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(Pro)insulin and insulin-like growth factor I complementary expression and roles in early development
C Alarcón1, A V Morales, B Pimentel
1Department of Cellular and Developmental Biology, Centro de Investigaciones Biológicas, Madrid, Spain.
Summary
Insulin plays a crucial role in early vertebrate development before insulin-like growth factors (IGFs) are expressed. Inhibiting insulin increases apoptosis, while its modulation aids neural development, suggesting coordinated actions.
Area of Science:
- Developmental Biology
- Endocrinology
- Neuroscience
Background:
- Insulin-like growth factors (IGFs) are known to influence embryonic and postnatal development, including central nervous system growth.
- Previous studies using knock-out models have not demonstrated IGF effects prior to organogenesis.
- The role of insulin and its precursor, proinsulin, in early vertebrate development remains less understood.
Purpose of the Study:
- To investigate the role of insulin and proinsulin in vertebrate development preceding the expression of IGFs.
- To explore the expression patterns of (pro)insulin and IGF-I during embryonic development.
- To elucidate the functional impact of (pro)insulin on apoptosis, DNA synthesis, and neuronal differentiation.
Main Methods:
- Analysis of (pro)insulin mRNA expression during chick embryo neurulation and early organogenesis.
- Inhibition of (pro)insulin using antisense oligodeoxynucleotides to assess effects on apoptosis.
- Comparative analysis of (pro)insulin and IGF-I expression in the proliferative neuroretina.
- Investigating the effects of (pro)insulin and IGF-I on apoptosis, DNA synthesis, and neuronal differentiation in the retina.
Main Results:
- (Pro)insulin mRNA is expressed in chick embryos during neurulation and early organogenesis.
- Inhibition of (pro)insulin leads to increased apoptosis.
- (Pro)insulin expression is predominant over IGF-I in the proliferative neuroretina, where it modulates apoptosis and stimulates DNA synthesis and neuronal differentiation.
- IGF-I, expressed later in the neuroretina, elicits similar effects.
Conclusions:
- Insulin, or its precursor proinsulin, plays a significant role in early vertebrate development prior to IGF expression.
- Insulin and IGFs exhibit complementary expression patterns during early embryogenesis, suggesting coordinated developmental functions.
- (Pro)insulin's modulation of apoptosis is a key mechanism underlying its effects on neural development and differentiation.