Factors in branching morphogenesis
_Proliferation
§Growth
factors, factors that promote pluripotency
_Differentiation
§Transcription
factors and downstream effectors leading to different cell types
§Proximal
and distal differences (e.g cartilage, type II cells)
_Inhibition of proliferation
§Growth
eventually stops, also a key to branch points
_Apoptosis
§Structures
must be remodeled in second wave of growth.
§May
deal with local proliferation excess.
_Coordinated growth of different cell populations –
ÒcrosstalkÓ
§Elements
may be intracellular pathways, cellular receptor specificity, as well as diffusable factors with very local gradients
_Differential adhesion.
§Cell
to cell, cell to matrix.
§Adhesion
molecules may be expressed reducing cellular fluidity, fostering attachment of epithelium to mesenchyme via common
extracellular matrix proteins