The niche employs a variety of mechanisms of cell-to-cell communication to regulate the quiescent, proliferative, and differentiative states of the resident stem cell.

TLS Online TPP Program

#Id: 10015

#Unit 4. Cell Communication and Cell Signaling

A cytosolic complex contains

kinases Fused ; PKA, GSK3β, and CK1, Ci, and SUFU

TLS Online TPP Program

#Id: 10016

#Unit 4. Cell Communication and Cell Signaling

Cytosolic complex is bound to a microtubule by the kinesin-related motor protein Costal-2 (Cos2).

TLS Online TPP Program

#Id: 10017

#Unit 4. Cell Communication and Cell Signaling

In this complex, Ci becomes phosphorylated in a series of steps catalyzed by PKA, GSK3β, and CK1.

TLS Online TPP Program

#Id: 10018

#Unit 4. Cell Communication and Cell Signaling

The phosphorylated Ci is proteolytically cleaved by the ubiquitin-proteasome pathway, generating an N-terminal fragment Ci75, which functions as a transcriptional repressor of Hh target genes.

TLS Online TPP Program

#Id: 10019

#Unit 4. Cell Communication and Cell Signaling

Hh binds to Ptc, causing Ptc to be endocytosed from the cell surface and degraded, relieving the inhibition of Smo.

TLS Online TPP Program

#Id: 10020

#Unit 4. Cell Communication and Cell Signaling

The C-terminal segment of Smo binds Cos2, and Smo is stabilized from degradation