"painOME": Deciphering pain mechanisms with spatial single cell resolution. – SEQ3012

• Applicant: Professor Dr. Ingo Kurth
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells ; Human Genetics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 497656546

Chronic pain affects a large group of the population and adequate therapy is still an unmet need with enormous impact on the quality of life. 6-7 % of people suffering daily debilitating pain. Simultaneously, as the population ages, about half of people aged over 65 years have chronic pain. A key aspect in the development of chronic pain is malfunctioning of peripheral sensory neurons. Understanding their function thus makes a significant contribution to understanding the development of pain. In this respect, rare genetic disorders that lead to a general absence of pain are ideally suited to understanding the central mechanisms of sensory neuron function and thus pain processing. In these monogenic pain loss syndromes, the mutation of only one gene leads to the loss of pain perception and thus all malfunctions can be traced back to this single molecule. In recent years, we have identified for the first time several genes expressed in sensory neurons whose mutations cause genetic pain loss (ATL3, FAM134B, SCN11A, FLVCR1) or have been involved in their identification (PRDM12, GMPPA, MADD). Meanwhile a total of 20 genes are identified as cause for monogenic pain loss. The affected genes can be classified into two large groups with respective mechanistic overlap: 1) sensory neuron dysfunction, or, 2) neurodegeneration / neurodevelopmental defects of sensory neurons. In previous studies we generated mouse and cellular models for the SCN11A-related pain loss (exemplifying mechanism 1) and the FAM134B-related painlessness (exemplifying mechanism 2). What has been missing so far, however, is an understanding of the pathophysiology of these disorders at single cell resolution. We will here use knockin and knockout mouse models of both conditions in single-cell experiments, together with patient-derived stem cells reprogrammed into nociceptors. We aim to address the following five main objectives: 1) Which neuronal cell populations are missing / degenerate in knockin mice harbouring a pain loss mutation in Scn11a? Does neurodegeneration, a developmental defect or a cell fate switch occur? Which genes are differentially expressed? Is there a topographical loss of neurons? 2) Which sensory neuron types are most vulnerable to neurodegeneration caused by Fam134b loss? 3) What are the consequences of Scn11a gain-of-function and Fam134b loss-of-function in the spinal cord projection laminae? Are interneurons affected? 4) Are satellite glia cells affected in the two disease models? 5) Can we identify and recapitulate mechanisms of pain loss disorders in human sensory neurons from patient-derived induced pluripotent stem cells? Using single cell sequencing we hope to gain deeper insights into the pathophysiology of these diseases and to describe molecules and signaling pathways that impact the pain system and its maintenance. Ultimately, with this approach we hope to be able to identify new target molecules for neuroprotection and pain therapy.

• DFG Programme: Research Grants