Role of the ubiquitin-like modifier FAT10 in protein degradation and ...
Role of the ubiquitin-like modifier FAT10 in protein degradation and ...
Role of the ubiquitin-like modifier FAT10 in protein degradation and ...
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Chapter 3<br />
Figure 25: HDAC6-deficient cells have defects <strong>in</strong> aggresome formation. (A) Verification<br />
<strong>of</strong> HDAC6 knock-out by Western blot. (B) Quantification <strong>of</strong> <strong>the</strong> percentage <strong>of</strong><br />
cells with <strong>ubiquit<strong>in</strong></strong> conta<strong>in</strong><strong>in</strong>g aggresomes, n ≥ 100. (C) Quantitative evaluation <strong>of</strong><br />
<strong>the</strong> size <strong>of</strong> <strong>ubiquit<strong>in</strong></strong> conta<strong>in</strong><strong>in</strong>g aggresomes, n ≥ 50. (D) Quantitative evaluation <strong>of</strong><br />
<strong>the</strong> size <strong>of</strong> <strong>FAT10</strong> conta<strong>in</strong><strong>in</strong>g aggresomes, n ≥ 10. Error bars represent <strong>the</strong> st<strong>and</strong>ard<br />
error <strong>of</strong> <strong>the</strong> mean (s.e.m.), statistical analysis was carried out us<strong>in</strong>g Student's t test.<br />
doma<strong>in</strong>s localized to aggresomes under proteasome <strong>in</strong>hibition (Fig. 26B). We can<br />
<strong>the</strong>refore conclude that each <strong>ubiquit<strong>in</strong></strong>-<strong>like</strong> doma<strong>in</strong> <strong>of</strong> <strong>FAT10</strong> is sufficient to <strong>in</strong>ter-<br />
act with HDAC6 <strong>and</strong> mediate localization to <strong>the</strong> aggresome.<br />
Discussion<br />
<strong>FAT10</strong> is unique among <strong>the</strong> family <strong>of</strong> <strong>ubiquit<strong>in</strong></strong>-<strong>like</strong> prote<strong>in</strong>s as it is <strong>the</strong> only<br />
member – aside from <strong>ubiquit<strong>in</strong></strong> – which can lead conjugated prote<strong>in</strong>s directly to<br />
proteasomal <strong>degradation</strong>. Here we report <strong>the</strong> discovery <strong>of</strong> a third non-covalent<br />
<strong>in</strong>teraction partner <strong>of</strong> <strong>FAT10</strong>, <strong>the</strong> cytosolic deacetylase HDAC6. HDAC6 has a<br />
b<strong>in</strong>d<strong>in</strong>g doma<strong>in</strong> for <strong>ubiquit<strong>in</strong></strong>-<strong>like</strong> prote<strong>in</strong>s <strong>in</strong> its C-term<strong>in</strong>us which belongs to <strong>the</strong><br />
family <strong>of</strong> ‘<strong>ubiquit<strong>in</strong></strong> carboxyl-term<strong>in</strong>al hydrolase-<strong>like</strong> z<strong>in</strong>c f<strong>in</strong>ger’ (Znf-UBP) do-<br />
95