Reference

Zheng, Z., Zong, Y., Ma, Y., Tian, Y., Pang, Y., Zhang, C., & Gao, J. (2024). Glucagon-like peptide-1 receptor: Mechanisms and advances in therapy. Signal Transduction and Targeted Therapy, 9(1), 1–29. https://doi.org/10.1038/s41392-024-01931-z


Yellow: Interesting

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GLP-1R, is a vital component of the G protein-coupled receptor (GPCR) family

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CLASSICAL PATHOPHYSIOLOGICAL MECHANISMS OF GLP-1

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The rise in cAMP activates protein kinase A (PKA), which then promotes the synthesis and secretion of insulin and inhibits the release of glucagon.178,179

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cAMP can activate Rap1 through EPAC (Exchange Protein directly Activated by cAMP),180–182 which is involved in regulating insulin secretion.180,181,183 GLP-1 also activates the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway, which is crucial for maintaining the survival and function of pancreatic β-cells.184–187

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increasing the sensitivity of peripheral tissues to insulin

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GLP-1 reduces hepatic glucose production

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The phosphorylation of Akt is necessary for its full activation, allowing it to regulate a variety of downstream effector proteins involved in cell survival, proliferation, metabolism, and glucose transport

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Simultaneously, Akt promotes cell survival by phosphorylating and inhibiting a series of pro-apoptotic proteins, such as Bad and the FOXO family.202–204 Moreover, Akt can activate mTORC1, further promoting

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GLP-1 not only plays a crucial role in the treatment of diabetes by enhancing the function and protecting pancreatic β-cells from apoptosis, but it may also offer potential therapeutic benefits in fields such as cardiovascular and neural protection

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In α-cells, increased cAMP affects glucagon synthesis and release.228 PKA, activated by cAMP, can regulate the activity of K-ATP channels in α-cells.228,229 The opening of these channels is controlled by the intracellular ATP/ ADP ratio.229 Specifically, PKA modifies the open state of K-ATP channels through phosphorylation, affecting the cell membrane’s potential and intracellular calcium ion concentration.230,231 By modulating the activity of K-ATP channels, GLP-1 indirectly controls the calcium signaling in α-cells, thereby influencing glucagon secretion.232,233 GLP-1 inhibits the release of glucagon from α-cells through multiple mechanisms. GLP-1 can directly bind to the receptors on the surface of α-cells in the pancreas, inhibiting the secretion of glucagon from these cells.

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GLP-1 can stimulate pancreatic β-cells to release insulin.236,237

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GLP-1 can reduce blood glucose production by delaying gastric emptying and decreasing appetite

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GLP-1 can slow down gastric emptying by activating the vagus nerve, a part of the autonomic nervous system crucial for regulating the activities of the gastrointestinal tract.268 When activated, the vagus nerve can reduce the contraction of the stomach, thereby slowing down food emptyin

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g.