5 research outputs found
Sonic hedgehog-dependent synthesis of laminin α1 controls basement membrane assembly in the myotome
Basement membranes have essential structural and signalling roles in tissue
morphogenesis during embryonic development, but the mechanisms that control
their formation are still poorly understood. Laminins are key components of
basement membranes and are thought to be essential for initiation of basement
membrane assembly. Here, we report that muscle progenitor cells populating the
myotome migrate aberrantly in the ventral somite in the absence of sonic
hedgehog (Shh) signalling, and we show that this defect is due to the failure
to form a myotomal basement membrane. We reveal that expression of
Lama1, which encodes laminin α1, a subunit of laminin-111, is
not activated in Shh-/- embryos. Recovery of
Lama1 expression or addition of exogenous laminin-111 to
Shh-/-;Gli3-/- embryos restores the
myotomal basement membrane, demonstrating that laminin-111 is necessary and
sufficient to initiate assembly of the myotomal basement membrane. This study
uncovers an essential role for Shh signalling in the control of laminin-111
synthesis and in the initiation of basement membrane assembly in the myotome.
Furthermore, our data indicate that laminin-111 function cannot be compensated
by laminin-511