Nidogen

Nidogens, formerly known as entactins, are a family of sulfated monomeric glycoproteins located in the basal lamina^[1] of parahoxozoans.^[2] Two nidogens have been identified in humans: nidogen-1 (NID1) and nidogen-2 (NID2).^[3] Remarkably, vertebrates are still capable of stabilizing basement membrane in the absence of either identified nidogen.^[4] In contrast, those lacking both nidogen-1 and nidogen-2 typically die prematurely during embryonic development as a result of defects existing in the heart and lungs.^[5] Nidogen have been shown to play a crucial role during organogenesis in late embryonic development, particularly in cardiac and lung development.^[6] Insufficient levels of nidogen in mice causes poorly developed organs such as the lungs and heart, which ultimately ensues to an early death.^[7] Due to nidogen being necessary in the formation of basement membranes, serving as a linker protein, and those basement proteins being shown to be necessary during tissue growth, nidogen is crucial for embryonic development.^[8] From an evolutionary perspective, nidogens are highly conserved across vertebrates and invertebrates, retaining their ability to bind laminin.^[9]

In nematodes, nidogen-1 is necessary for axon guidance, but not for basement membrane assembly.^[10]