Reduction of the polyQ repeats in the P/Q type Calcium Channel Splice Specific Variant causing Spinocerebellar Ataxia Type 6 using CRISPR-Cas9 System.

• Applicant: Professorin Dr. Melanie D. Mark
• Subject Area: Molecular and Cellular Neurology and Neuropathology ; Clinical Neurology; Neurosurgery and Neuroradiology
• Term: from 2016 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 310649331

• Final Report Year: 2023

Final Report Abstract

Spinocerebellar ataxia type 6 (SCA6) is an autosomal dominant, debilitating neurological disorder caused by CAG expansions of 20-33 repeats in the C terminus (CT) of the P/Q type calcium channel gene. CAG encodes the amino acid glutamine, leading to poly-glutamine repeats in the calcium channel protein. In humans, an alternative splicing event occurs at C-terminal end of P/Q type calcium channel gene resulting in two isoforms, one devoid or one containing the CT CAG expansion. Both isoform transcripts are equally abundant in adult cerebellar Purkinje cells (PC). However, in individuals suffering from SCA6, the diseased isoform transcript containing the CAG expansion is increased compared to control individuals. Moreover, the CT of the alpha subunit of the P/Q type calcium channel (Cavα12.1) undergoes proteolytic degradation leading to a more stable diseased CT peptide fragment which specifically accumulate in nuclear and cytosolic PC protein aggregates in adult SCA6 patients. Since there are no therapeutic treatments available for these individuals, we attempted to develop a potentially, new therapeutic method where we specifically reduce the CAG repeats in the CACNA1A gene using the CRISPR-Cas9 (Cas9 nucleases from microbial clustered regularly interspaced short palindromic repeat) system. Although we were not successful at targeting the diseased polyQ27 expansion efficiently in cell culture to eliminate the production of the diseased CT fragment, in the course of establishing this project we discovered that cerebellum contributes to cognitive deficits such as spatial learning and threat probability by using the cerebellar degenerative mouse models for SCA6. In addition, we were able to create an optogenetic tool which enhances motor learning in mice by increasing LTD in the cerebellum.

Publications

• (2017) Keeping Our Calcium in Balance to Maintain Our Balance. Biochem Biophys Res Commun. 483: 1040 -1050
  Mark, Melanie D.; Schwitalla, Jan Claudius; Groemmke, Michelle & Herlitze, Stefan
  
• (2019) A new projection from the deep cerebellar nuclei to the hippocampus via the ventrolateral and laterodorsal thalamus in mice. Frontiers in Neural Circuits. Aug 9. 13:51
  Bohne, Pauline; Schwarz, Martin K.; Herlitze, Stefan & Mark, Melanie D.
  
• (2019) RGS2 Drives Male Agression in Mice via the Serotonergic System. Communications Biology. Oct 11 2: 373
  Mark, Melanie D.; Wollenweber, Patric; Gesk, Annika; Kösters, Katja; Batzke, Katharina; Janoschka, Claudia; Maejima, Takashi; Han, Jing; Deneris, Evan S. & Herlitze, Stefan
  
• (2020) Lamprey Parapinopsin (“UVLamP”): a bistable UV-sensitive optogenetic switch for ultrafast control of GPCR pathways. Chembiochem. Mar 2
  Eickelbeck, Dennis; Rudack, Till; Tennigkeit, Stefan Alexander; Surdin, Tatjana; Karapinar, Raziye; Schwitalla, Jan‐Claudius; Mücher, Brix; Shulman, Maiia; Scherlo, Marvin; Althoff, Philipp; Mark, Melanie D.; Gerwert, Klaus & Herlitze, Stefan
  
• (2021) Reverse optogenetics of G protein signaling by zebrafish non-visual opsin Opn7b for synchronization of neuronal networks. Nature Commun. 12:4488
  Karapinar, Raziye; Schwitalla, Jan Claudius; Eickelbeck, Dennis; Pakusch, Johanna; Mücher, Brix; Grömmke, Michelle; Surdin, Tatjana; Knöpfel, Thomas; Mark, Melanie D.; Siveke, Ida & Herlitze, Stefan
  
• (2022) Cerebellar contribution to threat probability in a SCA6 mouse model. Hum Mol Genet. Jun 16:ddac135
  Bohne, Pauline; Rybarski, Max; Mourabit, Damian Boden-El; Krause, Felix & Mark, Melanie D.
  
• (2022). Cerebellum and Emotion Memory. In: Adamaszek, M., Manto, M., Schutter, D.J.L.G. (eds) The Emotional Cerebellum. Advances in Experimental Medicine and Biology, vol 1378. Springer, Cham
  Mark, Melanie; Pakusch, Johanna; Ernst, Thomas M. & Timmann, Dagmar
  
• (2022). Modulation of VGCCs by G-Protein Coupled Receptors and Their Second Messengers. Part II, p161-194. Book Chapter in: Zamponi GW, Weiss N (eds), Voltage-Gated Calcium Channels. Springer
  Mark, Melanie D.; Schwitalla, Jan Claudius & Herlitze, Stefan
  
• (2022) Optogenetic activation of mGluR1 signaling in the cerebellum induces synaptic plasticity. iScience. 26:105828
  Surdin, Tatjana; Preissing, Bianca; Rohr, Lennard; Grömmke, Michelle; Böke, Hanna; Barcik, Maike; Azimi, Zohre; Jancke, Dirk; Herlitze, Stefan; Mark, Melanie D. & Siveke, Ida