Testicular teratomagenesis from primordial germ cells with overexpression of germinal center-associated nuclear protein.

Testicular teratomas are the major histologic type of testicular germ cell tumors and their incidence continues to grow. Moreover, teratomas can develop from undifferentiated cells in induced pluripotent stem (iPS) cell transplantation therapy, seriously hampering the progress of regenerative medicine. Germinal center-associated nuclear protein (GANP) is thought to be important to the biogenetic control of primordial germ cells and is among the genes susceptible to testicular germ cell tumors. Thus, we analyzed the expression of GANP in human testicular postpubertal-type teratomas and established a novel mouse model to reveal the association between GANP and teratomagenesis. We analyzed 31 cases of human testicular postpubertal-type teratomas and, in all cases, GANP was overexpressed. The aberrant expression was also detected in germ cell neoplasia in situ accompanied by the teratoma. GANP expression was particularly high in the epithelia of the epidermis, cutaneous appendages, and trachea-like ciliated epithelium. To further clarify the association between GANP and teratomagenesis, we established a novel teratomagenesis mouse model (CAG-ganpTg mice). In the GANP-teratoma mice, GANP-overexpressing teratomas were more frequent at the testes and the middle portion of the uterus than has been seen in the previously established mouse models. In conclusion, GANP is overexpressed in testicular postpubertal-type teratomas and is an essential teratomagenic factor. We also found that CAG-ganpTg mice are useful mouse models of teratomagenesis that mimics human midline teratomas and that teratomas may originate from the overexpression of GANP in primordial germ cells.

The Human TREX-2 Complex Interacts with Subunits of the ORC Complex.

The TREX-2 protein complex is the key complex involved in the export of mRNA from the nucleus to the cytoplasm through the nuclear pores. Previously, a joint protein complex of TREX-2 with ORC was isolated in D. melanogaster. It was shown that the interaction of TREX-2 with ORC is necessary for efficient mRNA export from the nucleus to the cytoplasm. In this work, we showed that the TREX-2-ORC joint complex is also formed in human cells.

Family with primary periodic paralysis and a mutation in MCM3AP, a gene implicated in mRNA transport.

INTRODUCTION: Primary periodic paralyses (PPs) are rare genetic neuromuscular disorders commonly caused by mutations in genes related to ion channel function. However, 10%-20% of cases remain as genetically unexplained. Herein we present a family with PP with paralytic episodes generally lasting for 1-7 days at a time, associated with a drop in K+ levels. METHODS: Screening for mutations in known disease-causing genes was negative, hence we performed whole-exome sequencing of 5 family members. RESULTS: Minichromosome maintenance 3-associated protein (MCM3AP) c.2615G>A (p.C872Y) was found to cosegregate with disease in the family and was not present in control subjects. The mutation is novel, highly conserved across multiple species, and predicted to be damaging. DISCUSSION: MCM3AP encodes germinal center-associated nuclear protein (GANP), a protein involved in the export of certain messenger RNAs from the nucleus to the cytoplasm. Our findings suggest that a novel mutation in MCM3AP is associated with hypokalemic PP. Muscle Nerve, 2019.

MCM3AP in recessive Charcot-Marie-Tooth neuropathy and mild intellectual disability.

Defects in mRNA export from the nucleus have been linked to various neurodegenerative disorders. We report mutations in the gene MCM3AP, encoding the germinal center associated nuclear protein (GANP), in nine affected individuals from five unrelated families. The variants were associated with severe childhood onset primarily axonal (four families) or demyelinating (one family) Charcot-Marie-Tooth neuropathy. Mild to moderate intellectual disability was present in seven of nine affected individuals. The affected individuals were either compound heterozygous or homozygous for different MCM3AP variants, which were predicted to cause depletion of GANP or affect conserved amino acids with likely importance for its function. Accordingly, fibroblasts of affected individuals from one family demonstrated severe depletion of GANP. GANP has been described to function as an mRNA export factor, and to suppress TDP-43-mediated motor neuron degeneration in flies. Thus our results suggest defective mRNA export from nucleus as a potential pathogenic mechanism of axonal degeneration in these patients. The identification of MCM3AP variants in affected individuals from multiple centres establishes it as a disease gene for childhood-onset recessively inherited Charcot-Marie-Tooth neuropathy with intellectual disability.

GaP/GaNP Heterojunctions for Efficient Solar-Driven Water Oxidation.

The growth and characterization of an n-GaP/i-GaNP/p+ -GaP thin film heterojunction synthesized using a gas-source molecular beam epitaxy (MBE) method, and its application for efficient solar-driven water oxidation is reported. The TiO2 /Ni passivated n-GaP/i-GaNP/p+ -GaP thin film heterojunction provides much higher photoanodic performance in 1 m KOH solution than the TiO2 /Ni-coated n-GaP substrate, leading to much lower onset potential and much higher photocurrent. There is a significant photoanodic potential shift of 764 mV at a photocurrent of 0.34 mA cm-2 , leading to an onset potential of ≈0.4 V versus reversible hydrogen electrode (RHE) at 0.34 mA cm-2 for the heterojunction. The photocurrent at the water oxidation potential (1.23 V vs RHE) is 1.46 and 7.26 mA cm-2 for the coated n-GaP and n-GaP/i-GaNP/p+ -GaP photoanodes, respectively. The passivated heterojunction offers a maximum applied bias photon-to-current efficiency (ABPE) of 1.9% while the ABPE of the coated n-GaP sample is almost zero. Furthermore, the coated n-GaP/i-GaNP/p+ -GaP heterojunction photoanode provides a broad absorption spectrum up to ≈620 nm with incident photon-to-current efficiencies (IPCEs) of over 40% from ≈400 to ≈560 nm. The high low-bias performance and broad absorption of the wide-bandgap GaP/GaNP heterojunctions render them as a promising photoanode material for tandem photoelectrochemical (PEC) cells to carry out overall solar water splitting.

MCM3AP and POMP Mutations Cause a DNA-Repair and DNA-Damage-Signaling Defect in an Immunodeficient Child.

Immunodeficiency patients with DNA repair defects exhibit radiosensitivity and proneness to leukemia/lymphoma formation. Though progress has been made in identifying the underlying mutations, in most patients the genetic basis is unknown. Two de novo mutated candidate genes, MCM3AP encoding germinal center-associated nuclear protein (GANP) and POMP encoding proteasome maturation protein (POMP), were identified by whole-exome sequencing (WES) and confirmed by Sanger sequencing in a child with complex phenotype displaying immunodeficiency, genomic instability, skin changes, and myelodysplasia. GANP was previously described to promote B-cell maturation by nuclear targeting of activation-induced cytidine deaminase (AID) and to control AID-dependent hyperrecombination. POMP is required for 20S proteasome assembly and, thus, for efficient NF-κB signaling. Patient-derived cells were characterized by impaired homologous recombination, moderate radio- and cross-linker sensitivity associated with accumulation of damage, impaired DNA damage-induced NF-κB signaling, and reduced nuclear AID levels. Complementation by wild-type (WT)-GANP normalized DNA repair and WT-POMP rescued defective NF-κB signaling. In conclusion, we identified for the first time mutations in MCM3AP and POMP in an immunodeficiency patient. These mutations lead to cooperative effects on DNA recombination and damage signaling. Digenic/polygenic mutations may constitute a novel genetic basis in immunodeficiency patients with DNA repair defects.

GANP protein encoded on human chromosome 21/mouse chromosome 10 is associated with resistance to mammary tumor development.

Human chromosome 21 is known to be associated with the high risk of hematological malignancy but with resistance to breast cancer in the study of Down syndrome. In human cancers, we previously observed the significant alterations of the protein expression encoded by the ganp/MCM3AP gene on human chromosome 21q22.3. Here, we investigated GANP protein alterations in human breast cancer samples (416 cases) at various stages by immunohistochemical analysis. This cohort study clearly showed that expression of GANP is significantly decreased in human breast cancer cases with poor prognosis as an independent risk factor (relapse-free survival, hazard ratio = 2.37, 95% confidence interval, 1.27-4.42, P = 0.007 [univariate analysis]; hazard ratio = 2.70, 95% confidence interval, 1.42-5.13, P = 0.002 [multivariate analysis]). To investigate whether the altered GANP expression is associated with mammary tumorigenesis, we created mutant mice that were conditionally deficient in the ganp/MCM3AP gene using wap-cre recombinase transgenic mice. Mammary gland tumors occurred at a very high incidence in female mammary gland-specific GANP-deficient mice after severe impairment of mammary gland development during pregnancy. Moreover, tumor development also occurred in female post parous GANP-heterodeficient mice. GANP has a significant role in the suppression of DNA damage caused by estrogen in human breast cancer cell lines. These results indicated that the GANP protein is associated with breast cancer resistance.

Optimizing GaNP coaxial nanowires for efficient light emission by controlling formation of surface and interfacial defects.

We report on identification and control of important nonradiative recombination centers in GaNP coaxial nanowires (NWs) grown on Si substrates in an effort to significantly increase light emitting efficiency of these novel nanostructures promising for a wide variety of optoelectronic and photonic applications. A point defect complex, labeled as DD1 and consisting of a P atom with a neighboring partner aligned along a crystallographic ⟨ 111 ⟩ axis, is identified by optically detected magnetic resonance as a dominant nonradiative recombination center that resides mainly on the surface of the NWs and partly at the heterointerfaces. The formation of DD1 is found to be promoted by the presence of nitrogen and can be suppressed by reducing the strain between the core and shell layers, as well as by protecting the optically active shell by an outer passivating shell. Growth modes employed during the NW growth are shown to play a role. On the basis of these results, we identify the GaP/GaN(y)P(1-y)/GaN(x)P(1-x) (x < y) core/shell/shell NW structure, where the GaN(y)P(1-y) inner shell with the highest nitrogen content serves as an active light-emitting layer, as the optimized and promising design for efficient light emitters based on GaNP NWs.

Effects of Polytypism on Optical Properties and Band Structure of Individual Ga(N)P Nanowires from Correlative Spatially Resolved Structural and Optical Studies.

III-V semiconductor nanowires (NWs) have gained significant interest as building blocks in novel nanoscale devices. The one-dimensional (1D) nanostructure architecture allows one to extend band structure engineering beyond quantum confinement effects by utilizing formation of different crystal phases that are thermodynamically unfavorable in bulk materials. It is therefore of crucial importance to understand the influence of variations in the NWs crystal structure on their fundamental physical properties. In this work we investigate effects of structural polytypism on the optical properties of gallium phosphide and GaP/GaNP core/shell NW structures by a correlative investigation on the structural and optical properties of individual NWs. The former is monitored by transmission electron microscopy, whereas the latter is studied via cathodoluminescence (CL) mapping. It is found that structural defects, such as rotational twins in zinc blende (ZB) GaNP, have detrimental effects on light emission intensity at low temperatures by promoting nonradiative recombination processes. On the other hand, formation of the wurtzite (WZ) phase does not notably affect the CL intensity neither in GaP nor in the GaNP alloy. This suggests that zone folding in WZ GaP does not enhance its radiative efficiency, consistent with theoretical predictions. We also show that the change in the lattice structure have negligible effects on the bandgap energies of the GaNP alloys, at least within the range of the investigated nitrogen compositions of <2%. Both WZ and ZB GaNP are found to have a significantly higher efficiency of radiative recombination as compared with that in parental GaP, promising for potential applications of GaNP NWs as efficient nanoscale light emitters within the desirable amber-red spectral range.

Fabry-Perot Microcavity Modes in Single GaP/GaNP Core/Shell Nanowires.

Semiconductor nanowires (NWs) are attracting increasing interest as nanobuilding blocks for optoelectronics and photonics. A novel material system that is highly suitable for these applications are GaNP NWs. In this article, we show that individual GaP/GaNP core/shell nanowires (NWs) grown by molecular beam epitaxy on Si substrates can act as Fabry-Perot (FP) microcavities. This conclusion is based on results of microphotoluminescence (µ-PL) measurements performed on individual NWs, which reveal periodic undulations of the PL intensity that follow an expected pattern of FP cavity modes. The cavity is concluded to be formed along the NW axis with the end facets acting as reflecting mirrors. The formation of the FP modes is shown to be facilitated by an increasing index contrast with the surrounding media. Spectral dependence of the group refractive index is also determined for the studied NWs. The observation of the FP microcavity modes in the GaP/GaNP core/shell NWs can be considered as a first step toward achieving lasing in this quasidirect bandgap semiconductor in the NW geometry.

Recessive Charcot-Marie-Tooth and multiple sclerosis associated with a variant in MCM3AP.

Variants in MCM3AP, encoding the germinal-centre associated nuclear protein, have been associated with progressive polyneuropathy with or without intellectual disability and ptosis in some cases, and with a complex phenotype with immunodeficiency, skin changes and myelodysplasia. MCM3AP encoded protein functions as an acetyltransferase that acetylates the replication protein, MCM3, and plays a key role in the regulation of DNA replication. In this study, we report a novel variant in MCM3AP (p.Ile954Thr), in a family including three affected individuals with characteristic features of Charcot-Marie-Tooth neuropathy and multiple sclerosis, an inflammatory condition of the central nervous system without known genetic cause. The affected individuals were homozygous for a missense MCM3AP variant, located at the Sac3 domain, which was predicted to affect conserved amino acid likely important for the function of the germinal-centre associated nuclear protein. Our data support further expansion of the clinical spectrum linked to MCM3AP variant and highlight that MCM3AP should be considered in patients with accompaniment of recessive motor axonal Charcot-Marie-Tooth neuropathy and multiple sclerosis.

Impact of germinal center-associated nuclear protein polymorphisms on breast cancer risk and prognosis in a Japanese population.

BACKGROUND: Germinal center-associated nuclear protein (GANP) is a phosphoprotein involved in mRNA export and regulation of DNA recombination. Although GANP expression in human breast cancer tissue is associated with breast cancer prognosis, the association between the genetic background of GANP and susceptibility and prognosis of breast cancer is unclear. METHODS: We selected 694 breast cancer cases and 1376 age- and menopausal status-matched non-cancer controls from the Hospitable-based Epidemiologic Research Program, conducted at Aichi Cancer Center between 2001 and 2005. We evaluated the impact of two polymorphisms at the GANP locus (rs2839178 and rs11702450) on the susceptibility and prognosis of breast cancer. Reference alleles were defined as the A allele for rs2839178 and G allele for rs11702450. RESULTS: The GG genotype of rs2839178 was statistically significantly associated with breast cancer risk (odds ratio [OR] 0.48, 95% confidence interval [CI] 0.30-0.76, P = 0.002). In prognostic analysis, compared to those with AA genotype of rs2839178, patients with AG or GG genotypes had longer disease-free survival (DFS) (hazard ratio [HR] 0.71, 95% CI 0.49-1.04 and HR 0.42, 95% CI 013-1.42, respectively, P for trend = 0.04). eQTL analysis indicated that association with rs2839178 can be explained by the effect of rs2839173 on expression of GANP/MCM3AP. CONCLUSIONS: The G allele of rs2839178 at the GANP locus was significantly associated with reduced breast cancer risk and longer DFS in breast cancer patients, showing a consistent direction in the association between susceptibility and clinical outcome. GANP is, therefore, important for the occurrence and progression of sporadic breast cancer.

GANP enhances the efficiency of mRNA nuclear export in mammalian cells.

Nuclear export of mRNPs is mediated by transport factors such as NXF1 that bind mRNPs and mediate their translocation through the central channel of nuclear pores (NPC) using transient interactions with FG-nucleoporins. A number of nuclear factors enhance the efficiency of this process by concentrating mRNPs at the nuclear face of the pores. Although this enhancement has been explored mainly with the yeast TREX-2 complex, recent work has indicated that mammalian cells employ GANP (Germinal-centre Associated Nuclear Protein) for efficient mRNP nuclear export and for efficient recruitment of NXF1-containing mRNPs to NPCs. GANP is constructed from several domains that show local homology to FG-nucleoporins, the yeast mRNA export factor Sac3p and the mammalian MCM3 acetyltransferase. Whereas yeast TREX-2 is located primarily at nuclear pores, some GANP is located in the nuclear interior in addition to that found at the pores. GANP depletion inhibits bulk mRNA export, resulting in retention of mRNPs and NXF1 in punctate foci within the nucleoplasm, consistent with GANP's being an integral component of the mammalian mRNA export machinery. Here, we discuss the model for GANP function presented in our recent paper and its implications for the mechanism of mRNA export in mammalian cells.