Secreted frizzled-related protein 4 is a

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 is encoded by the ''SFRP4''

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 ...

Function

Secreted

frizzled Frizzled is a family of atypical G protein-coupled receptors that serve as receptors in the Wnt signaling pathway and other signaling pathways. When activated, Frizzled leads to activation of Dishevelled in the cytosol. Species distribution Fr ...

-related protein 4 (SFRP4) is a member of the SFRP family that contains a

cysteine Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, sometime ...

-rich domain homologous to the putative Wnt-binding site of Frizzled proteins. SFRPs act as soluble modulators of

Wnt signaling The Wnt signaling pathways are a group of signal transduction pathways which begin with proteins that pass signals into a cell through cell surface receptors. The name Wnt is a portmanteau created from the names Wingless and Int-1. Wnt signaling ...

. The expression of SFRP4 in ventricular

myocardium Cardiac muscle (also called heart muscle, myocardium, cardiomyocytes and cardiac myocytes) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that ...

correlates with

apoptosis Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes incl ...

related gene expression. Biallelic, recessive variants in the ''SFRP4'' gene result in the genetic disorder of bone, Pyle disease, that is characterized by a failure of long bone remodeling with increased fragility. The association between SFRP4 deficiency and Pyle disease has highlighted the importance of SFRP4 in the formation of the bone cortex, and of the importance of bone cortex for the mechanical stability of long bone elements. SFRP4 is a hub gene in a

Type 2 Diabetes Type 2 diabetes, formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent urination, ...

-associated gene coexpression module in human

islets An islet is a very small, often unnamed island. Most definitions are not precise, but some suggest that an islet has little or no vegetation and cannot support human habitation. It may be made of rock, sand and/or hard coral; may be permanent ...

, and reduces glucose-induced insulin secretion through decreased β-cell

exocytosis Exocytosis () is a form of active transport and bulk transport in which a cell transports molecules (e.g., neurotransmitters and proteins) out of the cell ('' exo-'' + ''cytosis''). As an active transport mechanism, exocytosis requires the use o ...

. Expression and release of SFRP4 from islets is enhanced by interleukin-1β. SFRP4 is elevated in serum several years before clinical diagnosis of Type 2 Diabetes. Individuals who have above-average levels of SFRP4 in the blood are five times more likely to develop diabetes in the next few years than those with below-average levels. SFRP4 concentration seems to correlate with obesity and systemic insulin resistance Hörbelt T., Knebel B., Fahlbusch P., Barbosa D., de Wiza D.H., Van de Velde F., Van Nieuwenhove Y., Lapauw B., Thoresen G.H., Al-Hasani H. The adipokine sFRP4 induces insulin resistance and lipogenesis in the liver. Biochim. Biophys. Acta. Mol. Basis Dis. 2019;1865:2671–2684. doi: 10.1016/j.bbadis.2019.07.008

Function

References

Further reading