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Shaban SM, Hassan RA, Hassanin AAI, Fathy A, El Nabtiti AAS. Mammary fat globules as a source of mRNA to model alterations in the expression of some milk component genes during lactation in bovines. BMC Vet Res 2024; 20:286. [PMID: 38961471 PMCID: PMC11220969 DOI: 10.1186/s12917-024-04130-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 06/11/2024] [Indexed: 07/05/2024] Open
Abstract
BACKGROUND The milk's nutritional value is determined by its constituents, including fat, protein, carbohydrates, and minerals. The mammary gland's ability to produce milk is controlled by a complex network of genes. Thereby, the fat, protein, and lactose synthesis must be boost in milk to increase milk production efficiency. This can be accomplished by fusing genetic advancements with proper management practices. Therefore, this study aimed to investigate the association between the Lipoprotein lipase (LPL), kappa casein CSN3, and Glucose transporter 1 (GLUT1) genes expression levels and such milk components as fat, protein, and lactose in different dairy breeds during different stages of lactation. METHODS To achieve such a purpose, 94 milk samples were collected (72 samples from 36 multiparous black-white and red-white Holstein-Friesian (HF) cows and 22 milk samples from 11 Egyptian buffaloes) during the early and peak lactation stages. The milk samples were utilized for milk analysis and genes expressions analyses using non- invasive approach in obtaining milk fat globules (MFGs) as a source of Ribonucleic acid (RNA). RESULTS LPL and CSN3 genes expressions levels were found to be significantly higher in Egyptian buffalo than Holstein-Friesian (HF) cows as well as fat and protein percentages. On the other hand, GLUT1 gene expression level was shown to be significantly higher during peak lactation than early lactation. Moreover, lactose % showed a significant difference in peak lactation phase compared to early lactation phase. Also, fat and protein percentages were significantly higher in early lactation period than peak lactation period but lactose% showed the opposite pattern of Egyptian buffalo. CONCLUSION Total RNA can be successfully obtained from MFGs. The results suggest that these genes play a role in glucose absorption and lactose synthesis in bovine mammary epithelial cells during lactation. Also, these results provide light on the differential expression of these genes among distinct Holstein-Friesian cow breeds and Egyptian buffalo subspecies throughout various lactation phases.
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Affiliation(s)
- Samar M Shaban
- Department of Animal Wealth Development (Animal Production Division), Faculty of Veterinary Medicine, Suez Canal University, Ismailia, 41522, Egypt.
| | - Rania A Hassan
- Department of Animal Wealth Development (Animal Production Division), Faculty of Veterinary Medicine, Suez Canal University, Ismailia, 41522, Egypt
| | - Abeer A I Hassanin
- Department of Animal Wealth Development (Genetics and Genetic Engineering Branch), Faculty of Veterinary Medicine, Suez Canal University, Ismailia, 41522, Egypt
| | - Ahmed Fathy
- Department of Animal Wealth Development (Biostatistics Division), Faculty of Veterinary Medicine, Suez Canal University, Ismailia, 41522, Egypt
| | - Adel A S El Nabtiti
- Department of Animal Wealth Development (Animal Production Division), Faculty of Veterinary Medicine, Suez Canal University, Ismailia, 41522, Egypt
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Mehdikhani F, Bahar A, Bashi M, Mohammadlou M, Yousefi B. From immunomodulation to therapeutic prospects: Unveiling the biology of butyrophilins in cancer. Cell Biochem Funct 2024; 42:e4081. [PMID: 38934382 DOI: 10.1002/cbf.4081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 06/12/2024] [Accepted: 06/17/2024] [Indexed: 06/28/2024]
Abstract
Butyrophilin (BTN) proteins are a type of membrane protein that belongs to the Ig superfamily. They exhibit a high degree of structural similarity to molecules in the B7 family. They fulfill a complex function in regulating immune responses, including immunomodulatory roles, as they influence γδ T cells. The biology of BTN molecules indicates that they are capable of inhibiting the immune system's ability to detect antigens within tumors. A dynamic association between BTN molecules and cellular surfaces is also recognized in specific contexts, influencing their biology. Notably, the dynamism of BTN3A1 is associated with the immunosuppression of T cells or the activation of Vγ9Vδ2 T cells. Cancer immunotherapy relies heavily on T cells to modulate immune function within the intricate interaction of the tumor microenvironment (TME). A significant interaction between the TME and antitumor immunity involves the presence of BTN, which should be taken into account when developing immunotherapy. This review explores potential therapeutic applications of BTN molecules, based on the current understanding of their biology.
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Affiliation(s)
- Fatemeh Mehdikhani
- Department of Clinical Biochemistry, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Aysa Bahar
- Department of Biochemistry, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Marzieh Bashi
- Cancer Research Center, Semnan University of Medical, Semnan, Iran
- Department of Immunology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Maryam Mohammadlou
- Department of Immunology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Bahman Yousefi
- Cancer Research Center, Semnan University of Medical, Semnan, Iran
- Department of Immunology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran
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Sugathan S, Lee SJ, Shiwani S, Singh NK. Transdifferentiation of bovine epithelial towards adipocytes in the presence of myoepithelium. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2019; 33:349-359. [PMID: 31010974 PMCID: PMC6946969 DOI: 10.5713/ajas.18.0806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 10/25/2018] [Indexed: 01/22/2023]
Abstract
Objective Orchastric changes in the mammary glands are vital, especially during lactation. The secretary epithelial cells together with the supporting myoepithelial and stromal cells function cordially to secrete milk. Increase in the number of luminal epithelial cells and a decrease in adipocytes are visible during lactation, whereas the reverse happens in the involution. However, an early involution occurs if the epithelial cells transdifferentiate towards adipocytes during the lactation period. We aimed to inhibit the adipocyte transdifferentiation of luminal cells by restraining the peroxisomal proliferator-activated receptor γ (PPARγ) pathway. Methods Linolenic acid (LA) and thiazolidinediones (TZDs) induced adipogenesis in mammary epithelial cells were conducted in monolayer, mixed culture as well as in transwell plate co-culture with mammary myoepithelial cells. Results Co-culture with myoepithelial cells showed higher adipogenic gene expression in epithelial cells under LA+TZDs treatment. Increase in the expressions of PPARγ, CCAAT/enhancer-binding protein α and vimentin in both mRNA as well as protein levels were observed. Whereas, bisphenol A diglycidyl ether treatment blocked LA+TZDs induced adipogenesis, as it could not show a significant rise in adipose related markers. Although comparative results were found in both mixed culture and monolayer conditions, co-culture technic was found to work better than the others. Conclusion Antagonizing PPARγ pathway in the presence of myoepithelial cells can significantly reduce the adipogenisis in epithelial cells, suggesting therapeutic inhibition of PPARγ can be considered to counter early involution or excessive adipogenesis in mammary epithelium in animals.
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Affiliation(s)
- Subi Sugathan
- Department of Animal Biotechnology, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Sung-Jin Lee
- Department of Animal Biotechnology, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Supriya Shiwani
- Department of Animal Biotechnology, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Naresh Kumar Singh
- Department of Veterinary Surgery and Radiology, Faculty of Veterinary and Animal Sciences, Institute of Agricultural Sciences, Banaras Hindu University,Varanasi-221005, Uttar Pradesh, India
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Th-POK regulates mammary gland lactation through mTOR-SREBP pathway. PLoS Genet 2018; 14:e1007211. [PMID: 29420538 PMCID: PMC5821406 DOI: 10.1371/journal.pgen.1007211] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 02/21/2018] [Accepted: 01/21/2018] [Indexed: 12/22/2022] Open
Abstract
The Th-inducing POK (Th-POK, also known as ZBTB7B or cKrox) transcription factor is a key regulator of lineage commitment of immature T cell precursors. It is yet unclear the physiological functions of Th-POK besides helper T cell differentiation. Here we show that Th-POK is restrictedly expressed in the luminal epithelial cells in the mammary glands that is upregulated at late pregnancy and lactation. Lineage restrictedly expressed Th-POK exerts distinct biological functions in the mammary epithelial cells and T cells in a tissue-specific manner. Th-POK is not required for mammary epithelial cell fate determination. Mammary gland morphogenesis in puberty and alveologenesis in pregnancy are phenotypically normal in the Th-POK-deficient mice. However, Th-POK-deficient mice are defective in triggering the onset of lactation upon parturition with large cellular lipid droplets retained within alveolar epithelial cells. As a result, Th-POK knockout mice are unable to efficiently secret milk lipid and to nurse the offspring. Such defect is mainly attributed to the malfunctioned mammary epithelial cells, but not the tissue microenvironment in the Th-POK deficient mice. Th-POK directly regulates expression of insulin receptor substrate-1 (IRS-1) and insulin-induced Akt-mTOR-SREBP signaling. Th-POK deficiency compromises IRS-1 expression and Akt-mTOR-SREBP signaling in the lactating mammary glands. Conversely, insulin induces Th-POK expression. Thus, Th-POK functions as an important feed-forward regulator of insulin signaling in mammary gland lactation.
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Battelli MG, Polito L, Bortolotti M, Bolognesi A. Xanthine oxidoreductase in cancer: more than a differentiation marker. Cancer Med 2016; 5:546-57. [PMID: 26687331 PMCID: PMC4799950 DOI: 10.1002/cam4.601] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 11/05/2015] [Accepted: 11/08/2015] [Indexed: 12/17/2022] Open
Abstract
Human xanthine oxidoreductase (XOR) catalyzes the last two steps of purine catabolism and is present in two interconvertible forms, which may utilize O2 or NAD(+) as electron acceptors. In addition to uric acid, XOR products may comprise reactive oxygen and nitrogen species that have many biologic effects, including inflammation, endothelial dysfunction, and cytotoxicity, as well as mutagenesis and induction of proliferation. XOR is strictly modulated at the transcriptional and post-translational levels, and its expression and activity are highly variable in cancer. Xanthine oxidoreductase (XOR) expression has been negatively associated with a high malignity grade and a worse prognosis in neoplasms of the breast, liver, gastrointestinal tract, and kidney, which normally express a high level of XOR protein. However, the level of XOR expression may be associated with a worse outcome in cancer of low XOR-expressing cells, in relation to the inflammatory response elicited through the tissue damage induced by tumor growth. Xanthine oxidoreductase (XOR) has been implicated in the process of oncogenesis either directly because it is able to catalyze the metabolic activation of carcinogenic substances or indirectly through the action of XOR-derived reactive oxygen and nitrogen species. The role of uric acid is characterized by both oxidant and antioxidant action; thus, it is still debatable whether control of uricemia may be helpful to improve the outcomes of tumor illness.
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Affiliation(s)
- Maria Giulia Battelli
- Department of Experimental, Diagnostic and Specialty Medicine – DIMESAlma Mater Studiorum – University of Bologna, General Pathology UnitVia S. Giacomo 1440126BolognaItaly
| | - Letizia Polito
- Department of Experimental, Diagnostic and Specialty Medicine – DIMESAlma Mater Studiorum – University of Bologna, General Pathology UnitVia S. Giacomo 1440126BolognaItaly
| | - Massimo Bortolotti
- Department of Experimental, Diagnostic and Specialty Medicine – DIMESAlma Mater Studiorum – University of Bologna, General Pathology UnitVia S. Giacomo 1440126BolognaItaly
| | - Andrea Bolognesi
- Department of Experimental, Diagnostic and Specialty Medicine – DIMESAlma Mater Studiorum – University of Bologna, General Pathology UnitVia S. Giacomo 1440126BolognaItaly
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Yang J, Jiang J, Liu X, Wang H, Guo G, Zhang Q, Jiang L. Differential expression of genes in milk of dairy cattle during lactation. Anim Genet 2015; 47:174-80. [PMID: 26692495 PMCID: PMC5064620 DOI: 10.1111/age.12394] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2015] [Indexed: 12/25/2022]
Abstract
The milk fat globule (MFG) is one of the most representative of mammary gland tissues and can be utilized to study gene expression of lactating cows during lactation. In this study, RNA-seq technology was employed to detect differential expression of genes in MFGs at day 10 and day 70 after calving between two groups of cows with extremely high (H group) and low (L group) 305-day milk yield, milk fat yield and milk protein yield. In total, 1232, 81, 429 and 178 significantly differentially expressed genes (false discovery rate q < 0.05) were detected between H10 and L10, H70 and L70, H10 and H70, and L10 and L70 respectively. Gene Ontology enrichment and pathway analysis revealed that these differentially expressed genes were enriched in biological processes involved in mammary gland development, protein and lipid metabolism process, signal transduction, cellular process, differentiation and immune function. Among these differentially expressed genes, 178 (H10 vs. L10), 4 (H70 vs. L70), 68 (H10 vs. H70) and 22 (L10 vs. L70) were found to be located within previously reported QTL regions for milk production traits. Based on these results, some promising candidate genes for milk production traits in dairy cattle were suggested.
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Affiliation(s)
- Jie Yang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Jicai Jiang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Xuan Liu
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Haifei Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Gang Guo
- Beijing Sanyuan Breeding Technology Co. Ltd., Beijing, 100029, China
| | - Qin Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Li Jiang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
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McCormick NH, Lee S, Hennigar SR, Kelleher SL. ZnT4 (SLC30A4)-null ("lethal milk") mice have defects in mammary gland secretion and hallmarks of precocious involution during lactation. Am J Physiol Regul Integr Comp Physiol 2015; 310:R33-40. [PMID: 26538236 DOI: 10.1152/ajpregu.00315.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 11/02/2015] [Indexed: 02/01/2023]
Abstract
During lactation, highly specialized secretory mammary epithelial cells (MECs) produce and secrete huge quantities of nutrients and nonnutritive factors into breast milk. The zinc (Zn) transporter ZnT4 (SLC30A4) transports Zn into the trans-Golgi apparatus for lactose synthesis, and across the apical cell membrane for efflux from MECs into milk. This is consistent with observations in "lethal milk" (lm/lm) mice, which have a truncation mutation in SLC30A4, and present with not only low milk Zn concentration, but also smaller mammary glands, decreased milk volume, and lactation failure by lactation day 2. However, the molecular underpinnings of these defects are not understood. Here, we used lactating C57BL/6J(lm/lm) (ZnT4-null) mice to explore the consequences of a ZnT4-null phenotype on mammary gland function during early lactation. Lactating C57BL/6J(lm/lm) mice had significantly fewer, smaller, and collapsed alveoli comprising swollen, lipid-filled MECs during early lactation. These defects were associated with decreased Akt expression and STAT5 activation, indicative of defects in MEC secretion. In addition, increased expression of ZnT2, TNF-α, and cleaved e-cadherin concomitant with increased activation of STAT3 implicated the loss of ZnT4 in precocious activation of involution. Collectively, our study indicates that the loss of ZnT4 has profound consequences on MEC secretion and may promote tissue remodeling in the mammary gland during early lactation.
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Affiliation(s)
- Nicholas H McCormick
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, Pennsylvania
| | - Sooyeon Lee
- Department of Cellular and Molecular Physiology, Penn State Hershey College of Medicine, Hershey, Pennsylvania
| | - Stephen R Hennigar
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, Pennsylvania
| | - Shannon L Kelleher
- Department of Cellular and Molecular Physiology, Penn State Hershey College of Medicine, Hershey, Pennsylvania; Department of Pharmacology, Penn State Hershey College of Medicine, Hershey, Pennsylvania; Department of Surgery, Penn State Hershey College of Medicine, Hershey, Pennsylvania; and Department of Nutritional Sciences, The Pennsylvania State University, University Park, Pennsylvania
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8
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Pathophysiology of circulating xanthine oxidoreductase: New emerging roles for a multi-tasking enzyme. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1502-17. [DOI: 10.1016/j.bbadis.2014.05.022] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 05/21/2014] [Accepted: 05/22/2014] [Indexed: 02/07/2023]
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Cunnick JM, Kim S, Hadsell J, Collins S, Cerra C, Reiser P, Flynn DC, Cho Y. Actin filament-associated protein 1 is required for cSrc activity and secretory activation in the lactating mammary gland. Oncogene 2014; 34:2640-9. [PMID: 25043309 PMCID: PMC4302073 DOI: 10.1038/onc.2014.205] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 04/25/2014] [Accepted: 06/09/2014] [Indexed: 12/12/2022]
Abstract
Actin filament-associated protein 1 (AFAP1) is an adaptor protein of cSrc that binds to filamentous actin and regulates the activity of this tyrosine kinase to affect changes to the organization of the actin cytoskeleton. In breast and prostate cancer cells, AFAP1 has been shown to regulate cellular responses requiring actin cytoskeletal changes such as adhesion, invadopodia formation and invasion. However, a normal physiologic role for AFAP1 has remained elusive. In this study, we generated an AFAP1 knockout mouse model that establishes a novel physiologic role for AFAP1 in lactation. Specifically, these animals displayed a defect in lactation that resulted in an inability to nurse efficiently. Histologically, the mammary glands of the lactating knockout mice were distinguished by the accumulation of large cytoplasmic lipid droplets in the alveolar epithelial cells. There was a reduction in lipid synthesis and the expression of lipogenic genes without a corresponding reduction in the production of β-casein, a milk protein. Furthermore, these defects were associated with histologic and biochemical signs of precocious involution. This study also demonstrated that AFAP1 responds to prolactin, a lactogenic hormone, by forming a complex with cSrc and becoming tyrosine phosphorylated. Taken together, these observations pointed to a defect in secretory activation. Certain characteristics of this phenotype mirrored the defect in secretory activation in the cSrc knockout mouse, but most importantly, the activity of cSrc in the mammary gland was reduced during early lactation in the AFAP1-null mouse and the localization of active cSrc at the apical surface of luminal epithelial cells during lactation was selectively lost in the absence of AFAP1. These data define, for the first time, the requirement of AFAP1 for the spatial and temporal regulation of cSrc activity in the normal breast, specifically for milk production.
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Affiliation(s)
- J M Cunnick
- Department of Basic Sciences, The Commonwealth Medical College, Scranton, PA, USA
| | - S Kim
- Graduate School of Medicine, The Commonwealth Medical College, Scranton, PA, USA
| | - J Hadsell
- Fortis Institute Scranton, Scranton, PA, USA
| | - S Collins
- Department of Basic Sciences, The Commonwealth Medical College, Scranton, PA, USA
| | - C Cerra
- Department of Pathology, Pocono Health System, East Stroudsburg, PA, USA
| | - P Reiser
- Department of Pathology, Pocono Health System, East Stroudsburg, PA, USA
| | - D C Flynn
- College of Health Science, University of Delaware, Newark, DE, USA
| | - Y Cho
- Department of Basic Sciences, The Commonwealth Medical College, Scranton, PA, USA
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McManaman JL. Lipid transport in the lactating mammary gland. J Mammary Gland Biol Neoplasia 2014; 19:35-42. [PMID: 24567110 PMCID: PMC4413448 DOI: 10.1007/s10911-014-9318-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 02/04/2014] [Indexed: 12/11/2022] Open
Abstract
Mammalian cells depend on phospholipid (PL) and fatty acid (FA) transport to maintain membrane structure and organization, and to fuel and regulate cellular functions. In mammary glands of lactating animals, copious milk secretion, including large quantities of lipid in some species, requires adaptation and integration of PL and FA synthesis and transport processes to meet secretion demands. At present few details exist about how these processes are regulated within the mammary gland. However, recent advances in our understanding of the structural and molecular biology of membrane systems and cellular lipid trafficking provide insights into the mechanisms underlying the regulation and integration of PL and FA transport processes the lactating mammary gland. This review discusses the PL and FA transport processes required to maintain the structural integrity and organization of the mammary gland and support its secretory functions within the context of current molecular and cellular models of their regulation.
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Affiliation(s)
- James L McManaman
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Mail Stop 8613, 12700 E. 19th Ave., Aurora, CO, 80045, USA,
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11
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Truchet S, Chat S, Ollivier-Bousquet M. Milk secretion: The role of SNARE proteins. J Mammary Gland Biol Neoplasia 2014; 19:119-30. [PMID: 24264376 DOI: 10.1007/s10911-013-9311-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 11/13/2013] [Indexed: 12/21/2022] Open
Abstract
During lactation, polarized mammary epithelial secretory cells (MESCs) secrete huge quantities of the nutrient molecules that make up milk, i.e. proteins, fat globules and soluble components such as lactose and minerals. Some of these nutrients are only produced by the MESCs themselves, while others are to a great extent transferred from the blood. MESCs can thus be seen as a crossroads for both the uptake and the secretion with cross-talks between intracellular compartments that enable spatial and temporal coordination of the secretion of the milk constituents. Although the physiology of lactation is well understood, the molecular mechanisms underlying the secretion of milk components remain incompletely characterized. Major milk proteins, namely caseins, are secreted by exocytosis, while the milk fat globules are released by budding, being enwrapped by the apical plasma membrane. Prolactin, which stimulates the transcription of casein genes, also induces the production of arachidonic acid, leading to accelerated casein transport and/or secretion. Because of their ability to form complexes that bridge two membranes and promote their fusion, SNARE (Soluble N-ethylmaleimide-Sensitive Factor Attachment Protein Receptor) proteins are involved in almost all intracellular trafficking steps and exocytosis. As SNAREs can bind arachidonic acid, they could be the effectors of the secretagogue effect of prolactin in MESCs. Indeed, some SNAREs have been observed between secretory vesicles and lipid droplets suggesting that these proteins could not only orchestrate the intracellular trafficking of milk components but also act as key regulators for both the coupling and coordination of milk product secretion in response to hormones.
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Affiliation(s)
- Sandrine Truchet
- INRA, UR1196 Génomique et Physiologie de la Lactation, 78352, Jouy-en-Josas Cedex, France,
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12
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Cidea is an essential transcriptional coactivator regulating mammary gland secretion of milk lipids. Nat Med 2012; 18:235-43. [PMID: 22245780 DOI: 10.1038/nm.2614] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 11/30/2011] [Indexed: 12/25/2022]
Abstract
Adequate lipid secretion by mammary glands during lactation is essential for the survival of mammalian offspring. However, the mechanism governing this process is poorly understood. Here we show that Cidea is expressed at high levels in lactating mammary glands and its deficiency leads to premature pup death as a result of severely reduced milk lipids. Furthermore, the expression of xanthine oxidoreductase (XOR), an essential factor for milk lipid secretion, is markedly lower in Cidea-deficient mammary glands. Conversely, ectopic Cidea expression induces the expression of XOR and enhances lipid secretion in vivo. Unexpectedly, as Cidea has heretofore been thought of as a cytoplasmic protein, we detected it in the nucleus and found it to physically interact with transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) in mammary epithelial cells. We also observed that Cidea induces XOR expression by promoting the association of C/EBPβ onto, and the dissociation of HDAC1 from, the promoter of the Xdh gene encoding XOR. Finally, we found that Fsp27, another CIDE family protein, is detected in the nucleus and interacts with C/EBPβ to regulate expression of a subset of C/EBPβ downstream genes in adipocytes. Thus, Cidea acts as a previously unknown transcriptional coactivator of C/EBPβ in mammary glands to control lipid secretion and pup survival.
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Kolb AF, Huber RC, Lillico SG, Carlisle A, Robinson CJ, Neil C, Petrie L, Sorensen DB, Olsson IAS, Whitelaw CBA. Milk lacking α-casein leads to permanent reduction in body size in mice. PLoS One 2011; 6:e21775. [PMID: 21789179 PMCID: PMC3138747 DOI: 10.1371/journal.pone.0021775] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 06/11/2011] [Indexed: 01/01/2023] Open
Abstract
The major physiological function of milk is the transport of amino acids, carbohydrates, lipids and minerals to mammalian offspring. Caseins, the major milk proteins, are secreted in the form of a micelle consisting of protein and calcium-phosphate. We have analysed the role of the milk protein α-casein by inactivating the corresponding gene in mice. Absence of α-casein protein significantly curtails secretion of other milk proteins and calcium-phosphate, suggesting a role for α-casein in the establishment of casein micelles. In contrast, secretion of albumin, which is not synthesized in the mammary epithelium, into milk is not reduced. The absence of α-casein also significantly inhibits transcription of the other casein genes. α-Casein deficiency severely delays pup growth during lactation and results in a life-long body size reduction compared to control animals, but has only transient effects on physical and behavioural development of the pups. The data support a critical role for α-casein in casein micelle assembly. The results also confirm lactation as a critical window of metabolic programming and suggest milk protein concentration as a decisive factor in determining adult body weight.
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Affiliation(s)
- Andreas F Kolb
- Molecular Recognition Group, Hannah Research Institute, Ayr, United Kingdom.
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Chong BM, Russell TD, Schaack J, Orlicky DJ, Reigan P, Ladinsky M, McManaman JL. The adipophilin C terminus is a self-folding membrane-binding domain that is important for milk lipid secretion. J Biol Chem 2011; 286:23254-65. [PMID: 21383012 DOI: 10.1074/jbc.m110.217091] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytoplasmic lipid droplets (CLD) in mammary epithelial cells undergo secretion by a unique membrane envelopment process to produce milk lipids. Adipophilin (ADPH/Plin2), a member of the perilipin/PAT family of lipid droplet-associated proteins, is hypothesized to mediate CLD secretion through interactions with apical plasma membrane elements. We found that the secretion of CLD coated by truncated ADPH lacking the C-terminal region encoding a putative four-helix bundle structure was impaired relative to that of CLD coated by full-length ADPH. We used homology modeling and analyses of the solution and membrane binding properties of purified recombinant ADPH C terminus to understand how this region possibly mediates CLD secretion. Homology modeling supports the concept that the ADPH C terminus forms a four-helix bundle motif and suggests that this structure can form stable membrane bilayer interactions. Circular dichroism and protease mapping studies confirmed that the ADPH C terminus is an independently folding α-helical structure that is relatively resistant to urea denaturation. Liposome binding studies showed that the purified C terminus binds to phospholipid membranes through electrostatic dependent interactions, and cell culture studies documented that it localizes to the plasma membrane. Collectively, these data provide direct evidence that the ADPH C terminus forms a stable membrane binding helical structure that is important for CLD secretion. We speculate that interactions between the four-helix bundle of ADPH and membrane phospholipids may be an initial step in milk lipid secretion.
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Affiliation(s)
- Brandi M Chong
- Graduate Program in Molecular Biology, Division of Basic Reproductive Science, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
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15
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Morrison B, Cutler ML. The contribution of adhesion signaling to lactogenesis. J Cell Commun Signal 2010; 4:131-9. [PMID: 21063503 DOI: 10.1007/s12079-010-0099-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Accepted: 08/30/2010] [Indexed: 11/28/2022] Open
Abstract
The mammary gland undergoes hormonally controlled cycles of pubertal maturation, pregnancy, lactation, and involution, and these processes rely on complex signaling mechanisms, many of which are controlled by cell-cell and cell-matrix adhesion. The adhesion of epithelial cells to the extracellular matrix initiates signaling mechanisms that have an impact on cell proliferation, survival, and differentiation throughout lactation. The control of integrin expression on the mammary epithelial cells, the composition of the extracellular matrix and the presence of secreted matricellular proteins all contribute to essential adhesion signaling during lactogenesis. In vitro and in vivo studies, including the results from genetically engineered mice, have shed light on the regulation of these processes at the cell and tissue level and have led to increased understanding of the essential signaling components that are regulated in temporal and cell specific manner during lactogenesis. Recent studies suggest that a secreted matricellular protein, CTGF/CCN2, may play a role in lactogenic differentiation through binding to β1 integrin complexes, enhancing the production of extracellular matrix components and contributions to cell adhesion signaling.
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16
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Dong J, Tong T, Reynado AM, Rosen JM, Huang S, Li Y. Genetic manipulation of individual somatic mammary cells in vivo reveals a master role of STAT5a in inducing alveolar fate commitment and lactogenesis even in the absence of ovarian hormones. Dev Biol 2010; 346:196-203. [PMID: 20691178 DOI: 10.1016/j.ydbio.2010.07.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 06/23/2010] [Accepted: 07/16/2010] [Indexed: 01/14/2023]
Abstract
Assessing the molecular control of development and cell fate in individual cells in the intact mammary epithelium has not been possible to date. By exploiting an intraductal retrovirus (RCAS)-mediated gene delivery method to introduce a marker gene, we found that ductal epithelial cells are turned over with a half time of approximately 1month in adult virgin mice. However, following RCAS-mediated introduction of a constitutively activated STAT5a (caSTAT5a), caSTAT5a-activated ductal epithelial cells expand and replace other cells in the epithelium, eventually forming a mammary gland resembling that in a late pregnant mouse, suggesting that STAT5a activation alone is sufficient to mediate pregnancy-induced mammary cell expansion, alveolar cell fate commitment, and lactogenesis. Furthermore, such caSTAT5a-induced alveolar differentiation does not require ovarian functions, although caSTAT5a-induced cell proliferation is partly reduced in ovariectomized mice. In conclusion, in this first report of studying the developmental role of a gene in a few cells in a normally developed virgin mammary ductal tree, STAT5a activation causes alveolar fate commitment and lactogenesis, and with the help of ovarian hormones, drives alveolar expansion.
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Affiliation(s)
- Jie Dong
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
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17
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Menzies KK, Lefèvre C, Macmillan KL, Nicholas KR. Insulin regulates milk protein synthesis at multiple levels in the bovine mammary gland. Funct Integr Genomics 2008; 9:197-217. [PMID: 19107532 DOI: 10.1007/s10142-008-0103-x] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 11/25/2008] [Accepted: 11/25/2008] [Indexed: 01/24/2023]
Abstract
The role of insulin in milk protein synthesis is unresolved in the bovine mammary gland. This study examined the potential role of insulin in the presence of two lactogenic hormones, hydrocortisone and prolactin, in milk protein synthesis. Insulin was shown to stimulate milk protein gene expression, casein synthesis and (14)C-lysine uptake in mammary explants from late pregnant cows. A global assessment of changes in gene expression in mammary explants in response to insulin was undertaken using Affymetrix microarray. The resulting data provided insight into the molecular mechanisms stimulated by insulin and showed that the hormone stimulated the expression of 28 genes directly involved in protein synthesis. These genes included the milk protein transcription factor, ELF5, translation factors, the folate metabolism genes, FOLR1 and MTHFR, as well as several genes encoding enzymes involved in catabolism of essential amino acids and biosynthesis of non-essential amino acids. These data show that insulin is not only essential for milk protein gene expression, but stimulates milk protein synthesis at multiple levels within bovine mammary epithelial cells.
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Affiliation(s)
- Karensa K Menzies
- Department of Zoology, University of Melbourne, Parkville, VIC, Australia.
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18
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Stiening C, Hoying J, Abdallah M, Hoying A, Pandey R, Greer K, Collier R. The Effects of Endocrine and Mechanical Stimulation on Stage I Lactogenesis in Bovine Mammary Epithelial Cells. J Dairy Sci 2008; 91:1053-66. [DOI: 10.3168/jds.2007-0161] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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19
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Watkin H, Richert MM, Lewis A, Terrell K, McManaman JP, Anderson SM. Lactation failure in Src knockout mice is due to impaired secretory activation. BMC DEVELOPMENTAL BIOLOGY 2008; 8:6. [PMID: 18215306 PMCID: PMC2266720 DOI: 10.1186/1471-213x-8-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Accepted: 01/23/2008] [Indexed: 11/17/2022]
Abstract
Background Mammary gland development culminates in lactation and is orchestrated by numerous stimuli and signaling pathways. The Src family of nonreceptor tyrosine kinases plays a pivotal role in cell signaling. In order to determine if Src plays a role in mammary gland development we have examined mammary gland development and function during pregnancy and lactation in mice in which expression of Src has been eliminated. Results We have characterized a lactation defect in the Src-/- mice which results in the death of over 80% of the litters nursed by Src-/- dams. Mammary gland development during pregnancy appears normal in these mice; however secretory activation does not seem to occur. Serum prolactin levels are normal in Src-/- mice compared to wildtype controls. Expression of the prolactin receptor at both the RNA and protein level was decreased in Src-/- mice following the transition from pregnancy to lactation, as was phosphorylation of STAT5 and expression of milk protein genes. These results suggest that secretory activation, which occurs following parturition, does not occur completely in Src-/- mice. Failed secretory activation results in precocious involution in the mammary glands of Src-/- even when pups were suckling. Involution was accelerated following pup withdrawal perhaps as a result of incomplete secretory activation. In vitro differentiation of mammary epithelial cells from Src-/- mice resulted in diminished production of milk proteins compared to the amount of milk proteins produced by Src+/+ cells, indicating a direct role for Src in regulating the transcription/translation of milk protein genes in mammary epithelial cells. Conclusion Src is an essential signaling modulator in mammary gland development as Src-/- mice exhibit a block in secretory activation that results in lactation failure and precocious involution. Src appears to be required for increased expression of the prolactin receptor and successful downstream signaling, and alveolar cell organization.
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Affiliation(s)
- Harriet Watkin
- Department of Pathology, University of Colorado Health Sciences Center, Research Complex I, South Tower, Mail Stop 8104, 12801 East 17th Avenue, Aurora, CO 80045, USA.
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20
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Monks J, Smith-Steinhart C, Kruk ER, Fadok VA, Henson PM. Epithelial cells remove apoptotic epithelial cells during post-lactation involution of the mouse mammary gland. Biol Reprod 2007; 78:586-94. [PMID: 18057312 DOI: 10.1095/biolreprod.107.065045] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Following the cessation of lactation, the mammary gland undergoes a physiologic process of tissue remodeling called involution in which glandular structures are lost, leaving an adipose tissue compartment that takes up a much larger proportion of the tissue. A quantitative morphometric analysis was undertaken to determine the mechanisms for clearance of the epithelial cells during this process. The involution process was set in motion by removal of pups from 14-day lactating C57BL/6 mice. Within hours, milk-secreting epithelial cells were shed into the glandular lumen. These cells became apoptotic, exhibiting exposure of phosphatidylserine residues on their surfaces, activation of effector caspase-3, staining for caspase-cleaved keratin 18, loss of internal organellar structure, and nuclear breakdown, but minimal blebbing or generation of apoptotic bodies. Clearance of residual milk and the shed epithelial cells was rapid, with most of the removal occurring in the first 72 h. Intact apoptotic epithelial cells were engulfed in large numbers by residual viable epithelial cells into spacious efferosomes. This process led to essentially complete involution within 4 days, at which point estrous cycling recommenced. Macrophages and other inflammatory cells did not contribute to the clearance of either residual milk or apoptotic cells, which appeared to be due entirely to the epithelium itself.
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Affiliation(s)
- Jenifer Monks
- Program in Cell Biology, Department of Pediatrics, National Jewish Medical & Research Center, Denver, Colorado 80206, USA.
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21
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McManaman JL, Russell TD, Schaack J, Orlicky DJ, Robenek H. Molecular determinants of milk lipid secretion. J Mammary Gland Biol Neoplasia 2007; 12:259-68. [PMID: 17999166 DOI: 10.1007/s10911-007-9053-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Accepted: 10/24/2007] [Indexed: 12/20/2022] Open
Abstract
Mammary epithelial cells secrete lipids by an envelopment process that produces lipid droplets coated by membranes derived from the plasma membrane and possibly secretory vesicles. This secretion process, which resembles viral budding, is hypothesized to be mediated by specific interactions between molecules on the surface of intracellular lipids and membrane elements of the cell. Multiple lines of evidence indicate that milk lipid secretion occurs through a tripartite complex between the integral transmembrane protein, butyrophilin (BTN); the soluble metabolic enzyme, xanthine oxidoreductase (XOR); and the lipid droplet surface protein, adipophilin (ADPH). However, topological evidence from freeze-fracture replica immunolabelling (FRIL) challenge this model and suggests that milk lipid secretion is mediated by butyrophilin alone. Advances in our understanding of the molecular, structural, and functional properties of these proteins now make it possible to understand the physiological functions of each of these molecules in detail and to identify the specific molecular determinants that mediate milk lipid secretion.
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Affiliation(s)
- James L McManaman
- Department of Obstetrics and Gynecology, University of Colorado Denver and Health Sciences Center, Aurora, CO, USA.
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22
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Anderson SM, Rudolph MC, McManaman JL, Neville MC. Key stages in mammary gland development. Secretory activation in the mammary gland: it's not just about milk protein synthesis! Breast Cancer Res 2007; 9:204. [PMID: 17338830 PMCID: PMC1851396 DOI: 10.1186/bcr1653] [Citation(s) in RCA: 283] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The transition from pregnancy to lactation is a critical event in the survival of the newborn since all the nutrient requirements of the infant are provided by milk. While milk contains numerous components, including proteins, that aid in maintaining the health of the infant, lactose and milk fat represent the critical energy providing elements of milk. Much of the research to date on mammary epithelial differentiation has focused upon expression of milk protein genes, providing a somewhat distorted view of alveolar differentiation and secretory activation. While expression of milk protein genes increases during pregnancy and at secretory activation, the genes whose expression is more tightly regulated at this transition are those that regulate lipid biosynthesis. The sterol regulatory element binding protein (SREBP) family of transcription factors is recognized as regulating fatty acid and cholesterol biosynthesis. We propose that SREBP1 is a critical regulator of secretory activation with regard to lipid biosynthesis, in a manner that responds to diet, and that the serine/threonine protein kinase Akt influences this process, resulting in a highly efficient lipid synthetic organ that is able to support the nutritional needs of the newborn.
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Affiliation(s)
- Steven M Anderson
- Department of Pathology, University of Colorado Health Sciences Center, East 17th Avenue, Aurora, CO 80045, USA
- Program in Molecular Biology, University of Colorado Health Sciences Center, East 17th Avenue, Aurora, CO 80045, USA
| | - Michael C Rudolph
- Department of Physiology and Biophysics, University of Colorado Health Sciences Center, East 17th Avenue, Aurora, CO 80045, USA
| | - James L McManaman
- Program in Molecular Biology, University of Colorado Health Sciences Center, East 17th Avenue, Aurora, CO 80045, USA
- Department of Physiology and Biophysics, University of Colorado Health Sciences Center, East 17th Avenue, Aurora, CO 80045, USA
- Department of Obstetrics and Gynecology, University of Colorado Health Sciences Center, East 17th Avenue, Aurora, CO 80045, USA
| | - Margaret C Neville
- Department of Physiology and Biophysics, University of Colorado Health Sciences Center, East 17th Avenue, Aurora, CO 80045, USA
- Department of Obstetrics and Gynecology, University of Colorado Health Sciences Center, East 17th Avenue, Aurora, CO 80045, USA
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23
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German JB, Schanbacher FL, Lönnerdal B, Medrano JF, McGuire MA, McManaman JL, Rocke DM, Smith TP, Neville MC, Donnelly P, Lange M, Ward R. International milk genomics consortium. Trends Food Sci Technol 2006. [DOI: 10.1016/j.tifs.2006.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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McManaman JL, Reyland ME, Thrower EC. Secretion and fluid transport mechanisms in the mammary gland: comparisons with the exocrine pancreas and the salivary gland. J Mammary Gland Biol Neoplasia 2006; 11:249-68. [PMID: 17136613 DOI: 10.1007/s10911-006-9031-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Milk is a complex fluid composed of proteins, sugars, lipids and minerals, in addition to a wide variety of bioactive molecules including vitamins, trace elements and growth factors. The composition of these components reflects the integrated activities of distinct synthetic, secretion and transport processes found in mammary epithelial cells, and mirrors the differing nutritional and developmental requirements of mammalian neonates. Five general pathways have been described for secretion of milk components. With the exception of lipids, which are secreted a unique pathway, milk components are thought to be secreted by adaptations of pathways found in other secretory organs. However little is known about the molecular and cellular mechanisms that constitute these pathways or the physiological mechanisms by which they are regulated. Comparisons of current secretion and transport models in the mammary gland, exocrine pancreas and salivary gland indicate that significant differences exist between the mammary gland and other exocrine organs in how proteins and lipids are packaged and secreted, and how fluid is transported.
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Affiliation(s)
- James L McManaman
- Department of Obstetrics and Gynecology, University of Colorado Health Sciences Center at Fitzsimons, Mail Stop 8309, P.O. Box 6511, Aurora, CO 80045, USA.
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Renard C, Hart E, Sehra H, Beasley H, Coggill P, Howe K, Harrow J, Gilbert J, Sims S, Rogers J, Ando A, Shigenari A, Shiina T, Inoko H, Chardon P, Beck S. The genomic sequence and analysis of the swine major histocompatibility complex. Genomics 2006; 88:96-110. [PMID: 16515853 DOI: 10.1016/j.ygeno.2006.01.004] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 01/18/2006] [Accepted: 01/18/2006] [Indexed: 10/25/2022]
Abstract
We describe the generation and analysis of an integrated sequence map of a 2.4-Mb region of pig chromosome 7, comprising the classical class I region, the extended and classical class II regions, and the class III region of the major histocompatibility complex (MHC), also known as swine leukocyte antigen (SLA) complex. We have identified and manually annotated 151 loci, of which 121 are known genes (predicted to be functional), 18 are pseudogenes, 8 are novel CDS loci, 3 are novel transcripts, and 1 is a putative gene. Nearly all of these loci have homologues in other mammalian genomes but orthologues could be identified with confidence for only 123 genes. The 28 genes (including all the SLA class I genes) for which unambiguous orthology to genes within the human reference MHC could not be established are of particular interest with respect to porcine-specific MHC function and evolution. We have compared the porcine MHC to other mammalian MHC regions and identified the differences between them. In comparison to the human MHC, the main differences include the absence of HLA-A and other class I-like loci, the absence of HLA-DP-like loci, and the separation of the extended and classical class II regions from the rest of the MHC by insertion of the centromere. We show that the centromere insertion has occurred within a cluster of BTNL genes located at the boundary of the class II and III regions, which might have resulted in the loss of an orthologue to human C6orf10 from this region.
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Affiliation(s)
- C Renard
- LREG INRA CEA, Jouy en Josas, France
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26
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Flint DJ, Travers MT, Barber MC, Binart N, Kelly PA. Diet-induced obesity impairs mammary development and lactogenesis in murine mammary gland. Am J Physiol Endocrinol Metab 2005; 288:E1179-87. [PMID: 15671082 DOI: 10.1152/ajpendo.00433.2004] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have developed a mouse model of diet-induced obesity that shows numerous abnormalities relating to mammary gland function. Animals ate approximately 40% more calories when offered a high-fat diet and gained weight at three times the rate of controls. They exhibited reduced conception rates, increased peripartum pup mortality, and impaired lactogenesis. The impairment of lactogenesis involved lipid accumulation in the secretory epithelial cells indicative of an absence of copius milk secretion. Expression of mRNAs for beta-casein, whey acid protein, and alpha-lactalbumin were all decreased immediately postpartum but recovered as lactation was established over 2-3 days. Expression of acetyl-CoA carboxylase (ACC)-alpha mRNA was also decreased at parturition as was the total enzyme activity, although there was a compensatory increase in the proportion in the active state. By day 10 of lactation, the proportion of ACC in the active state was also decreased in obese animals, indicative of suppression of de novo fatty acid synthesis resulting from the supply of preformed fatty acids in the diet. Although obese animals consumed more calories in the nonpregnant and early pregnant states, they showed a marked depression in fat intake around day 9 of pregnancy before food intake recovered in later pregnancy. Food intake increased dramatically in both lean and obese animals during lactation although total calories consumed were identical in both groups. Thus, despite access to high-energy diets, the obese animals mobilized even more adipose tissue during lactation than their lean counterparts. Obese animals also exhibited marked abnormalities in alveolar development of the mammary gland, which may partially explain the delay in differentiation evident during lactogenesis.
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Sriram G, Martinez JA, McCabe ERB, Liao JC, Dipple KM. Single-gene disorders: what role could moonlighting enzymes play? Am J Hum Genet 2005; 76:911-24. [PMID: 15877277 PMCID: PMC1196451 DOI: 10.1086/430799] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Accepted: 04/05/2005] [Indexed: 11/03/2022] Open
Abstract
Single-gene disorders with "simple" Mendelian inheritance do not always imply that there will be an easy prediction of the phenotype from the genotype, which has been shown for a number of metabolic disorders. We propose that moonlighting enzymes (i.e., metabolic enzymes with additional functional activities) could contribute to the complexity of such disorders. The lack of knowledge about the additional functional activities of proteins could result in a lack of correlation between genotype and phenotype. In this review, we highlight some notable and recent examples of moonlighting enzymes and their possible contributions to human disease. Because knowledge and cataloging of the moonlighting activities of proteins are essential for the study of cellular function and human physiology, we also review recently reported and recommended methods for the discovery of moonlighting activities.
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Affiliation(s)
- Ganesh Sriram
- Department of Human Genetics and Division of Medical Genetics, Department of Pediatrics, David Geffen School of Medicine, Department of Chemical Engineering, Henry Samueli School of Engineering and Applied Science, and Mattel Children’s Hospital, University of California–Los Angeles, Los Angeles
| | - Julian A. Martinez
- Department of Human Genetics and Division of Medical Genetics, Department of Pediatrics, David Geffen School of Medicine, Department of Chemical Engineering, Henry Samueli School of Engineering and Applied Science, and Mattel Children’s Hospital, University of California–Los Angeles, Los Angeles
| | - Edward R. B. McCabe
- Department of Human Genetics and Division of Medical Genetics, Department of Pediatrics, David Geffen School of Medicine, Department of Chemical Engineering, Henry Samueli School of Engineering and Applied Science, and Mattel Children’s Hospital, University of California–Los Angeles, Los Angeles
| | - James C. Liao
- Department of Human Genetics and Division of Medical Genetics, Department of Pediatrics, David Geffen School of Medicine, Department of Chemical Engineering, Henry Samueli School of Engineering and Applied Science, and Mattel Children’s Hospital, University of California–Los Angeles, Los Angeles
| | - Katrina M. Dipple
- Department of Human Genetics and Division of Medical Genetics, Department of Pediatrics, David Geffen School of Medicine, Department of Chemical Engineering, Henry Samueli School of Engineering and Applied Science, and Mattel Children’s Hospital, University of California–Los Angeles, Los Angeles
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