Human molecular genetics最新文献

The Shoc2 scaffold protein is crucial in transmitting signals within the Epidermal Growth Factor Receptor (EGFR)-mediated Extracellular signal-Regulated Kinase (ERK1/2) pathway. While the significance of Shoc2 in this pathway is well-established, the precise mechanisms through which Shoc2 governs signal transmission remain to be fully elucidated. Hereditary variants in Shoc2 are responsible for Noonan Syndrome with Loose anagen Hair (NSLH). However, due to the absence of known enzymatic activity in Shoc2, directly assessing how these variants affect its function is challenging. ERK1/2 phosphorylation is used as a primary parameter of Shoc2 function, but the impact of Shoc2 mutants on the pathway activation is unclear. This study investigates how the NSLH-associated Shoc2 variants influence EGFR signals in the context of the ERK1/2 and AKT downstream signaling pathways. We show that when the ERK1/2 pathway is a primary signaling pathway activated downstream of EGFR, Shoc2 variants cannot upregulate ERK1/2 phosphorylation to the level of the WT Shoc2. Yet, when the AKT and ERK1/2 pathways were activated, in cells expressing Shoc2 variants, ERK1/2 phosphorylation was higher than in cells expressing WT Shoc2. In cells expressing the Shoc2 NSLH mutants, we found that the AKT signaling pathway triggers the PAK activation, followed by phosphorylation of Raf-1/MEK1/2 and activation of the ERK1/2 signaling axis. Hence, our studies reveal a previously unrecognized feedback regulation downstream of the EGFR and provide additional evidence for the role of Shoc2 as a "gatekeeper" in controlling the selection of downstream effectors within the EGFR signaling network.

We have recently discovered that the so-called subcortical maternal complex (SCMC) proteins composing of cytoplasmic lattices are destabilized in Uhrf1 knockout murine fully grown oocytes (FGOs). Here we report that human UHRF1 interacts with human NLRP5 and OOEP, which are core components of the SCMC. Moreover, NLRP5 and OOEP interact with DPPA3, which is an essential factor for exporting UHRF1 from the nucleus to the cytoplasm in oocytes. We identify that NLRP5, not OOEP, stabilizes UHRF1 protein in the cytoplasm utilizing specifically engineered cell lines mimicking UHRF1 status in oocytes and preimplantation embryos. Further, UHRF1 is destabilized both in the cytoplasm and nucleus of Nlrp5 knockout murine FGOs. Since pathogenic variants of the SCMC components frequently cause multilocus imprinting disturbance and UHRF1 is essential for maintaining CpG methylation of imprinting control regions during preimplantation development, our results suggest possible pathogenesis behind the disease, which has been a long-standing mystery.

Spinocerebellar ataxia type 10 (SCA10) is a rare autosomal dominant ataxia caused by a large expansion of the (ATTCT)n repeat in ATXN10. SCA10 was described in Native American and Asian individuals which prompted a search for an expanded haplotype to confirm a common ancestral origin for the expansion event. All patients with SCA10 expansions in our cohort share a single haplotype defined at the 5'-end by the minor allele of rs41524547, located ~35 kb upstream of the SCA10 expansion. Intriguingly, rs41524547 is located within the miRNA gene, MIR4762, within its DROSHA cleavage site and just outside the seed sequence for mir4792-5p. The world-wide frequency of rs41524547-G is less than 5% and found almost exclusively in the Americas and East Asia-a geographic distribution that mirrors reported SCA10 cases. We identified rs41524547-G(+) DNA from the 1000 Genomes/International Genome Sample Resource and our own general population samples and identified SCA10 repeat expansions in up to 25% of these samples. The reduced penetrance of these SCA10 expansions may be explained by a young (pre-onset) age at sample collection, a small repeat size, purity of repeat units, or the disruption of miR4762-5p function. We conclude that rs41524547-G is the most robust at-risk SNP allele for SCA10, is useful for screening of SCA10 expansions in population genetics studies and provides the most compelling evidence to date for a single, prehistoric origin of SCA10 expansions sometime prior to or during the migration of individuals across the Bering Land Bridge into the Americas.

Trichorhinophalangeal syndrome (TRPS) is a genetic disorder caused by point mutations or deletions in the gene-encoding transcription factor TRPS1. TRPS patients display a range of skeletal dysplasias, including reduced jaw size, short stature, and a cone-shaped digit epiphysis. Certain TRPS patients experience early onset coxarthrosis that leads to a devastating drop in their daily activities. The etiologies of congenital skeletal abnormalities of TRPS were revealed through the analysis of Trps1 mutant mouse strains. However, early postnatal lethality in Trps1 knockout mice has hampered the study of postnatal TRPS pathology. Here, through epigenomic analysis we identified two previously uncharacterized candidate gene regulatory regions in the first intron of Trps1. We deleted these regions, either individually or simultaneously, and examined their effects on skeletal morphogenesis. Animals that were deleted individually for either region displayed only modest phenotypes. In contrast, the Trps1Δint/Δint mouse strain with simultaneous deletion of both genomic regions exhibit postnatal growth retardation. This strain displayed delayed secondary ossification center formation in the long bones and misshaped hip joint development that resulted in acetabular dysplasia. Reducing one allele of the Trps1 gene in Trps1Δint mice resulted in medial patellar dislocation that has been observed in some patients with TRPS. Our novel Trps1 hypomorphic strain recapitulates many postnatal pathologies observed in human TRPS patients, thus positioning this strain as a useful animal model to study postnatal TRPS pathogenesis. Our observations also suggest that Trps1 gene expression is regulated through several regulatory elements, thus guaranteeing robust expression maintenance in skeletal cells.

The MRE11/RAD50/NBS1 (MRN) complex plays critical roles in cellular responses to DNA double-strand breaks. MRN is involved in end binding and processing, and it also induces cell cycle checkpoints by activating the ataxia-telangiectasia mutated (ATM) protein kinase. Hypomorphic pathogenic variants in the MRE11, RAD50, or NBS1 genes cause autosomal recessive genome instability syndromes featuring variable degrees of dwarfism, neurological defects, anemia, and cancer predisposition. Disease-associated MRN alleles include missense and nonsense variants, and many cause reduced protein levels of the entire MRN complex. However, the dramatic variability in the disease manifestation of MRN pathogenic variants is not understood. We sought to determine if low protein levels are a significant contributor to disease sequelae and therefore generated a transgenic murine model expressing MRE11 at low levels. These mice display dramatic phenotypes including small body size, severe anemia, and impaired DNA repair. We demonstrate that, distinct from ataxia telangiectasia-like disorder caused by MRE11 pathogenic missense or nonsense variants, mice and cultured cells expressing low MRE11 levels do not display the anticipated defects in ATM activation. Our findings indicate that ATM signaling can be supported by very low levels of the MRN complex and imply that defective ATM activation results from perturbation of MRN function caused by specific hypomorphic disease mutations. These distinct phenotypic outcomes underline the importance of understanding the impact of specific pathogenic MRE11 variants, which may help direct appropriate early surveillance for patients with these complicated disorders in a clinical setting.

Venous thromboembolism (VTE) is a significant contributor to morbidity and mortality, with large disparities in incidence rates between Black and White Americans. Polygenic risk scores (PRSs) limited to variants discovered in genome-wide association studies in European-ancestry samples can identify European-ancestry individuals at high risk of VTE. However, there is limited evidence on whether high-dimensional PRS constructed using more sophisticated methods and more diverse training data can enhance the predictive ability and their utility across diverse populations. We developed PRSs for VTE using summary statistics from the International Network against Venous Thrombosis (INVENT) consortium genome-wide association studies meta-analyses of European- (71 771 cases and 1 059 740 controls) and African-ancestry samples (7482 cases and 129 975 controls). We used LDpred2 and PRS-CSx to construct ancestry-specific and multi-ancestry PRSs and evaluated their performance in an independent European- (6781 cases and 103 016 controls) and African-ancestry sample (1385 cases and 12 569 controls). Multi-ancestry PRSs with weights tuned in European-ancestry samples slightly outperformed ancestry-specific PRSs in European-ancestry test samples (e.g. the area under the receiver operating curve [AUC] was 0.609 for PRS-CSx_combinedEUR and 0.608 for PRS-CSxEUR [P = 0.00029]). Multi-ancestry PRSs with weights tuned in African-ancestry samples also outperformed ancestry-specific PRSs in African-ancestry test samples (PRS-CSxAFR: AUC = 0.58, PRS-CSx_combined AFR: AUC = 0.59), although this difference was not statistically significant (P = 0.34). The highest fifth percentile of the best-performing PRS was associated with 1.9-fold and 1.68-fold increased risk for VTE among European- and African-ancestry subjects, respectively, relative to those in the middle stratum. These findings suggest that the multi-ancestry PRS might be used to improve performance across diverse populations to identify individuals at highest risk for VTE.

The hexanucleotide G4C2 repeat expansion (HRE) in C9ORF72 gene is the major cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), leading to both loss- and gain-of-function pathomechanisms. The wide clinical heterogeneity among C9ORF72 patients suggests potential modifying genetic and epigenetic factors. Notably, C9ORF72 HRE often co-occurs with other rare variants in ALS/FTD-associated genes, such as NEK1, which encodes for a kinase involved in multiple cell pathways, including DNA damage response and ciliogenesis. In this study, we generated induced pluripotent stem cells (iPSCs) and differentiated motoneurons (iPSC-MNs) from an ALS patient carrying both C9ORF72 HRE and a NEK1 loss-of-function mutation to investigate the biological effect of NEK1 haploinsufficiency on C9ORF72 pathology in a condition of oligogenicity. Double mutant C9ORF72/NEK1 cells showed increased pathological C9ORF72 RNA foci in iPSCs and higher DNA damage levels in iPSC-MNs compared to single mutant C9ORF72 cells, but no effect on DNA damage response. When we analysed the primary cilium, we observed a defective ciliogenesis in C9ORF72 iPSC-MNs which was not worsened by NEK1 haploinsufficiency in the double mutant iPSC-MNs. Altogether, our study shows that NEK1 haploinsufficiency influences differently DNA damage and cilia length, potentially acting as a modifier at biological level in an in vitro ALS patient-derived disease model of C9ORF72 pathology.

Regions of Homozygosity (ROH) typically reflect normal demographic history of a human population, but may also relate to cryptic consanguinity, and, additionally, have been associated with specific medical conditions. The objective of this study was to investigate the location, size, and prevalence of common ROH segments in a Middle Eastern cohort. This retrospective study included 13 483 samples collected from all Chromosomal Microarray analyses (CMA) performed using Single Nucleotide Polymorphism (SNP) arrays at the genetic clinical laboratory of Rabin Medical Center between 2017-2023 (primary data set). An additional replication cohort including 100 842 samples from another SNP array platform, obtained from Maccabi Health Organization, was analyzed. Common ROH locations were defined as those ROH locations involving 1% or more of the samples. A total of 66 710 ROH segments, involving 13 035 samples (96.7%) were identified in the primary data set. Of the 4069 cytogenetic ROH locations, 68 were identified as common. The prevalence of non-common ROH was relatively high in affected individuals, and for acrocentric chromosomes, chromosomes associated with common trisomies, and non-imprinted chromosomes. In addition, differences in common ROH locations were observed between the primary and the replication cohorts. Our findings highlight the need for population-specific guidelines in determining ROH reporting cutoffs, considering factors such as population-specific prevalence and testing platform differences. Future research with larger, varied cohorts is essential to advance understanding of ROH's associations with medical conditions and to improve clinical practices accordingly.

This study explored the roles of methionine adenosyltransferase 2A (MAT2A) and tripartite motif containing 25 (TRIM25) in the progression of thoracic aortic aneurysm (TAA). The TAA model was established based on the β-aminopropionitrile method. The effects of MAT2A on thoracic aortic lesions and molecular levels were analyzed by several pathological staining assays (hematoxylin-eosin, Verhoeff-Van Gieson, TUNEL) and molecular biology experiments (qRT-PCR, Western blot). Angiotensin II (Ang-II) was used to induce injury in vascular smooth muscle cells (VSMCs) in vitro. The effects of MAT2A, shMAT2A, shTRIM25 and/or Wnt inhibitor (IWR-1) on the viability, apoptosis and protein expressions of VSMCs were examined by CCK-8, Annexin V-FITC/PI and Western blot assays. In TAA mice, overexpression of MAT2A alleviated thoracic aortic injury, inhibited the aberrant expressions of aortic contractile proteins and dedifferentiation markers, and blocked the activation of Wnt/β-catenin pathway. In Ang-II-induced VSMCs, up-regulation of MAT2A increased cellular activity and repressed the expression of β-catenin protein. TRIM25 knockdown promoted activity of VSMCs, inhibited apoptosis, and blocked the Wnt/β-catenin pathway activation by binding to MAT2A. IWR-1 partially counteracted the regulatory effects of shMAT2A. Collectively, TRIM25 destabilises the mRNA of MAT2A to activate Wnt/β-catenin signaling and ultimately exacerbate TAA injury.

Chronic pancreatitis (CP) is an etiologically and genetically heterogeneous inflammatory syndrome characterised by progressive damage to the exocrine and endocrine components of the pancreas [ 1]. The multigenic paradigm of CP has sparked research in recent years [ 2]. We aimed to expand the current knowledge of genetic susceptibility of pancreatitis in patients of Indian origin. By employing whole-exome sequencing in an Indian hospital cohort, we dissect the genetic landscape associated with CP or recurrent acute pancreatitis (RAP). Notably, all patients had at least one genetic variant identified in a pancreatitis-risk gene, and most had a co-occurrence of a second variant in an additional risk gene. Based on the presence of both acinar and ductal gene variants in individual patients, we propose a two-hit hypothesis where variants in proteins expressed in both acinar and ductal cells are critical for RAP/CP development.