Berson and Yalow-Reminiscences
Shimon M. Glick, MD
Ref: Ped. Endocrinol. Rev. 2011;8(4):350-353
Key words: Berson, Yalow, radioimmunoasaay, Nobel Prize, Bronx VA Hospital
The Impact of microRNAs on Endocrinology
Harel Zalts1, Noam Shomron2, PhD
The endocrine system controls various cellular functions, constitutes a communication network between cells and distant tissues, and is vital for maintaining homeostasis. The couriers of this system are the hormones, which are produced by endocrine cells, secreted into the bloodstream and interact with receptors to exert their effect. The regulatory effect is manifested by either activating signaling cascades or by altering transcription patterns. Though thoroughly examined, many aspects of the endocrine system’s function are still unclear. MicroRNAs (miRNAs) are short (~22nt), non-coding RNAs that comprise a new subset of cellular regulatory molecules. MiRNAs regulate gene expression post-transcriptionally, by base pairing with the messenger RNA’s (mRNA) 3’ untranslated region (3’UTR). In recent years, miRNAs have emerged as key players in all cellular processes, and their aberrant expression has been linked with different types of disease and malignancies. This review focuses on the role of miRNAs in the function of the endocrine system, emphasizing the intricate reciprocal relationship between these two important regulatory systems.
Ref: Ped. Endocrinol. Rev. 2011;8(4):354-362
Key words: endocrine system, hormone, microRNA, noncoding RNA
Growth Hormone Therapy: Emerging Dilemmas
Zvi Laron, MD, PhD, (h.c.)
The history of pituitary growth hormone (GH) started 100 years ago but the isolation purification and determination of the chemical structure of the human GH (hGH) took another 50 years. Starting in 1957 hGH was extracted from cadaver pituitaries and its clinical use was restricted to severe GH deficient patient. With the invention of recombinant biosynthetic hGH in 1985;the indications for its use were extended. The major approved medications are GH deficiency and short statured children of various etiologies. This is a critical review of present and future use of human GH. To evaluate the effectiveness of the hGH treatment several pharmaceutical companies established postmarketing follow-up programs which are based on the reliability and cooperation of the treating physicians. Unfortunately they stop when the treatment is terminated and most studies refer to growth stimulation effectiveness during initial years but do not follow the children until final height. The long-term experience enabled to evaluate adverse effects (AE), the majority being due to large dosage. The most serious AE reported are increases in malignancies and early or late mortality in adult age. There is consensus that GH deficient children need replacement therapy. As long-term hGH treatment is expensive and the final height gains in non-GH deficient children small the cost-benefit indications to treat short children without a disease has been questioned. To avoid the need of daily injections, long-acting hGH preparations undergo clinical trials. The future will show their effectiveness and eventual adverse effects.
Ref: Ped. Endocrinol. Rev. 2011;8(4):364-373
Key words: Growth hormone, GH deficiency, GH treatment, short stature treatment, adverse effects of GH, long-acting GH.
Molecular Mechanisms Underlying Insulin-Like Growth Factor Action How Mutations in the GH: IGF Axis Lead to Short Stature
Briony E Forbes, PhD
Insulin-like growth factors (IGFs) act via the Type 1 IGF receptor (IGF-1R) to promote growth and development. Recent structural and site-directed mutagenesis studies have provided detailed insight into the mechanism of interaction between the IGFs and the IGF-1R. Studies of the insulin: insulin receptor interaction have provided important additional understanding of the mechanisms underlying the IGF:IGF-1R interaction. The recent crystal structure of the insulin receptor ectodomain showed a folded over conformation accommodating two potential ligand binding pockets. The ligand interacts with the receptor at two different sites within a binding pocket to achieve high affinity binding and activation of the receptor. In this review the effect of mutations in the human IGF1 and IGF-1R genes so far reported are explained in terms of the effect on ligand binding and receptor activation. The severity of patient phenotype can generally be correlated to the effect of the mutation on protein structure and function.
Ref: Ped. Endocrinol. Rev. 2011;8(4):374-381
Key words: Growth hormone, insulin-like growth factor, IGF-1R, IGF-I mutations, IGF-1R mutations
IGFBP-2 at the Interface of Growth and Metabolism – Implications for Childhood Obesity
Matthew A Sabin1, MB, BS, PhD, Vincenzo C Russo1, PhD, Walid J Azar1, BSc, Steven W Yau BSc, Wieland Kiess2, MD, George A Werther1, MD
Defects in the growth hormone (GH)-insulin-like growth factor (IGF)-I axis may cause GH resistance characterized by IGF-I deficiency and growth failure. The range of defects causing GH resistance is broad as are their biochemical and phenotypical characteristics. We propose that GH-IGF-I axis defects form a continuum of clinical and biochemical effects ranging from GH deficiency to GH resistance. The pathophysiology of GH resistance is described followed by a scheme for investigation of the child with severe short stature and normal GH secretion. We critically discuss GH therapy for such patients and define acceptable growth responsiveness. Finally we discuss therapy Childhood obesity is associated with an increased risk of long-term morbidity and mortality, but the factors that determine which obese children will develop these longterm complications are not fully understood. IGFBP-2 may be integrally involved in the molecular processes that govern the development of obesity and subsequent weightrelated disease. Within this manuscript, we explore the associations between IGFBP-2 and obesity with a particular emphasis on how an increased understanding of the role of IGFBP-2 in metabolism may lead to improvements in the prevention and treatment of childhood obesity.
Ref: Ped. Endocrinol. Rev. 2011;8(4):382-393
Key words: IGFBP-2, children, obesity, adipogenesis, insulin resistance, Type 2 diabetes, metabolic syndrome, metabolism
The Pygmy Short Stature Enigma
Cristina Meazza, PhD, Sara Pagani, PhD, Mauro Bozzola, MD
The Pygmy populations of Central Africa are known as the shortest human populations worldwide showing an endocrine profile similar to Caucasian individuals with idiopathic short stature. Therefore, the study of these subjects may significantly improve our knowledge of the mechanisms regulating normal growth in humans. In this review we summarize the existing knowledge on Pygmies’ short stature, including evolutionary hypothesis, studies on their GH/IGF-I axis and their immune system functioning. We illustrate in depth our recent studies on the ethnic group of Pygmies called Babinga, living in the forest of Cameroon, suggesting that the size of Pygmy subjects is reduced from birth, compared to a neighbouring population, and that it is associated with reduced GH and GH receptor gene expression. These results provide a research target for future epigenetic investigations and suggest that the short stature of African Pygmies is probably determined by complex genetic systems.
Ref: Ped. Endocrinol. Rev. 2011;8(4):394-399
Keywords: African Pygmies, short stature, growth hormone, growth hormone receptor
8th Annual World Congress in Insulin Resistance, Diabetes & Cardiovascular Disease November 4-6, 2010
Sonia Caprio, MD
Ref: Ped. Endocrinol. Rev. 2011;8(4): 400-402
Key words: Epigenetic, cardiovascular, complications and genetics of fatty liver in childhood obesity.