Finalized projects

1)

Platform for CRISPR/Cas9 technology and AAV8 atherosclerosis model

S03N will generate and test CRISPR/Cas genome editing tools which can inactivate or modify the desired loci in cellular and mouse models. S03N will elucidate in detail the phenotype of the already established Glo1 KO Mouse line and the Akr1b3-deficient line which is still to be generated, incorporating the expertise of numerous projects. Additionally, a flexible, non-genetic animal model for the study of macroangipathic complications will be provided, which can be implemented into established mouse lines by a single virus injection and combined with diabetes models.

Project in: SFB 1118: Reaktive Metabolite als Ursache diabetischer Folgeschäden
Project leads: Professor Dr. Marc Freichel; Dr. Rebekka Medert, seit 7/2022; Dr. Dagmar Schumacher, bis 6/2022
Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 236360313

2)

TRPC-cation channels in hypoglycemia-accociated autonomic failure in diabetes models (B02) (2014 – 2023 – Sonderforschungsbereich 1118)

In B02, the role of TRPC channel-mediated sympatho.adrenal counterregulation will be studied in catecholaminergic neurons and neuroendocrine cells, such as neurons in the brainstem and chromaffin cells of the adrenal medulla. The TRPC channel functions and their significance in Ca²⁺ homeostasis and Ca²⁺-dependent exocytosis of catecholamines will be analyzed in these cells. Based on previous and further metabolome analyses, we will develop the basis for interventional therapies for defective autonomic counterregulation in HAAF (“hypoglycemia-associated autonomic failure”).

Project in: SFB 1118: Reaktive Metabolite als Ursache diabetischer Folgeschäden
Project lead: Professor Dr. Marc Freichel
Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 236360313

3)

The membrane proteins TMEM1, 2 and 4 (A15) (2011 – 2012 – Collaborative Research Center 894)

We aim to characterize the cellular functions of the previously unannotated membrane proteins TMEM1-, TMEM2- and TMEM4 with regard to cellular cation homeostasis and their integrative systemic physiological functions in mice. We expect groundbreaking insights from studies on subcellular localization. We use the insights from the observed phenotype of the TMEM-deficient mice as well as from the properties of the structurally similar TRPML proteins, the mucolipins, which form cation channels in the plasma membrane and in intracellular organelles.

Project in: SFB 894: Ca2+-Signale: Molekulare Mechanismen und Integrative Funktionen
Project lead: Professor Dr. Marc Freichel
Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 157660137

4)

Deletion and functional analysis of calcium channels in mice. (A 06) (2002 – 2011 – Collaborative Research Center 530)

With the help of transgenic mouse models, we investigate the biological functions of TRP proteins as subunits of cation channels that are activated by extracellular agonists or intracellular signaling molecules. The focus of the project will be to identify the roles of TRPV6 for male fertility and of TRPCs, TRPM3, TRPM4 and TRPM7 for Ca²⁺ influx into vascular smooth muscle cells, vascular contractility and blood pressure regulation as well as for platelet functions.

Project in: SFB 530: Räumlich-zeitliche Interaktionen zellulärer Signalmoleküle
Project lead: Professor Dr. Marc Freichel
Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 5483434

5)

GRK 1874: Diabetic microangiopathy (2013 – 2021 – International Graduate School)

Project in: SFB 530: Räumlich-zeitliche Interaktionen zellulärer Signalmoleküle
Project lead: Professor Dr. Marc Freichel
Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 5483434

5)

GRK 1874: Diabetic microangiopathy (2013 – 2021 – International Graduate School)

Chronic hyperglycemia explains about 10% of the variability of diabetic microvascular complications. The remaining 90% is unexplained. Nevertheless, chronic hyperglycemia is the most important risk factor, e.g. for diabetic retinopathy. Recent research also shows that complications not only damage small vessels in the eye, kidney and nerve, but more or less all cells of an affected organ with varying proportions of individual cells in the total damage. The list of factors relevant to our understanding of pathogenesis and therapies based on it includes general mechanisms of glucose toxicity, protective factors against glycemic stress and cells or (sub)cellular components that are resistant to hyperglycemic damage. With a continued focus on the DIAMAP goals (a roadmap for diabetes research in Europe until 2020), the International Research Training Group 1874 “DIAMICOM” investigates these common mechanisms of early tissue damage, factors that mediate protection from damage, including those with beneficial or harmful memory function, and novel pathogenetically based therapies in four research areas (mechanisms – eye – kidney – nerve). The scientific projects are in line with the main objective of DIAMICOM, the joint training of excellent graduates from the fields of medicine and life sciences, in order to bridge the “valley of death” of mutual lack of understanding of the respective research on the one hand, and to support the training of clinical researchers of the future on the other. Researchers at the University of Heidelberg (Mannheim and Heidelberg sites) have a good reputation in the field of experimental and clinical microangiopathy research and work in an excellent scientific environment, which is particularly supported by the establishment of the SFB 1118 (Reactive Metabolites as a Cause of Diabetic Complications; spokespersons P Nawroth and S Herzig). The partners in Groningen (UMCG) are internationally recognized for their excellence in experimental diabetology, vascular biology and pharmacotherapy. Both universities enjoy a long-standing collaboration in the field of joint graduate education with an established international MDPhD program. Sanofi as a partner supports the consortium in a very sustainable way through scientific and technological contributions, and supports graduate education with targeted contributions to individual project development and general career perspectives. Overall, DIAMICOM combines scientific excellence in microangiopathy research with a unique coeducational model of graduate education that includes important aspects of the private sector.

DFG-project International Graduate school (The Netherlands)
Collaborating scientists: Professorin Dr. Karen Bieback; Dr. Uta Binzen; Privatdozentin Dr. Yuxi Feng; Dr. Thomas Henry Fleming; Professor Dr. Marc Freichel; Dr. Wolfgang Greffrath; Professor Markus Hecker, Ph.D.; Dr. Aimo Kannt; Professor Dr. Jens Kroll; Professor Dr. Bernhard K. Krämer; Professorin Julia Kzhyshkowska, Ph.D.; Professor Dr. Peter Nawroth; Professor Dr. Martin Schmelz; Professor Dr. Rudolf Schubert; Dr. Dagmar Schumacher; Professor Dr. Jonathan Paul Sleeman; Professor Dr. Rolf-Detlef Treede; Professor Dr. Andreas H. Wagner; Dr. Paulus Wohlfahrt; Professor Dr. Benito Antonio Yard
Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 214631492

6)

Neuronal intracellular calcium stores in inflammatory neurodegeneration (2015-2023) (Research group (Forschungsgruppe) 2289)

Multiple sclerosis (MS) is the most common inflammatory disease of the CNS. The MS-associated inflammatory response leads to a continuous degeneration of axons and neurons, resulting in progressive and permanent neurological disability of patients as the disease progresses. We have recently shown that the neuronal calcium-activated cation channel TRPM4 from the TRP cation channel family is activated by MS-associated inflammatory stimuli and plays a crucial role in the development of neurodegeneration. However, the role of other members of the TRP channel family with regard to protection or aggravation of neuronal cell death in inflammatory processes in the CNS is still completely unknown. Since many members of the TRP channel family act as sensitive sensor proteins for different environmental stimuli, we would like to identify those channel proteins that contribute directly or indirectly to the damage or protection of neurons by influencing immune responses or endothelial functions. Our preliminary work shows that the expression of TRPV4 is strongly upregulated in inflamed CNS tissue, and Tprv4-deficient mice show attenuated disease progression in the animal model of MS, experimental autoimmune encephalomyelitis (EAE). Part 1 of the work program will investigate how TRPV4 channel activity contributes to the pathogenesis of this disease in order to elucidate the key TRPV4 channel-mediated mechanisms of MS pathogenesis. In part 2 of the work program, our analysis will be extended to identify differentially expressed cation channels and their regulators in cells and tissues affected in the EAE model. By establishing new genome editing technologies in neuronal cells, in particular CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-mediated recombination, it should be possible in the medium term to identify new regulators of neuronal calcium homeostasis in an unbiased experimental approach and to investigate them functionally with regard to neurodegeneration and neuroprotection. In summary, our proposal aims to identify the contribution of TRP channels and other regulators of neuronal calcium homeostasis to neurodegeneration in the CNS driven by inflammatory processes and to develop the basis for new neuroprotective therapeutic strategies for MS.

Project in:: FOR 2289: Kalzium-Homöostase bei Neuroinflammation und -degeneration: Neue Ansatzpunkte für die Therapie der multiplen Sklerose?
Project Lead: Professor Dr. Marc Freichel; Professor Dr. Manuel A. Friese
Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 262890264

7)

The role of TRPC1 C4 C5 C6 and related proteins for Ca2+ signaling in mast cells (2009 – 2017) (Schwerpunktprogramme 1394)

A sustained elevation of intracellular Ca²⁺ concentration is an obligatory signal for mast cell activation induced by most stimulants. Recently, several membrane proteins were identified in primary mast cell models that regulate Ca²⁺ entry either as ion conducting constituents (e.g. Orai1), as direct activators of Ca²⁺ entry channels (e.g. Stim1) or by functional agonism/antagonism (e.g. SK4, TRPM4). However, numerous additional proteins including members of the TRPC family of cation channels, that are able to build or regulate Ca²⁺ conducting channels, were identified in mast cells. Despite an extensive search for TRP channel modulators, studies to unravel their function and activation mode in primary cells and on organismic level still rely on experiments using transgenic animals in most cases due to the lack of agonists or antagonists with sufficient potency and specificity. We aim to define new and to refine known communication pathways contributing to agonist-induced [Ca²⁺]_i rise in peritoneal mast cells (PMCs) as a model for mature connective tissue mast cells which differ in many aspects including their Ca²⁺ signals from other mast cell models. We conduct a systematic expression analysis of genes encoding TRP channels and structurally and functionally related membrane proteins in PMCs. We have identified four TRPC proteins as important regulators of Ca²⁺ signaling induced by FcεRI-stimulation and Endothelin-1 and aim to identify the underlying channel, the mechanisms by which it regulates Ca²⁺ entry and its relevance for mast cell functions.

Project in: SPP 1394: Mast-cells – promoters of health and modulators of disease
Project Lead: Professor Dr. Marc Freichel
Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 124742924

8)

The role of TRP channels in cardiac remodeling (2007 – 2015) (Clinical research group (Klinische Forschungsgruppe) 196)

TRP cation channels open after stimulation of Gq/11-coupled receptors (e.g. AT1, ETA and α1 receptors) and activation of phospholipase C. In the heart, these channels could trigger sustained Ca²⁺ signaling and thereby signaling pathways involving CaM kinase, protein kinase C and calcineurin, leading to hypertrophy and insufficiency or tachyarrhythmias. To verify this possible involvement of TRP channels, we will 1) identify individual TRPs in cardiomyocytes; 2) analyze TRP-induced Ca²⁺ signals and currents in cardiomyocytes; 3) characterize TRPC-deficient mice with respect to cardiac function compared to wild-type animals; 4) identify TRPM4- or TRPM5-deficient mice in comparison to wild-type animals in terms of cardiac rhythmicity under “normal” and Ca²⁺ overload conditions and 5) try to transfer the results obtained in 1) to 4) to human heart tissue. Our hypotheses are that TRPC and TRPM4 channels are involved in the pathogenesis of cardiac hypertrophy and tachyarrhythmias, respectively, and represent targets of new drug strategies for these diseases. We have produced a large proportion of the TRP-deficient mouse animal models relevant for the proposed investigations in Homburg; others are available within the framework of collaborations. We have also produced specific antibodies against some of the relevant TRPs, which enable the identification of TRP proteins in cardiomyocytes. Our aim is to transfer the findings obtained in mice to humans in collaboration with the sub-projects of the proposed Clinical Research Unit.

Project lead: Professor Dr. Marc Freichel
Collaborator: Professor Dr. Veit Flockerzi
Project in: KFO 196: Signaltransduktion bei adaptiven und maladaptiven kardialen Remodeling-Prozessen
Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 35635434