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<title>Microfibril</title>

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Microfibril</span></span>

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<div id="mw-content-text" class="mw-body-content mw-content-ltr" lang="en" dir="ltr"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><p>A <b>microfibril</b> is a very fine <a href="Fibril" title="Fibril">fibril</a>, or fiber-like strand, consisting of <a href="Glycoproteins" class="mw-redirect" title="Glycoproteins">glycoproteins</a> and <a href="Cellulose" title="Cellulose">cellulose</a>. It is usually, but not always, used as a general term in describing the structure of protein fiber, e.g. <a href="Hair" title="Hair">hair</a> and <a href="Spermatozoon" title="Spermatozoon">sperm</a> tail. Its most frequently observed structural pattern is the 9+2 pattern in which two central protofibrils are surrounded by nine other pairs. Cellulose inside plants is one of the examples of non-protein compounds that are using this term with the same purpose. Cellulose microfibrils are laid down in the inner surface of the primary <a href="Cell_wall" title="Cell wall">cell wall</a>. As the cell absorbs water, its volume increases and the existing microfibrils separate and new ones are formed to help increase cell strength.

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<div class="mw-heading mw-heading2"><h2 id="Synthesis_and_function">Synthesis and function</h2></div>

<p>Cellulose is synthesized by <a href="Cellulose_synthase" class="mw-redirect" title="Cellulose synthase">cellulose synthase</a> or Rosette terminal complexes which reside on a cells membrane. As cellulose fibrils are synthesized and grow extracellularly they push up against neighboring cells. Since the neighboring cell can not move easily the Rosette complex is instead pushed around the cell through the fluid phospholipid membrane. Eventually this results in the cell becoming wrapped in a microfibril layer. This layer becomes the cell wall. The organization of microfibrils forming the primary cell wall is rather disorganized. However, another mechanism is used in secondary cell walls leading to its organization. Essentially, lanes on the secondary cell wall are built with microtubules. These lanes force microfibrils to remain in a certain area while they wrap. During this process microtubules can spontaneously depolymerize and repolymerize in a different orientation. This leads to a different direction in which the cell continues getting wrapped.

</p><p><a href="Fibrillin" title="Fibrillin">Fibrillin</a> microfibrils are found in <a href="Connective_tissue" title="Connective tissue">connective tissues</a>, which mainly makes up <a href="Fibrillin_1" class="mw-redirect" title="Fibrillin 1">fibrillin-1</a><sup id="cite_ref-:0_1-0" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> and provides elasticity. During the assembly, mirofibrils exhibit a repeating stringed-beads arrangement produced by the cross-linking of molecules forming a striated pattern with a given periodicity when viewed stained under an electron microscope. In the formation of <a href="Elastic_fiber" title="Elastic fiber">elastic fiber</a>, fibrillin microfibrils guides the deposit of <a href="Tropoelastin" class="mw-redirect" title="Tropoelastin">tropoelastin</a> and remains in the outer layer of mature elastin fibers.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The microfibril is also associated in cell communication. Formation of fibrillin microfibrils in the pericellular region affects the activity of a <a href="Growth_factor" title="Growth factor">growth factor</a> called <a href="TGF%CE%B2" class="mw-redirect" title="TGFβ">TGFβ</a>.<sup id="cite_ref-:0_1-1" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading2"><h2 id="Marfan_syndrome">Marfan syndrome</h2></div>

<p>In <a href="Marfan_syndrome" title="Marfan syndrome">Marfan syndrome</a>, a connective tissue disorder, mutations in the gene encoding for the <a href="Fibrillin_1" class="mw-redirect" title="Fibrillin 1">fibrillin-1</a> protein impact nearly every one of its domains.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Such defects in fibrillin-1 affect the signaling of <a href="TGF%CE%B2" class="mw-redirect" title="TGFβ">TGFβ</a>, as microfibrils directly govern the activity of TGFβ.<sup id="cite_ref-:0_1-2" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> This hinders the formation of the <a href="Extracellular_matrix" title="Extracellular matrix">extracellular matrix</a>, and ultimately results in a severe phenotype which involves a few organ systems, including the <a href="Central_nervous_system" title="Central nervous system">central nervous system</a>, <a href="Circulatory_system" title="Circulatory system">circulatory system</a>, <a href="Visual_system" title="Visual system">ocular system</a>, and <a href="The_skeletal_system" class="mw-redirect" title="The skeletal system">skeletal system</a>.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup>

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<ul><li><a href="Fibril" title="Fibril">Fibril</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite id="CITEREFMassam-WuChiuChoudhuryChaudhry2010" class="citation journal cs1">Massam-Wu, Teresa; Chiu, Maybo; Choudhury, Rawshan; Chaudhry, Shazia S.; Baldwin, Andrew K.; McGovern, Amanda; Baldock, Claire; Shuttleworth, C. Adrian; Kielty, Cay M. (2010). <a rel="nofollow" class="external text" href="https://jcs.biologists.org/content/joces/123/17/3006.full.pdf">"Assembly of fibrillin microfibrils governs extracellular deposition of latent TGFβ"</a> <span class="cs1-format">(PDF)</span>. <i>J Cell Sci</i>. <b>123</b> (17): <span class="nowrap">3006–</span>3018. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1242%2Fjcs.073437">10.1242/jcs.073437</a>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2923573">2923573</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/20699357">20699357</a> – via JCS.</cite></span>

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<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><cite id="CITEREFKieltyBaldockLeeRock2002" class="citation journal cs1">Kielty, Cay M.; Baldock, Claire; Lee, David; Rock, Matthew J.; Ashworth, Jane L.; Shuttleworth, C. Adrian (28 February 2002). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1692929">"Fibrillin: from microfibril assembly to biomechanical function"</a>. <i>Philos Trans R Soc Lond B Biol Sci</i>. <b>357</b> (1148): <span class="nowrap">207–</span>217. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1098%2Frstb.2001.1029">10.1098/rstb.2001.1029</a>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1692929">1692929</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/11911778">11911778</a>.</cite></span>

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<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite id="CITEREFReinhardt2014" class="citation journal cs1">Reinhardt, Dieter P. (October–November 2014). <a rel="nofollow" class="external text" href="https://doi.org/10.1097%2FIJG.0000000000000114">"Microfibril-associated Disorders: Fibrillinopathies"</a>. <i>Journal of Glaucoma</i>. <b>23</b> (8 Suppl 1): S34-5. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1097%2FIJG.0000000000000114">10.1097/IJG.0000000000000114</a></span>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1057-0829">1057-0829</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/25275902">25275902</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:31705597">31705597</a>.</cite></span>

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<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><cite id="CITEREFBonetti2009" class="citation journal cs1">Bonetti, Maria Ida (October 2009). "Microfibrils: a cornerstone of extracellular matrix and a key to understand Marfan syndrome". <i>Italian Journal of Anatomy and Embryology = Archivio Italiano di Anatomia ed Embriologia</i>. <b>114</b> (4): <span class="nowrap">201–</span>224. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1122-6714">1122-6714</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/20578676">20578676</a>.</cite></span>

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