Heteroligoremic interactions of the kv1.3 channelosome
- Autores: Sara Raquel Roig Merino
- Directores de la Tesis: Antonio Felipe Campo (dir. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2017
- Idioma: español
- Programa de doctorado: Programa de Doctorado en Biomedicina por la Universidad de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Voltage-gated potassium channels are proteins that allow the flux of potassium ions across the plasma membrane in response to a voltage stimulus. Kv1.3 is expressed at the immune system and it has been associated with the activation and proliferation of leukocytes as well as apoptosis. The fine-tunning of the channel is highly relevant to control the final cell decision. Several different families have been described to modulate some channel features. Kvβ family are cytoplasmic proteins that can enhance their traffic to the plasma membrane and modify the electrophysiology. KCNEs are single spanning proteins that modulate several different Kvα-subunits. Depending on the KCNE subtype, the effect on the channels can present diverse natures.
This thesis described the positioning of Kvβ2.1 in specific regions of the plasma membrane: lipid raft microdomains. The possible mechanism involved is the palmitoylation of its amino acidic sequence; even other causes are not discarded. Proliferation signals are enhancing this localization while PMA treatment generates the opposite effect. This protein, as well as its partner Kvβ1.1, can form oligomers. Their affinity and stoichiometry was addressed and multiprotein complexes were detected at membrane purifications. Regarding their function on the channel, Kv1.3 was removed from lipid raft microdomains and Kvβs prevented partially its PMA-dependent internalization.
The molecular determinants involved in the Kv1.3 traffic to the membrane were localised at the C-terminal domain. Previous published data determined that KCNE4 is impairing the traffic of the channel. This thesis deciphered the molecular mechanisms involved in this effect concluding a bipartite system: (i) masking of Kv1.3 export signal and (ii) transference of a retention signal to the channelosome. Moreover, the specific domains of Kv1.3 and KCNE4 implicated in their interaction were mapped and pointed out to the C-terminal regions of both peptides. KCNE4 was also found to form oligomers and present several signals for its retention at the endoplasmic reticulum.
Finally, the combination of both subunits (Kvβ2.1 and KCNE4) on the channel showed a dominance of KCNE4 effects, but an electrophysiological function of Kvβ2.1 on Kv1.3 kept preserved. Thus, the present thesis brought light to the comprehension of Kv1.3 channelosome.
