Missense, silent, non-sense and frame-shift mutations in exon 3 of the filaggrin gene in patients with bronchial asthma, atopic dermatitis, allergic rhinitis and mixed atopy

Changes of GH-IGFs and its relationship with growth retardation in children with bronchial asthma

OBJECTIVE

To explore the relationship between Growth Hormone Insulin-like Growth Factors (GH-IGFs) and growth retardation in children with bronchial asthma.

METHODS

112 children with bronchial asthma and 50 healthy children were studied. Serum GH, IGF-1, and Insulin-like Growth Factor Binding Protein 3 (IGFBP3) were assessed by ELISA. GH-IGFs-related parameters were compared, and the correlation between the parameters and bronchial asthma severity was analyzed. The bronchial asthma group was divided into the growth retardation group and non-growth retardation group to analyze the diagnostic value of GH-IGFs in growth retardation and the relationship between GH-IGFs and growth retardation.

RESULTS

GH, IGF-1, and IGFBP3 in the bronchial asthma group were lower. GH, IGF-1, and IGFBP3 levels were decreased with the severity of bronchial asthma. GH, IGF-1, and IGFBP3 in the growth retardation group were lower than those in the non-growth retardation group. The AUC of GH-IGFs combined detection was higher than that of GH and IGFBP3 alone detection. GH < 9.27 μg/L and IGF-1 < 179.53 mmoL/L were risk factors for growth retardation in patients with bronchial asthma.

CONCLUSION

GH-IGFs-related parameters have diagnostic value for growth retardation in children, and decreased levels of GH and IGF-1 are risk factors for growth retardation in children.

Heterogeneous splicing patterns resulting from KIF5A variants associated with amyotrophic lateral sclerosis

Single-nucleotide variants (SNVs) in the gene encoding Kinesin Family Member 5A (KIF5A), a neuronal motor protein involved in anterograde transport along microtubules, have been associated with amyotrophic lateral sclerosis (ALS). ALS is a rapidly progressive and fatal neurodegenerative disease that primarily affects the motor neurons. Numerous ALS-associated KIF5A SNVs are clustered near the splice-site junctions of the penultimate exon 27 and are predicted to alter the carboxy-terminal (C-term) cargo-binding domain of KIF5A. Mis-splicing of exon 27, resulting in exon exclusion, is proposed to be the mechanism by which these SNVs cause ALS. Whether all SNVs proximal to exon 27 result in exon exclusion is unclear. To address this question, we designed an in vitro minigene splicing assay in human embryonic kidney 293 cells, which revealed heterogeneous site-specific effects on splicing: only 5' splice-site (5'ss) SNVs resulted in exon skipping. We also quantified splicing in select clustered, regularly interspaced, short palindromic repeats-edited human stem cells, differentiated to motor neurons, and in neuronal tissues from a 5'ss SNV knock-in mouse, which showed the same result. Moreover, the survival of representative 3' splice site, 5'ss, and truncated C-term variant KIF5A (v-KIF5A) motor neurons was severely reduced compared with wild-type motor neurons, and overt morphological changes were apparent. While the total KIF5A mRNA levels were comparable across the cell lines, the total KIF5A protein levels were decreased for v-KIF5A lines, suggesting an impairment of protein synthesis or stability. Thus, despite the heterogeneous effect on ribonucleic acid splicing, KIF5A SNVs similarly reduce the availability of the KIF5A protein, leading to axonal transport defects and motor neuron pathology.

Association of FLG mutation with tumor mutation load and clinical outcomes in patients with gastric cancer

Background: Stomach adenocarcinoma (STAD) is one of the most frequently diagnosed cancers in the world with a poor prognosis due to genetic heterogeneity. The present study aimed to explore potential prognostic predictors and therapeutic targets that can be used for STAD treatment.

Methods: We collected relevant data of STAD patients from the Cancer Genome Atlas (TCGA), including somatic mutation, transcriptome, and survival data. We performed a series of analyses such as tumor mutational burden (TMB), immune infiltration, and copy number variation (CNV) analysis to evaluate the potential mechanism of filaggrin (FLG) mutation in gastric cancer. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and gene set enrichment analysis (GSEA) were performed for annotation of differentially expressed genes (DEGs). The STRING online database was used to construct the protein–protein interaction (PPI) and ceRNA network and hub genes were identified. Univariate and multivariate Cox regression analyses were used to determine the effect of selected DEGs on tumor prognosis.

Results: The FLG-mutant group (FLG-MT) showed a higher mutation load and immunogenicity in gastric cancer. GO and KEGG analyses identified and ranked unique biologic processes and immune-related pathway maps that correlated with the FLG-mutant target. GSEA analysis showed that several tumorigenesis and metastasis-related pathways were indeed enriched in FLG-mutant tumor tissue. Both cell cycle–related pathways and the DNA damage and repair associated pathways were also enriched in the FLG-MT group. The FLG mutations resulted in increased gastric cancer sensitivity to 24 chemotherapeutic drugs. The ceRNA network was established using Cytoscape and the PPI network was established in the STRING database. The results of the prognostic information further demonstrated that the OS and DFS were significantly higher in FLG mutation carriers, and the FLG gene mutation might be a protective factor.

Conclusion: The multiple molecular mechanisms of the FLG gene in STAD are worthy of further investigation and may reveal novel therapeutic targets and biomarkers for STAD treatment.

Keratosis pilaris and filaggrin loss-of-function mutations in patients with atopic dermatitis - Results of a Finnish cross-sectional study

Keratosis pilaris (KP) associates with epidermal barrier defects in atopic dermatitis (AD) but its role in disease severity and concomitant atopic diseases seems to vary between populations. We performed a cross‐sectional observational study with 502 randomly selected AD patients of a Finnish tertiary health care center. At a single clinical examination, disease severity (Rajka Langeland severity score and EASI), clinical signs and patient history were evaluated and total IgE levels and frequent filaggrin (FLG) loss‐of‐function mutations were investigated. There was no link with disease severity (p = 0.649, 95% CI 0.569–0.654), asthma (p = 0.230, 95% CI 0.206–0.281) or atopic sensitization (p = 0.351, 95% CI 0.309–0.392). Keratosis pilaris was significantly associated with palmar hyperlinearity (p < 0.000, 95% CI 0.000–0.006, OR 4.664, 95% CI 2.072–10.496) and the filaggrin loss‐of‐function mutation 2282del4 (p < 0.000, 95% CI 0.000–0.009, OR 4.917, 95%CI 1.961–12.330). The prevalence of KP in the cohort was generally low and KP seems to be infrequent in Finnish AD patients. This may be explained by the fact that the tested FLG loss‐of‐function mutations are rarer in the Finnish population compared for example, with central Europe or Asia. Mutations in other locations of the FLG gene or other genes of the epidermal barrier may play a more important role.

The Discovery and Function of Filaggrin

Keratohyalin granules were discovered in the mid-19th century in cells that terminally differentiate to form the outer, cornified layer of the epidermis. The first indications of the composition of these structures emerged in the 1960s from a histochemical stain for histidine, followed by radioautographic evidence of a high incidence of histidine incorporation into newly synthesized proteins in cells containing the granules. Research during the next three decades revealed the structure and function of a major protein in these granules, which was initially called the ‘histidine-rich protein’. Steinert and Dale named the protein ‘filaggrin’ in 1981 because of its ability to aggregate keratin intermediate filaments. The human gene for the precursor, ‘profilaggrin,’ was reported in 1991 to encode 10, 11 or 12 nearly identical repeats. Remarkably, the mouse and rat genes encode up to 20 repeats. The lifetime of filaggrin is the time required for keratinocytes in the granular layer to move into the inner cornified layer. During this transition, filaggrin facilitates the collapse of corneocytes into ‘building blocks’ that become an impermeable surface barrier. The subsequent degradation of filaggrin is as remarkable as its synthesis, and the end-products aid in maintaining moisture in the cornified layer. It was apparent that ichthyosis vulgaris and atopic dermatitis were associated with the absence of this protein. McLean’s team in 2006 identified the cause of these diseases by discovering loss-of-function mutations in the profilaggrin gene, which led to dysfunction of the surface barrier. This story illustrates the complexity in maintaining a healthy, functional epidermis.