Combining two "stomach" and one, opening up the blocking point in the development of cholecystokinin receptor-targeted drugs

Combining two "stomach" and one, opening up the blocking point in the development of cholecystokinin receptor-targeted drugs

Combine two "stomach" one, open up the blocking point for the development of cholecystokinin receptor targeted drugs Combine two "stomach" one, open up the blocking point for the development of cholecystokinin receptor targeted drugs

In 1968, cholecystokinin (CCK), one of the important gastrointestinal hormones, was extracted and identified
.

Cholecystokinin receptor (CCKR) is a potential therapeutic target for diseases such as obesity, type 2 diabetes and anxiety

On September 23, "Nature-Chemical Biology" published two "back-to-back" research results online
.

One is titled "Cholecystokinin receptor peptide ligand recognition and G-coupled protein selectivity mechanism", and the other is titled "Cholecystokinin receptor and agonist and inhibitor complex three-dimensional structure"

The research systematically revealed the structural basis for the specific recognition of cholecystokinin receptor subtypes by a variety of peptides and small molecule ligands, clarified the molecular mechanism of ligand selectivity and receptor activation, and cracked the type A human cholecystectomy The mystery of life of the selective coupling of different G proteins to CCKAR provides important information for the development of drugs targeting this type of receptor
.

The above two research results were completed by the team of Jiang Yi/Xu Huaqiang, the team of Zhao Qiang, the team of Wu Beili, the team of Wang Mingwei/Yang Dehua, and the team of Assistant Professor Zhao Suwen of Shanghai University of Science and Technology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (hereinafter referred to as Shanghai Institute of Materia Medica, Chinese Academy of Sciences )
.

Chinese Academy of Sciences

Reveal the mechanism of G protein selectivity

Reveal the mechanism of G protein selectivity

CCK and Gastrin are abundant in the gastrointestinal tract and central nervous system.
They play the role of hormone regulation and neurotransmitter by binding to cholecystokinin receptors
.

Both are members of the tyrosyl sulfonated polypeptide family and have a conserved carboxy-terminal octapeptide sequence

Among them, CCK receptors include two subtypes A and B (CCKAR and CCKBR), which belong to the class A G protein-coupled receptor (GPCR)
.

CCKAR specifically recognizes sulfonated CCK, while CCKBR has a strong affinity for both sulfonated and non-sulfonated CCK and Gastrin

These two types of CCK receptors are involved in the regulation of physiological functions such as satiety, pancreatic enzyme secretion and gallbladder contraction.
They are also related to anxiety, memory and drug addiction.
They are used to treat obesity, type 2 diabetes, anxiety and other related diseases Potential targets
.

However, due to problems such as low efficacy and bioavailability, most drug candidates that target CCKR are terminated in clinical studies
.

Highly selective CCKAR non-peptide antagonists, such as Devazepide and Lintitript are typical examples of forced termination.

Therefore, conducting research on the structure and function of CCKR will deepen the understanding of its ligand recognition mechanism, which is of great significance for the creation of related new drugs
.

After GPCR is activated by ligand, signal transduction is mainly carried out by coupling to the G protein in the cell
.

According to the different α subunits, G proteins can be divided into four subfamilies: Gi/o, Gs, Gq/11 and G12/13

In the first study, the team led by Yi Jiang/Huaqiang Xu and the team of Wang Mingwei/Yang Dehua, etc.
, analyzed the cryo-EM structure of the complex of CCKAR activated by sulfonated CCK-8 and Gq, Gs, and Gi proteins, and resolved it.
The rates are 2.
9 angstroms, 3.
1 angstroms, and 3.
2 angstroms, respectively
.

Combined with structural analysis and functional verification, the researchers demonstrated the binding mode of the endogenous polypeptide hormone-sulfonated CCK-8 (hereinafter referred to as CCK-8), that is, the amino terminal of CCK-8 is composed of three extracellular loops (ECL) of the receptor.

In addition, they also identified the key amino acid residues of CCK-8 and the key sites where the sulfonated group exerts CCK-8 activity, and described the molecular mechanism of CCKAR's selective coupling of Gq, Gs and Gi, and proposed The new mechanism that ICL3 participates in the coupling of CCKAR and Gq
.

Jiang Yi told the Chinese Journal of Science, "This study reveals the endogenous modification of peptides-the mechanism of sulfonation in peptide hormone recognition receptors and activity, which is of great significance for understanding the mechanism of GPCR activity
.

Next, , We will continue to in-depth study of the mechanism of peptide hormone action

Cracking the mystery of CCKR's peptide ligand recognition

Cracking the mystery of CCKR's peptide ligand recognition

"Both agonists and antagonists of CCK1 can be used as drugs to treat different human diseases
.
Therefore, understanding the structure of the receptor in the excited and inhibited state is of great significance for drug development
.
" Zhao Qiang told China Science Daily
.

He said that CCKAR is a G protein-coupled receptor, which has a certain degree of structural flexibility.
It is a big challenge to stabilize the receptor in an excited or inhibited state
.
Especially the structure in the inhibited state needs to be obtained by X-ray crystallography, which has higher requirements for the preparation and quality control of protein samples
.

In the second study, Zhao Qiang's team and Wu Beili's team led and combined with Wang Mingwei/Yang Dehua's team and Zhao Suwen's team.
After overcoming many difficulties, they analyzed the three crystals of CCKAR combined with the small molecule antagonist Devazepide, Lintitript and the agonist NN9056 The structure, and the cryo-EM structure of two complexes of CCKBR that binds to the peptide Gastrin and Gi and Gqo, respectively
.

This study revealed the molecular mechanism by which peptides and small molecule antagonists recognize CCKR, and found that ECL2 is the determinant of CCKAR and CCKBR's selective recognition of peptide ligands
.
At the same time, researchers also found that N3336.
55 and R3366.
58 played a key role in CCKAR's identification of Devazepide and Lintitript
.

By comparing the structure of the CCKAR binding antagonist Devazepide, the structure of the CCKAR binding agonist NN9056, and the structure of the CCKAR binding agonist CCK-8ns and Gq protein, combined with molecular dynamics simulation experiments, the researchers explained the gradual activation process of CCKAR
.

"By analyzing different structural states, it will help to understand the activation mechanism of cholecystokinin receptors and assist in the development of new drugs
.
" Zhao Qiang said, "Next, we will further focus on the activation process of cholecystokinin receptors and carry out In-depth research
.
"

This work was funded by the Key R&D Program of the Ministry of Science and Technology, the Major Science and Technology Project of the National Health Commission, the National Natural Science Foundation of China, the Pilot Project of the Chinese Academy of Sciences, and the Major Science and Technology Project of Shanghai
.
(Source: Tian Ruiying, China Science News)

Related paper information:

https://doi.
org/10.
1038/s41589-021-00841-3

https://doi.
org/10.
1038/s41589-021-00841-3

https://doi.
org/10.
1038/s41589-021-00866-8

https://doi.
org/10.
1038/s41589-021-00866-8