Corrigendum: Neuroimaging in PRUNE1 syndrome: a mini-review of the literature

[This corrects the article DOI: 10.3389/fneur.2023.1301147.].

PRUNE1 and NME/NDPK family proteins influence energy metabolism and signaling in cancer metastases

We describe here the molecular basis of the complex formation of PRUNE1 with the tumor metastasis suppressors NME1 and NME2, two isoforms appertaining to the nucleoside diphosphate kinase (NDPK) enzyme family, and how this complex regulates signaling the immune system and energy metabolism, thereby shaping the tumor microenvironment (TME). Disrupting the interaction between NME1/2 and PRUNE1, as suggested, holds the potential to be an excellent therapeutic target for the treatment of cancer and the inhibition of metastasis dissemination. Furthermore, we postulate an interaction and regulation of the other Class I NME proteins, NME3 and NME4 proteins, with PRUNE1 and discuss potential functions. Class I NME1-4 proteins are NTP/NDP transphosphorylases required for balancing the intracellular pools of nucleotide diphosphates and triphosphates. They regulate different cellular functions by interacting with a large variety of other proteins, and in cancer and metastasis processes, they can exert pro- and anti-oncogenic properties depending on the cellular context. In this review, we therefore additionally discuss general aspects of class1 NME and PRUNE1 molecular structures as well as their posttranslational modifications and subcellular localization. The current knowledge on the contributions of PRUNE1 as well as NME proteins to signaling cascades is summarized with a special regard to cancer and metastasis.

Neuroimaging in PRUNE1 syndrome: a mini-review of the literature

Prune exopolyphosphatase 1 (PRUNE1) is a short-chain phosphatase that is part of the aspartic acid-histidine-histidine (DHH) family of proteins. PRUNE1 is highly expressed in the central nervous system and is crucially involved in neurodevelopment, cytoskeletal rearrangement, cell migration, and proliferation. Recently, biallelic PRUNE1 variants have been identified in patients with neurodevelopmental disorders, hypotonia, microcephaly, variable cerebral anomalies, and other features. PRUNE1 hypomorphic mutations mainly affect the DHH1 domain, leading to an impactful decrease in enzymatic activity with a loss-of-function mechanism. In this review, we explored both the clinical and radiological spectrum related to PRUNE1 pathogenic variants described to date. Specifically, we focused on neuroradiological findings that, together with clinical phenotypes and genetic data, allow us to best characterize affected children with diagnostic and potential prognostic implications.

PRUNE1 (located on chromosome 1q21.3) promotes multiple myeloma with 1q21 Gain by enhancing the links between purine and mitochondrion

Patients with multiple myeloma (MM) with chromosome 1q21 Gain (1q21+) are clinically and biologically heterogeneous. 1q21+ in the real world actually reflects the prognosis for gain/amplification of the CKS1B gene. In this study, we found that the copy number of prune exopolyphosphatase 1 (PRUNE1), located on chromosome 1q21.3, could further stratify the prognosis of MM patients with 1q21+. Using selected reaction monitoring/multiple reaction monitoring (SRM/MRM) analysis, liquid chromatography-tandem mass spectrometry (LC-MS/MS), transmission electron microscopy (TEM), confocal fluorescence microscopy, calculation of adenosine triphosphate (ATP), intracellular reactive oxygen species (ROS) and mitochondrial oxygen consumption rates (OCRs), we demonstrated for the first time that PRUNE1 promotes the proliferation and invasion of MM cells by stimulating purine metabolism, purine synthesis enzymes and mitochondrial functions, enhancing links between purinosomes and mitochondria. SOX11 was identified as a transcription factor for PRUNE1. Through integrated analysis of the transcriptome and proteome, CD73 was determined to be the downstream target of PRUNE1. Furthermore, it has been determined that dipyridamole can effectively suppress the proliferation of MM cells with high-expression levels of PRUNE1 in vitro and in vivo. These findings provide insights into disease-causing mechanisms and new therapeutic targets for MM patients with 1q21+.

Generation of Conditional Knockout Alleles for PRUNE-1

PRUNE1 is a member of the aspartic acid-histidine-histidine (DHH) protein superfamily, which could display an exopolyphosphatase activity and interact with multiple cellular proteins involved in the cytoskeletal rearrangement. It is widely expressed during embryonic development and is essential for embryogenesis. PRUNE1 could also be critical for postnatal development of the nervous system as it was found to be mutated in patients with microcephaly, brain malformations, and neurodegeneration. To determine the cellular function of PRUNE1 during development and in disease, we have generated conditional mouse alleles of the Prune1 in which loxP sites flank exon 6. Crossing these alleles with a ubiquitous Cre transgenic line resulted in a complete loss of PRUNE1 expression and embryonic defects identical to those previously described for Prune1 null embryos. In addition, breeding these alleles with a Purkinje cell-specific Cre line (Pcp2-Cre) resulted in the loss of Purkinje cells similar to that observed in patients carrying a mutation with loss of PRUNE1 function. Therefore, the Prune1 conditional mouse alleles generated in this study provide important genetic tools not only for dissecting the spatial and temporal roles of PRUNE1 during development but also for understanding the pathogenic role of PRUNE1 dysfunction in neurodegenerative or neurodevelopmental disease. In addition, from this work, we have described an approach that allows one to efficiently generate conditional mouse alleles based on mouse zygote electroporation.

Neurodevelopmental disorder with microcephaly, hypotonia, and variable brain anomalies in a consanguineous Iranian family is associated with a homozygous start loss variant in the PRUNE1 gene

Background

Homozygous or compound heterozygous PRUNE1 mutations cause a neurodevelopmental disorder with microcephaly, hypotonia, and variable brain malformations (NMIHBA) (OMIM #617481). The PRUNE1 gene encodes a member of the phosphoesterase (DHH) protein superfamily that is involved in the regulation of cell migration. To date, most of the described mutations in the PRUNE1 gene are clustered in DHH domain.

Methods

We subjected 4 members (two affected and two healthy) of a consanguineous Iranian family in the study. The proband underwent whole-exome sequencing and a start loss identified variant was confirmed by Sanger sequencing. Co-segregation of the detected variant with the disease in family was confirmed.

Results

By whole-exome sequencing, we identified the a start loss variant, NM_021222.3:c.3G>A; p.(Met1?), in the PRUNE1 in two patients of a consanguineous Iranian family with spastic quadriplegic cerebral palsy (CP), hypotonia, developmental regression, and cerebellar atrophy. Sanger sequencing confirmed the segregation of the variant with the disease in the family. Protein structure analysis also revealed that the variant probably leads to the deletion of DHH (Asp-His-His) domain, the active site of the protein, and loss of PRUNE1 function.

Conclusion

We identified a start loss variant, NM_021222.3:c.3G>A; p.(Met1?) in the PRUNE1 gene in two affected members as a possible cause of NMIHBA in an Iranian family. We believe that the study adds a new pathogenic variant in spectrum of mutations in the PRUNE1 gene as a cause of PRUNE1-related syndrome.

An identical-by-descent novel splice-donor variant in PRUNE1 causes a neurodevelopmental syndrome with prominent dystonia in two consanguineous Sudanese families

PRUNE1 is linked to a wide range of neurodevelopmental and neurodegenerative phenotypes. Multiple pathogenic missense and stop-gain PRUNE1 variants were identified in its DHH and DHHA2 phosphodiesterase domains. Conversely, a single splice alteration was previously reported. We investigated five patients from two unrelated consanguineous Sudanese families with an inherited severe neurodevelopmental disorder using whole-exome sequencing coupled with homozygosity mapping, segregation, and haplotype analysis. We identified a founder haplotype transmitting a homozygous canonical splice-donor variant (NM_021222.3:c.132+2T > C) in intron 2 of PRUNE1 segregated with the phenotype in all the patients. This splice variant possibly results in an in-frame deletion in the DHH domain or premature truncation of the protein. The phenotypes of the affected individuals showed phenotypic similarities characterized by remarkable pyramidal dysfunction and prominent extrapyramidal features (severe dystonia and bradykinesia). In conclusion, we identified a novel founder variant in PRUNE1 and corroborated abnormal splicing events as a disease mechanism in PRUNE1-related disorders. Given the phenotypes' consistency coupled with the founder effect, canonical and cryptic PRUNE1 splice-site variants should be carefully evaluated in patients presenting with prominent dystonia and pyramidal dysfunction.

Altered MR imaging findings in a Japanese female child with PRUNE1-related disorder

Autosomal recessive PRUNE1 mutations on chromosome 1q21.3 are reported to cause a neurodevelopmental disorder with microcephaly, hypotonia, and variable brain malformations. Here, we report a Japanese case with a reported PRUNE1 mutation whose brain magnetic resonance imaging (MRI) showed specific imaging findings that have not been reported before. The patient was a 12-month-old girl, the first child of healthy and nonconsanguineous Japanese parents. She showed global developmental delay, intellectual disability, hypotonia, spastic quadriparesis, and hyperreflexia. Brain MRI showed cerebral and cerebellar atrophy, thin corpus callosum, white matter changes, and abnormal signal intensity of the brainstem, all of which were reported in the literature. In addition, we emphasize the three following imaging findings: a transient cerebral subcortical white matter lesion, atrophy of the midbrain and pontine tegmentum with a preserved pontine base, and abnormal signal intensity of the bilateral swelling putamina and medial portions of the thalami, which emerged after 4 years of age. The whole-exome sequencing (WES) analysis performed at the age of 4 years identified biallelic PRUNE1 variants, namely compound heterozygous mutations (c.[316G > A];[540 T > A],p.[Asp106Asn];[Cys180*]). Although the diagnosis of PRUNE1-related disorder requires WES, we think that these new characteristic MRI findings may help in the diagnosis of PRUNE1-related disorder.

A homozygous canonical splice acceptor site mutation in PRUNE1 is responsible for a rare childhood neurodegenerative disease in Manitoba Cree families

Autosomal recessive PRUNE1 mutations are reported to cause a severe neurodevelopmental disorder with microcephaly, hypotonia, and brain malformations. We describe clinical and neuropathological features in a cohort of nine individuals of Cree descent who, because of a founder effect, are homozygous for the same PRUNE1 mutation. They follow the course of a combined neuromuscular and neurodegenerative disease, rather than a pure failure of normal development. This cohort presented in infancy with features of lower motor neuron disease, such as hypotonia, contractures, tongue fasciculations, and feeding difficulties in the absence of congenital brain anomalies and microcephaly. A neurodegenerative course followed with onset of seizures, spasticity, and respiratory insufficiency. Muscle biopsies showed denervation/reinnervation features, nonspecific atrophy and end-stage atrophy. Autopsy findings in two patients are also described, suggesting length dependent central motor axon degeneration, peripheral motor axon degeneration, possible spinal motor neuron degeneration, and accumulation of beta amyloid precursor protein inclusions in select brainstem nuclei. Exome sequencing and homozygosity mapping identified a homozygous PRUNE1 mutation in a canonical splice site, which produces two abnormal PRUNE1 mRNA products. Based on our studies and the histopathology and phenotypic data, we provide further evidence that this disorder leads to a neurodegenerative disease affecting both the peripheral and central nervous systems and suggest that the pathogenic c.521-2A>G mutation could lead to an altered effect on tubulin dynamics.

PRUNE Syndrome Is a New Neurodevelopmental Disorder: Report and Review

PRUNE syndrome, or neurodevelopmental disorder with microcephaly, hypotonia, and variable brain anomalies (OMIM#617481), is a new rare autosomal recessive neurodevelopmental disease that is caused by homozygous or compound heterozygous mutation in PRUNE1 on chromosome 1q21. Here, We report on 12-month-old and 30-month-old girls from 2 unrelated Saudi families with typical presentations of PRUNE syndrome. Both patients had severe developmental delay, progressive microcephaly, and dysmorphic features. Brain magnetic resonance imaging showed slight thinning in the corpus callosum, mild frontal brain atrophy, and delayed myelination in one of the patients. Both patients had the same missense mutation in PRUNE1 (c.383G>A, p.Arg128Gln), which was not reported before in a homozygous state. We compared our patients to previously reported cases. In conclusion, We suggest that clinicians consider PRUNE syndrome in any child presenting with dysmorphic features, developmental delay, progressive microcephaly, central hypotonia, peripheral spasticity, delayed myelination, brain atrophy, and a thin corpus callosum.

Homozygous mutation in PRUNE1 in an Oji-Cree male with a complex neurological phenotype

The PRUNE1 gene encodes a member of the phosphoesterases (DHH) protein superfamily that is highly expressed in the human fetal brain and involved in the regulation of cell migration. Homozygous or compound heterozygous PRUNE1 mutations were recently identified in five individuals with brain malformations from four families. We present a case of a 2-year-old male with a complex neurological phenotype and abnormalities on brain MRI. Re-annotation of clinical whole-exome sequencing data revealed a homozygous likely pathogenic variant in PRUNE1 (c.521-2A>G). These results further delineate a new PRUNE1-related syndrome, and highlight the importance of periodic data re-annotation in individuals who remain without a diagnosis after undergoing genome-wide testing. © 2017 Wiley Periodicals, Inc.

PRUNE is crucial for normal brain development and mutated in microcephaly with neurodevelopmental impairment

PRUNE is a member of the DHH (Asp-His-His) phosphoesterase protein superfamily of molecules important for cell motility, and implicated in cancer progression. Here we investigated multiple families from Oman, India, Iran and Italy with individuals affected by a new autosomal recessive neurodevelopmental and degenerative disorder in which the cardinal features include primary microcephaly and profound global developmental delay. Our genetic studies identified biallelic mutations of PRUNE1 as responsible. Our functional assays of disease-associated variant alleles revealed impaired microtubule polymerization, as well as cell migration and proliferation properties, of mutant PRUNE. Additionally, our studies also highlight a potential new role for PRUNE during microtubule polymerization, which is essential for the cytoskeletal rearrangements that occur during cellular division and proliferation. Together these studies define PRUNE as a molecule fundamental for normal human cortical development and define cellular and clinical consequences associated with PRUNE mutation.