Functional characterization of a humanPOU1F1mutation associated with isolated growth hormone deficiency: a novel etiology for IGHD

Abstract

POU1F1, a pituitary-specific POU-homeo domain transcription factor, plays an essential role in the specification of the somatotroph, lactotroph and thyrotroph lineages and in the activation of GH1, PRL and TSHβ transcription. Individuals with mutations in POU1F1 present with combined deficiency of GH, PRL and TSH. Here, we identified a heterozygous missense mutation with evidence of pathogenicity, at the POU1F1 locus, in a large family in which an isolated growth hormone deficiency segregates as an autosomal dominant trait. The corresponding p.Pro76Leu mutation maps to a conserved site within the POU1F1 transactivation domain. Bandshift assays revealed that the mutation alters wild-type POU1F1 binding to cognate sites within the hGH-LCR and hGH1 promoter, but not to sites within the PRL promoter, and it selectively increases binding affinity to sites within the hGH-LCR. Co-immunoprecipitation studies reveal that this substitution enhances interactions of POU1F1 with three of its cofactors, PITX1, LHX3a and ELK1, and that residue 76 plays a critical role in these interactions. The insertion of the mutation at the mouse Pou1f1 locus results in a dramatic loss of protein expression despite normal mRNA concentrations. Mice heterozygous for the p.Pro76Leu mutation were phenotypically normal while homozygotes demonstrated a dwarf phenotype. Overall, this study unveils the involvement of POU1F1 in dominantly inherited isolated GH deficiency and demonstrates a significant impact of the Pro76Leu mutation on DNA-binding activities, alterations in transactivating functions and interactions with cofactors. Our data further highlight difficulties in modeling human genetic disorders in the mouse despite apparent conservation of gene expression pathways and physiologic functions.

Lethality of inappropriate plasma exposure on chicken embryonic development

“…IGFBP2, the major IGFBP in chicken, has a specific, high-affinity for IGF1 and blocks IGF1 access to IGF1R, thereby inducing antiproliferative effects [ 47 ]. POU1F1 has a high affinity DNA binding domain which targets the genes that encode GH [ 48 ]. Our results indicate plasma exposure slows the signaling cascade involving GH and IGF-1, which induces the inhibition of cell reproduction and growth during embryonic development.…”

Functional Annotation of the Transcriptome of the Pig, Sus scrofa, Based Upon Network Analysis of an RNAseq Transcriptional Atlas

“…ESR1, GHR, GNRHR, GSHR, TRHR). Many transcriptional regulators of pituitary development are also contained with cluster 2, including ISL1, GATA2, PITX1, PITX2, POU1F1, PROP1, SIX3, and SIX6 (Charles et al, 2006;Castinetti et al, 2015;Xie et al, 2015;Sobrier et al, 2016). Cluster 14 contains transcripts encoding the other major pituitary hormone, POMC, regulatory receptors GHRHR and CASR (Mamillapalli and Wysolmerski, 2010) and the key transcriptional regulator of POMC, PAX7 (Drouin, 2016).…”

Machine-learning dissection of Human Accelerated Regions in primate neurodevelopment

“…Using all vertebrate TRANSFAC (Matys et al, 2006) motifs with a p-value threshold of 10 -5 , we characterized TFBS that were only present in the human allele (98 TFBS) or only in the chimp allele (137 TFBS) ( Table S5). Some notable transcription factors that appear to have gained binding sites as a result of human substitutions in HAR enhancers are zinc finger proteins from the early growth response (EGR)1/2/3/4 families which play a role in neuronal plasticity (Liu et al, 2000;Knapska et al, 2004;Lu et al, 2011), POU1F1 which activates growth hormone genes (Sobrier et al, 2016), and FOXP1 which plays a role in radial migration and morphogenesis of cortical neurons and associated with autism and speech disorders (Li et al, 2015;Lozano et al, 2015;Teramitsu et al, 2004). It is worth noting that 2xHAR.548, one of our top scoring differentially active HARs (Table S3), is located within the topologically associating domain (TAD; (Dixon et al, 2012)) that encompasses FOXP1.…”