Project Details
Projekt
The role of the non-coding RNAs Malat1 and 7SK in motoneuron disease
Applicants
Dr. Michael Briese; Professor Dr. Michael A. Sendtner
Subject Area
Molecular and Cellular Neurology and Neuropathology
Molecular Biology and Physiology of Neurons and Glial Cells
Molecular Biology and Physiology of Neurons and Glial Cells
Term
from 2014 to 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 255331586
Non-coding RNAs are emerging as key regulators of cellular functions. Whilst the number of identified non-coding RNAs has increased substantially over the last years their individual role in specialized cells has remained relatively elusive. Highly polarized cells such as neurons might utilize non-coding RNAs to establish and maintain their often extensive axonal processes. Additionally, the role of non-coding RNAs in neurodegenerative diseases is not well-understood. In the proposed project we would like to investigate the roles of the non-coding RNAs 7SK and Malat1 in spinal muscular atrophy (SMA), one of the most common genetic causes of infant lethality. In SMA, deficiency of the Survival Motor Neuron (SMN) protein causes degeneration of spinal motoneurons leading to atrophy of associated muscles. We previously identified the RNA-binding protein hnRNP R as an interactor of SMN. During the first SPP 1738 funding period we characterized the RNA interactome of hnRNP R in motoneurons by iCLIP and found the non-coding RNA 7SK as the top candidate. We detected hnRNP R/7SK complexes in the cytosol of motoneurons including their axons and found that knockdown of either hnRNP R or 7SK reduced axon outgrowth accompanied by similar transcriptome alterations in the axons and somata. In the proposed project we would like to expand upon these findings and investigate the functions of 7SK and hnRNP R in vivo. For this purpose we would like to generate a 7SK knockout mouse and characterize it using cell biology techniques and transcriptome analyses. Additionally, we would like to characterize a newly generated hnRNP R knockout mouse and determine whether similar defects occur. In addition to 7SK, hnRNP R also interacts with Malat1, an abundant nuclear long non-coding RNA. Our preliminary data show that Malat1 is upregulated in Smn-deficient motoneurons and that nuclear hnRNP R levels are increased and cytosolic levels are decreased in these cells. These data suggest that subcellular hnRNP R/7SK complexes might be disturbed in SMA in a Malat1-dependent manner. Therefore, we would like to investigate the composition of cytosolic hnRNP R/7SK complexes by proteome analysis and determine whether these complexes are altered in SMA motoneurons. Finally, we will determine whether upregulation of Malat1 as seen in SMA causes such alterations of hnRNP R/7SK complexes and whether reduction of Malat1 can restore these defects. We anticipate that the techniques used in this project, such as primary motoneuron culture, and functional and histopathological analyses of mouse models of SMA will be of interest to other members of the SPP 1738. Taken together, the results generated in this project will help to further understand the functions of 7SK, Malat1 and hnRNP R in motoneurons and their roles in the pathomechanism of SMA.
DFG Programme
Priority Programmes
