BOARD-INVITED REVIEW: The biology and regulation of preadipocytes and adipocytes in meat animals1,2

Hausman, Gary; Dodson, Michael V.; Ajuwon, Kolapo M.; Azain, M. J.; Barnes, Kimberly M; Guan, Le Luo; Jiang, Zhihua; Poulos, Sylvia P.; Sainz, Roberto Daniel; Smith, Stephen B.; Spurlock, Michael E.; Novakofski, J.; Fernyhough, Melinda E.; Bergen, Werner G.

doi:10.2527/jas.2008-1427

Cited by 291 publications

(332 citation statements)

References 322 publications

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“…Picard et al, 1995 and2002) and adipose tissues (e.g. reviews from Boone et al, 2000;Hausman et al, 2009) in different species, the precise pattern of IMF ontogenesis and its regulation remains still poorly characterized. At the cellular level, triglycerides are generally initially stored within muscle fibres in mammals.…”

Section: How Might Marbling Begin?mentioning

confidence: 99%

“…As assessing IMF content at this period of time is difficult, this emphasizes the usefulness of early predicting markers. As for non-muscular adipose tissue differentiation programme (Figure 1), it is then likely that a variety of genes involved in adipocyte development (such as insulin-responsiveness glucose transport GLUT4, LPL, lipogenic enzymes), and the master regulators of adipogenesis (peroxisome proliferatoractivated receptor gamma (PPARG) and sterol-regulatory element-binding protein-1(SREBP1); for review, see Hausman et al, 2009) would be of great potential for predicting subsequent IMF development. Whether they could serve as early biomarkers should be discussed later in the text.…”

Section: How Might Marbling Begin?mentioning

confidence: 99%

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Intramuscular fat content in meat-producing animals: development, genetic and nutritional control, and identification of putative markers

Hocquette

Gondret

Baéza³

et al. 2010

Animal

637

447

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Intramuscular fat (IMF) content plays a key role in various quality traits of meat. IMF content varies between species, between breeds and between muscle types in the same breed. Other factors are involved in the variation of IMF content in animals, including gender, age and feeding. Variability in IMF content is mainly linked to the number and size of intramuscular adipocytes. The accretion rate of IMF depends on the muscle growth rate. For instance, animals having a high muscularity with a high glycolytic activity display a reduced development of IMF. This suggests that muscle cells and adipocytes interplay during growth. In addition, early events that influence adipogenesis inside the muscle (i.e proliferation and differentiation of adipose cells, the connective structure embedding adipocytes) might be involved in interindividual differences in IMF content. Increasing muscularity will also dilute the final fat content of muscle. At the metabolic level, IMF content results from the balance between uptake, synthesis and degradation of triacylglycerols, which involve many metabolic pathways in both adipocytes and myofibres. Various experiments revealed an association between IMF level and the muscle content in adipocyte-type fatty acid-binding protein, the activities of oxidative enzymes, or the delta-6-desaturase level; however, other studies failed to confirm such relationships. This might be due to the importance of fatty acid fluxes that is likely to be responsible for variability in IMF content during the postnatal period rather than the control of one single pathway. This is evident in the muscle of most fish species in which triacylglycerol synthesis is almost zero. Genetic approaches for increasing IMF have been focused on live animal ultrasound to derive estimated breeding values. More recently, efforts have concentrated on discovering DNA markers that change the distribution of fat in the body (i.e. towards IMF at the expense of the carcass fatness). Thanks to the exhaustive nature of genomics (transcriptomics and proteomics), our knowledge on fat accumulation in muscles is now being underpinned. Metabolic specificities of intramuscular adipocytes have also been demonstrated, as compared to other depots. Nutritional manipulation of IMF independently from body fat depots has proved to be more difficult to achieve than genetic strategies to have lipid deposition dependent of adipose tissue location. In addition, the biological mechanisms that explain the variability of IMF content differ between genetic and nutritional factors. The nutritional regulation of IMF also differs between ruminants, monogastrics and fish due to their digestive and nutritional particularities.

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Section: How Might Marbling Begin?mentioning

confidence: 99%

Section: How Might Marbling Begin?mentioning

confidence: 99%

Intramuscular fat content in meat-producing animals: development, genetic and nutritional control, and identification of putative markers

Hocquette

Gondret

Baéza³

et al. 2010

Animal

637

447

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“…However, mature adipocytes are post-mitotic, which implies that proliferative adipocyte precursor cells must exist and be poised to respond to metabolic demands to maintain adipose dynamics in adults. Adipocyte precursors have been isolated from the stromal vascular fraction of bovine WAT (Hausman et al, 2009).…”

Section: Dynamics Of At Growthmentioning

confidence: 99%

Ontogenesis of muscle and adipose tissues and their interactions in ruminants and other species

Bonnet

Cassar-Malek

Chilliard

et al. 2010

Animal

110

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The lean-to-fat ratio, that is, the relative masses of muscle and adipose tissue, is a criterion for the yield and quality of bovine carcasses and meat. This review describes the interactions between muscle and adipose tissue (AT) that may regulate the dynamic balance between the number and size of muscle v. adipose cells. Muscle and adipose tissue in cattle grow by an increase in the number of cells (hyperplasia), mainly during foetal life. The total number of muscle fibres is set by the end of the second trimester of gestation. By contrast, the number of adipocytes is never set. Number of adipocytes increases mainly before birth until 1 year of age, depending on the anatomical location of the adipose tissue. Hyperplasia concerns brown pre-adipocytes during foetal life and white pre-adipocytes from a few weeks after birth. A decrease in the number of secondary myofibres and an increase in adiposity in lambs born from mothers severely underfed during early pregnancy suggest a balance in the commitment of a common progenitor into the myogenic or adipogenic lineages, or a reciprocal regulation of the commitment of two distinct progenitors. The developmental origin of white adipocytes is a subject of debate. Molecular and histological data suggested a possible transdifferentiation of brown into white adipocytes, but this hypothesis has now been challenged by the characterization of distinct precursor cells for brown and white adipocytes in mice. Increased nutrient storage in fully differentiated muscle fibres and adipocytes, resulting in cell enlargement (hypertrophy), is thought to be the main mechanism, whereby muscle and fat masses increase in growing cattle. Competition or prioritization between adipose and muscle cells for the uptake and metabolism of nutrients is suggested, besides the successive waves of growth of muscle v. adipose tissue, by the inhibited or delayed adipose tissue growth in bovine genotypes exhibiting strong muscular development. This competition or prioritization occurs through cellular signalling pathways and the secretion of proteins by adipose tissue (adipokines) and muscle (myokines), putatively regulating their hypertrophy in a reciprocal manner. Further work on the mechanisms underlying cross-talk between brown or white adipocytes and muscle fibres will help to achieve better understanding as a prerequisite to improving the control of body growth and composition in cattle.

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“…In addition, genetic selection in meat animals has favoured lean carcasses, leading to a reduction in the IMF content in beef. Generalized AT reduction could adversely affect meat quality, in that a certain amount of IMF is needed to assure such attributes as juiciness, tenderness and taste (Maltin et al, 2003;Hausman et al, 2009), but excess abdominal or subcutaneous (SC) fat is not desirable, because it decreases feed efficiency and depreciates the carcass. Thus, a balance in the amount of AT accumulated in the different anatomical depots would be beneficial, and this has been a goal viewed in recent years as a window of opportunity for improving both meat quality and feed efficiency in beef cattle.…”

Section: Introductionmentioning

confidence: 99%

“…The current emphasis of cattle selection programmes has, therefore, been on increasing the IMF without impacting the SC fat (Hausman et al, 2009), deriving knowledge regarding the molecular mechanisms involved in AT development being a complementary goal. Despite recent gains in our comprehension of AT regulation in meat animals, many issues still need to be explained before this process is fully understood.…”

Section: Introductionmentioning

confidence: 99%

Expression of genes involved in adipogenesis and lipid metabolism in subcutaneous adipose tissue and longissimus muscle in low-marbled Pirenaica beef cattle

Soret

Mendizábal

Arana

et al. 2016

animal

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The ability to accumulate intramuscular fat (IMF) is a highly variable characteristic in beef cattle. In breeds with a low tendency to accumulate IMF, this can lead to compromised meat quality because of the contribution of fat to such organoleptic attributes as juiciness and taste. This study considered adiposity and gene expression of some of the main markers involved in adipogenesis and lipid metabolism in the subcutaneous (SC) adipose tissue (AT) and the longissimus thoracis muscle (LM) and investigated differences in adipogenic regulation between the tissues during growth and fattening under different conditions. Pirenaica beef cattle were chosen for the study due to the breed's low tendency to accumulate IMF and the breed's regional importance. The young Pirenaica bulls used (n = 16) were allocated to four groups and slaughtered at 6, 12 and 18 months. From 12 months onwards the bulls slaughtered at 18 months were fed diets having different energy densities. Backfat thickness increased from 6 to 12 months (P < 0.05) but then was unchanged, while other fattening parameters such as percentage chemical fat and marbling did not vary. The adipose cell size distribution displayed a bimodal distribution for SC adipocytes and a unimodal distribution for IMF cells, suggestive of tissue-specific hyperplasia. Gene expression of peroxisome proliferator-activated receptor γ (PPARG), CCAAT/enhancer-binding protein α (CEBPA), sterol regulatory element-binding transcription factor 1 (SREBF1), wingless-type MMTV integration site family 10B (WNT10B), fatty acid-binding protein 4 (FABP4), acetyl Co-A carboxylase α, lipoprotein lipase and fatty acid synthase (FASN) were determined by real-time quantitative PCR. Expression did not differ between the experimental groups within the tissues but did differ between the tissues: PPARG, FABP4 and FASN were upregulated in the SC AT, while CEBPA, WNT10B and SREBF1 were upregulated in the LM. Although age and diet energy density did not have a significant effect on increasing the amount of IMF, these factors could have influenced adipocyte development in this tissue differently than in the SC AT. This was evidenced by the different size distributions of the cells in the two tissues, and the differing expression patterns of certain markers in the SC AT and the LM, which may indicate a differential role of PPARG and WNT10B in triggering adipocyte proliferation and fat accumulation capacity.

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BOARD-INVITED REVIEW: The biology and regulation of preadipocytes and adipocytes in meat animals1,2

Cited by 291 publications

References 322 publications

Intramuscular fat content in meat-producing animals: development, genetic and nutritional control, and identification of putative markers

Intramuscular fat content in meat-producing animals: development, genetic and nutritional control, and identification of putative markers

Ontogenesis of muscle and adipose tissues and their interactions in ruminants and other species

Expression of genes involved in adipogenesis and lipid metabolism in subcutaneous adipose tissue and longissimus muscle in low-marbled Pirenaica beef cattle

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