Answer :
Juxtacrine signaling is a type of cell signaling that involves direct contact between the signaling cell and the target cell. In this process, the ligand and receptor are both membrane-bound, and the cells are in close proximity or physically in contact.
Among the signaling pathways listed:
Notch Signaling Pathway - This is a classic example of juxtacrine signaling. The Notch receptor on one cell interacts with a transmembrane ligand (like Delta or Jagged) on an adjacent cell. This direct cell-to-cell communication is essential for various processes, like differentiation and tissue development. The interaction of these membrane-bound proteins leads to cleavage of the Notch receptor and release of the Notch intracellular domain, which then proceeds to the nucleus to affect gene expression.
TGF-Beta Pathway - Typically involved in paracrine signaling, where the TGF-beta ligand is secreted into the extracellular space and influences neighboring cells.
Wingless (Wnt) Signaling Pathway - Generally an example of paracrine signaling, although it can have juxtacrine aspects given certain contexts where Wnt is tethered to the cell membrane.
Fibroblast Growth Factor Pathway - Primarily paracrine, where growth factors are secreted and act over a distance, though sometimes can be also linked to juxtacrine interactions when bound to the extracellular matrix.
Therefore, the correct choice for an example of juxtacrine signaling from the options given is Notch signaling pathway.
