Grb10-Interacting GYF Protein-2 Research Articles

Therapeutic targets for endometriosis: Genome-wide Mendelian randomization and colocalization analyses

BackgroundEndometriosis (EM) greatly affects women's reproductive health, identifying new drug targets for EM is urgently needed. This study utilizes comprehensive genome-wide Mendelian randomization (MR) and colocalization analyses, using genomic data, to identify potential therapeutic approaches for EM. MethodsGenome-wide cis-expression quantitative trait loci (cis-eQTL) data were obtained from GTEx V8, which included 838 participants across 49 tissues or cells, and the eQTLGen consortium, which included 31,684 participants. Genome-wide association analysis (GWAS) data for EM were sourced from the FinnGen study, which consisted of 8,288 cases and 68,969 controls, as well as the UK Biobank study, which included 1,496 cases and 359,698 controls. This study utilized MR analysis to assess the correlation between genes and the risk of EM. Subsequently, colocalization analysis was conducted to investigate potential shared causal variants between the identified genes and EM. ResultsAfter conducting MR and colocalization analyses, we identified a total of 13 genes that showed significant evidence of colocalization. These genes are considered promising therapeutic candidates for treating EM. Among them, inner membrane mitochondrial protein (IMMT), src kinase associated phosphoprotein 1 (SKAP1), lysine methyltransferase 5A (KMT5A), KLF transcription factor 12 (KLF12), GRB10 interacting GYF protein 1 (GIGYF1), Wnt family member 7A (WNT7A), Sad1 and UNC84 domain containing 1 (SUN1), and poly (ADP-ribose) polymerase family member 3 (PARP3) were found to have positive associations with the risk of EM. On the other hand, progestin and adipoQ receptor family member 8 (PAQR8), adaptor related protein complex 3 subunit mu 1 (AP3M1), surfeit 6 (SURF6), TUB bipartite transcription factor (TUB), and DNA polymerase delta interacting protein 2 (POLDIP2) were found to have inverse relationships with the risk of EM. ConclusionsThrough genome-wide MR studies, a comprehensive set of genes associated with EM has been identified. Among them, IMMT, PAQR8, SKAP1, KMT5A, AP3M1, SURF6, KLF12, GIGYF1, TUB, WNT7A, SUN1, POLDIP2, and PARP3 show potential as therapeutic targets for EM treatment. Nonetheless, it is crucial to conduct further rigorous investigations to validate these prospects.

Aberrant hyper-expression of the RNA binding protein GIGYF2 in endothelial cells modulates vascular aging and function

Vascular endothelial cells (ECs) senescence plays a crucial role in vascular aging that promotes the initiation and progression of cardiovascular disease. The mutation of Grb10-interacting GYF protein 2 (GIGYF2) is strongly associated with the pathogenesis of aging-related diseases, whereas its role in regulating ECs senescence and dysfunction still remains elusive. In this study, we found aberrant hyperexpression of GIGYF2 in senescent human ECs and aortas of old mice. Silencing GIGYF2 in senescent ECs suppressed eNOS-uncoupling, senescence, and endothelial dysfunction. Conversely, in nonsenescent cells, overexpressing GIGYF2 promoted eNOS-uncoupling, cellular senescence, endothelial dysfunction, and activation of the mTORC1-SK61 pathway, which were ablated by rapamycin or antioxidant N-Acetyl-l-cysteine (NAC). Transcriptome analysis revealed that staufen double-stranded RNA binding protein 1 (STAU1) is remarkably downregulated in the GIGYF2-depleted ECs. STAU1 depletion significantly attenuated GIGYF2-induced cellular senescence, dysfunction, and inflammation in young ECs. Furthermore, we disclosed that GIGYF2 acting as an RNA binding protein (RBP) enhances STAU1 mRNA stability, and that the intron region of the late endosomal/lysosomal adaptor MAPK and mTOR activator 4 (LAMTOR4) could bind to STAU1 protein to upregulate LAMTOR4 expression. Immunofluorescence staining showed that GIGYF2 overexpression promoted the translocation of mTORC1 to lysosome. In the mice model, GIGYF2flox/flox Cdh-Cre+ mice protected aged mice from aging-associated vascular endothelium-dependent relaxation and arterial stiffness. Our work discloses that GIGYF2 serving as an RBP enhances the mRNA stability of STAU1 that upregulates LAMTOR4 expression through binding with its intron region, which activates the mTORC1-S6K1 signaling via recruitment of mTORC1 to the lysosomal membrane, ultimately leading to ECs senescence, dysfunction, and vascular aging. Disrupting the GIGYF2-STAU1-mTORC1 signaling cascade may represent a promising therapeutic approach against vascular aging and aging-related cardiovascular diseases.

Low Expression of GIGYF1 Inhibits Metastasis, Proliferation, and Promotes Apoptosis and Autophagy of Gastric Cancer Cells.

GRB10 interacting GYF protein 1 (GIGYF1) binds to the N-terminal region of Grb10, regulates multiple signaling pathways. However, it is not clear what happens to cell proliferation, metastasis, apoptosis, and autophagy when the expression level of GIGYF1 gene is reduced. Detection of GIGYF1 expression in clinical tissue specimens and gastric cancer (GC) cell lines by quantitative Real-time PCR (qRT-PCR), GIGYF1 gene was knocked down in MGC-803 cells using small interfering RNA, the effect of GIGYF1 gene on cell metastasis was detected using Transwell assay and wound healing assay, the effect on cell proliferation was detected using plate cloning assay and cck-8 assay, the effect on apoptosis was detected using flow cytometry, autophagosomes were detected using laser confocal microscopy, and the effect on protein expression was detected using immunofluorescence and Western blotting. GIGYF1 gene expression was higher in tumor tissue samples than in paracancer tissue samples, and higher in human GC cell lines than in human normal gastric epithelial cells. GIGYF1 gene knockdown inhibited cell migration, scratch healing ability and EMT process, weakened cell proliferation ability, increased apoptosis rate, promoted the formation of autophagosomes, and changed the corresponding protein expression level. Meanwhile, GIGYF1 knockdowns inhibited the ERK and AKT signaling. In conclusion, the low expression of GIGYF1 gene can inhibit the occurrence and progression of gastric cancer, during which the ERK and AKT signaling pathways are inhibited.

Regulation of the Golgi Apparatus by p38 and JNK Kinases during Cellular Stress Responses.

p38 and c-Jun N-terninal kinase (JNK) are activated in response to acute stress and inflammatory signals. Through modification of a plethora of substrates, these kinases profoundly re-shape cellular physiology for the optimal response to a harmful environment and/or an inflammatory state. Here, we utilized phospho-proteomics to identify several hundred substrates for both kinases. Our results indicate that the scale of signaling from p38 and JNK are of a similar magnitude. Among the many new targets, we highlight the regulation of the transcriptional regulators grb10-interacting GYF protein 1 and 2 (GIGYF1/2) by p38-dependent MAP kinase-activated protein kinase 2 (MK2) phosphorylation and 14–3–3 binding. We also show that the Golgi apparatus contains numerous substrates, and is a major target for regulation by p38 and JNK. When activated, these kinases mediate structural rearrangement of the Golgi apparatus, which positively affects protein flux through the secretory system. Our work expands on our knowledge about p38 and JNK signaling with important biological ramifications.

The eIF4E homolog 4EHP (eIF4E2) regulates hippocampal long-term depression and impacts social behavior

BackgroundThe regulation of protein synthesis is a critical step in gene expression, and its dysfunction is implicated in autism spectrum disorder (ASD). The eIF4E homologous protein (4EHP, also termed eIF4E2) binds to the mRNA 5′ cap to repress translation. The stability of 4EHP is maintained through physical interaction with GRB10 interacting GYF protein 2 (GIGYF2). Gene-disruptive mutations in GIGYF2 are linked to ASD, but causality is lacking. We hypothesized that GIGYF2 mutations cause ASD by disrupting 4EHP function.MethodsSince homozygous deletion of either gene is lethal, we generated a cell-type-specific knockout model where Eif4e2 (the gene encoding 4EHP) is deleted in excitatory neurons of the forebrain (4EHP-eKO). In this model, we investigated ASD-associated synaptic plasticity dysfunction, ASD-like behaviors, and global translational control. We also utilized mice lacking one copy of Gigyf2, Eif4e2 or co-deletion of one copy of each gene to further investigate ASD-like behaviors.Results4EHP is expressed in excitatory neurons and synaptosomes, and its amount increases during development. 4EHP-eKO mice display exaggerated mGluR-LTD, a phenotype frequently observed in mouse models of ASD. Consistent with synaptic plasticity dysfunction, the mice displayed social behavior impairments without being confounded by deficits in olfaction, anxiety, locomotion, or motor ability. Repetitive behaviors and vocal communication were not affected by loss of 4EHP in excitatory neurons. Heterozygous deletion of either Gigyf2, Eif4e2, or both genes in mice did not result in ASD-like behaviors (i.e. decreases in social behavior or increases in marble burying). Interestingly, exaggerated mGluR-LTD and impaired social behaviors were not attributed to changes in hippocampal global protein synthesis, which suggests that 4EHP and GIGYF2 regulate the translation of specific mRNAs to mediate these effects.LimitationsThis study did not identify which genes are translationally regulated by 4EHP and GIGYF2. Identification of mistranslated genes in 4EHP-eKO mice might provide a mechanistic explanation for the observed impairment in social behavior and exaggerated LTD. Future experiments employing affinity purification of translating ribosomes and mRNA sequencing in 4EHP-eKO mice will address this relevant issue.ConclusionsTogether these results demonstrate an important role of 4EHP in regulating hippocampal plasticity and ASD-associated social behaviors, consistent with the link between mutations in GIGYF2 and ASD.

Genome-wide association study of birth weight in sheep

Birth weight is the earliest available growth trait with considerable impacts on lamb survivability and growth performance traits. This study was conducted to perform a genome-wide association study of birth weight in a meat-type sheep. A total of 132 Lori-Bakhtiari sheep were selected based on estimated of breeding values (EBVs) for BW analyses. The selected animals were genotyped using Illumina Ovine SNP50 Bead Chip. After quality control, a total of 41 323 single-nucleotide polymorphisms (SNPs) and 130 sheep were used for subsequent analyses. Plink 1.90 beta software was used for the analyses. Seven SNPs on chromosomes 1, 16, 19 and 22 were detected based on genome-wide unadjusted P-values (P <10−6), which jointly accounted for 1.2% of total genetic variation. However, based on Bonferroni-adjusted P-values, only three SNPs on chromosome 1 had significant associations with EBVs for birth weight (P <0.05), which jointly explained 0.8% of total genetic variation. A total of seven genes were found in 50 kb intervals from the three significant SNPs on chromosome 1, but only three genes, including RAB6B (a member of RAS oncogene family), Tf serotransferrin and GIGYF2 (a GRB10 interacting GYF protein 2), could be considered as candidate genes for birth weight in future studies. The results of this study may facilitate potential use of the genes involving in growth and production traits for genetic improvement of productivity in sheep.

4EHP-independent repression of endogenous mRNAs by the RNA-binding protein GIGYF2.

Initially identified as a factor involved in tyrosine kinase receptor signaling, Grb10-interacting GYF protein 2 (GIGYF2) has later been shown to interact with the 5′ cap-binding protein 4EHP as part of a translation repression complex, and to mediate post-transcriptional repression of tethered reporter mRNAs. A current model proposes that GIGYF2 is indirectly recruited to mRNAs by specific RNA-binding proteins (RBPs) leading to translation repression through its association with 4EHP. Accordingly, we recently observed that GIGYF2 also interacts with the miRNA-induced silencing complex and probably modulates its translation repression activity. Here we have further investigated how GIGYF2 represses mRNA function. In a tethering reporter assay, we identify three independent domains of GIGYF2 with repressive activity. In this assay, GIGYF2-mediated repression is independent of 4EHP but largely dependent on the CCR4/NOT complex that GIGYF2 recruits through multiple interfaces. Importantly, we show that GIGYF2 is an RBP and identify for the first time endogenous mRNA targets that recapitulate 4EHP-independent repression. Altogether, we propose that GIGYF2 has two distinct mechanisms of repression: one depends on 4EHP binding and mainly affects translation; the other is 4EHP-independent and involves the CCR4/NOT complex and its deadenylation activity.

Drosophila Gyf/GRB10 interacting GYF protein is an autophagy regulator that controls neuron and muscle homeostasis

Autophagy is an essential process for eliminating ubiquitinated protein aggregates and dysfunctional organelles. Defective autophagy is associated with various degenerative diseases such as Parkinson disease. Through a genetic screening in Drosophila, we identified CG11148, whose product is orthologous to GIGYF1 (GRB10-interacting GYF protein 1) and GIGYF2 in mammals, as a new autophagy regulator; we hereafter refer to this gene as Gyf. Silencing of Gyf completely suppressed the effect of Atg1-Atg13 activation in stimulating autophagic flux and inducing autophagic eye degeneration. Although Gyf silencing did not affect Atg1-induced Atg13 phosphorylation or Atg6-Pi3K59F (class III PtdIns3K)-dependent Fyve puncta formation, it inhibited formation of Atg13 puncta, suggesting that Gyf controls autophagy through regulating subcellular localization of the Atg1-Atg13 complex. Gyf silencing also inhibited Atg1-Atg13-induced formation of Atg9 puncta, which is accumulated upon active membrane trafficking into autophagosomes. Gyf-null mutants also exhibited substantial defects in developmental or starvation-induced accumulation of autophagosomes and autolysosomes in the larval fat body. Furthermore, heads and thoraxes from Gyf-null adults exhibited strongly reduced expression of autophagosome-associated Atg8a-II compared to wild-type (WT) tissues. The decrease in Atg8a-II was directly correlated with an increased accumulation of ubiquitinated proteins and dysfunctional mitochondria in neuron and muscle, which together led to severe locomotor defects and early mortality. These results suggest that Gyf-mediated autophagy regulation is important for maintaining neuromuscular homeostasis and preventing degenerative pathologies of the tissues. Since human mutations in the GIGYF2 locus were reported to be associated with a type of familial Parkinson disease, the homeostatic role of Gyf-family proteins is likely to be evolutionarily conserved.

The contribution of GIGYF2 to Parkinson’s disease: a meta-analysis

The contribution of the gene of GIGYF2, Grb10-Interacting GYF Protein 2, to Parkinson's disease (PD) is still ambiguous. To explore the contribution of GIGYF2 to PD at the genetic level, we analyzed the relationship between all reported GIGYF2 variants (including mutations and polymorphisms) and PD through a meta-analysis. Databases including Medline, Embase, etc., were searched to find relevant studies. All eligible publications have to meet the strict inclusion and exclusion criteria listed. Two authors independently selected trials, assessed the article's quality and extracted data. Odds ratios (ORs) and relative risks with 95% confidence intervals (CIs) were used to evaluate the strength of associations. All analyses were carried out by using the Review Manager software package v.5.2. More than 100 variants of GIGYF2 were reported either or both in patients and controls in 10 included publications. The 10 publications totally included 5466 patients and 6517 controls. We conducted meta-analyses for the following variants: N56S, N457T, Del LPQQQQQQ 1209-1216, Del Q 1210 (rs10555297), rs12328151, rs2289912, rs2305138, rs3816334, A572A and H1171R. The ORs for N56S were 2.86 (95% CI 1.10, 7.41) for PD and 4.75 (95% CI 1.35, 16.68) for FPD. And the OR for N457T in FPD was 4.53 (95% CI 1.04, 19.66). On the other hand, other variants involved in meta-analyses were not related to PD. This research results suggest that the N56S and N457T of GIGYF2 are risk factors for PD in Caucasians, but not in Asians.

Negative regulation of Grb10 Interacting GYF Protein 2 on insulin-like growth factor-1 receptor signaling pathway caused diabetic mice cognitive impairment.

Heterozygous Gigyf2 +/− mice exhibits histopathological evidence of neurodegeneration such as motor dysfunction. Several lines of evidence have demonstrated the important role of insulin-like growth factor-1 receptor (IGF1R) signaling pathway in the neuropathogenic process of cognitive impairment, while decreased Grb10-Interacting GYF Protein 2 (GIGYF2) expression can alter IGF1R trafficking and its downstream signaling pathways. Growth factor receptor-bound protein 10 (Grb10), a suppressor of IGF1R pathway, has been shown to play a critical role in regulating diabetes-associated cognitive impairment. It remains unknown whether endogenous GIGYF2 expression contributes to the development of diabetes-associated cognitive impairment. Using streptozotocin (STZ)-induced diabetic mice model, we first demonstrated that a significantly increased level of GIGYF2 expression was correlated with a significant decrease in the expression of phosphorylated IGF1R as well as the phosphorylation of AKT and ERK1/2, two signaling pathways downstream of IGF1R, in the hippocampus of diabetic mice. On the contrary, in situ knockdown of GIGYF2 expression in hippocampus resulted in increased expression of phosphorylated IGF1R expression and correspondingly reversed the down-regulation of ERK1/2 phsophorylation but had no obvious effect on Grb10 expression. Functionally, knockdown of GIGYF2 expression markedly ameliorated diabetes-associated cognitive dysfunction as well as the ultrastructural pathology and abnormal neurobehavioral changes. These results suggest that increased expression of GIGYF2 might contribute to the development of diabetes-associated cognitive disorder via negatively regulating IGF1R signaling pathway. Therefore, down-regulation of GIGYF2 expression may provide a potential novel approach to treat diabetes-associated cognitive impairment caused by aberrant IGF1R signaling pathway.

Meta-analyses of seven GIGYF2 polymorphisms with Parkinson's disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder that affects ~2% of the global population aged ≥65 years. Grb10-interacting GYF protein-2 (GIGYF2) can influence the development of PD through the regulation of insulin-like growth factor-1. The aim of the present meta-analysis study was to establish the contribution of GIGYF2 polymorphisms to PD. The study was conducted based on nine eligible studies consisting of 7,246 PD patients and 7,544 healthy controls. The results indicated that the GIGYF2 C.3630A>G polymorphism increased the risk of PD by 37% [P=0.008; odds ratio (OR), 1.37; 95% confidence interval (CI), 1.08-1.73] and that the GIGYF2 C.167G>A polymorphism was significantly associated with PD (P=0.003; OR, 3.67; 95% CI, 1.56-8.68). The meta-analyses of the other five GIGYF2 polymorphisms (C.1378C>A, C.1554G>A, C.2940A>G, C.1370C>A and C.3651G>A) did not reveal any significant associations. The present meta-analyses of the GIGYF2 genetic polymorphisms may provide a comprehensive overview of this PD candidate gene for future studies.

Ridaifen B, a tamoxifen derivative, directly binds to Grb10 interacting GYF protein 2

Ridaifen B (RID-B) is a tamoxifen derivative that potently inhibits breast tumor growth. RID-B was reported to show anti-proliferating activity for a variety of estrogen receptor (ER)-positive human cancer cells. Interestingly, RID-B was also reported to possess higher potency than that of tamoxifen even for some ER-negative cells, suggesting an ER-independent mechanism of action. In this study, a T7 phage display screen and subsequent binding analyses have identified Grb10 interacting GYF protein 2 (GIGYF2) as a RID-B-binding protein. Using a cell-based assay, the Akt phosphorylation level mediated by GIGYF2 was found to have decreased in the presence of RID-B.

A Novel 4EHP-GIGYF2 Translational Repressor Complex Is Essential for Mammalian Development

The binding of the eukaryotic initiation factor 4E (eIF4E) to the mRNA 5' cap structure is a rate-limiting step in mRNA translation initiation. eIF4E promotes ribosome recruitment to the mRNA. In Drosophila, the eIF4E homologous protein (d4EHP) forms a complex with binding partners to suppress the translation of distinct mRNAs by competing with eIF4E for binding the 5' cap structure. This repression mechanism is essential for the asymmetric distribution of proteins and normal embryonic development in Drosophila. In contrast, the physiological role of the mammalian 4EHP (m4EHP) was not known. In this study, we have identified the Grb10-interacting GYF protein 2 (GIGYF2) and the zinc finger protein 598 (ZNF598) as components of the m4EHP complex. GIGYF2 directly interacts with m4EHP, and this interaction is required for stabilization of both proteins. Disruption of the m4EHP-GIGYF2 complex leads to increased translation and perinatal lethality in mice. We propose a model by which the m4EHP-GIGYF2 complex represses translation of a subset of mRNAs during embryonic development, as was previously reported for d4EHP.

Follow-up study of variants of the GIGYF2 gene in Chinese patients with Parkinson’s disease

The Grb10-interacting GYF protein-2 gene ( GIGYF2) is a PARK11 gene that reportedly has a causal role in familial Parkinson’s disease (PD) among populations from Italy and France. However, no comprehensive study of the GIGYF2 gene has been conducted among PD patients from mainland China. In our previous study, the GIGYF2 gene was directly sequenced, and nine missense variants and 14 polymorphisms were identified. For these 14 polymorphisms, in the present study we performed a case–control analysis for 300 PD patients and 200 healthy controls from mainland China. The c.297T>C p.Ala99Ala polymorphism was associated with increased risk with respect to the pathogenesis of sporadic PD. In conclusion, within the Chinese population, the c.297T>C p.Ala99Ala polymorphism of the GIGYF2 gene may be associated with an increased risk of developing PD.

Proteomic Analysis of Native Hepatocyte Nuclear Factor-4α (HNF4α) Isoforms, Phosphorylation Status, and Interactive Cofactors

Hepatocyte nuclear factor-4α (HNF4α, NR2A1) is a nuclear receptor that has a critical role in hepatocyte differentiation and the maintenance of homeostasis in the adult liver. However, a detailed understanding of native HNF4α in the steady-state remains to be elucidated. Here we report the native HNF4α isoform, phosphorylation status, and complexes in the steady-state, as shown by shotgun proteomics in HepG2 hepatocarcinoma cells. Shotgun proteomic analysis revealed the complexity of native HNF4α, including multiple phosphorylation sites and inter-isoform heterodimerization. The associating complexes identified by label-free semiquantitative proteomic analysis include the following: the DNA-dependent protein kinase catalytic subunit, histone acetyltransferase complexes, mRNA splicing complex, other nuclear receptor coactivator complexes, the chromatin remodeling complex, and the nucleosome remodeling and histone deacetylation complex. Among the associating proteins, GRB10 interacting GYF protein 2 (GIGYF2, PERQ2) is a new candidate cofactor in metabolic regulation. Moreover, an unexpected heterodimerization of HNF4α and hepatocyte nuclear factor-4γ was found. A biochemical and genomewide analysis of transcriptional regulation showed that this heterodimerization activates gene transcription. The genes thus transcribed include the cell death-inducing DEF45-like effector b (CIDEB) gene, which is an important regulator of lipid metabolism in the liver. This suggests that the analysis of the distinctive stoichiometric balance of native HNF4α and its cofactor complexes described here are important for an accurate understanding of transcriptional regulation.

Critical involvement of RQCD1 in the EGFR-Akt pathway in mammary carcinogenesis

We previously reported an important role of RQCD1 in mammary carcinogenesis through the interaction with Grb10 interacting GYF protein 1 (GIGYF1), Grb10 interacting GYF protein 2 (GIGYF2) and growth factor receptor binding protein 10 (Grb10). In this study, we investigated the biological mechanism of RQCD1 in regulation of the Akt activity as the downstream signal of epidermal growth factor receptor (EGFR). Knockdown of RQCD1 reduced the Akt phosphorylation level that was induced by epidermal growth factor (EGF) stimulation. We found a possible formation of the big complex involved in the Akt activity including Akt, EGFR, GIGYF1 and GIGYF2, Grb10 and RQCD1. We subsequently defined that a region corresponding to 620-665th amino acids of GIGYF1 and 667-712th amino acids of GIGYF2 interacted with RQCD1. Furthermore, we found that RQCD1 was required for enhancement of the interaction of Grb10 with GIGYF1 and GIGYF2. Our findings in this study imply the functional mechanism of RQCD1 in the Akt activity regulation as a mediator in the EGFR-signaling pathway.

GIGYF2 is present in endosomal compartments in the mammalian brains and enhances IGF‐1‐induced ERK1/2 activation

GIGYF2 has been reported as a candidate gene for PARK11-linked Parkinson's disease (PD). Heterozygous knockout of GIGYF2 results in neurodegeneration, suggesting important roles for GIGYF2 (Grb10 interacting GYF protein 2) in the CNS. In this study, we used novel GIGYF2 antibodies to clarify the distribution and function of GIGYF2. GIGYF2 was widely expressed, most highly in the pancreas and testis, and moderately in brain, lung, liver, kidney and spleen. In the brain, GIGYF2 was tightly associated with membrane in the S3 fraction, and localised in neuronal perikarya and proximal dendrites. Immunohistochemical analysis indicated sites of GIGYF2 localisation throughout the mouse brain, with high levels in the cerebral cortex, hippocampus, cerebellum, olfactory bulb and brainstem nuclei, but low levels in the substantia nigra and striatum. GIGYF2 was present in endosomes immunopositive for Rab4 and Grb10. Expression of GIGYF2 altered insulin-like growth factor-1 (IGF-1) receptor trafficking and enhanced IGF-1-induced extracellular signal-regulated kinase 1/2 phosphorylation, but not IGF-1 receptor or serine/threonine protein kinase Akt phosphorylation. There were no significant differences in signalling activation between cells expressing wild-type and putative PD-associated mutant GIGYF2. In PD brains, GIGYF2 did not localise to Lewy bodies. Our findings indicate a role for GIGYF2 in the regulation of signalling at endosomes, but no contribution of GIGYF2 to the pathogenesis of PD.

No evidence for pathogenic role of GIGYF2 mutation in Parkinson disease in Japanese patients

Grb10-Interacting GYF Protein-2 ( GIGYF2) is a candidate gene for PARK11 locus. To date, seven different GIGYF2 missense mutations have been identified in patients with familial Parkinson disease (PD) of European descent. To clarify the pathogenic role of GIGYF2 in PD, we analyzed the frequency of GIGYF2 mutations in 389 Japanese patients with PD (including 93 patients with late-onset familial PD, 276 with sporadic PD, and 20 with a single heterozygous mutation in the PD-associated genes), and 336 Japanese normal controls, by direct sequencing and/or high-resolution melting analysis. None of the reported GIGYF2 mutations or digenic mutations were detected. Two novel non-synonymous variants were identified (p.Q1211delQ and p.H1023Q), however, we could not determine their roles in PD. In summary, we found no evidence for PD-associated roles of GIGYF2 mutations. Our data suggest that GIGYF2 is unlikely to play a major role in PD in Japanese patients, similar to other populations.

Novel GIGYF2 gene variants in patients with Parkinson's disease in Chinese population

The Grb10-Interacting GYF Protein-2 gene ( GIGYF2), located in the chromosomal region 2q36-q37, has been reported as a PARK11 gene with a causal role in familial Parkinson's disease (PD) in Italian and French populations. However, there is no comprehensive study of GIGYF2 gene conducted in Chinese patients with PD from mainland China. The 27 coding exons and intron/exon boundaries of the GIGYF2 gene were sequenced in 300 sporadic patients with Parkinson's disease. Eight heterozygous and one homozygous novel missense variants were identified in nine patients with PD, and not in 300 controls. p.Leu580Phe locates in the GYF domain and might interrupt the potentially function of GIGYF2 protein. Another variant Gln979stop encodes a truncated protein. In conclusion, we identified nine novel variants in GIGYF2 gene, which might be associated with PD in the Chinese population.

Mutational screening and zebrafish functional analysis of GIGYF2 as a Parkinson-disease gene

The Grb10-Interacting GYF Protein-2 (GIGYF2) gene has been proposed as the Parkinson-disease (PD) gene underlying the PARK11 locus. However, association of GIGYF2 with PD has been challenged and a functional validation of GIGYF2 mutations is lacking. In this frame, we performed a mutational screening of GIGYF2 in an Italian PD cohort. Exons containing known mutations were analyzed in 552 cases and 552 controls. Thereafter, a subset of 184 familial PD cases and controls were subjected to a full coding-exon screening. These analyses identified 8 missense variations in 9 individuals (4 cases, 5 controls). Furthermore, we developed a zebrafish model of gigyf2 deficiency. Abrogation of gigyf2 function in zebrafish embryos did not lead to a drastic cell loss in diencephalic dopaminergic (DA) neuron clusters, suggesting that gigyf2 is not required for DA neuron differentiation. Notably, gigyf2 functional abrogation did not increase diencephalic DA neurons susceptibility to the PD-inducing drug MPP+. These data, together with those recently reported by other groups, suggest that GIGYF2 is unlikely to be the PARK11 gene.