Multi-omics analysis of glucose-mediated signaling by a moonlighting Gβ protein Asc1/RACK1

Heterotrimeric G proteins were originally discovered through efforts to understand the effects of hormones, such as glucagon and epinephrine, on glucose metabolism. On the other hand, many cellular metabolites, including glucose, serve as ligands for G protein-coupled receptors. Here we investigate the consequences of glucose-mediated receptor signaling, and in particular the role of a Gα subunit Gpa2 and a non-canonical Gβ subunit, known as Asc1 in yeast and RACK1 in animals. Asc1/RACK1 is of particular interest because it has multiple, seemingly unrelated, functions in the cell. The existence of such “moonlighting” operations has complicated the determination of phenotype from genotype. Through a comparative analysis of individual gene deletion mutants, and by integrating transcriptomics and metabolomics measurements, we have determined the relative contributions of the Gα and Gβ protein subunits to glucose-initiated processes in yeast. We determined that Gpa2 is primarily involved in regulating carbohydrate metabolism while Asc1 is primarily involved in amino acid metabolism. Both proteins are involved in regulating purine metabolism. Of the two subunits, Gpa2 regulates a greater number of gene transcripts and was particularly important in determining the amplitude of response to glucose addition. We conclude that the two G protein subunits regulate distinct but complementary processes downstream of the glucose-sensing receptor, as well as processes that lead ultimately to changes in cell growth and metabolism.

Download Full-text

Multi-omics analysis of glucose-mediated signaling by a moonlighting Gβ protein Asc1/RACK1

10.1101/2021.01.12.426444 ◽

2021 ◽

Author(s):

Shuang Li ◽

Yuanyuan Li ◽

Blake R. Rushing ◽

Susan L. McRitchie ◽

Janice C. Jones ◽

...

Keyword(s):

G Protein ◽

Sugar Metabolism ◽

Integrated Approach ◽

Glucose Sensing ◽

Cell Surface Receptor ◽

Protein Subunit ◽

Glucose Fermentation ◽

Α Subunit ◽

Protein Subunits ◽

Individual Gene

ABSTRACTG proteins were originally discovered through efforts to understand the effects of hormones, such as glucagon and epinephrine, on glucose metabolism. On the other hand, many cellular metabolites, including glucose, serve as ligands for G protein-coupled receptors. Here we investigate the consequences of glucose-mediated receptor signaling, and in particular the role of a Gα subunit Gpa2 and a non-canonical Gβ subunit, known as Asc1 in yeast and RACK1 in animals. Asc1/RACK1 is of particular interest because it has multiple, seemingly unrelated, functions in the cell. The existence of such “moonlighting” operations has complicated the determination of phenotype from genotype. Through a comparative analysis of individual gene deletion mutants, and by integrating transcriptomics and metabolomics measurements, we have determined the relative contributions of the Gα and Gβ protein subunits to glucose-initiated processes in yeast. We determined that Gpa2 is primarily involved in regulating sugar metabolism while Asc1 is primarily involved in amino acid metabolism. Both proteins are involved in regulating purine metabolism. Of the two subunits, Gpa2 regulates a greater number of gene transcripts and was particularly important in determining the amplitude of response to glucose addition. We conclude that the two G protein subunits regulate distinct but complementary processes downstream of the glucose-sensing receptor, as well as processes that lead ultimately to changes in cell growth and metabolism.AUTHOR SUMMARYDespite the societal importance of glucose fermentation in yeast, the mechanisms by which these cells detect and respond to glucose have remained obscure. Glucose detection requires a cell surface receptor coupled to a G protein that is comprised of two subunits, rather than the more typical heterotrimer: an α subunit Gpa2 and the β subunit Asc1 (or RACK1 in humans). Asc1/RACK1 also serves as a subunit of the ribosome, where it regulates the synthesis of proteins involved in glucose fermentation. This manuscript uses global metabolomics and transcriptomics to demonstrate the distinct roles of each G protein subunit in transmitting the glucose signal. Whereas Gpa2 is primarily involved in the metabolism of sugars, Asc1/RACK1 contributes to production of amino acids necessary for protein synthesis and cell division. These findings reveal the initial steps of glucose signaling and several unique and complementary functions of the G protein subunits. More broadly, the integrated approach used here is likely to guide efforts to determine the topology of complex G protein and metabolic signaling networks in humans.

Download Full-text

Minireview: Role of Intracellular Scaffolding Proteins in the Regulation of Endocrine G Protein-Coupled Receptor Signaling

Molecular Endocrinology ◽

10.1210/me.2015-1091 ◽

2015 ◽

Vol 29 (6) ◽

pp. 814-830 ◽

Cited By ~ 22

Author(s):

Cornelia Walther ◽

Stephen S. G. Ferguson

Keyword(s):

Signaling Pathways ◽

G Protein ◽

Potential Role ◽

Cell Physiology ◽

Scaffolding Proteins ◽

Receptor Signaling ◽

Heterotrimeric G Proteins ◽

Zona Occludens ◽

G Protein Coupled

Abstract The majority of hormones stimulates and mediates their signal transduction via G protein-coupled receptors (GPCRs). The signal is transmitted into the cell due to the association of the GPCRs with heterotrimeric G proteins, which in turn activates an extensive array of signaling pathways to regulate cell physiology. However, GPCRs also function as scaffolds for the recruitment of a variety of cytoplasmic protein-interacting proteins that bind to both the intracellular face and protein interaction motifs encoded by GPCRs. The structural scaffolding of these proteins allows GPCRs to recruit large functional complexes that serve to modulate both G protein-dependent and -independent cellular signaling pathways and modulate GPCR intracellular trafficking. This review focuses on GPCR interacting PSD95-disc large-zona occludens domain containing scaffolds in the regulation of endocrine receptor signaling as well as their potential role as therapeutic targets for the treatment of endocrinopathies.

Download Full-text

Faculty Opinions recommendation of Obestatin induction of early-response gene expression in gastrointestinal and adipose tissues and the mediatory role of G protein-coupled receptor, GPR39.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1117805.573887 ◽

2008 ◽

Author(s):

Willis Samson

Keyword(s):

Gene Expression ◽

G Protein ◽

Early Response ◽

G Protein Coupled Receptor ◽

Response Gene ◽

Adipose Tissues ◽

Early Response Gene ◽

G Protein Coupled

Download Full-text

Marijuana and β-estradiol interactions on spatial learning and memory in young female rats: Lack of role of the G protein-coupled estrogen receptor (GPR30)

Life Sciences ◽

10.1016/j.lfs.2021.119723 ◽

2021 ◽

pp. 119723

Author(s):

Mohadeseh Chahkandi ◽

Gholamreza Komeili ◽

Gholamreza Sepehri ◽

Mohammad Khaksari ◽

Sedigheh Amiresmaili

Keyword(s):

Estrogen Receptor ◽

Learning And Memory ◽

G Protein ◽

Spatial Learning ◽

Young Female ◽

Female Rats ◽

Spatial Learning And Memory ◽

G Protein Coupled

Download Full-text

Every Detail Matters. That Is, How the Interaction between Gα Proteins and Membrane Affects Their Function

Membranes ◽

10.3390/membranes11030222 ◽

2021 ◽

Vol 11 (3) ◽

pp. 222

Author(s):

Agnieszka Polit ◽

Paweł Mystek ◽

Ewa Błasiak

Keyword(s):

Signal Transduction ◽

G Protein ◽

G Proteins ◽

Lipid Membranes ◽

Signaling Proteins ◽

Heterotrimeric G Proteins ◽

Membrane Attachment ◽

The Individual ◽

Multicellular Organisms ◽

G Protein Coupled

In highly organized multicellular organisms such as humans, the functions of an individual cell are dependent on signal transduction through G protein-coupled receptors (GPCRs) and subsequently heterotrimeric G proteins. As most of the elements belonging to the signal transduction system are bound to lipid membranes, researchers are showing increasing interest in studying the accompanying protein–lipid interactions, which have been demonstrated to not only provide the environment but also regulate proper and efficient signal transduction. The mode of interaction between the cell membrane and G proteins is well known. Despite this, the recognition mechanisms at the molecular level and how the individual G protein-membrane attachment signals are interrelated in the process of the complex control of membrane targeting of G proteins remain unelucidated. This review focuses on the mechanisms by which mammalian Gα subunits of G proteins interact with lipids and the factors responsible for the specificity of membrane association. We summarize recent data on how these signaling proteins are precisely targeted to a specific site in the membrane region by introducing well-defined modifications as well as through the presence of polybasic regions within these proteins and interactions with other components of the heterocomplex.

Download Full-text