The absence of nidogen 1 does not affect murine basement membrane formation

Nidogen 1 is a highly conserved protein in mammals, Drosophila melanogaster , Caenorhabditis elegans, and ascidians and is found in all basement membra nes. It has been proposed that nidogen 1 connects the laminin and collagen IV networks, so stabilizing the basement membrane, and integrates other pro teins, including perlecan, into the basement membrane. To define the role o f nidogen 1 in basement membranes in vivo, we produced a null mutation of t he NID-1 gene in embryonic stem cells and used these to derive mouse lines. Homozygous animals produce neither nidogen 1 mRNA nor protein. Surprisingl y, they show no overt abnormalities and are fertile, their basement membran e structures appearing normal. Nidogen 2 staining is increased in certain b asement membranes, where it is normally only found in scant amounts. This o ccurs by either redistribution from other extracellular matrices or unmaski ng of nidogen 2 epitopes, as its production does not appear to be upregulat ed, The results show that nidogen 1 is not required for basement membrane f ormation or maintenance.