TY  - JOUR
A1  - Schwarz, Jessica Denise
A1  - Lukassen, Sören
A1  - Bhandare, Pranjali
A1  - Eing, Lorenz
A1  - Snaebjörnsson, Marteinn Thor
A1  - García, Yiliam Cruz
A1  - Kisker, Jan Philipp
A1  - Schulze, Almut
A1  - Wolf, Elmar
T1  - The glycolytic enzyme ALDOA and the exon junction complex protein RBM8A are regulators of ribosomal biogenesis
JF  - Frontiers in Cell and Developmental Biology
N2  - Cellular growth is a fundamental process of life and must be precisely controlled in multicellular organisms. Growth is crucially controlled by the number of functional ribosomes available in cells. The production of new ribosomes depends critically on the activity of RNA polymerase (RNAP) II in addition to the activity of RNAP I and III, which produce ribosomal RNAs. Indeed, the expression of both, ribosomal proteins and proteins required for ribosome assembly (ribosomal biogenesis factors), is considered rate-limiting for ribosome synthesis. Here, we used genetic screening to identify novel transcriptional regulators of cell growth genes by fusing promoters from a ribosomal protein gene (Rpl18) and from a ribosomal biogenesis factor (Fbl) with fluorescent protein genes (RFP, GFP) as reporters. Subsequently, both reporters were stably integrated into immortalized mouse fibroblasts, which were then transduced with a genome-wide sgRNA-CRISPR knockout library. Subsequently, cells with altered reporter activity were isolated by FACS and the causative sgRNAs were identified. Interestingly, we identified two novel regulators of growth genes. Firstly, the exon junction complex protein RBM8A controls transcript levels of the intronless reporters used here. By acute depletion of RBM8A protein using the auxin degron system combined with the genome-wide analysis of nascent transcription, we showed that RBM8A is an important global regulator of ribosomal protein transcripts. Secondly, we unexpectedly observed that the glycolytic enzyme aldolase A (ALDOA) regulates the expression of ribosomal biogenesis factors. Consistent with published observations that a fraction of this protein is located in the nucleus, this may be a mechanism linking transcription of growth genes to metabolic processes and possibly to metabolite availability.
KW  - ribosome biogenesis
KW  - Ribosomal protein gene
KW  - genetic screen
KW  - genome-wide screen
KW  - RBM8A
KW  - Y14
KW  - AldoA
KW  - aldolase A
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-290875
SN  - 2296-634X
VL  - 10
ER  - 
TY  - JOUR
A1  - Otto, Christoph
A1  - Kastner, Carolin
A1  - Schmidt, Stefanie
A1  - Uttinger, Konstantin
A1  - Baluapuri, Apoorva
A1  - Denk, Sarah
A1  - Rosenfeldt, Mathias T.
A1  - Rosenwald, Andreas
A1  - Roehrig, Florian
A1  - Ade, Carsten P.
A1  - Schuelein-Voelk, Christina
A1  - Diefenbacher, Markus E.
A1  - Germer, Christoph-Thomas
A1  - Wolf, Elmar
A1  - Eilers, Martin
A1  - Wiegering, Armin
T1  - RNA polymerase I inhibition induces terminal differentiation, growth arrest, and vulnerability to senolytics in colorectal cancer cells
JF  - Molecular Oncology
N2  - Ribosomal biogenesis and protein synthesis are deregulated in most cancers, suggesting that interfering with translation machinery may hold significant therapeutic potential. Here, we show that loss of the tumor suppressor adenomatous polyposis coli (APC), which constitutes the initiating event in the adenoma carcinoma sequence for colorectal cancer (CRC), induces the expression of RNA polymerase I (RNAPOL1) transcription machinery, and subsequently upregulates ribosomal DNA (rDNA) transcription. Targeting RNAPOL1 with a specific inhibitor, CX5461, disrupts nucleolar integrity, and induces a disbalance of ribosomal proteins. Surprisingly, CX5461-induced growth arrest is irreversible and exhibits features of senescence and terminal differentiation. Mechanistically, CX5461 promotes differentiation in an MYC-interacting zinc-finger protein 1 (MIZ1)- and retinoblastoma protein (Rb)-dependent manner. In addition, the inhibition of RNAPOL1 renders CRC cells vulnerable towards senolytic agents. We validated this therapeutic effect of CX5461 in murine- and patient-derived organoids, and in a xenograft mouse model. These results show that targeting ribosomal biogenesis together with targeting the consecutive, senescent phenotype using approved drugs is a new therapeutic approach, which can rapidly be transferred from bench to bedside.
KW  - CRC
KW  - CX5461
KW  - MIZ1
KW  - MYC
KW  - ribosome
KW  - RNAPOL1
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312806
VL  - 16
IS  - 15
ER  -