specifying cell fate

cell fate

what a cell will eventually become

stem cells

cells with the functional potential (potency) to give rise to an array of cell types

totipotency

can differentiate into any cell type

pluripotency

can differentiate into cells from any of the 3 germ layers, but not external cell types like placenta

multipotency

can develop into a limited number of cell types in a particular lineage

commitment

the process through which cells are told what to become (their fate)

name the 3 stages of commitment

1. specification - labile; only stays that cell fate in a neutral environment

2. determination - stable, stays that cell fate even in non-neutral environment

3. differentiation - different phenotypes + overt changes

specification

cells have a limitation on what cell fates they can become, but this is labile (can be easily changed due to different factors)

• commitment is reversible

determination

limitation on cell fate is stable. cells become their specialized cell fate in a non-neutral environment.

• commitment is irreversible

differentiation

process through which an unspecialized cell becomes specialized. overt changes in cell phenotype

neutral vs. labile

neutral - contains no other factors

labile - can be easily changed

fate map

diagram “mapping” larval or adult cell fate on the region of an embryo from which it arose

what are critical factors in the commitment process?

1. changes in factors in cells

2. cell-cell communication which commonly result in changes

what are the two modes of induction

1. instructive interaction - responder cell hasn’t started process, need signal from inducer

2. permissive interaction- responding cell already has been specified, but the induction signal provides an environment that allows the rest of commitment to happen

induction

process by which one cell influence the development of a neighbor through local cell-interaction

conditional vs. autonomous specification

conditional: based on interactions with other cells

autonomous: only based on factors within the cell

what are the three types of specification (cell starting to reach its fate)?

1. autonomous - cells are specified because of signal within them

2. conditional - due to neighboring cells

3. syncytial - mix of both

syncytial specification

a combo of factors in the cell and interactions with neighbor cells

morphogen

“form giver” a specific type of factor that determines cell fate; must be diffusible, present in a gradient, the concentration of the morphogen determines that response of the cell

describe the three types of cell interactions

direct signaling - connected through specific protein/connection

paracrine signaling - not physically connected, travel short distances

endocrine signaling - travel over long distances

name the key features of the Turing mechanism