Milk lipid and protein traffic in mammary epithelial cells: joint 
and independent pathways

Ollivier-Bousquet, Michèle

doi:10.1051/rnd:2002014

Cited by 37 publications

(27 citation statements)

References 59 publications

(72 reference statements)

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“…The synthesis and secretion of the caseins (via the endoplasmic reticulum -golgi -secretory Differences between groups at P < 0.05. ***P < 0.001. vesicle axis) and lipids (via the endoplasmic reticulum -CLD -MFG axis) involve joint and independent secretory pathways in lactocytes (Ollivier-Bousquet, 2002).…”

Section: Discussionmentioning

confidence: 99%

“…Most of the studies dealing with the effect of the composition of the milk proteins and MFG diameter looked at very specific proteins such as butyrophiline, xanthine oxidoreductase and adipophiline (also known as perilipin-2 or adipose differentiation-related protein) (McManaman et al, 2007;Jeong et al, 2013) or proteins involved in lipid synthesis (Cohen et al, 2015). These three proteins, by forming a bridge between the CLD membrane and the apical membrane, are involved in the membrane enwrapping process during MFG secretion by budding (Ollivier-Bousquet, 2002;Jeong et al, 2013) as well as the phosphatidylethanolamine content in the membrane, as mentioned above (Keenan and Huang, 1972). Our results cannot support these explanations and further work is still needed.…”

Section: Discussionmentioning

confidence: 99%

“…Triglycerides are synthesized in the reticulum endoplasmic membrane and then released into the cytoplasm in the form of a triglyceride core coated by a monolayer of phospholipids derived from the reticulum membrane, the so-called cytoplasmic lipid droplets (CLD). The droplets grow during their migration to the apical pole of the cell due to the continuation of the synthesis of lipids (Ollivier-Bousquet, 2002;Heid and Keenan, 2005;McManaman et al, 2007). The secretion would correspond to the membrane enwrapping the CLD and its secretion in association with the exocytosis of the golgiderived secretory vesicles containing caseins micelles (Wu et al, 2000;Keenan and Mather, 2006;Robenek et al, 2006;McManaman et al, 2007;Truchet et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Relationships between milks differentiated on native milk fat globule characteristics and fat, protein and calcium compositions

Couvreur

Hurtaud

2017

Animal

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Many studies have shown that milk fat globule (MFG) diameter varies in dairy cows in relation to diet and/or breed. However, the mechanisms governing the size of the fat globules remain hypothetical. Our objective was to determine the variable biochemical characteristics (fat, protein, fatty acids (FA), casein and calcium (Ca) contents) between individual milk which differed in both MFG diameter and membrane content, in order to speculate about the links between milk synthesis and MFG secretion. With this aim, we built five databases of individual milk samples from 21 experiments performed between 2003 and 2011. Three of them grouped data from trials dealing with breed/diet effects and included information about: (i) MFG size/membrane, fat and protein contents (n = 982), (ii) previous parameters plus FA profile (n = 529) and (iii) previous parameters plus true protein composition and calcium contents (n = 101). A hierarchical clustering analysis performed on these three databases yielded four groups differing in the MFG characteristics. We observed significant differences among groups for the following parameters: (i) fat content and fat : protein ratio; (ii) de novo and polyunsaturated FA contents; (iii) Ca contents. These relationships could result from potential process regulating the synthesis and secretion of MFG: (i) the apical membrane turnover for MFG secretion and (ii) cytoplasmic lipid droplet formation in the lactocyte during its migration from the basal to the apical pole. The two other databases grouped data from trials dealing with milking frequency (n = 211), milking kinetics and milk type (residual v. cisternal) (n = 224). They were used to study the relationships between the size of the MFG and milk composition for high native fat contents (from 60 up to 100 g/kg in residual milks). We observed curvilinear relationships between the size of the MFG and fat content, as well as with the fat : protein ratio. This result suggests that MFG diameter reaches a threshold but mechanisms are still unknown.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relationships between milks differentiated on native milk fat globule characteristics and fat, protein and calcium compositions

Couvreur

Hurtaud

2017

Animal

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“…Adipose tissue mobilization accounts for less than 10% of preformed FA in milk fat, except during periods of negative energy balance when their proportion increases substantially ). Lastly, due to the hydrophobic nature of esterified FA, milk fat is secreted from the mammary epithelial cell as a lipid droplet surrounded by a protein-rich polar lipid coat called the milk fat globule membrane (MFGM; see reviews by Mather and Keenan (1998), Keenan (2001) and Olivier-Bousquet (2002)). The origin of the MFGM and the mechanism of cellular milk fat secretion continue to be areas of intense investigation.…”

Section: Introductionmentioning

confidence: 99%

Recent advances in the regulation of milk fat synthesis

Harvatine

Boisclair

Bauman

2009

Animal

251

272

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In addition to its economic value, milk fat is responsible for many of milk's characteristics and can be markedly affected by diet. Diet-induced milk fat depression (MFD) was first described over a century ago and remains a common problem observed under both intensive and extensive management. The biohydrogenation theory established that MFD is caused by an inhibition of mammary synthesis of milk fat by specific fatty acids (FA) produced as intermediates in ruminal biohydrogenation. During MFD, lipogenic capacity and transcription of key lipid synthesis genes in the mammary gland are down-regulated in a coordinated manner. Our investigations have established that expressions of sterol response element-binding protein 1 (SREBP1) and SREBP-activation proteins are down-regulated during MFD. Importantly, key lipogenic enzymes are transcriptionally regulated via SREBP1. Collectively, these results provide strong evidence for SREBP1 as a central signaling pathway in the regulation of mammary FA synthesis. Spot 14 is also down-regulated during MFD, consistent with a lipogenic role for this novel nuclear protein. In addition, SREBP1c and Spot 14 knock-out mice exhibit reduced milk fat similar to the magnitude and pattern of MFD in the cow. Application of molecular biology approaches has provided the latest chapter in the regulation of milk fat synthesis and is reviewed along with a brief background in nutritional regulation of milk fat synthesis in ruminants.

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“…There is a certain controversy about the influence of CSN1S1 polymorphism on the mRNA expression of lipid metabolism genes, with studies that support a regulatory effect (Badaoui 2008) and others that do not (Leroux et al 2003). Since lipids and proteins are synthesized in the endoplasmic reticulum and their transport is, to a certain extent, coupled and co-regulated, it has been hypothesized that the perturbation of casein transport induced by the CSN1S1 genotype might also alter lipid trafficking resulting in a reduced fat secretion (Ollivier-Bousquet et al 2002).…”

Section: Genementioning

confidence: 99%