DICER1 platform domain missense variants inhibit miRNA biogenesis and lead to tumor susceptibility

Dylan Pelletier; Anne-Laure Chong; Mona Wu; Leora Witkowski; Sophie Albert; Nelly Sabbaghian; Marc R Fabian; William D Foulkes

doi:10.1093/narcan/zcad030

DICER1 platform domain missense variants inhibit miRNA biogenesis and lead to tumor susceptibility

NAR Cancer. 2023 Jun 16;5(3):zcad030. doi: 10.1093/narcan/zcad030. eCollection 2023 Sep.

Authors

Dylan Pelletier^{1

2

3}, Anne-Laure Chong^{1

2}, Mona Wu^{1

2}, Leora Witkowski¹, Sophie Albert², Nelly Sabbaghian^{1

2}, Marc R Fabian^{2

4

5

6}, William D Foulkes^{1

2

4

7}

Affiliations

¹ Department of Human Genetics, Medicine, McGill University, Montreal, QC, Canada.
² Cancer Axis, Lady Davis Institute, Jewish General Hospital, Montreal, QC, Canada.
³ Faculty of Medicine, Université de Montréal, Montreal, QC, Canada.
⁴ Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada.
⁵ Division of Experimental Medicine, McGill University, Montreal, QC, Canada.
⁶ Department of Biochemistry, McGill University, Montreal, QC, Canada.
⁷ Cancer Research Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.

Abstract

The endoribonuclease DICER1 plays an essential role in the microRNA (miRNA) biogenesis pathway, cleaving precursor miRNA (pre-miRNA) stem-loops to generate mature single-stranded miRNAs. Germline pathogenic variants (GPVs) in DICER1 result in DICER1 tumor predisposition syndrome (DTPS), a mainly childhood-onset tumor susceptibility disorder. Most DTPS-causing GPVs are nonsense or frameshifting, with tumor development requiring a second somatic missense hit that impairs the DICER1 RNase IIIb domain. Interestingly, germline DICER1 missense variants that cluster in the DICER1 Platform domain have been identified in some persons affected by tumors that also associate with DTPS. Here, we demonstrate that four of these Platform domain variants prevent DICER1 from producing mature miRNAs and as a result impair miRNA-mediated gene silencing. Importantly, we show that in contrast to canonical somatic missense variants that alter DICER1 cleavage activity, DICER1 proteins harboring these Platform variants fail to bind to pre-miRNA stem-loops. Taken together, this work sheds light upon a unique subset of GPVs causing DTPS and provides new insights into how alterations in the DICER1 Platform domain can impact miRNA biogenesis.