Functional assessment of a novel biallelic MYH3 variation causing CPSKF1B (contractures, pterygia, and spondylocarpotarsal fusion syndrome1B).

BACKGROUND: The MYH3-associated myosinopathies comprise a spectrum of rare neuromuscular disorders mainly characterized by distal arthrogryposis with or without other features like pterygia and vertebrae fusion. CPSKF1B (contractures, pterygia, and spondylocarpotarsal fusion syndrome1B) is the only known autosomal recessiveMYH3-associated myosinopathy so far, with no more than two dozen cases being reported. MATERIALS AND METHODS: A boy with CPSKF1B was recruited and subjected to a comprehensive clinical and imaging evaluation. Genetic detection with whole-exome sequencing (WES) was performed on the patient and extended family members to identify the causative variation. A series of in silico and in vitro investigations were carried out to verify the pathogenicity of the two variants of the identified compound heterozygous variation. RESULTS: The patient exhibited moderate CPSKF1B symptoms including multiarticular contractures, webbed neck, and spondylocarpotarsal fusion. WES detected a compound heterozygous MYH3 variation consisting of two variants, namely NM_002470.4: c.3377A>G; p. (E1126G) and NM_002470.4: c.5161-2A>C. It was indicated that the NM_002470.4: c.3377A>G; p. (E1126G) variant mainly impaired the local hydrogen bond formation and impacted the TGF-B pathway, while the NM_002470.4: c.5161-2A>C variant could affect the normal splicing of pre-mRNA, resulting in the appearance of multiple abnormal transcripts. CONCLUSIONS: The findings of this study expanded the mutation spectrum of CPSKF1B, provided an important basis for the counseling of the affected family, and also laid a foundation for the functional study of MYH3 mutations.

NTRK1 knockdown induces mouse cognitive impairment and hippocampal neuronal damage through mitophagy suppression via inactivating the AMPK/ULK1/FUNDC1 pathway.

Hippocampal neuronal damage may induce cognitive impairment. Neurotrophic tyrosine kinase receptor 1 (NTRK1) reportedly regulates neuronal damage, although the underlying mechanism remains unclear. The present study aimed to investigate the role of NTRK1 in mouse hippocampal neuronal damage and the specific mechanism. A mouse NTRK1-knockdown model was established and subjected to pre-treatment with BAY-3827, followed by a behavioral test, Nissl staining, and NeuN immunofluorescence (IF) staining to evaluate the cognitive impairment and hippocampal neuronal damage. Next, an in vitro analysis was conducted using the CCK-8 assay, TUNEL assay, NeuN IF staining, DCFH-DA staining, JC-1 staining, ATP content test, mRFP-eGFP-LC3 assay, and LC3-II IF staining to elucidate the effect of NTRK1 on mouse hippocampal neuronal activity, apoptosis, damage, mitochondrial function, and autophagy. Subsequently, rescue experiments were performed by subjecting the NTRK1-knockdown neurons to pre-treatment with O304 and Rapamycin. The AMPK/ULK1/FUNDC1 pathway activity and mitophagy were detected using western blotting (WB) analysis. Resultantly, in vivo analysis revealed that NTRK1 knockdown induced mouse cognitive impairment and hippocampal tissue damage, in addition to inactivating the AMPK/ULK1/FUNDC1 pathway activity and mitophagy in the hippocampal tissues of mice. The treatment with BAY-3827 exacerbated the mouse depressive-like behavior induced by NTRK1 knockdown. The results of in vitro analysis indicated that NTRK1 knockdown attenuated viability, NeuN expression, ATP production, mitochondrial membrane potential, and mitophagy, while enhancing apoptosis and ROS production in mouse hippocampal neurons. Conversely, pre-treatment with O304 and rapamycin abrogated the suppression of mitophagy and the promotion of neuronal damage induced upon NTRK1 silencing. Conclusively, NTRK1 knockdown induces mouse hippocampal neuronal damage through the suppression of mitophagy via inactivating the AMPK/ULK1/FUNDC1 pathway. This finding would provide insight leading to the development of novel strategies for the treatment of cognitive impairment induced due to hippocampal neuronal damage.

Prenatal Cases Reflect the Complexity of the COL1A1/2 Associated Osteogenesis Imperfecta.

INTRODUCTION: Osteogenesis imperfecta (OI) is a rare mendelian skeletal dysplasia with autosomal dominant or recessive inheritance pattern, and almost the most common primary osteoporosis in prenatal settings. The diversity of clinical presentation and genetic etiology in prenatal OI cases presents a challenge to counseling yet has seldom been discussed in previous studies. METHODS: Ten cases with suspected fetal OI were enrolled and submitted to a genetic detection using conventional karyotyping, chromosomal microarray analysis (CMA), and whole-exome sequencing (WES). Sanger sequencing was used as the validation method for potential diagnostic variants. In silico analysis of specific missense variants was also performed. RESULTS: The karyotyping and CMA results of these cases were normal, while WES identified OI-associated variants in the COL1A1/2 genes in all ten cases. Six of these variants were novel. Additionally, four cases here exhibited distinctive clinical and/or genetic characteristics, including the situations of intrafamilial phenotypic variability, parental mosaicism, and "dual nosogenesis" (mutations in collagen I and another gene). CONCLUSION: Our study not only expands the spectrum of COL1A1/2-related OI, but also highlights the complexity that occurs in prenatal OI and the importance of clarifying its pathogenic mechanisms.

TAT&RGD Peptide-Modified Naringin-Loaded Lipid Nanoparticles Promote the Osteogenic Differentiation of Human Dental Pulp Stem Cells.

Background: Naringin is a naturally occurring flavanone that promotes osteogenesis. Owing to the high lipophilicity, poor in vivo bioavailability, and extensive metabolic alteration upon administration, the clinical efficacy of naringin is understudied. Additionally, information on the molecular mechanism by which it promotes osteogenesis is limited. Methods: In this study, we prepared TAT & RGD peptide-modified naringin-loaded nanoparticles (TAT-RGD-NAR-NPs), evaluated their potency on the osteogenic differentiation of human dental pulp stem cells (hDPSCs), and studied its mechanism of action through metabolomic analysis. Results: The particle size and zeta potential of TAT-RGD-NAR-NPs were 160.70±2.05 mm and -20.77±0.47mV, respectively. The result of cell uptake assay showed that TAT-RGD-NAR-NPs could effectively enter hDPSCs. TAT-RGD-NAR-NPs had a more significant effect on cell proliferation and osteogenic differentiation promotion. Furthermore, in metabolomic analysis, naringin particles showed a strong influence on the glycerophospholipid metabolism pathway of hDPSCs. Specifically, it upregulated the expression of PLA2G3 and PLA2G1B (two isozymes of phospholipase A2, PLA2), increased the biosynthesis of lysophosphatidic acid (LPA). Conclusion: These results suggested that TAT-RGD-NPs might be used for transporting naringin to hDPSCs for modulating stem cell osteogenic differentiation. The metabolomic analysis was used for the first time to elucidate the mechanism by which naringin promotes hDPSCs osteogenesis by upregulating PLA2G3 and PLA2G1B.

Investigation of a Novel NTRK1 Variation Causing Congenital Insensitivity to Pain With Anhidrosis.

Background: Congenital insensitivity to pain with anhidrosis (CIPA), a rare autosomal recessive sensory neuropathy, was caused mainly by biallelic mutations in the NTRK1 gene. The pathogenesis of CIPA still needs further elucidation. Methods: Here, we recruited a CIPA case and introduced whole-exome sequencing (WES) to identify the causative variation. Subsequently, an in silico molecular dynamic (MD) analysis was performed to explore the intramolecular impact of the novel missense variant. Meanwhile, in vitro functional study on the novel variant from a metabolomic perspective was conducted via the liquid chromatography-mass spectrometry (LC-MS) approach, of which the result was verified by quantitative real-time PCR (qRT-PCR). Results: A novel compound heterozygous variation in NTRK1 gene was detected, consisting of the c.851-33T > A and c.2242C > T (p.Arg748Trp) variants. MD result suggested that p.Arg748Trp could affect the intramolecular structure stability. The results of the LC-MS and metabolic pathway clustering indicated that the NTRK1Arg748Trp variant would significantly affect the purine metabolism in vitro. Further analysis showed that it induced the elevation of NT5C2 mRNA level. Conclusion: The findings in this study extended the variation spectrum of NTRK1, provided evidence for counseling to the affected family, and offered potential clues and biomarkers to the pathogenesis of CIPA.

Metabolic and biophysical study of the MFN2Ile213Thr mutant causing Hereditary Motor and Sensory Neuropathy (HMSN).

Charcot-Marie-Tooth (CMT) 2A disease, a genetic axonal nervous lesion, results from MFN2 pathogenic variation, and this gene plays a pivotal role in mitochondrial dynamics and calcium signaling. However, the underlying mechanism linking MFN2 defect to progressive dying-back of peripheral nerves is still unclear. The present work focused on analyzing one CMT2A patient from multiple perspectives. Clinical and pathologic evaluation was initially conducted on the recruited case. Subsequently, Sanger sequencing and whole-exome sequencing (WES) were performed for genetic detection. To reveal the cell metabolic alteration caused by the identified variant, this study also established and transfected plasmid vectors in HEK293 cells and analyzed cell metabolites through liquid chromatography in combination with quadrupole time-of-flight tandem mass spectrometry (UPLC Q-TOF MS). Additionally, we completed structural modeling and molecular dynamic (MD) simulation to investigate the intramolecular impact of the variant. According to our results, the clinical and neuropathologic manifestations of the proband matched with the diagnosis of CMT. The causative variant MFN2: c.638T>C: (p.Ile213Thr) was identified through genetic analysis. Moreover, metabolic pathway enrichment results demonstrated that this variant significantly affected the metabolism of sphingolipids and glycerophospholipids. MD analysis indicated that this variant crippled the binding ability of MFN2 to GTP. Taken together, our study deduced preliminary clues for the underlying mechanism by which mutant MFN2 affects cell metabolism and provided a novel perspective to understand the cellular and molecular impacts of MFN2 variants.

Identification of novel variations in the NTRK1 gene causing congenital insensitivity to pain with anhidrosis.

BACKGROUND: Congenital insensitivity to pain (CIP) conditions are a group of Mendelian disorders with clinical and genetic heterogeneity. CIP with anhidrosis (CIPA) is a distinct subtype caused by biallelic variants in the NTRK1 gene. METHODS: In this study, six families with CIPA were recruited and submitted to a series of clinical and genetic examinations. Whole-exome sequencing and whole-genome sequencing were applied to perform a comprehensive genetic analysis. Sanger sequencing was used as a validation method. RESULTS: These patients exhibited phenotypic variability. All probands in the six families were positive for biallelic pathogenic variants in NTRK1. Five individual variants, namely NTRK1: (NM_002529.3) c.851-33T>A, c.717+2T>C, c.1806-2A>G, c.1251+1G>A, and c.851-794C>G, including three novel ones, were identified, which were carried by the six patients in a homozygous or compound heterozygous way. The validation results indicated that all the parents of the six probands, except for one father and one mother, were monoallelic carriers of a single variant. CONCLUSIONS: The findings in our study extended the variation spectrum of the NTRK1 gene and highlighted the advantage of the integrated application of multiplatform genetic technologies.

Novel Biallelic DNAH1 Variations Cause Multiple Morphological Abnormalities of the Sperm Flagella.

Sperm motility is vital to human reproduction, and malformed sperm flagella can cause male infertility. Individuals with multiple morphological abnormalities of the flagella mostly have absent, short, coiled, bent, and/or irregular-caliber flagella. In this study, a patient with male infertility underwent a physical examination along with his wife. Genetic testing was performed by whole-exome sequencing of the couple, and Sanger sequencing was performed for validation. Novel biallelic variations in the DNAH1: (NM_015512.4) gene consisting of c.1336G>C (p.E446Q) and c.2912G>A (p.R971H) were identified. In silico structural analysis revealed that the amino acid residues affected by the variation were evolutionarily conserved, and the variant p.R971H influenced the stability of the DNAH1 protein. Morphological studies of the patient's sperm showed defects in its flagella. Results of Papanicolaou staining and scanning electron microscopy demonstrated coiled and short flagella with multiple anomalies. Transmission electron microscopy of the sperm flagella showed that the inner dynein arm and radial spoke were absent, and the dense fiber and microtubule doublets were displaced. Quantitative PCR of the mRNA of the patient's sperm showed that the expression of DNALI1 was dramatically reduced. Collectively, these findings elucidated the genetic cause of the family's infertility and provided insight into the functioning of the DNAH1 gene.

Comprehensive strategy improves the genetic diagnosis of different polycystic kidney diseases.

Polycystic kidney disease (PKD) is known to occur in three main forms, namely autosomal dominant PKD (ADPKD), autosomal recessive PKD (ARPKD) and syndromic PKD (SPKD), based on the clinical manifestations and genetic causes, which are diagnosable from the embryo stage to the later stages of life. Selection of the genetic test for the individuals with diagnostic imaging reports of cystic kidneys without a family history of the disease continues to be a challenge in clinical practice. With the objective of maintaining a limit on the time and medical cost of the procedure, a practical strategy for genotyping and targeted validation to resolve cystogene variations was developed in our clinical laboratory, which combined the techniques of whole-exome sequencing (WES), Long-range PCR (LR-PCR), Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) to work in a stepwise approach. In this context, twenty-six families with renal polycystic disorders were enrolled in the present study. Thirty-two variants involving four ciliary genes (PKD1, PKHD1, TMEM67 and TMEM107) were identified and verified in 23 families (88.5%, 23/26), which expanded the variant spectrum by 16 novel variants. Pathogenic variations in five foetuses of six families diagnosed with PKD were identified using prenatal ultrasound imaging. Constitutional biallelic and digenic variations constituted the pathogenic patterns in these foetuses. The preliminary clinical data highlighted that the WES + LR PCR-based workflow followed in the present study is efficient in detecting divergent variations in PKD. The biallelic and digenic mutations were revealed as the main pathogenic patterns in the foetuses with PKD.