TY - JOUR
T1 - Functional Characterisation of the Circular RNA, circHTT(2-6), in Huntington’s Disease
AU - Gantley, Laura
AU - Stringer, Brett W.
AU - Conn, Vanessa M.
AU - Ootsuka, Youichirou
AU - Holds, Duncan
AU - Slee, Mark
AU - Aliakbari, Kamelya
AU - Kirk, Kirsty
AU - Ormsby, Rebecca J.
AU - Webb, Stuart T.
AU - Hanson, Adrienne
AU - Lin, He
AU - Selth, Luke A.
AU - Conn, Simon J.
PY - 2023/5
Y1 - 2023/5
N2 - Trinucleotide repeat disorders comprise ~20 severe, inherited, human neuromuscular and neurodegenerative disorders, which result from an abnormal expansion of repetitive sequences in the DNA. The most common of these, Huntington’s disease (HD), results from expansion of the CAG repeat region in exon 1 of the HTT gene via an unknown mechanism. Since non-coding RNAs have been implicated in the initiation and progression of many diseases, herein we focused on a circular RNA (circRNA) molecule arising from non-canonical splicing (backsplicing) of HTT pre-mRNA. The most abundant circRNA from HTT, circHTT(2-6), was found to be more highly expressed in the frontal cortex of HD patients, compared with healthy controls, and positively correlated with CAG repeat tract length. Furthermore, the mouse orthologue (mmu_circHTT(2-6)) was found to be enriched within the brain and specifically the striatum, a region enriched for medium spiny neurons that are preferentially lost in HD. Transgenic overexpression of circHTT(2-6) in two human cell lines—SH-SY5Y and HEK293—reduced cell proliferation and nuclear size without affecting cell cycle progression or cellular size, or altering the CAG repeat region length within HTT. CircHTT(2-6) overexpression did not alter total HTT protein levels, but reduced its nuclear localisation. As these phenotypic and genotypic changes resemble those observed in HD patients, our results suggest that circHTT(2-6) may play a functional role in the pathophysiology of this disease.
AB - Trinucleotide repeat disorders comprise ~20 severe, inherited, human neuromuscular and neurodegenerative disorders, which result from an abnormal expansion of repetitive sequences in the DNA. The most common of these, Huntington’s disease (HD), results from expansion of the CAG repeat region in exon 1 of the HTT gene via an unknown mechanism. Since non-coding RNAs have been implicated in the initiation and progression of many diseases, herein we focused on a circular RNA (circRNA) molecule arising from non-canonical splicing (backsplicing) of HTT pre-mRNA. The most abundant circRNA from HTT, circHTT(2-6), was found to be more highly expressed in the frontal cortex of HD patients, compared with healthy controls, and positively correlated with CAG repeat tract length. Furthermore, the mouse orthologue (mmu_circHTT(2-6)) was found to be enriched within the brain and specifically the striatum, a region enriched for medium spiny neurons that are preferentially lost in HD. Transgenic overexpression of circHTT(2-6) in two human cell lines—SH-SY5Y and HEK293—reduced cell proliferation and nuclear size without affecting cell cycle progression or cellular size, or altering the CAG repeat region length within HTT. CircHTT(2-6) overexpression did not alter total HTT protein levels, but reduced its nuclear localisation. As these phenotypic and genotypic changes resemble those observed in HD patients, our results suggest that circHTT(2-6) may play a functional role in the pathophysiology of this disease.
KW - circular RNA
KW - HTT
KW - Huntingtin
KW - Huntington’s disease
KW - triplet repeat disorders
UR - http://www.scopus.com/inward/record.url?scp=85159199191&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/NHMRC/1190814
UR - http://purl.org/au-research/grants/ARC/FT160100318
U2 - 10.3390/cells12091337
DO - 10.3390/cells12091337
M3 - Article
AN - SCOPUS:85159199191
SN - 2073-4409
VL - 12
JO - Cells
JF - Cells
IS - 9
M1 - 1337
ER -