Keratin 19

Template:Cs1 config Template:Short description Template:Infobox gene Keratin, type I cytoskeletal 19 (Keratin-19)) also known as cytokeratin-19 (CK-19) is a 40 kDa protein that in humans is encoded by the KRT19 gene.<ref name="pmid16831889">Template:Cite journal</ref><ref name="entrez">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Keratin-19 is a type I keratin.

FunctionEdit

Keratin-19 is a member of the keratin family. The keratins are intermediate filament proteins responsible for the structural integrity of epithelial cells and are subdivided into cytokeratins and hair keratins.

Keratin-19 is a type I keratin. The type I cytokeratins consist of acidic proteins which are arranged in pairs of heterotypic keratin chains. Unlike its related family members, this smallest known acidic cytokeratin is not paired with a basic cytokeratin in epithelial cells. It is specifically found in the embryonic periderm, the transiently superficial layer that envelops the developing epidermis. The type I cytokeratins are clustered in a region of chromosome 17 (q12-q21).<ref name="entrez" />

Use as biomarkerEdit

CYFRA 21-1, a soluble fragment of KRT19, is a tumor marker of various types of cancer, including lung, breast, stomach, pancreas, ovary. KRT19 is commonly expressed in carcinomas of these organs and CYFRA 21-1 is produced when KRT19 is cleaved during cell apoptosis.<ref name="Asami">Template:Cite journal</ref><ref>Template:Cite journal</ref>

Due to its high sensitivity, KRT19 is the most used marker for the RT-PCR-mediated detection of tumor cells disseminated in lymph nodes, peripheral blood, and bone marrow of breast cancer patients. Depending on the assays, KRT19 has been shown to be both a specific and a non-specific marker.

False positivity in CYFRA 21-1 / KRT19 RT-PCR studies include:

illegitimate transcription (expression of small amounts of KRT19 mRNA by tissues in which it has no real physiological role)
haematological disorders (KRT19 induction in peripheral blood cells by cytokines and growth factors, which circulate at higher concentrations in inflammatory conditions and neutropenia)
the presence of pseudogenes (two KRT19 pseudogenes, KRT19a and KRT19b, have been identified, which have significant sequence homology to KRT19 mRNA. Subsequently, attempts to detect the expression of the authentic KRT19 may result in the detection of either or both of these pseudogenes)
sample contamination (introduction of contaminating epithelial cells during peripheral blood sampling for subsequent RT-PCR analysis).<ref name="Lacroix06">Template:Cite journal</ref>
trauma and stress (such as shear stress, heat shock, toxins, infection, aging and oxidative stress such as from smoking), which increase KRT19 expression and cell apoptosis<ref name="Asami"/>
weight loss and muscle wasting/apoptosis (KRT19 is expressed in muscle)<ref name="Asami"/>

Moreover, Ck-19 is widely applied as post-operative diagnostic marker of papillary thyroid carcinoma.<ref name=pmid25978681>Template:Cite journal</ref>

Keratin-19 is often used together with keratin 8 and keratin 18 to differentiate cells of epithelial origin from hematopoietic cells in tests that enumerate circulating tumor cells in blood.<ref>Template:Cite journal</ref>

InteractionsEdit

Keratin-19 has been shown to interact with Pinin.<ref name=pmid10809736>Template:Cite journal</ref>

ReferencesEdit

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Keratin 19

Contents

FunctionEdit

Use as biomarkerEdit

InteractionsEdit

ReferencesEdit

Further readingEdit