The role of the U12-dependent spliceosome in differentiation

Maureen Veronica Akinyi, Mariia Shcherbii, Mikko Juhani Frilander

Forskningsoutput: KonferensbidragSammanfattning


Previous studies in our laboratory have identified an auto/crossregulation system that regulates minor spliceosome cellular abundance via core 48K and 65K proteins [1]. This regulatory program uses evolutionarily ultraconserved sequence elements (USSE) located in the introns of both 65K and 48K pre-mRNAs that function as splicing enhancers. The USSE element employs alternative splicing activated by U11 snRNP binding, to generate non-functional mRNA isoforms that are either degraded by nonsense-mediated decay (NMD) in the case of 48K following the inclusion of a mini exon, or trapped in the nucleus in the case of 65K, due to a long 3’UTR [1]. More recently, work in our laboratory has shown that the USSE-mediated downregulation of 65K is strongly activated during neuronal differentiation which suggested that the minor spliceosome may play a role in cellular differentiation and proliferation programs [2]. To address the significance of 65K USSE mediated regulation during differentiation we examined three different differentiation models. For neuronal differentiation, we used the SH-SY5Y neuronal differentiation model, which can be induced to differentiate into dopaminergic-like neurons by retinoic acid. We also analyzed 65K downregulation in differentiating pancreatic and bi-potential gonad cells.
During normal neuronal differentiation, 65K protein expression is downregulated due to a USSE-dependent shift toward the long 3’UTR isoform. We asked if this isoform shift is essential for neuronal differentiation in SH-SY5Y cells by blocking the USSE element using an antisense morpholino oligonucleotide, which results in a shift towards production of functional short 3´UTR containing isoform. We found that the differentiation is indeed disturbed as the neurite outgrowth appeared to be inhibited and there was enrichment of fibroblast-like cells as opposed to mature neurons. Blocking the 65K-USSE in later stages of the differentiation pathway led to a rapid degeneration of already established synaptic connections. With regards to other differentiation systems, our preliminary experiments reveal that 65K-USSE mediated downregulation is also operational in pancreas and bi-potential gonad cell differentiation, however the significance of this regulation for the differentiation process is yet to be established. Thus far, our preliminary data strongly suggest that 65K USSE–mediated regulation, and consequently the control of minor spliceosome abundance, appears to be important for neuronal survival and development. This may have implications in minor spliceosome-associated diseases that are reported to have neuronal defects such as Lowry Wood Syndrome (LWS), microcephalic osteodysplastic primordial dwarfism, type 1 (MOPD1) or Taybi-Linder syndrome (TALS), Roifman syndrome, and Early Onset Cerebellar Ataxia (EOCA) [3,4]. This work may provide a significant leap forward in understanding the regulatory function and targets of the minor spliceosome and will help to understand the human diseases resulting from the minor spliceosome dysfunction.

1. Niemelä (2015) RNA Biol. 12:1256–1264.
2. Verbeeren (2017). PLoS Genetics, 13(5):e1006824.
3. Verma (2018) Semin. Cell Dev. Biol., 79, 103-112.
4. Jutzi (2018) Cell Stress, 2:40-54
StatusPublicerad - 18 nov 2018
MoE-publikationstypEj behörig
EvenemangRNA and Disease 2018 - Uppsala, Sverige
Varaktighet: 18 nov 201820 nov 2018


KonferensRNA and Disease 2018


  • 1182 Biokemi, cell- och molekylärbiologi

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