[Show abstract][Hide abstract] ABSTRACT: Cognitive impairments are a major clinical feature of the common neurogenetic disease neurofibromatosis type 1 (NF1). Previous studies have demonstrated that increased neuronal inhibition underlies the learning deficits in NF1, however, the molecular mechanism underlying this cell-type specificity has remained unknown. Here, we identify an interneuron-specific attenuation of hyperpolarization-activated cyclic nucleotide-gated (HCN) current as the cause for increased inhibition in Nf1 mutants. Mechanistically, we demonstrate that HCN1 is a novel NF1-interacting protein for which loss of NF1 results in a concomitant increase of interneuron excitability. Furthermore, the HCN channel agonist lamotrigine rescued the electrophysiological and cognitive deficits in two independent Nf1 mouse models, thereby establishing the importance of HCN channel dysfunction in NF1. Together, our results provide detailed mechanistic insights into the pathophysiology of NF1-associated cognitive defects, and identify a novel target for clinical drug development.Molecular Psychiatry advance online publication, 28 April 2015; doi:10.1038/mp.2015.48.
[Show abstract][Hide abstract] ABSTRACT: Children and adults with neurofibromatosis type 1 (NF1) are predisposed to developing CNS tumors, including optic pathway gliomas (OPGs), brainstem gliomas (BSGs) and high-grade gliomas. Although current first-line treatments for low-grade gliomas (OPGs and BSGs) may prevent further tumor growth, they rarely result in restoration of the associated visual or neurological deficits. The availability of accurate small-animal models of NF1-associated brain tumors has established tractable experimental platforms for the discovery and evaluation of promising therapeutic agents. On the basis of these preclinical studies, biologically targeted agents are now being evaluated in children with NF1-associated low-grade brain tumors. Collectively, these models have also begun to reveal potential neuroprotective and risk assessment strategies for this brain tumor-prone population.
[Show abstract][Hide abstract] ABSTRACT: In the vertebrate central nervous system, myelinating oligodendrocytes are postmitotic and derive from proliferative oligodendrocyte precursor cells (OPCs). The molecular mechanisms that govern oligodendrocyte development are incompletely understood, but recent studies implicate the adhesion class of G protein-coupled receptors (aGPCRs) as important regulators of myelination. Here, we use zebrafish and mouse models to dissect the function of the aGPCR Gpr56 in oligodendrocyte development. We show that gpr56 is expressed during early stages of oligodendrocyte development. In addition, we observe a significant reduction of mature oligodendrocyte number and myelinated axons in gpr56 zebrafish mutants. This reduction results from decreased OPC proliferation, rather than increased cell death or altered neural precursor differentiation potential. Finally, we show that these functions are mediated by Gα12/13 proteins and Rho activation. Together, our data establish Gpr56 as a regulator of oligodendrocyte development.
[Show abstract][Hide abstract] ABSTRACT: Background Children with neurofibromatosis type 1 (NF1) develop optic pathway gliomas, which result from impaired NF1 protein regulation of Ras activity. One obstacle to the implementation of biologically targeted therapies is an incomplete
understanding of the individual contributions of the downstream Ras effectors (mitogen-activated protein kinase kinase [MEK],
Akt) to optic glioma maintenance. This study was designed to address the importance of MEK and Akt signaling to Nf1 optic glioma growth.
[Show abstract][Hide abstract] ABSTRACT: One of the potential etiologies for non-familial Neurofibromatosis Type 1 (NF1) is increasing parental age. We sought to evaluate recent evidence for parental age effects in NF1 in a large study. Individuals with NF1 and a comparison group from the U.S. general population born between 1994 and 2012 were ascertained from the NF1 Patient Registry Initiative (NPRI) and the National Center for Vital Statistics, respectively. Multiple linear regression analysis was employed to identify differences between familial NF1, non-familial NF1, and U.S. population subjects in the mean parental ages at the time of the birth of offspring in each group. In addition, we also evaluated the effect of parental age on NF1 offspring with and without a pediatric brain tumor history. A total of 313 subjects from the NPRI (including 99 brain tumor cases) matched by birth year at a 1:3 ratio to U.S. general population births (n = 939) were included. Compared to the U.S. general population and familial NF1 cases, the mean paternal age for non-familial NF1 cases was 4.34 years (95 % CI 3.23-5.46, p ≤ 0.0001) and 3.39 years (95 % CI 1.57-5.20, p ≤ 0.0001) older, respectively, after adjusting for birth year. A similar pattern was observed for maternal age. There were no statistically significant differences in the mean maternal or paternal ages between NF1 offspring with and without a pediatric brain tumor. In conclusion, these data support a parental age effect for non-familial NF1 cases, but not for pediatric brain tumors in NF1.
Familial Cancer 12/2014; 14(2). DOI:10.1007/s10689-014-9774-8 · 1.62 Impact Factor