Biology Reference
In-Depth Information
21
Neuroepithelial Differentiation Induced
by ECM Molecules
José María Frade and Alfredo Rodriguez Tébar
1. Introduction
Many important processes in the development of the vertebrate central ner-
vous system (CNS) rely on signals induced by extracellular matrix (ECM) com-
ponents
(1
,
2)
. These molecules are known to contain multiple functional
domains that deliver distinct signals to the cells with which they interact. We
will focus here on a well-known ECM glycoprotein, laminin-1, which plays a
variety of roles in the development of the CNS
(2)
.
Laminins are a family of ECM glycoproteins, one of which, laminin-1, was
first isolated from the murine Engelbreth-Holm-Swarm sarcoma
(3)
. Laminin-1
has been shown to exist as a heterotrimeric cross-shaped molecule containing a
large
1 chains. Further studies showed that
other isoforms of the three chains exist, giving rise to various classes of
laminins
(4)
including merosin
(5)
and Schwannoma laminin
(6)
.
One of the biological activities of laminin-1 during the development of the
CNS is the induction of neuroblast differentiation (pipetthe exit from the cell
cycle and the acquisition of neuronal markers). This activity can be tested in
vitro, such an assay being a useful tool to dissect out the inductive forces
provided by any extracellular factor. In our case, a bioassay analyzing
neurogenesis induced by ECM molecules should mimic the in vivo conditions
in which neurons are generated. Therefore, such a bioassay for neuron differ-
entiation would require i) a source of CNS proliferating precursor cells; ii) the
presence of soluble factors necessary for neuronal differentiation, and iii) an
appropriate ECM substrate which will be the object of this communication.
The chick retina is a region of the CNS that has been extensively studied and
possesses multiple advantages as a model system. Its morphology is quite
α
1 chain and two smaller
β
1 and
γ
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