Ruminants genome no longer contains Whey Acidic Protein gene but only a pseudogene

Hajjoubi, Siham; Rival‐Gervier, Sylvie; Hayes, Hélène; Floriot, Sandrine; Eggen, Andre A.; Piumi, François; Chardon, Patrick; Houdebiné, Louis‐Marie; Thépot, Dominique

doi:10.1016/j.gene.2005.11.025

Cited by 42 publications

(29 citation statements)

References 40 publications

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“…The fact that marsupials also show XCI and yet have no gene homologous to Xist (refs 12, 13 and references therein) suggests that multiple strategies for initiating XCI must exist. To explore XCI during early embryogenesis in other eutherian mammals, we analysed human (primate) and rabbit (lagomorph) embryos, the latter being closely related to rodents 14 . First we examined rabbit embryos in vivo, from the 4-cell stage to the blastocyst stage, using Xist RNA fluorescence in situ hybridization (FISH; Fig.…”

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confidence: 99%

Eutherian mammals use diverse strategies to initiate X-chromosome inactivation during development

Okamoto

Patrat

Thépot

et al. 2011

Nature

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410

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X-chromosome inactivation (XCI) in female mammals allows dosage compensation for X-linked gene products between the sexes1. The developmental regulation of this process has been extensively investigated in mice, where the X chromosome of paternal origin (Xp) is silenced during early embryogenesis owing to imprinted expression of the regulatory RNA, Xist (X-inactive specific transcript). Paternal XCI is reversed in the inner cell mass of the blastocyst and random XCI subsequently occurs in epiblast cells. Here we show that other eutherian mammals have very different strategies for initiating XCI. In rabbits and humans, the Xist homologue is not subject to imprinting and XCI begins later than in mice. Furthermore,Xist is upregulated on both X chromosomes in a high proportion of rabbit andhuman embryo cells, even in the inner cell mass. In rabbits, this triggers XCI on both X chromosomes in some cells. In humans, chromosome-wide XCI has not initiated even by the blastocyst stage, despite the upregulation of XIST. The choice of which X chromosome will finally become inactive thus occurs downstream of Xist upregulation in both rabbits and humans, unlike in mice. Our study demonstrates the remarkable diversity in XCI regulation and highlights differences between mammals in their requirement for dosage compensation during early embryogenesis

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confidence: 99%

Eutherian mammals use diverse strategies to initiate X-chromosome inactivation during development

Okamoto

Patrat

Thépot

et al. 2011

Nature

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410

458

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“…In humans and ruminants, the WAP gene is frame-shifted and is a pseudogene. WAP functions as a proteinase inhibitor, is involved in terminal differentiation in the mammary gland and has antibacterial activity (for reviews see Simpson and Nicholas 2002;Hajjoubi et al 2006;Martin et al 2011). …”

Section: Whey Acidic Proteinmentioning

confidence: 99%

Milk Proteins

Fox¹,

Uniacke‐Lowe²,

McSweeney³

et al. 2015

Dairy Chemistry and Biochemistry

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“…All are secreted proteins, including proteins in respiratory, reproductive and other epithelial secretions (Hagiwara et al, 2003;Bingle et al, 2006). The structural similarity of WAP to other WFDC-containing proteins has led to speculation that WAP may also have antibacterial or proteinase inhibition functions, but attempts to demonstrate this have failed (Hajjoubi et al, 2006;Sharp et al, 2007). There is evidence that WFDC domains influence cell proliferation and growth in vitro and in transgenic mice (reviewed by Topcic et al, 2009), but when the WAP gene is deleted in knockout mice, the mice continue to develop normal mammary glands indicating that WAP is not essential for mammary cell differentiation or proliferation (Triplett et al, 2005).…”

Section: Evolution Of Milk Secretionmentioning

confidence: 99%

“…At least some eutherians have lost WAP in entirety. Although the genes for WAP synthesis have been found in sheep, goats, and cattle, they are missing a nucleotide at the end of the first exon, causing a frameshift mutation (Hajjoubi et al, 2006). They are not transcribed and are thus pseudogenes.…”

Section: Evolution Of Milk Secretionmentioning

confidence: 99%

The evolution of milk secretion and its ancient origins

Oftedal

2012

Animal

187

142

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Lactation represents an important element of the life history strategies of all mammals, whether monotreme, marsupial, or eutherian. Milk originated as a glandular skin secretion in synapsids (the lineage ancestral to mammals), perhaps as early as the Pennsylvanian period, that is, approximately 310 million years ago (mya). Early synapsids laid eggs with parchment-like shells intolerant of desiccation and apparently dependent on glandular skin secretions for moisture. Mammary glands probably evolved from apocrine-like glands that combined multiple modes of secretion and developed in association with hair follicles. Comparative analyses of the evolutionary origin of milk constituents support a scenario in which these secretions evolved into a nutrient-rich milk long before mammals arose. A variety of antimicrobial and secretory constituents were co-opted into novel roles related to nutrition of the young. Secretory calcium-binding phosphoproteins may originally have had a role in calcium delivery to eggs; however, by evolving into large, complex casein micelles, they took on an important role in transport of amino acids, calcium and phosphorus. Several proteins involved in immunity, including an ancestral butyrophilin and xanthine oxidoreductase, were incorporated into a novel membrane-bound lipid droplet (the milk fat globule) that became a primary mode of energy transfer. An ancestral c-lysozyme lost its lytic functions in favor of a role as a-lactalbumin, which modifies a galactosyltransferase to recognize glucose as an acceptor, leading to the synthesis of novel milk sugars, of which free oligosaccharides may have predated free lactose. An ancestral lipocalin and an ancestral whey acidic protein four-disulphide core protein apparently lost their original transport and antimicrobial functions when they became the whey proteins b-lactoglobulin and whey acidic protein, which with a-lactalbumin provide limiting sulfur amino acids to the young. By the late Triassic period (ca 210 mya), mammaliaforms (mammalian ancestors) were endothermic (requiring fluid to replace incubatory water losses of eggs), very small in size (making large eggs impossible), and had rapid growth and limited tooth replacement (indicating delayed onset of feeding and reliance on milk). Thus, milk had already supplanted egg yolk as the primary nutrient source, and by the Jurassic period (ca 170 mya) vitellogenin genes were being lost. All primary milk constituents evolved before the appearance of mammals, and some constituents may have origins that predate the split of the synapsids from sauropsids (the lineage leading to 'reptiles' and birds). Thus, the modern dairy industry is built upon a very old foundation, the cornerstones of which were laid even before dinosaurs ruled the earth in the Jurassic and Cretaceous periods.Keywords: evolution, lactation, milk composition, casein, milk fat globule ImplicationsLactation has an evolutionary origin and biological context within which its secretory processes and milk constituents evolved. This revi...

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Ruminants genome no longer contains Whey Acidic Protein gene but only a pseudogene

Cited by 42 publications

References 40 publications

Eutherian mammals use diverse strategies to initiate X-chromosome inactivation during development

Eutherian mammals use diverse strategies to initiate X-chromosome inactivation during development

Milk Proteins

The evolution of milk secretion and its ancient origins

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