Journal Article

Neurofibromin regulates somatic growth through the hypothalamic–pituitary axis

Balazs Hegedus, Tu-Hsueh Yeh, Da Yong Lee, Ryan J. Emnett, Jia Li and David H. Gutmann

in Human Molecular Genetics

Volume 17, issue 19, pages 2956-2966
Published in print October 2008 | ISSN: 0964-6906
Published online July 2008 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/ddn194
Neurofibromin regulates somatic growth through the hypothalamic–pituitary axis

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To study the role of the neurofibromatosis-1 (NF1) gene in mammalian brain development, we recently generated mice in which Nf1 gene inactivation occurs in neuroglial progenitor cells using the brain lipid binding protein (BLBP) promoter. We found that Nf1BLBPCKO mice exhibit significantly reduced body weights and anterior pituitary gland sizes. We further demonstrate that the small anterior pituitary size reflects loss of neurofibromin expression in the hypothalamus, leading to reduced growth hormone releasing hormone, pituitary growth hormone (GH) and liver insulin-like growth factor-1 (IGF1) production. Since neurofibromin both negatively regulates Ras activity and positively modulates cAMP levels, we examined the signaling pathway responsible for these abnormalities. While BLBP-mediated expression of an activated Ras molecule did not recapitulate the body weight and hypothalamic/pituitary defects, treatment of Nf1BLBPCKO mice with rolipram to increase cAMP levels resulted in a partial restoration of the body weight phenotype. Furthermore, conditional expression of the Ras regulatory GAP domain of neurofibromin also did not rescue the body weight or Igf1 mRNA defects in Nf1BLBPCKO mice. Collectively, these data demonstrate a critical role for neurofibromin in hypothalamic–pituitary axis function and provide further insights into the short stature and GH deficits seen in children with NF1.

Journal Article.  6129 words.  Illustrated.

Subjects: Genetics and Genomics

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