The adrenergic-induced ERK3 pathway drives lipolysis and suppresses energy dissipation

Area of Science:

• Molecular Biology
• Metabolic Disease Research
• Cell Signaling

Background:

• Obesity-induced diabetes impacts over 400 million globally.
• Uncontrolled lipolysis, or free fatty acid release from adipocytes, is linked to obesity and diabetes.
• Identifying novel therapeutic targets for lipolysis is crucial.

Purpose of the Study:

• To identify novel regulators of lipolysis through a high-throughput screen.
• To elucidate the signaling pathway involving extracellular-regulated kinase 3 (ERK3) in adipocytes.
• To investigate the therapeutic potential of targeting the ERK3/MAP kinase-activated protein kinase 5 (MK5) axis for metabolic diseases.

Main Methods:

• High-throughput screening to identify key proteins in lipolysis.
• Biochemical assays to determine protein interactions and complex formation (ERK3/MK5).
• Analysis of downstream targets, including transcription factor FOXO1 and lipolytic enzyme ATGL.
• Genetic manipulation (targeted deletion of ERK3) in mouse adipocytes to assess in vivo effects.

Main Results:

• Extracellular-regulated kinase 3 (ERK3) was identified as a key regulator of lipolysis.
• β-adrenergic stimulation stabilizes ERK3, leading to complex formation with MAP kinase-activated protein kinase 5 (MK5).
• The ERK3/MK5 pathway upregulates the transcription factor FOXO1, increasing ATGL expression and promoting lipolysis.
• Targeted deletion of ERK3 in mouse adipocytes reduced lipolysis but increased energy dissipation, leading to a lean phenotype and improved diabetes markers.

Conclusions:

• The ERK3/MK5 signaling axis is a novel regulator of lipolysis in adipose tissue.
• This pathway plays a significant role in the development of obesity-induced diabetes.
• Targeting the ERK3/MK5 axis presents a promising therapeutic strategy for combating obesity and type 2 diabetes.