File:Placenta-maternal neuroendocrine links.jpg

Fig. 3. Placental regulation of maternal neuroendocrine and neural function. Placentally produced steroid hormones determine forward maternal planning by directing/orchestrating maternal physiology and postnatal maternalism to synchronize with the development of the fetus.

Reference

Proc Natl Acad Sci U S A. 2015 Jun 2;112(22):6834-40. doi: 10.1073/pnas.1411253111. Epub 2014 Nov 17. Genomic imprinting, action, and interaction of maternal and fetal genomes. Keverne EB1. Author information Abstract Mammalian viviparity (intrauterine development of the fetus) introduced a new dimension to brain development, with the fetal hypothalamus and fetal placenta developing at a time when the fetal placenta engages hypothalamic structures of the maternal generation. Such transgenerational interactions provide a basis for ensuring optimal maternalism in the next generation. This success has depended on genomic imprinting and a biased role of the matriline. Maternal methylation imprints determine parent of origin expression of genes fundamental to both placental and hypothalamic development. The matriline takes a further leading role for transgenerational reprogramming of these imprints. Developmental errors are minimized by the tight control that imprinted genes have on regulation of downstream evolutionary expanded gene families important for placental and hypothalamic development. Imprinted genes themselves have undergone purifying selection, providing a framework of stability for in utero development with most growth variance occurring postnatally. Mothers, not fathers, take the lead in the endocrinological and behavior adaptations that nurture, feed, and protect the infant. In utero coadaptive development of the placenta and hypothalamus has thus required a concomitant development to ensure male masculinization. Only placental male mammals evolved the sex determining SRY, which activates Sox9 for testes formation. SRY is a hybrid gene of Dgcr8 expressed in the developing placenta and Sox3 expressed in hypothalamic development. This hybridization of genes that take their origin from the placenta and hypothalamus has enabled critical in utero timing for the development of fetal Leydig cells, and hence testosterone production for hypothalamic masculinization.

KEYWORDS: development; genomic imprinting; genomic reprogramming; hypothalamus; placenta PMID: 25404322 PMCID: PMC4460494 DOI: 10.1073/pnas.1411253111

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