Accumulation of fat mass in obesity may result from hypertrophy and/or hyperplasia and is frequently associated with adipose tissue (AT) dysfunction in adults. Here we assessed early alterations in AT biology and function by comprehensive experimental and clinical characterization of 171 AT samples from lean and obese children aged 0 to 18 years. We show an increase in adipocyte size and number in obese compared with lean children beginning in early childhood. These alterations in AT composition in obese children were accompanied by decreased basal lipolytic activity and significantly enhanced stromal vascular cell proliferation in vitro, potentially underlying the hypertrophy and hyperplasia seen in obese children, respectively. Furthermore, macrophage infiltration, including the formation of crownlike structures, was increased in AT of obese children from 6 years on and was associated with higher hs-CRP serum levels. Clinically, adipocyte hypertrophy was not only associated with leptin serum levels but was highly and independently correlated with HOMA-IR as a marker of insulin resistance in children. In summary, we show that adipocyte hypertrophy is linked to increased inflammation in AT in obese children, thereby providing evidence that obesity-associated AT dysfunction develops in early childhood and is related to insulin resistance.Obesity is characterized by the accumulation of fat mass and is often associated with adipose tissue (AT) dysfunction (1). Clinical data indicate that obesity already develops during early childhood between 2 and 6 years of age (2). Expansion of AT can be achieved by hyperplasia (increase in adipocyte number) or hypertrophy (increase in adipocyte size) or the combination of both (3). Early studies suggested that adipocyte number is determined in childhood and remains relatively constant during adulthood, implying that expansion of AT mass in (adult) obesity occurs via hypertrophy of adipocytes (4,5). On the other hand, the capability for cell renewal, achieved by differentiation of preadipocytes into mature adipocytes, persists throughout life (6). Whether AT expansion in the development of obesity occurs primarily by hyperplasia or hypertrophy and the time point when AT dysfunction emerges are still a matter of debate.In addition to the mere accumulation of fat mass, obesity is often associated with changes in AT biology and
We found evidence for linkage of BECTS to a region on chromosome 15q14. Either the alpha 7 AChR subunit gene or a closely linked gene are implicated in pedigrees with BECTS. The disorder is genetically heterogeneous. Surprisingly, the same chromosomal area has been reported to be linked to the phenotype in families with an auditory neurophysiologic deficit as well as in families with juvenile myoclonic epilepsy, another idiopathic but generalized epilepsy syndrome.
Little is known about genes regulating male puberty. Further, while many identified pubertal timing variants associate with age at menarche, a late manifestation of puberty, and body mass, little is known about these variants' relationship to pubertal initiation or tempo. To address these questions, we performed genome-wide association meta-analysis in over 11 000 European samples with data on early pubertal traits, male genital and female breast development, measured by the Tanner scale. We report the first genome-wide significant locus for male sexual development upstream of myocardin-like 2 (MKL2) (P = 8.9 × 10(-9)), a menarche locus tagging a developmental pathway linking earlier puberty with reduced pubertal growth (P = 4.6 × 10(-5)) and short adult stature (p = 7.5 × 10(-6)) in both males and females. Furthermore, our results indicate that a proportion of menarche loci are important for pubertal initiation in both sexes. Consistent with epidemiological correlations between increased prepubertal body mass and earlier pubertal timing in girls, body mass index (BMI)-increasing alleles correlated with earlier breast development. In boys, some BMI-increasing alleles associated with earlier, and others with delayed, sexual development; these genetic results mimic the controversy in epidemiological studies, some of which show opposing correlations between prepubertal BMI and male puberty. Our results contribute to our understanding of the pubertal initiation program in both sexes and indicate that although mechanisms regulating pubertal onset in males and females may largely be shared, the relationship between body mass and pubertal timing in boys may be complex and requires further genetic studies.
Serum amyloid A (SAA) 3 has been characterized as an inflammatory adipocyte-secreted acute-phase reactant. In the current study, regulation of SAA3 by the proinflammatory and insulin resistance-inducing cytokine interleukin (IL)-1beta was determined in 3T3-L1 and brown adipocytes. Interestingly, SAA3 mRNA and protein synthesis were dramatically increased by IL-1beta in a time-dependent fashion with maximal induction after 24 h. Furthermore, IL-1beta significantly induced SAA3 mRNA expression dose-dependently with maximal 36.4-fold upregulation seen at 2 ng/ml effector. Moreover, IL-1beta-induced SAA3 expression was mediated by nuclear factor-kappaB and janus kinase 2. Taken together, our data show a potent upregulation of SAA3 by IL-1beta.
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