumors. Wnt signal deregulation leads to other type of cancers such as Cancers of Breast, Colon, oesophageal and ovarian and Skin.

E. The readout (the effects) of Wnt Signal:

When the Wnt Signalling pathway deregulated it leads to disastrous events such as different Cancers, Skeletal defects and human birth defect disorders, namely Spina bifida( Bones don't form properly around part of the baby's spinal cord) and human neural tube closure.

G. Wnt is involved in indirect signaling:

Canonical or Wnt/β-catenin dependent pathway and the non-canonical or β-catenin-independent pathway stimulated by the extracellular signals that triggers several intracellular signals. This pathway regulates several of Cellular processes such as Stem cell renewal, Organogenesis and Cell fate etc.