R-spondin 2 also known as roof plate-specific spondin-2 is a secreted

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

that in humans that is encoded by the ''RSPO2''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

. R-spondin 2 synergizes with canonical WNT to activate

beta-catenin Catenin beta-1, also known as beta-catenin (β-catenin), is a protein that in humans is encoded by the ''CTNNB1'' gene. Beta-catenin is a dual function protein, involved in regulation and coordination of cell–cell adhesion and gene transcripti ...

. RSPO2 has been proposed to regulate

craniofacial Craniofacial (''cranio-'' combining form meaning head or skull + ''-facial'' combining form referring to the facial structures grossly) is an adjective referring to the parts of the head enclosing the brain and the face. The term is typically used ...

patterning and

morphogenesis Morphogenesis (from the Greek ''morphê'' shape and ''genesis'' creation, literally "the generation of form") is the biological process that causes a cell, tissue or organism to develop its shape. It is one of three fundamental aspects of devel ...

within

pharyngeal arch 1 The pharyngeal arches, also known as visceral arches'','' are structures seen in the embryonic development of vertebrates that are recognisable precursors for many structures. In fish, the arches are known as the branchial arches, or gill arc ...

through

ectoderm The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from t ...

-mesenchyme signaling via the endothelin-Dlx5/6 pathway. In dogs, a variant on the Rspo2 gene is associated moustache and eyebrow thickness. In humans,

recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

mutations in RSPO2 abrogate

limb Limb may refer to: Science and technology *Limb (anatomy), an appendage of a human or animal *Limb, a large or main branch of a tree *Limb, in astronomy, the curved edge of the apparent disk of a celestial body, e.g. lunar limb *Limb, in botany, ...

and

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

development.

Bruno Reversade Bruno Reversade (born 1978) is an American human geneticist and developmental biologist . He is a Director of the Institute of Molecular and Cellular Biology and the Genome Institute of Singapore at A*STAR (Singapore) and holds several faculty ...

and colleagues have reported in 2018 that loss of RSPO2 results in a syndrome of

Tetra-amelia Tetra-amelia syndrome (''tetra-'' + '' amelia''), also called autosomal recessive tetraamelia, is an extremely rare autosomal recessive congenital disorder characterized by the absence of all four limbs. Other areas of the body are also affected b ...

with lung

agenesis In medicine, agenesis () refers to the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue. Many forms of agenesis are referred to by individual names, depending on the organ affected: * A ...

References

{{gene-8-stub Glycoproteins Extracellular matrix proteins