Molecular sensory physiology group (Head: Alexandra Koschak)   

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Staff


Researchers:
- Kathrin Kähler
- Irem Kilicarslan
- Hartwig Seitter
- Lucia Zanetti
- Alexandra Koschak
Technician:
- Bettina Tschugg
Collaborators:
- Tom Fenzl (MUI)
- Simone Sartori, Nicolas Singewald
- Jörg Striessnig


This research group is interested in L-type calcium channels in molecular sensory physiology and pharmacology and currently focuses on the following three topics


  1. Contribution of L-type calcium channels in sensory physiology of vision
  2. Role of L-type calcium channels in visual disorders
  3. The retina as window to the brain
 

1.       Contribution of L-type calcium channels in sensory physiology of vision


Photoreceptors are morphologically and physiological highly specialised light sensing cells of the retina. In darkness their membrane potential is depolarized up to -36 mV due to the activity of cGMP activated cation channels. Sustained release of glutamate from photoreceptor ribbon synapses is Ca2+ dependent and L-type calcium channels (LTCCs) serve as the predominant source for Ca2+ entry. Cav1.4 LTCCs channels – which are encoded by the CACNA1F gene - are located in close vicinity to the typical horseshoe shaped ribbon synapses and play an important role for signal retinal transmission.

 

 

2.       Role of L-type calcium channels in visual disorders



A number of channel dysfunctions 2 have been described that are caused by mutations in the CACNA1F gene, which encodes for the Cav1.4 LTCC alpha1 subunits. A majority of mutations was, however, identified among patients originally diagnosed with congenital night blindness type 2 (CSNB2; OMIM: 30071). Many Cav1.4 mutations are predicted to cause severe structural changes that they are unlikely to form functional channels, often due to premature truncation forming a large group of ‘loss-of-function’ mutations. ‘Gain-of-function’ mutations would promote pronounced Ca2+ entry through the channel. We still wish to better understand how the different functional channel phenotypes can all result in defective retinal synaptic transmission underlying CSNB2 symptoms.


 

3.       The retina as window to the brain



Major central nervous system disorders that affect the brain and spinal cord are also manifested in the eye, and ocular symptoms often precede conventional diagnosis of those CNS disorders. To better understand the retina as a biomarker for different Parkinsonian diseases we are currently investigating the neuroretina of animal models.

If you are interested in more general information about:
‘The Organisation of the Retina and the Visual System’ – click here

 
‘Pathologies of Calcium Channels’– click here
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