Non-Coding RNA Has Role in Inherited Neurological Disorder

Photo: Illustration of a neuron and a switch

Researchers have discovered that
expression of the ataxin‑7 gene,
the cause of the neurological dis-
order spinocerebellar ataxia type 7,
has two regulators: a highly con-
served, multi‑tasking protein called
CTCF and, surprisingly, an adjacent
promoter containing non‑coding RNA;
© Illustration courtesy of Christina
Takamatsu‑Butler, UC San Diego

The discovery promises to have broad ramifications, suggesting that abundant non-coding transcripts of ribonucleic acid (RNA) may be key players in neurological development and function, and could be powerful targets for future clinical therapies.

Spinocerebellar ataxia 7 is one of several types of spinocerebellar ataxia (SCA), genetic degenerative disorders characterized by atrophy in the cerebellum of the brain, progressive loss of physical coordination – and in the case of type 7 – retinal degeneration that can result in blindness. There is currently no known cure.

The researchers found not one, but two, regulators. The first is called CTCF, a highly conserved protein that regulates a variety of transcriptional processes, most notable establishing insulator domains and controlling genomic imprinting. But they also discovered an adjacent, alternative promoter dubbed intron 2 promoter (P2A) and a transcribed antisense, non-coding RNA, which they labeled SpinoCerebellarAtaxia-AntisenseNoncodingTranscript1 or SCAANT1.

Professor Albert La Spada, chief of the division of genetics in the UCSD department of pediatrics and colleagues highlight one function, at least for SCAANT1. When they investigated how CTCF regulated ataxin-7 gene expression in transgenic mice, they discovered that CTCF promotes the production of SCAANT1 which in turn represses the newly discovered ataxin-7 sense promoter P2A. In mice lacking SCAANT1, sense promoter P2A is de-repressed, allowing a mutant ataxin-7 gene to be expressed, resulting in mice with a version of SCA7. The scientists found a similar lack of antisense SCAANT1 in the fibroblasts and white blood cells taken from human patients with SCA7, implicating deregulation of this pathway in the disease process.

As many inherited neurological disorders are now known to exhibit such overlapping "bidirectional" transcription, the findings in SCA7 could shed light on similar abnormalities with non-coding RNA function in a number of brain diseases.


MEDICA.de; Source: University of California - San Diego