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Development of orphan G-protein coupled receptor peptidic ligand identification system



Project Title: „Development of orphan G-protein coupled receptor peptidic ligand identification system” 

Funding: European Regional Development Fund (ERDF), Measure “Industry-Driven Research”

Project Nr.:

Period: 1st January 2017 – 31st December 2019

Project costs: 285 245,84 EUR

Principle Investigator: Dr. biol. D. Fridmanis


The aim of this Project is to develop humanized yeast S.cerevisiae based GPCR peptide ligand identification system and to evaluate its effectiveness by de-orphanization of C.intestinalis orexin-like receptor and determination of novel ligand’s pharmacological properties. The results of this Project shall provide instrument for the development of novel pharmaceutical compounds and promote development of biopharmaceutical industry in Latvia.

Information published: 02.01.2017.


Progress of the project

1 January 2017 - 31 March 2017

Experimental development

According to plan the first three months of the project were devoted to creation of double expression plasmid. Since p426GPD and p426TEF expression plasmids that have been successfully employed by our group are nearly identical, then within the scope of these activities we altered the multi-clonal sites of the expression loci in a way that each would contain only two unique cloning/restriction sites, thus becoming mutually compatible. Following the modification of both plasmids we performed the sequencing analysis of both expression loci to ascertain the conformity of acquired sequences to planned ones and carried out the transfer of TEF containing locus from p426TEF to p426GPD plasmid. At the moment we are performing the sequencing analysis of thus acquired construct.

Information published: 31.03.2017.

Progress of the project

1 April 2017 - 30 June 2017

Experimental development

During this project phase the functional regions of TEF promoter containing plasmid that were relevant for gene expression were transferred to GDP promoter containing plasmid. Further within thus acquired double expression plasmid MC4R and a-MSH coding genes were inserted and following their insertion conformity of acquired results with the plans was established by sequencing analysis. After acquisition of expression constructs we commenced with evaluation of its functionality.

Information published: 30.06.2017.


Progress of the project

1 July 2017 - 30 September 2017

Experimental development

During this project phase we initiated the functional testing of previously created double expression plasmid. Within the scope of these activities the newly created plasmid was inserted into the cells of humanized yeast S.cerevisiae strain MMY28, which were subsequently seeded within the selective media containing petri dish. The media within selected dishes was supplemented with MC4R ligand - a-MSH as the means of positive control. Acquired results were ambiguous therefore experiments shall be repeated during further project stages.

Information published: 29.09.2017.


Progress of the project

1 October 2017 - 31 December 2017

Experimental development

During this stage of the project we continued with the evaluation of previously created double expression. During these activities plasmids were repeated transformed within yeast S.cerevisiae strain MMY28 cells, which subsequently were seeded on peri-dishes with selective media that in several cases was supplemented with a-MSH. Acquired results, unfortunately, were again ambiguous, therefore it was decided to assess the expression activity of the plasmids employing Western-Blot with a‑MSH specific antibodies. In parallel to facilitate the progress of the whole project we developed an experimental plan that involved successive yeast S.cerevisiae strain MMY28 cell transformation with two separate plasmids.

Information published: 02.01.2018.


Progress of the project

1 January 2018 - 31 March 2018

 Experimental development

Within the scope of Experimental development activity experiments on evaluation previously created plasmid ability to secrete a-MSH were re carried out. These experiments involved employment of Western-Blot spotting with a-MSH specific antibody. Acquired results confirmed that a-MSH is being successfully secreted, however, since the signal was rather week, it was concluded that its amount could be insufficient to effectively activate the co-expressed MC4R, which could explain ambiguity in previously acquired results. To resolve this issue, an in-depth literature analysis was carried out and as the result it was concluded that it might be necessary to insert the linker peptide between the secretion signal and secreted peptide. T the moment the creation of this construct is being carried out. In parallel with these activities, an experiment on sequential transformation of two separate (first receptor and then random peptide) plasmids into the yeast S.cerevisiae MMY28 strain cells and their subsequent the culturing in histidine lacking media, that promotes propagation of only those cells that expressed receptor is activated. Acquired results were promising, because cells cultures that contained both plasmids were growing faster that thos that contained only the receptor expression plasmid.

System validation

Since the results that were gained within the scope of “Experimental development activity” displayed that the developed experimental system could be operational, within the scope of this activity we attempted to assess it. During these experiments we created plasmid that instead of a-MSH coding sequence contained coding sequence for randomized peptide. Further this plasmid along with MC4R coding sequence containing plasmid were successively transformed into yeast S.cerevisiae MMY28 strain cells, then cultured for several days within the histidine lacking media and extracted. Further, thus acquired plasmid DNA along with randomized source plasmid were used for generation of randomized region Next Generation Sequencing libraries and sequenced using IonTorrent PGM sequencing system. Acquired results showed that selection of clones which contained a-MSH coding sequence has taken place during the randomization and not culturing stage. Therefore during the next project stages improvements in randomization process shall be made.

Information published: 29.03.2018.

Mājas lapas izstrādi finansēja ERAF aktivitātes projekts Nr. 2010/0196/2DP/ "Latvijas biomedicīnas pētījumu integrācija Eiropas zinātnes telpā".