Increased expression of laminin-1 and collagen (IV) subunits in the aganglionic bowel of ls/ls, but not c-ret -/- mice.
Extracellular matrix molecules, including laminin, affect the development of enteric neurons and accumulate in the aganglionic colon of ls/ls mice. Quantitative Northern analysis revealed that mRNAs encoding the beta 1 and gamma 1 subunits of laminin and collagens alpha 1(IV) and alpha 2(IV) are increased in the colons of ls/ls mice. Transcripts of laminin alpha 1 were evaluated quantitatively with reverse transcription and the competitive polymerase chain reaction (RT-cPCR). The abundance of laminin alpha 1 transcripts was developmentally regulated, but greater in the ls/ls than the wild-type colon at each age examined. In situ hybridization revealed that transcripts in the colon encoding laminin alpha 1 and beta 1 and collagen alpha 2(IV) were initially expressed in the endoderm, but by E15, expression shifted to cells of the colonic mesenchyme (ls/ls > wild type) where crest-derived cells migrate. The expression of laminin alpha 1 was examined in the totally aganglionic intestine of E15 and newborn c-ret -/- mice, to determine whether an increase occurs when neurogenesis fails independently of the ls/ls defect. RT-cPCR revealed no difference from control in mRNA encoding laminin alpha 1 in the c-ret -/- colon in either E15 or newborn animals. The accumulation of immunohistochemically demonstrable laminin that is prominent in the newborn ls/ls colon could not be detected in that of c-ret -/- animals. These observations suggest that transcripts encoding laminin-1 and collagen (IV) are increased in the colon and surrounding pelvic mesenchyme of ls/ls mice because of an intrinsic lesion, rather than a secondary consequence of aganglionosis. The data are compatible with the hypothesis that the increased expression of laminin-1 contributes to the failure of crest-derived cells to complete their colonization of the ls/ls colon.
Rothman
T P
TP
Department of Anatomy and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
Chen
J
J
Howard
M J
MJ
Costantini
F
F
Schuchardt
A
A
Pachnis
V
V
Gershon
M D
MD
D000818:Animals; D003094:Collagen / Q000096:biosynthesis* / Q000235:genetics; D003106:Colon / Q000196:embryology / Q000294:innervation / Q000378:metabolism*; D003714:Denervation; D005724:Ganglia; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D007421:Intestine, Small / Q000196:embryology / Q000294:innervation / Q000378:metabolism*; D007797:Laminin / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008817:Mice, Mutant Strains; D016133:Polymerase Chain Reaction
D007797:Laminin; D003094:Collagen