Touch sensation is built upon the ability of sensory neurons to detect and transduce nanometer scale mechanical displacements. The underlying process has been termed mechanotransduction: the high sensitivity and speed of which is enabled by direct gating (opening) of ion channels by mechanical force. Force detection is functionally compartmentalized and only takes place at the peripheral endings of sensory neurons in vivo. Two molecules are known to be genetically necessary for touch in many sensory neurons, the force gated ion channel PIEZO2 and its modulator STOML3. However, mechanotransduction complexes in all touch receptors absolutely require tethering to the extracellular matrix for function. Tethering is dependent on large extracellular proteins that are sensitive to site-specific proteases. Here we will not only identify the nature of these tethers, but will develop technology to acutely and reversibly abolish tethers and other mechanotransducer components. We will use genome engineering to tag tether and mechanotranduction components in order to visualize and manipulate these proteins at their in vivo sites of action. By engineering de novo cleavage sites for site-specific proteases we will render tethers and ion channels newly sensitive to normally ineffective proteases in the skin. We will engineer mutations into candidate ion channels that dramatically alter biophysical properties to physiologcally “mark” function in vivo. Finally we will develop new behavioural paradigms in mice that allow us to measure touch perception from the forepaw. Psychometric curves for different vibrotactile tasks can then be precisely compared between humans and mice. Furthermore, the impact of acute and reversible manipulation of mechanotransduction on touch perception can be measured. Understanding how molecules assemble to function in a mechanotransduction complex in the skin will open up avenues to develop therapeutic strategies to modulate touch.

SMALL MOLECULES TO TREAT METABOLIC SYNDROME Metabolic Syndrome (MS) is defined as a cluster of inter-related symptoms including central obesity, insulin resistance, dyslipidemia, and hypertension that promote the development of type 2 diabetes mellitus, cardiovascular diseases and certain cancers. In this project a pharmacological strategy will be developed that could alleviate the vicious circle of hyperglycemia (elevated blood glucose) and elevated insulin observed in metabolic syndrome that accelerates the onset of type 2 diabetes. We have identified a new protein that participates in insulin-dependent increase in glucose uptake from the blood. Loss of this protein leads to reduced insulin dependent glucose uptake and a metabolic syndrome like disease in mice. In this project small molecules that modulate the function of the said protein will be developed and evaluated. New molecules that enhance glucose uptake into cells could be potentially powerful new tools to reverse insulin resistance a key pathology of metabolic syndrome that can accelerate the onset of type 2 diabetes.

Heart disease is a staggering clinical and public health problem and the leading cause of death for both men and women in Western countries. The underlying pathomechanism of nearly all aetiologies relates to altered contractility and cardiac tissue tension but also gene expression changes and epigenomic remodelling. Within the sarcomere, the fundamental contractile unit in striated muscle, the giant protein titin is the major source of cardiac passive tension. Since sarcomeres are connected to the nucleus, I hypothesise that titin passive tension is transmitted to the nucleus and sensed by the mechano-sensitive nuclear lamina, affecting chromatin structure and gene expression, similar to cytoskeleton passive tension in nonmuscle cells. I will test this hypothesis in human cardiomyocytes derived from induced pluripotent stem cells (hiPSC-CMs) with either a low or high titin-derived passive tension by editing the titin gene locus. I will also investigate whether changes of titin tension affect sarcomere-resident chromatin remodellers: Smyd1, Smyd2, and HP1γ. Combining fluorescence and super-resolution imaging with chromatin-immunoprecipitation sequencing and RNA sequencing, I will delineate a comprehensive map of titin-derived epigenetic remodelling in hiPSC-CMs. The TiGER project will dissect a complex biophysical mechanism leveraging on hiPSC-CMs as they represent an exceptional platform to unveil human cardiac-specific phenomena that require extensive gene editing, culture, and imaging. As titin-derived passive tension changes during development, physiology, and disease, TiGER’s results could have major implications for cardiac pathophysiology and could unlock future compelling research avenues. I will explore this novel role for titin as an epigenetic remodeller under the supervision of Prof. Dr. Gotthardt, a world-leading expert of cardiac mechanotransduction and titin at the Max Delbrück Center (MDC) in Berlin.

Stem cells and organoids have revolutionized our ability to build tissues and organ-like structures ‘in a dish’. Organoid models of a wide range of human tissues are increasingly applied to drug and treatment development and to fundamental and translational studies. However, the challenge of simultaneously growing more than one different tissues in a single functional organoid remains. Human neuromuscular organoids (NMOs) represent a landmark discovery toward building more complex and physiologically relevant human tissues in vitro. NMOs closely capture the cellular repertoire and structural and functional properties of the neuromuscular system, but, similar to other organoids, they do not reach adult tissue stages of maturation, at least in part, due to lack of connectivity and in vivo-like sensory inputs, including bioelectrical cues, essential in physiological phenomena. In a multi-disciplinary approach, the eNeuroMus project aims to test the hypothesis that delivery of brain-like input, currently excluded from NMO models, will enhance the complexity and maturation status of NMOs toward adult tissue stages. To this end, NMOs will be interfaced with conformable multielectrode arrays, based on organic conducting polymers, to expose NMOs to brain-like input via electrical stimulation and to record NMO electrophysiological activity in a growth stage-dependent manner. To decipher the effects of electrical stimulation on tissue maturation, electrophysiology assays will be combined with cutting-edge technologies, including spatial transcriptomics, optogenetics and advanced imaging. This analysis pipeline will result in a rich dataset, unravelling the long-term effects of electrical stimulation and the molecular pathways involved in the maturation of human neuromuscular organoids. Overall, the eNeuroMus project will deliver a novel and sophisticated framework for engineering the next generation of biohybrid organoids as tools for modelling human development and disease.