Matrix metallopeptidase 27 also known as MMP-27 is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

which in humans is encoded by the ''MMP27''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

Structure

MMP-27 was discovered and cloned in 1998 by Yang and Kurkinen. Initially compared to the so-called Chicken MMP (CMMP), MMP-27 actually shows very little sequence homology with this protease. Sequence homology predicts that the human MMP-27 gene encodes the canonical domains shared by most MMPs (annotation based on Uniprot entry Q9H306): (i) a

signal peptide A signal peptide (sometimes referred to as signal sequence, targeting signal, localization signal, localization sequence, transit peptide, leader sequence or leader peptide) is a short peptide (usually 16–30 amino acids long) present at the ...

(residues 1-17), (ii) a

propeptide A protein precursor, also called a pro-protein or pro-peptide, is an inactive protein (or peptide) that can be turned into an active form by post-translational modification, such as breaking off a piece of the molecule or adding on another molecule ...

(18-98) containing the cysteine switch motif (89-96), (iii) a

catalytic domain In biology and biochemistry, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of amino acid residues that form temporary bonds with the substrate, the ''binding si ...

(99-263) containing the typical HEXXHXXGXXH motif of the metzincins (M10 and M12 families of the MEROPS database), (iv) a proline-rich hinge region (264-278) and (v) a hemopexin-like domain (279-465) folded as a four-bladed β-propeller through disulfide bond formation between the two flanking Cys residues (Cys279 and Cys465). MMP-27 could be classified in the stromelysin group of MMPs, since MMP-27 shows 51,6% homology with stromelysin-2 (MMP-10) and localizes in the cluster of MMPs located on chromosome 11. Like the six known MT-MMPs, human MMP-27 is prolonged by an additional C-terminal domain (466-513). The Spoctopus algorithm for topological prediction suggests that this C-terminal extension (CTE) includes a potential

transmembrane domain A transmembrane domain (TMD, TM domain) is a membrane-spanning protein domain. TMDs may consist of one or several alpha-helices or a transmembrane beta barrel. Because the interior of the lipid bilayer is hydrophobic, the amino acid residues in ...

(490-510). However, this sequence is less hydrophobic than in transmembrane MT-MMPs (MMP-14, -15, -16 and -24) as it contains hydrophilic/charged residues, in particular His492, Lys493, His504 and Lys507.

Function

Proteins of the

matrix metalloproteinase Matrix metalloproteinases (MMPs), also known as matrix metallopeptidases or matrixins, are metalloproteinases that are calcium-dependent zinc-containing endopeptidases; other family members are adamalysins, serralysins, and astacins. The MMPs be ...

(MMP) family are involved in the breakdown of

extracellular matrix In biology, the extracellular matrix (ECM), also called intercellular matrix (ICM), is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and bio ...

in normal physiological processes, such as embryonic development, reproduction, and tissue remodeling, as well as in disease processes, such as

arthritis Arthritis is a general medical term used to describe a disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, Joint effusion, swelling, and decreased range of motion of ...

and

metastasis Metastasis is a pathogenic agent's spreading from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, ...

. Most MMPs are secreted as inactive proproteins which are activated when cleaved by extracellular

proteinase A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do ...

s. Cominelli A. and colleagues demonstrated that MMP-27 is an unusual protease which is not secreted and is efficiently retained in the

endoplasmic reticulum The endoplasmic reticulum (ER) is a part of a transportation system of the eukaryote, eukaryotic cell, and has many other important functions such as protein folding. The word endoplasmic means "within the cytoplasm", and reticulum is Latin for ...

in three mammalian

cell lines An immortalised cell line is a population of cells from a multicellular organism that would normally not proliferate indefinitely but, due to mutation, have evaded normal cellular senescence and instead can keep undergoing division. The cells ...

. Deletion mutants and swapping with recombinant MMP-10 demonstrate that the unique MMP-27 C-terminal extension (CTE) is necessary and sufficient for endoplasmic reticulum retention but does not provide a stable membrane anchorage. Despite sequence homology with MT-MMPs, the CTE is not a transmembrane domain and does not interact permanently with membrane. This unique feature for an MMP raises important questions about potential functions of MMP-27, which remains to be investigated.

Clinical significance

Sparse information about MMP-27 expression was found in studies of gene expression profiling ( micro-array) or in expression pattern analysis of MMP family members during developmental, physiological or pathological processes. MMP-27 transcript is detected in almost every tissue, except the brain, with the highest expression found in the liver during mouse development In the adult, MMP-27 mRNA is mostly abundant in anti-IgG/IgM stimulated B lymphocytes, bone and kidney but is present at lower levels in the heart. A recent investigation of the transcriptome from distinct tissue compartments of the menstrual

endometrium The endometrium is the inner epithelium, epithelial layer, along with its mucous membrane, of the mammalian uterus. It has a basal layer and a functional layer: the basal layer contains stem cells which regenerate the functional layer. The funct ...

disclosed specific MMP-27 overexpression in areas of stromal breakdown. In another transcriptomic study, MMP-27 was found to be increased in the human endometrium at the end of the secretory phase, before menstruation. Moreover, MMP-27 expression is down-regulated in macrophages when co-cultured with ovarian cancer cells but up-regulated in cartilages from patients with osteoarthritis or in abdominal aortic aneurysms. MMP-27 was also identified, at the protein level, in

MDA-MB-231 Scientists study the behaviour of isolated cells grown in the laboratory for insights into how cells function in the body in health and disease. Experiments using cell culture are used for developing new diagnostic tests and new treatments for dise ...

breast cancer cell line and in primary human breast cancer. Recently, MMP-27 has been demonstrated to be expressed by CD163⁺/CD206⁺ macrophages in the human endometrium and in superficial endometriotic lesions.

References

External links

* The

MEROPS MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibito ...

online database for peptidases and their inhibitors
M10.027
{{Metalloendopeptidases Matrix metalloproteinases