Stefan Huttelmaier - Academia.edu (original) (raw)

Papers by Stefan Huttelmaier

Nucleic acids research, Jan 29, 2018

The oncofetal mRNA-binding protein IGF2BP1 and the transcriptional regulator SRF modulate gene ex... more The oncofetal mRNA-binding protein IGF2BP1 and the transcriptional regulator SRF modulate gene expression in cancer. In cancer cells, we demonstrate that IGF2BP1 promotes the expression of SRF in a conserved and N6-methyladenosine (m6A)-dependent manner by impairing the miRNA-directed decay of the SRF mRNA. This results in enhanced SRF-dependent transcriptional activity and promotes tumor cell growth and invasion. At the post-transcriptional level, IGF2BP1 sustains the expression of various SRF-target genes. The majority of these SRF/IGF2BP1-enhanced genes, including PDLIM7 and FOXK1, show conserved upregulation with SRF and IGF2BP1 synthesis in cancer. PDLIM7 and FOXK1 promote tumor cell growth and were reported to enhance cell invasion. Consistently, 35 SRF/IGF2BP1-dependent genes showing conserved association with SRF and IGF2BP1 expression indicate a poor overall survival probability in ovarian, liver and lung cancer. In conclusion, these findings identify the SRF/IGF2BP1-, miRN...

Molecular cell, Jan 19, 2018

The RNA-binding protein HuD promotes neurogenesis and favors recovery from peripheral axon injury... more The RNA-binding protein HuD promotes neurogenesis and favors recovery from peripheral axon injury. HuD interacts with many mRNAs, altering both stability and translation efficiency. We generated a nucleotide resolution map of the HuD RNA interactome in motor neuron-like cells, identifying HuD target sites in 1,304 mRNAs, almost exclusively in the 3' UTR. HuD binds many mRNAs encoding mTORC1-responsive ribosomal proteins and translation factors. Altered HuD expression correlates with the translation efficiency of these mRNAs and overall protein synthesis, in a mTORC1-independent fashion. The predominant HuD target is the abundant, small non-coding RNA Y3, amounting to 70% of the HuD interaction signal. Y3 functions as a molecular sponge for HuD, dynamically limiting its recruitment to polysomes and its activity as a translation and neuron differentiation enhancer. These findings uncover an alternative route to the mTORC1 pathway for translational control in motor neurons that is ...

Experimental neurology, 2018

Nucleic acids research, Jan 12, 2018

The oncofetal IGF2 mRNA binding proteins (IGF2BPs) are upregulated in most cancers but their para... more The oncofetal IGF2 mRNA binding proteins (IGF2BPs) are upregulated in most cancers but their paralogue-specific roles in tumor cells remain poorly understood. In a panel of five cancer-derived cell lines, IGF2BP1 shows highly conserved oncogenic potential. Consistently, the deletion of IGF2BP1 impairs the growth and metastasis of ovarian cancer-derived cells in nude mice. Gene expression analyses in ovarian cancer-derived cells reveal that the knockdown of IGF2BPs is associated with the downregulation of mRNAs that are prone to miRNA regulation. All three IGF2BPs preferentially associate upstream of miRNA binding sites (MBSs) in the 3'UTR of mRNAs. The downregulation of mRNAs co-regulated by miRNAs and IGF2BP1 is abrogated at low miRNA abundance or when miRNAs are depleted. IGF2BP1 associates with these target mRNAs in RISC-free complexes and its deletion enhances their association with AGO2. The knockdown of most miRNA-regulated target mRNAs of IGF2BP1 impairs tumor cell proper...

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Nature cell biology, 2018

N-methyladenosine (mA) is the most prevalent modification in eukaryotic messenger RNAs (mRNAs) an... more N-methyladenosine (mA) is the most prevalent modification in eukaryotic messenger RNAs (mRNAs) and is interpreted by its readers, such as YTH domain-containing proteins, to regulate mRNA fate. Here, we report the insulin-like growth factor 2 mRNA-binding proteins (IGF2BPs; including IGF2BP1/2/3) as a distinct family of mA readers that target thousands of mRNA transcripts through recognizing the consensus GG(mA)C sequence. In contrast to the mRNA-decay-promoting function of YTH domain-containing family protein 2, IGF2BPs promote the stability and storage of their target mRNAs (for example, MYC) in an mA-dependent manner under normal and stress conditions and therefore affect gene expression output. Moreover, the K homology domains of IGF2BPs are required for their recognition of mA and are critical for their oncogenic functions. Thus, our work reveals a different facet of the mA-reading process that promotes mRNA stability and translation, and highlights the functional importance of ...

Nature cell biology, 2017

Leukaemogenesis requires enhanced self-renewal, which is induced by oncogenes. The underlying mol... more Leukaemogenesis requires enhanced self-renewal, which is induced by oncogenes. The underlying molecular mechanisms remain incompletely understood. Here, we identified C/D box snoRNAs and rRNA 2'-O-methylation as critical determinants of leukaemic stem cell activity. Leukaemogenesis by AML1-ETO required expression of the groucho-related amino-terminal enhancer of split (AES). AES functioned by inducing snoRNA/RNP formation via interaction with the RNA helicase DDX21. Similarly, global loss of C/D box snoRNAs with concomitant loss of rRNA 2'-O-methylation resulted in decreased leukaemia self-renewal potential. Genomic deletion of either C/D box snoRNA SNORD14D or SNORD35A suppressed clonogenic potential of leukaemia cells in vitro and delayed leukaemogenesis in vivo. We further showed that AML1-ETO9a, MYC and MLL-AF9 all enhanced snoRNA formation. Expression levels of C/D box snoRNAs in AML patients correlated closely with in vivo frequency of leukaemic stem cells. Collectivel...

Cancer research, May 16, 2017

Myc oncoproteins exert tumorigenic effects by regulating expression of target oncogenes. Histone ... more Myc oncoproteins exert tumorigenic effects by regulating expression of target oncogenes. Histone H3 lysine 79 (H3K79) methylation at Myc-responsive elements of target gene promoters is a strict prerequisite for Myc-induced transcriptional activation, and DOT1L is the only known histone methyltransferase that catalyses H3K79 methylation. Here we show that N-Myc upregulatsd DOT1L mRNA and protein expression by binding to the DOT1L gene promoter. shRNA-mediated depletion of DOT1L reduced mRNA and protein expression of N-Myc target genes ODC1 and E2F2. DOT1L bound to the Myc Box II domain of N-Myc protein, and knockdown of DOT1L reduced histone H3K79 methylation and N-Myc protein binding at the ODC1 and E2F2 gene promoters and reduced neuroblastoma cell proliferation. Treatment with the small molecule DOT1L inhibitor SGC0946 reduced H3K79 methylation and proliferation of MYCN gene-amplified neuroblastoma cells. In mice xenografts of neuroblastoma cells stably expressing doxycycline-indu...

RNA Biology, 2016

In metazoan the 3 0-end processing of histone mRNAs is a conserved process involving the concerte... more In metazoan the 3 0-end processing of histone mRNAs is a conserved process involving the concerted action of many protein factors and the non-coding U7 snRNA. Recently, we identified that the processing of histone pre-mRNAs is promoted by an additional ncRNA, the Y3-derived Y3 ÃÃ RNA. U7 modulates the association of the U7 snRNP whereas Y3 ÃÃ promotes recruitment of CPSF (cleavage and polyadenylation specific factor) proteins to nascent histone transcripts at histone locus bodies (HLBs) in mammals. This enhances the 3 0-end cleavage of nascent histone pre-mRNAs and modulates HLB assembly. Here we discuss new insights in the role of ncRNAs in the spatiotemporal control of histone synthesis. We propose that ncRNAs scaffold the formation of functional protein-RNA complexes and their sequential deposition on nascent histone pre-mRNAs at HLBs. These findings add to the multiple roles of ncRNAs in controlling gene expression and may provide new avenues for targeting histone synthesis in cancer.

Mol Cell Biol, 2007

Cytoplasmic mRNA localization regulates gene expression by spatially restricting protein translat... more Cytoplasmic mRNA localization regulates gene expression by spatially restricting protein translation. Recent evidence has shown that nuclear proteins (such as hnRNPs) are required to form mRNPs capable of cytoplasmic localization. ZBP1 and ZBP2, two hnRNP K homology domain-containing proteins, were previously identified by their binding to the zipcode, the sequence element necessary and sufficient for ␤-actin mRNA localization. ZBP1 colocalizes with nascent ␤-actin mRNA in the nucleus but is predominantly a cytoplasmic protein. ZBP2, in contrast, is predominantly nuclear. We hypothesized that the two proteins cooperate to localize ␤-actin mRNA and sought to address where and how this might occur. We demonstrate that ZBP2, a homologue of the splicing factor KSRP, binds initially to nascent ␤-actin transcripts and facilitates the subsequent binding of the shuttling ZBP1. ZBP1 then associates with the RNA throughout the nuclear export and cytoplasmic localization process.

Molecular and Cellular Biology, 2007

Molecular and Cellular Biology, 2009

Cancer research, Jan 15, 2015

MYCN gene amplification in neuroblastoma drives a gene expression program that correlates strongl... more MYCN gene amplification in neuroblastoma drives a gene expression program that correlates strongly with aggressive disease. Mechanistically, trimethylation of histone H3 lysine 4 (H3K4) at target gene promoters is a strict pre-requisite for this transcriptional program to be enacted. WDR5 is a histone H3K4 presenter that has been found to have an essential role in H3K4 trimethylation. For this reason, in this study we investigated the relationship between WDR5-mediated H3K4 trimethylation and N-Myc transcriptional programs in neuroblastoma cells. N-Myc up-regulated WDR5 expression in neuroblastoma cells. Gene expression analysis revealed that WDR5 target genes included those with MYC binding elements at promoters such as MDM2. We showed that WDR5 could form a protein complex at the MDM2 promoter with N-Myc, but not p53, leading to histone H3K4 trimethylation and activation of MDM2 transcription. RNAi-mediated attenuation of WDR5 up-regulated expression of wild type but not mutant p5...

Genes & development, 2015

We demonstrate that the Y3/Y3** noncoding RNAs (ncRNAs) bind to the CPSF (cleavage and polyadenyl... more We demonstrate that the Y3/Y3** noncoding RNAs (ncRNAs) bind to the CPSF (cleavage and polyadenylation specificity factor) and that Y3** associates with the 3' untranslated region (UTR) of histone pre-mRNAs. The depletion of Y3** impairs the 3' end processing of histone pre-mRNAs as well as the formation and protein dynamics of histone locus bodies (HLBs), the site of histone mRNA synthesis and processing. HLB morphology is also disturbed by knockdown of the CPSF but not the U7-snRNP components. In conclusion, we propose that the Y3** ncRNA promotes the 3' end processing of histone pre-mRNAs by enhancing the recruitment of the CPSF to histone pre-mRNAs at HLBs.

OncoImmunology, 2015

In human tumors of distinct origin including renal cell carcinoma (RCC), the non-classical human ... more In human tumors of distinct origin including renal cell carcinoma (RCC), the non-classical human leukocyte antigen G (HLA-G) is frequently expressed, thereby inhibiting the cytotoxic activity of T and natural killer (NK) cells. Recent studies demonstrated a strong post-transcriptional gene regulation of the HLA-G by miR-152, ¡148A, ¡148B and ¡133A. Standard methods were applied to characterize the expression and function of HLA-G, HLA-G-regulatory microRNAs (miRs) and the immune cell infiltration in 453 RCC lesions using a tissue microarray and five RCC cell lines linking these results to clinical parameters. Direct interactions with HLA-G regulatory miRs and the HLA-G 3 0 untranslated region (UTR) were detected and the affinities of these different miRs to the HLA-G 3 0-UTR compared. qPCR analyses and immunohistochemical staining revealed an inverse expression of miR-148A and ¡133A with the HLA-G protein in situ and in vitro. Stable miR overexpression caused a downregulation of HLA-G protein enhancing the NK and LAK cellmediated cytotoxicity in in vitro CD107a activation assays revealing a HLA-G-dependent cytotoxic activity of immune effector cells. A significant higher frequency of CD3 C /CD8 C T cell lymphocytes, but no differences in the activation markers CD69, CD25 or in the presence of CD56 C , FoxP3 C and CD4 C immune cells were detected in HLA-G C compared to HLA-G ¡ RCC lesions. This could be associated with higher WHO grade, but not with a disease-specific survival. These data suggest a miR-mediated control of HLA-G expression in RCC, which is associated with a distinct pattern of immune cell infiltration.

Biomolecules, 2013

Y RNAs constitute a family of highly conserved small noncoding RNAs (in humans: 83-112 nt; Y1, Y3... more Y RNAs constitute a family of highly conserved small noncoding RNAs (in humans: 83-112 nt; Y1, Y3, Y4 and Y5). They are transcribed from individual genes by RNA-polymerase III and fold into conserved stem-loop-structures. Although discovered 30 years ago, insights into the cellular and physiological role of Y RNAs remains incomplete. In this review, we will discuss knowledge on the structural properties, associated proteins and discuss proposed functions of Y RNAs. We suggest Y RNAs to be an integral part of ribonucleoprotein networks within cells and could therefore have substantial influence on many different cellular processes. Putative functions of Y RNAs include small RNA quality control, DNA replication, regulation of the cellular stress response and proliferation. This suggests Y RNAs as essential regulators of cell fate and indicates future avenues of research, which will provide novel insights into the role of small noncoding RNAs in gene expression.

Nucleic acids research, Jan 27, 2015

During cellular stress, protein synthesis is severely reduced and bulk mRNA is recruited to stres... more During cellular stress, protein synthesis is severely reduced and bulk mRNA is recruited to stress granules (SGs). Previously, we showed that the SG-recruited IGF2 mRNA-binding protein 1 (IGF2BP1) interferes with target mRNA degradation during cellular stress. Whether this requires the formation of SGs remained elusive. Here, we demonstrate that the sustained inhibition of visible SGs requires the concomitant knockdown of TIA1, TIAR and G3BP1. FRAP and photo-conversion studies, however, indicate that these proteins only transiently associate with SGs. This suggests that instead of forming a rigid scaffold for mRNP recruitment, TIA proteins and G3BP1 promote SG-formation by constantly replenishing mRNPs. In contrast, RNA-binding proteins like IGF2BP1 or HUR, which are dispensable for SG-assembly, are stably associated with SGs and the IGF2BP1/HUR-G3BP1 association is increased during stress. The depletion of IGF2BP1 enhances the degradation of target mRNAs irrespective of inhibiting ...

News in physiological sciences : an international journal of physiology produced jointly by the International Union of Physiological Sciences and the American Physiological Society, 2003

RNA processing, directed transport along cytoskeletal tracks, and site-specific translation of mR... more RNA processing, directed transport along cytoskeletal tracks, and site-specific translation of mRNA at the cell periphery are considered discrete steps in the generation of microfilament-membrane adhesion complexes. A recently identified member of the heterogeneous nuclear ribonucleoprotein family, raver1, may couple these steps and contribute to the assembly and maintenance of these structures.