2015 Group 3 Project

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Elastin

--Mark Hill (talk) 10:51, 16 April 2015 (EST) Only a single picture and a list of sub-headings. Please update this project page before the next practical class.

Introduction

Elastin is a structural protein of elastic fibres present within the extracellular matrix of connective tissues providing strength and rigidity to stabilise the structure of cells. It provides resilience and the elastic properties of tissues and organs to repetitively deform and reform to its original shape without compromising structural integrity of cells. [1] The study of elastin was significantly hindered due to it’s insolubility. However with the discovery of tropoelastin, the soluble precursor of elastin, scientists were able to describe chemical properties of elastin. The impairment or loss of elastic tissues result in profound pathological implications.


Cross section of arteries with elastin (Left) and with elastin removed (Right)

History

Structure

The organisation of elastic fibres varies in different tissues. In the lungs skin and ligaments, elastic fibres are organised in a rope-like manner, in blood vessels it is organised as thin concentric sheets and has a large honeycomb structure in elastic cartilage. [1] Under a light microscope, elastin is typically recognised by its wavy appearance.


Elastic fibres are composed of two significant components; an amorphous core of highly cross-linked elastin protein that makes up 90% of elastic fibres and a fibrillar mantle of micro fibrils in the remaining 10%.Elastin is a very insoluble complex structure, being one of the most insoluble proteins of the human body. [2][1] Desmosines are a unique feature of elastin and is responsible for the it’s hydrophobic properties due to desmosines, unique feature of extensive cross-linking of fourlysine residues. [1] Tropoelastin and elastin are made significantly of only four hydrophobic amino acids: glycine, alanine, valine and proline. An important feature of composition of pure elastin is the absence of methionine, histidine and tryptophan. The microfibril region is composed of many distinct proteins.[1] It contains two types of acidic glycoprotein fibrillins organised in 8-16nm beaded fibrils with associated glycoproteins MAGP-1 and MAGP-2. Lysyl oxidase, the enzyme that initiates cross-linking within elastin and elastin binding proteins (EBP) are both found within the elastic fibre. Other microfibrillar-associated proteins include proteoglycans, osteopontin, emilin and fibulin-1.[2] [1]

Assembly

Role of MFAP-4 in Elastic fiber assembly

Function

Article 1 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2593497/

Elastin is commonly found in the arteries due to the high pressure of blood coming from the heart, and its function to supply oxygenated blood to all organs, its elasticity is important due to enormous pressure it needs to withstand. Pulmonary arterial hypertension (PAH) causes stiffness in these arteries affecting the ability for these arteries to stretch and maintain a relatively constant pressure with high blood flow. This article looks at the structure and function of this relationship in PAH and the mechanobiological adaptations that are undergone by elastic arteries in response to PAH.


Article 2 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2799629/pdf/403_2009_Article_989.pdf

elastin is important in adults for restoring backing the normal tissue architecture example pinching of skin. According to this research, extracellurar components such as elastin are important in the scarless healing process that takes places in on early fetal gestation. The role that elastin or another name, tropo(elastin) is investigated. Elastin is not found in fetal skin up till week 22. Although it is not a primary Extracelluar component for scarless healing in fetal wounds, it is still plays a role in skin regeneration. A comparison between fetal skin and adult skin is looked at.

Article 3 http://atvb.ahajournals.org/content/31/12/2889.full

Arteries within the human consists of three layers and are most evident closest to the heart due to the properties that make them withhold the enormous pressure the heart pumps. The walls of the arteries exist in three layers where the outermost layer, called the tunica adventitia providing tensile strength, the hypothesis this research grouped investigated was whether the elastin fibres are subject to longitudinal stretch.

Clinical Significance

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 <pubmed>9851686</pubmed>
  2. 2.0 2.1 <pubmed>12082143</pubmed>

In silico analysis suggests interaction between Ebola virus and the extracellular matrix. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4333865/ <pubmed>PMC4333865</pubmed>

Matrix metalloproteinases in destructive lung disease. http://www.sciencedirect.com/science/article/pii/S0945053X15000396

Thrombosis, like other cardiovascular diseases, has a strong genetic component, with largely unknown determinants. EMILIN2, Elastin Microfibril Interface Located Protein2, was identified as a candidate gene for thrombosis in mouse and human quantitative trait loci studies. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4319747/ <pubmed>PMC4319747</pubmed>

Vitamin a deficiency and alterations in the extracellular matrix. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4245576/ <pubmed>PMC4245576</pubmed>