Elastin is an essential protein in our bodies that is able to extend and recoil, allowing several of our organs to function. Though it makes up only 2% of dermal protein, it is a major component of the lungs, bladder, large blood vessels, certain ligaments and even ear cartilage. In many vertebrates, elastin is an important constituent of load-bearing tissues. Though elastin has a similar role to collagen, it is estimated to be 1000 times stretchier and is much less abundant.
Elastin is structured as a disordered network of polypeptide chains. It is made primarily of hydrophobic (water-hating) amino acids (mainly proline, glycine, alanine, leucine and valine), grouped together in small repeated sequences of 3 to 9 amino acids, creating sturdy yet flexible structures.
It is synthesised by a process known as elastogenesis, which includes several steps both within and outside of the cell. Inside the cell a coil shaped molecule of around 700 amino acids called tropoelastin is synthesised once a single gene, ELN, is translated. The resulting molecule activates a series of steps that leads to the final protein being formed. Covalent cross linkages between molecules make the protein especially strong.
Once outside of the cell, the existing structure acts as a scaffold for other molecules involved in the synthesis of elastin to be deposited. Mature elastin is insoluble, and its stabilised polymer structure allows for the unique elasticity.
So why does this protein matter?
Connective tissue made up of elastin (and other structures) allows for organs regain their shape after contraction, expansion or distortion. For example, in our lungs, elastic tissue means are diaphragms can contract, facilitating breathing. Elastin gives arteries flexibility required to withstand changing pressures and is found in large quantities in major blood vessels like the aorta. Lastly, elastin allows the skin to return to its natural position after it is stretched. You can see this in your own skin - pinch the skin on the back of your hand and see how quickly it adopts its natural position. This is because of elastin!
What is the relevance of the research surrounding this lesser-known protein?
Most of the research surrounding elastin revolves around skin elasticity and how to preserve youthful looking skin with clinically formulated cosmetics. ‘Aged’ skin is characterised by dehydration, a rougher texture, uneven pigment and wrinkles. In part, this is a result of free radical damage (very reactive species) which at increasingly high concentrations can damage proteins like elastin as well as DNA, fatty acids and carbohydrates in the dermis. Photo-aging is a process by which UV rays from the sun or artificial light sources gradually deteriorate the skin. UV radiation that can splice the elastin gene causing an inadequate synthesis of the structures needed to form elastic fibres. Furthermore, with age, the enzyme used to form elastin becomes less efficient. A process known as solar elastosis results in reduced elastin synthesis and destruction of existing elastic fibres, and the skin loses elasticity that was conferred by these protein structures, causing visible ageing.
Many simply avoid photo-ageing by using sunscreens, though a separate class of cosmetic products that can reverse this process is where the money lies for beauty companies. Scientists have turned to all types of chemicals and formulas to achieve this goal. For instance, a soybean extract formulation was linked to an ‘elasticity inducing effect’ when was used on aged skin. A yellow pigment found primarily in turmeric called curcumin has also been proved to increase the expression of tropoelatin in the dermis and dill seed extract can improve elasticity also. However, by far the most powerful substance for reducing the effects of photoaging are retinols: fat-soluble vitamins within the vitamin A family. It has been proposed that they can enhance elastin synthesis and elastin fibre formation, though primarily they work by increasing skin cell turnover. But if you really want to avoid sun damage in your skin, by far the most crucial thing you can do is wear your SPF every day.
The process
Proteins are formed on the endoplasmic reticulum. The Golgi complex stores and transports these proteins to the extracellular matrix where elastin-binding proteins associate with tropoelastin monomers to become a complex form before being released on the cell surface.
Microfibril components act as a scaffold for elastin and other molecules to be deposited
Mature elastin is formed by cross-linking of lysine and tropoelastin catalysed by the enzyme lysyl oxidase (EBP disassociates and is recycled in the cell)
Comentários