25.01.2013 Views

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 ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Abstract<br />

Chapter 3<br />

Dur<strong>in</strong>g misfolded prote<strong>in</strong> stress, <strong>the</strong> cytoplasmatic prote<strong>in</strong> Histone Deacetylase<br />

(HDAC) 6 functions as a l<strong>in</strong>ker between <strong>the</strong> dyne<strong>in</strong> motor <strong>and</strong> poly<strong>ubiquit<strong>in</strong></strong> to<br />

mediate <strong>the</strong> transport <strong>of</strong> polyubiquitylated cargo to <strong>the</strong> aggresome. Here we iden-<br />

tify a new b<strong>in</strong>d<strong>in</strong>g partner <strong>of</strong> HDAC6, <strong>the</strong> <strong>ubiquit<strong>in</strong></strong>-<strong>like</strong> <strong>modifier</strong> <strong>FAT10</strong>, which<br />

is cytok<strong>in</strong>e-<strong>in</strong>ducible <strong>and</strong> – <strong>like</strong> <strong>ubiquit<strong>in</strong></strong> – serves as a signal for proteasomal<br />

<strong>degradation</strong>. In vivo, <strong>the</strong> two prote<strong>in</strong>s only <strong>in</strong>teracted under conditions <strong>of</strong> pro-<br />

teasome impairment. The b<strong>in</strong>d<strong>in</strong>g <strong>of</strong> HDAC6 to <strong>FAT10</strong> was mediated by two<br />

separate doma<strong>in</strong>s, its C-term<strong>in</strong>al <strong>ubiquit<strong>in</strong></strong>-b<strong>in</strong>d<strong>in</strong>g z<strong>in</strong>c-f<strong>in</strong>ger (BUZ doma<strong>in</strong>) as<br />

well as its first catalytic doma<strong>in</strong>, even though catalytic activity <strong>of</strong> HDAC6 was<br />

not required for this <strong>in</strong>teraction. Both endogenous <strong>and</strong> ectopically expressed<br />

<strong>FAT10</strong> as well as <strong>the</strong> model conjugate <strong>FAT10</strong>-GFP localized to <strong>the</strong> aggresome<br />

<strong>in</strong> a microtubule-dependent manner. Fur<strong>the</strong>rmore, <strong>FAT10</strong>-conta<strong>in</strong><strong>in</strong>g as well<br />

as <strong>ubiquit<strong>in</strong></strong>-conta<strong>in</strong><strong>in</strong>g aggresomes were reduced <strong>in</strong> both size <strong>and</strong> number <strong>in</strong><br />

HDAC6 deficient fibroblasts. We conclude that if <strong>FAT10</strong> fails to subject is tar-<br />

get prote<strong>in</strong>s for proteasomal <strong>degradation</strong>, an alternative route is taken to ensure<br />

<strong>the</strong>ir sequestration <strong>and</strong> possibly also <strong>the</strong>ir subsequent removal by transport<strong>in</strong>g<br />

<strong>the</strong>m to <strong>the</strong> aggresome via <strong>the</strong> association with HDAC6.<br />

78

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!