Nidogens, formerly known as entactins, are a family of sulfated

monomer A monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called polymerization. Classification Chemis ...

glycoprotein Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known a ...

s located in the

basal lamina The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often incorrectly referred to as the basement membrane, though it does constitute a portion of the basement membrane. The b ...

of parahoxozoans. Two nidogens have been identified in humans: nidogen-1 (NID1) and

nidogen-2 Nidogen-2, also known as osteonidogen, is a basal lamina protein of the nidogen family. It was the second nidogen to be described after nidogen-1 (entactin). Both play key roles during late embryonic development. In humans it is encoded by the ...

(NID2). Remarkably,

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s are still capable of stabilizing

basement membrane The basement membrane, also known as base membrane, is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between epithelial tis ...

in the absence of either identified nidogen. 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. Nidogen have been shown to play a crucial role during

organogenesis Organogenesis is the phase of embryonic development that starts at the end of gastrulation and continues until birth. During organogenesis, the three germ layers formed from gastrulation (the ectoderm, endoderm, and mesoderm) form the internal org ...

in late

embryonic development In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm, sperm cell (spermat ...

, particularly in cardiac and lung development. Insufficient levels of nidogen in mice causes poorly developed organs such as the lungs and heart, which ultimately ensues to an early death. 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. From an evolutionary perspective, nidogens are highly conserved across vertebrates and invertebrates, retaining their ability to bind

laminin Laminins are a family of glycoproteins of the extracellular matrix of all animals. They are major constituents of the basement membrane, namely the basal lamina (the protein network foundation for most cells and organs). Laminins are vital to bi ...

. In

nematodes The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (he ...

, nidogen-1 is necessary for axon guidance, but not for basement membrane assembly.

References

{{reflist, 2 Human proteins Protein families Extracellular matrix proteins