Deficiency of the Housekeeping Gene Hypoxanthine–Guanine Phosphoribosyltransferase (HPRT) Dysregulates Neurogenesis

Abstract

Neuronal transcription factors play vital roles in the specification and development of neurons, including dopaminergic (DA) neurons. Mutations in the gene encoding the purine biosynthetic enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT) cause the resulting intractable and largely untreatable neurological impairment of Lesch-Nyhan disease (LND). The disorder is associated with a defect in basal ganglia DA pathways. The mechanisms connecting the purine metabolic defect and the central nervous system (CNS) phenotype are poorly understood but have been presumed to reflect a developmental defect of DA neurons. We have examined the effect of HPRT deficiency on the differentiation of neurons in the well-established human (NT2) embryonic carcinoma neurogenesis model. We have used a retrovirus expressing a small hairpin RNA (shRNA) to knock down HPRT gene expression and have examined the expression of a number of transcription factors essential for neuronal differentiation and marker genes involved in DA biosynthetic pathway. HPRT-deficient NT2 cells demonstrate aberrant expression of several transcription factors and DA markers. Although differentiated HPRT-deficient neurons also demonstrate a striking deficit in neurite outgrowth during differentiation, resulting neurons demonstrate wild-type electrophysiological properties. These results represent direct experimental evidence for aberrant neurogenesis in HPRT deficiency and suggest developmental roles for other housekeeping genes in neurodevelopmental disease.

Impairment of adenylyl cyclase 2 function and expression in hypoxanthine phosphoribosyltransferase-deficient rat B103 neuroblastoma cells as model for Lesch–Nyhan disease: BODIPY–forskolin as pharmacological tool

“…Implications of our study for understanding LND HPRT deficiency has been repeatedly associated with defects in neuronal differentiation (Ma et al 2001;Connolly 2001;Jinnah 2009;Erdorf et al 2011a;Kang et al 2011;Guibinga et al 2010Guibinga et al , 2012Mastrangelo et al 2012). We could confirm this differentiation defect since HPRT − cells underwent much less striking morphological changes upon exposure to FS and BODIPY-FS than control cells (Fig.…”

“…5). The differentiation defect of HPRT − cells is seen under different experimental conditions and involves multiple signal transduction pathways including purinoceptors, microRNAs and the canonical Wnt pathway (Ma et al 2001;Connolly 2001;Jinnah 2009;Erdorf et al 2011a;Kang et al 2011;Guibinga et al 2010Guibinga et al , 2012Mastrangelo et al 2012).…”

Purinergic signaling in human pluripotent stem cells is regulated by the housekeeping gene encoding hypoxanthine guanine phosphoribosyltransferase

“…Because LND is a classical inborn error of purine metabolism, and because we and other groups have demonstrated aberrant neurogenesis and neural pathway development in LND (8,35), we have based much of our recent work and most of the present study on the underlying working hypothesis that aberrant purine metabolism in LND plays a direct causative role in the neurological phenotype of the disorder through disturbed purinergic signaling. In this study, we aimed to generate an in vitro human iPS and ES cell-based system in which to study the development of dopaminergic pathways.…”

MicroRNAs

“…CREB association with miR-181a has also recently been confirmed in another neuronal system in which miR-181a overexpression has been associated with inhibition of dendritic spine growth in hippocampus neurons (Liu et al, 2013). In the context of HPRT deficiency, dendritic spine and neurite growth abnormalities have been reported in vitro and in vivo (Guibinga et al, 2010;Mikolaenko, Rao, Roberts, Kolb, & Jinnah, 2005). Within the framework of HPRT deficiency, it remains to be determined whether these structural dendritic abnormalities are directly linked to miR-181a and CREB dysregulation.…”

“…Several signaling pathways converge onto CREB to regulate the expression of a wide number of genes, such as synapsin I, Tyrosine hydroxylase (TH), and DARPP-32 (dopamine and cAMP-regulated neuronal phosphoprotein) (Guibinga, Barron, & Pandori, 2014;Guibinga, Hsu, & Friedmann, 2010;) that possess a cyclic AMP response element (CRE) consensus sequence in their promoters (Browning, Huganir, & Greengard, 1985;Di Benedetto, D'Addario, Candeletti, & Romualdi, 2007;Hemmings, Nairn, & Greengard, 1986). Together with the aforementioned neurodevelopmental transcription factor genes identified by gene ontology (GO) analysis of miR-181a and other analyses (Guibinga et al, 2012;Guibinga et al, 2010), CREB1 was also shown to be among the potential targets of miR-181a . CREB association with miR-181a has also recently been confirmed in another neuronal system in which miR-181a overexpression has been associated with inhibition of dendritic spine growth in hippocampus neurons (Liu et al, 2013).…”