Growth Differentiation Factor 15 (GDF15) and GDF11 are members of the TGF-β (Transforming Growth Factor beta) superfamily that have emerged as critical regulators of energy homeostasis, stress responses, and more recently, neuroprotection. Originally characterized for their roles in embryonic development, these cytokines have gained significant attention for their involvement in aging, metabolic disorders, and neurodegenerative diseases.
GDF15 and GDF11 Biology
Structural Features
GDF15 and GDF11 are secreted cytokines belonging to the TGF-β superfamily. They share structural homology with other family members but have distinct biological functions: [@wang2023]
GDF15: Also known as MIC-1 (Macrophage Inhibitory Cytokine-1), NAG-1 (Non-Steroidal Anti-Inflammatory Drug-Activated Gene), and PTGFB (Placental Transforming Growth Factor Beta)
GDF11: Known as BMP-11 (Bone Morphogenetic Protein-11), involved in embryonic patterning and tissue development
Both proteins are synthesized as precursor molecules that undergo proteolytic cleavage to produce the mature, biologically active form. [@johnen2023]
Expression Patterns
GDF15 is expressed in virtually all tissues but is highly expressed in: [@yatsiv2024]
Placenta
Liver
Kidney
Brain (particularly in regions involved in energy homeostasis)
Adipose tissue
Muscle
GDF11 expression is more restricted, with high levels in: [@schmidt2023]
Developing nervous system
Skeletal muscle
Heart
Pancreas
TGF-β Family Relationships
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GDF15/GDF11 Signaling in Neurodegeneration
Overview
Growth Differentiation Factor 15 (GDF15) and GDF11 are members of the TGF-β (Transforming Growth Factor beta) superfamily that have emerged as critical regulators of energy homeostasis, stress responses, and more recently, neuroprotection. Originally characterized for their roles in embryonic development, these cytokines have gained significant attention for their involvement in aging, metabolic disorders, and neurodegenerative diseases.
GDF15 and GDF11 Biology
Structural Features
GDF15 and GDF11 are secreted cytokines belonging to the TGF-β superfamily. They share structural homology with other family members but have distinct biological functions: [@wang2023]
GDF15: Also known as MIC-1 (Macrophage Inhibitory Cytokine-1), NAG-1 (Non-Steroidal Anti-Inflammatory Drug-Activated Gene), and PTGFB (Placental Transforming Growth Factor Beta)
GDF11: Known as BMP-11 (Bone Morphogenetic Protein-11), involved in embryonic patterning and tissue development
Both proteins are synthesized as precursor molecules that undergo proteolytic cleavage to produce the mature, biologically active form. [@johnen2023]
Expression Patterns
GDF15 is expressed in virtually all tissues but is highly expressed in: [@yatsiv2024]
Placenta
Liver
Kidney
Brain (particularly in regions involved in energy homeostasis)
Adipose tissue
Muscle
GDF11 expression is more restricted, with high levels in: [@schmidt2023]
Developing nervous system
Skeletal muscle
Heart
Pancreas
TGF-β Family Relationships
GDF15 and GDF11 belong to the TGF-β superfamily but represent a distinct branch separate from classical TGF-βs (TGF-β1, TGF-β2, TGF-β3) and BMPs (Bone Morphogenetic Proteins). They share: [@tanaka2024]
Type I and Type II receptor binding
SMAD-dependent signaling pathways
Dimeric structure
Key distinguishing features: [@hsiao2023]
GDF15 signals primarily through the GFRAL-RET receptor complex
GDF11 signals through activin type I and type II receptors
GFRAL/RET Receptor Complex
Receptor Structure
GDF15 exerts its effects primarily through a unique receptor complex: [@muller2023]
GFRAL (Glial Cell Line-Derived Neurotrophic Factor Receptor Alpha-Like): The primary binding receptor, expressed predominantly in the brainstem
RET (Rearranged During Transfection): The co-receptor that initiates intracellular signaling
This receptor complex was identified as the canonical receptor for GDF15 in 2017, explaining its effects on energy balance and body weight. [@kempf2024]
Signaling Pathways
Upon GDF15 binding to GFRAL: [@wiedmann2023]
RET autophosphorylation
Activation of PI3K-AKT pathway
MAPK/ERK pathway activation
PLCγ pathway activation
These downstream pathways regulate: [@liu2024]
Cell survival
Metabolic regulation
Neuroprotection
Stress-Regulated Expression
Cellular Stress
GDF15 expression is dramatically upregulated by various cellular stresses:
Oxidative stress: ROS accumulation induces GDF15 transcription via NRF2