- strongly increase mtorc1 activity
- activates mtorc2
- IGFs are peptide growth factors structurally similar to
- Endocrine Hormone
- Paracrine Hormone
- Autocrine Hormone
-
- Central to growth, development, metabolism, and tissue repair
Types
- IGF-1 - Chromosome 12 - Synthesized primarily in Liver
- IGF-2 - Chromosome 11
Characteristics
- Produced locally in
- brain
- skeletal-muscle primarily but also in other tissues
- Bone
- Adipose tissue
Role in the nervous system
- Strong neurotrophic factor
- Promotes:
- Neuronal survival
- Neurogenesis
- Synaptic plasticity
- Myelination
- Enhances learning, memory, and cognition
- Interacts with BDNF and Nerve Growth Factor
Endocrine regulation
-
↑ IGF-1 by:
- Growth hormone
- Adequate protein intake
- Sleep
- Exercise (especially resistance training)
-
↓ IGF-1 by:
- Fasting
- Malnutrition
- Chronic inflammation
- Aging
- Liver disease
Pathophysiological roles
-
Deficiency
- Growth failure
- Muscle wasting
- Cognitive impairment
-
Excess
- Acromegaly-like features
- Increased cancer risk (via mitogenic signaling)
-
Cancer
- Promotes tumor growth, angiogenesis, and metastasis
-
Aging
- Declines with age
- Longevity trade-off: high IGF = growth, low IGF = lifespan extension (context-dependent)