- In wild type C. elegans hermaphrodites, two adjacent cells, Z1.ppp and Z4.aaa, have the potential to become the anchor cell. They interact in a manner that causes one of them to become the anchor cell, while the other one becomes the precursor of the uterine tissue. The
following statements are given to describe the interaction of the two cells:
A. The cell secreting LAG-2 becomes the anchor cell.
B. The cell secreting LIN-12 remains as the precursor of the uterine tissue.
C. The LIN-12 secreting cell takes the fate of anchor cell while the LAG-2 secreting cell takes the fate of uterine precursor cell.
D. The Hippo kinase signaling pathway brings lateral inhibition so that one cell is inhibited and the other cell is promoted to become the anchor cell.
Which one of the following options represents the combination of all correct statements?
(1) A and D (2) A and B
(3) D only (4) C only
In Caenorhabditis elegans hermaphrodites, the specification of the anchor cell (AC) and the ventral uterine precursor cell from two adjacent equipotent cells, Z1.ppp and Z4.aaa, is a pivotal developmental event. This binary cell fate decision is governed by a tightly controlled intercellular communication process, primarily mediated by Notch signaling and further refined by Hippo pathway activity.
Detailed Explanation of Cell Fate Specification
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Role of LAG-2 and LIN-12:
The two cells express different components of the Notch signaling pathway:-
The cell expressing LAG-2, a Notch ligand (Delta homolog), adopts the anchor cell fate.
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The adjacent cell, responding through the LIN-12 receptor (Notch homolog), receives the LAG-2 signal and adopts the ventral uterine precursor fate.
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Nature of the Interaction:
Notch-Delta signaling induces lateral inhibition, whereby reciprocal signaling between the two cells causes them to adopt exclusive fates. This prevents both cells from becoming anchor cells or uterine precursors simultaneously. The LAG-2 secreting cell effectively inhibits the other cell from choosing the same fate. -
Hippo Signaling Pathway:
Recent research highlights the contribution of the Hippo kinase pathway in reinforcing this lateral inhibition. It acts as a regulatory safeguard, promoting the stabilization of one cell’s identity as the anchor cell while inhibiting the other from adopting that fate. This enhances the robustness and irreversibility of the binary cell fate decision. -
Correction of Misconceptions:
The statement that the LIN-12 secreting cell becomes the anchor cell (Statement C) is incorrect, as LIN-12 functions as a receptor, not a ligand, and its activation directs the cell away from anchor cell fate.
Correct Combination of Statements
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A. The cell secreting LAG-2 becomes the anchor cell. — Correct.
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B. The cell secreting LIN-12 remains as the uterine precursor. — Correct.
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D. The Hippo kinase signaling pathway mediates lateral inhibition to promote one cell as anchor cell and inhibit the other. — Correct.
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C is incorrect.
Hence, the combination representing all correct statements is:
(1) A and D
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