Cytosolic domain of SIDT2 carries an arginine-rich motif that binds to RNA/DNA and is important for the direct transport of nucleic acids into lysosomes.

Cytosolic domain of SIDT2 carries an arginine-rich motif that binds to RNA/DNA and is important for the direct transport of nucleic acids into lysosomes. Autophagy. 2020 Jan 16;:1-15 Authors: Hase K, Contu VR, Kabuta C, Sakai R, Takahashi M, Kataoka N, Hakuno F, Takahashi SI, Fujiwara Y, Wada K, Kabuta T Abstract RNautophagy and DNautophagy (RDA) are unconventional autophagic pathways where nucleic acids are directly transported through the lysosomal membrane, then degraded inside lysosomes. We have previously shown that bitopic protein LAMP2C and putative RNA transporter SIDT2, both lysosomal membrane proteins, mediate the direct transport of nucleic acids into lysosomes and that LAMP2C interacts with the nucleic acids and functions as a receptor during RDA. Because SIDT2-mediated RDA occurs in isolated lysosomes that lack LAMP2C, in this study, we tested the hypothesis that SIDT2 itself could also interact with the nucleic acids. Our results show that SIDT2 directly binds RNA and DNA through an arginine-rich motif (ARM) located within its main cytosolic domain, and disruption of this motif dramatically impairs SIDT2-mediated RNautophagic activity. We also found that SIDT2 interacts with exon 1 of HTT (huntingtin) transcript through the ARM in a CAG-dependent manner. Moreover, overexpression of SIDT2 promoted degradation of HTT mRNA and reduced the levels of polyglutamine-expanded HTT aggregates, hallmarks of Huntington disease. In ...
Source: Autophagy - Category: Cytology Authors: Tags: Autophagy Source Type: research