Significance of Fibrillin-1, Filamin A, MMP2 and SOX9 in Mitral Valve Pathology.

Genetic factors play a significant role in the pathogenesis of mitral valve diseases, including mitral valve prolapse (MVP) and mitral valve regurgitation. Genes like Fibrillin-1 (FBN1), Filamin A (FLNA), matrix metalloproteinase 2 (MMP2), and SRY-box transcription factor 9 (SOX9) are known to influence mitral valve pathology but knowledge of the exact mechanism is far from clear. Data regarding serum parameters, transesophageal echocardiography, and genetic and histopathologic parameters were investigated in 54 patients who underwent cardiovascular surgery for mitral valve regurgitation. The possible association between Fibrillin-1, Filamin A, MMP2, and SOX9 gene expressions was checked in relationship with the parameters of systemic inflammatory response. The mRNA expression levels (RQ-relative quantification) were categorized into three distinct groups: low (RQ < 1), medium/normal (RQ = 1-2), and high (RQ > 2). Severe fibrosis of the mitral valve was reflected by high expression of FBN1 and low expression of MMP2 (p < 0.05). The myxoid degeneration level was associated with the mRNA expression level for FBN1 and a low lymphocyte-monocyte ratio was associated with an increased mRNA expression of FBN1 (p < 0.05). A high number of monocytes was associated with high values of FBN1 whereas the increase in the number of lymphocytes was associated with high levels of MMP2. In addition, we observed that the risk of severe hyalinization was enhanced by a low mRNA expression of FLNA and/or SOX9. In conclusion, a lower FLNA mRNA expression can reflect the aging process that is highlighted in mitral valve pathology as a higher risk for hyalinization, especially in males, that might be prevented by upregulation of the SOX9 gene. FBN1 and MMP2 influence the inflammation-related fibrotic degeneration of the mitral valve. Understanding the genetic base of mitral valve pathology can provide insights into disease mechanisms, risk stratification, and potential therapeutic targets.

Congenital short bowel syndrome: Cases series in the same family and review of literature.

INTRODUCTION: Congenital short bowel syndrome (CSBS) is a rare congenital gastrointestinal disease and defined as a shortage of consecutive small bowel length present from birth. This syndrome is often accompanied by intestinal malrotation, reduction of peristalsis, and malabsorption. CASES PRESENTATION: This article reports on siblings carrying the Filamin A (FLNA) genetic mutation with CSBS The first case involved a child admitted to the hospital due to intestinal obstruction, undergoing four surgeries due to intestinal torsion with the remaining length of the small intestine only 60 cm, ultimately resulting in the child's death. The second case is a sibling of the first case, admitted to the hospital due to recurrent abdominal pain, diarrhea, and weight loss. With our previous experience, we conducted genetic testing for the filamin A gene (FLNA), revealing that both siblings and their mothers carried a mutation in the gene. CLINICAL DISCUSSION: The diagnosis can be indirectly based on the upper gastrointestinal tract contrast study, however, most of diagnoses are confirmed by exploratory surgery. There is no consensus on nutritional treatment guidelines for infants with congenital short-bowel syndrome. Bowel lengthening procedures have not been recommended for infants with CSBS. A lot of disease-causing mutations have been recorded as CXADR-like membrane protein (CLMP) and FLNA. CONCLUSION: Congenital short bowel syndrome is a rare condition with a poor prognosis. It requires multidisciplinary coordination for effective diagnosis and treatment. Ongoing research into genetic mutations like CLMP and FLNA is vital for understanding CSBS and enhancing patient care.

CircRNA ATF6 suppresses bladder cancer cell proliferation and migration via miR-146a-5p/FLNA axis.

BACKGROUND: Bladder cancer (BCa) is the most common malignancy with increasing morbidity and mortality. Circular RNA (circRNA) ATF6 level was downregulated in BCa after GSE92675 CircRNA microarray dataset was analyzed using GEO2R. However, its function and mechanism in BCa remain largely unknown. METHODS: GEO2R and reverse transcription quantitative polymerase chain reaction (RT-qPCR) were used to measure levels of circRNA ATF6, microRNA-146a-5p (miR-146a-5p), and filamin A (FLNA). CircRNA ATF6 stability was assessed by actinomycin D and RNase R assays, while circRNA ATF6 cellular localization was examined by FISH experiments in T24 cells. Cell counting kit-8 (CCK-8), colony formation, wound-healing, and transwell assays were used to study circRNA ATF6's function in growth, motility, and invasion. By examining luciferase, starBase, RNA pull-down, and RNA immunoprecipitation (RIP) experiments, we anticipated and confirmed miR-146a-5p interactions with circRNA ATF6, as well as miR-146a-5p interactions with FLNA. On tumor-bearing mice, in vivo experiments were conducted. RESULTS: MiR-146a-5p expression in Bca was elevated, while circRNA ATF6 and FLNA were downregulated. CircRNA ATF6 showed better stability in BCa cells, with its expression primarily in the cytoplasm. Upregulating circRNA ATF6 lowered BCa cell viability, colony numbers, and invasion numbers, but broadened their migratory pattern. MiR-146a-5p was directly sponged up by circRNA ATF6, which also detrimentally affected miR-146a-5p levels in BCa. MiR-146a-5p reduced BCa FLNA expression by targeting FLNA. FLNA silencing abolished circRNA ATF6's mitigating function in BCa cell proliferation, motility, and invasion. In vivo, overexpression of circRNA ATF6 significantly reduced tumor volume and weight. CONCLUSION: CircRNA ATF6 suppresses BCa cell growth, migration and invasion through the miR-146a-5p/FLNA axis.

Pathogenic FLNA variants affecting the hinge region of filamin A are associated with male survival.

Pathogenic variants in FLNA cause a diversity of X-linked developmental disorders associated with either preserved or diminished levels of filamin A protein and are conceptualized dichotomously as relating to underlying gain- or loss-of-function pathogenic mechanisms. Hemizygosity for germline deletions or truncating variants in FLNA is generally considered to result in embryonic lethality. Structurally, filamin A is composed of an N-terminal actin-binding region, followed by 24 immunoglobulin-like repeat units. The repeat domains are separated into distinct segments by two regions of low-complexity known as hinge-1 and hinge-2. Hinge-1 is proposed to confer flexibility to the otherwise rigid protein and is a target for cleavage by calpain with the resultant filamin fragments mediating crucial cellular signaling processes. Here, three families with pathogenic variants in FLNA that impair the function of hinge-1 in males are described, leading to distinct clinical phenotypes. One large in-frame deletion that includes the hinge leads to frontometaphyseal dysplasia in affected males and females, while two germline truncating variants located within the exon encoding hinge 1 result in phenotypes in males that are explained by exon skipping and under-expression of a transcript that deletes hinge-1 from the resultant protein. These three variants affecting hinge-1 indicate that this domain does not mediate cellular functions that, when deficientresult in embryonic lethality in males and that germline truncating variants in this region of FLNA can result in viable phenotypes in males.

Label free quantitative proteomic profiling of serum samples of intellectually disabled young patients revealed dysregulation of complement coagulation and cholesterol cascade systems.

Intellectual disability is a heterogeneous disorder, diagnosed using intelligence quotient (IQ) score criteria. Currently, no specific clinical test is available to diagnose the disease and its subgroups due to inadequate understanding of the pathophysiology. Therefore, current study was designed to explore the molecular mechanisms involved in disease perturbation, and to identify potential biomarkers for disease diagnosis and prognosis. A total of 250 participants were enrolled in this study, including 200 intellectually disabled (ID) subjects from the subgroups (mild, moderate, and severe) with age and gender matched healthy controls (n = 50). Initially, IQ testing score and biochemical profile of each subject was generated, followed by label-free quantitative proteomics of subgroups of IQ and healthy control group through nano-LC/MS- mass spectrometry. A total of 310 proteins were identified, among them198 proteins were common among all groups. Statistical analysis (ANOVA) of the subgroups of ID showed 142 differentially expressed proteins, in comparison to healthy control group. From these, 120 proteins were found to be common among all subgroups. The remaining 22 proteins were categorized as exclusive proteins found only in disease subgroups. Furthermore, the hierarchical cluster analysis (HCL) of common significant proteins was also performed, followed by PANTHER protein classification and GO functional enrichment analysis. Results provides that the datasets of differentially expressed proteins, belong to the categories of immune / defense proteins, transfer carrier proteins, apolipoproteins, complement proteins, protease inhibitors, hemoglobin proteins etc., they are known to involvein immune system, and complement and coagulation pathway cascade and cholesterol metabolism pathway. Exclusively expressed 22 proteins were found to be disease stage specific and strong PPI network specifically those that have significant role in platelets activation and degranulation, such as Filamin A (FLNA). Furthermore, to validate the mass spectrometric findings, four highly significant proteins (APOA4, SAP, FLNA, and SERPING) were quantified by ELISA in all the study subjects. AUROC analysis showed a significant association of APOA4 (0.830), FLNA (0.958), SAP (0.754) and SERPING (0.600) with the disease. Apolipoprotein A4 (APOA4) has a significant role in cholesterol transport, and in modulation of glucose and lipid metabolism in the CNS. Similarly, FLNA has a crucial role in the nervous system, especially in the functioning of synaptic network. Therefore, both APOA4, and FLNA proteins represent good potential for candidate biomarkers for the diagnosis and prognosis of the intellectual disability. Overall, serum proteome of ID patients provides valuable information of proteins/pathways that are altered during ID progression.

Curcumin suppresses the malignant phenotype of laryngeal squamous cell carcinoma through downregulating E2F1 to inhibit FLNA.

Curcumin is a kind of polyphenol substance extracted from the rhizome of Curcuma longa. Because of its good biological activity and pharmacological effects, it has been used in anti-tumor research. The aim of this study was to investigate the anti-cancer mechanism of curcumin on laryngeal squamous cell carcinoma (LSCC). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to check the expression level of transcription factor E2F1 (E2F1) and filamin A (FLNA) mRNA. E2F1 and FLNA protein and proliferation-associated protein were detected through western blot. Cell viability was showed by MTT assay, and flow cytometry was used to exhibit cell cycle distribution and cell apoptosis. Tube formation assay was used to detect the angiogenesis ability of cells. Transwell was used as a method to observe cell migration and invasion. The online website JASPAR predicted the binding site of E2F1 and FLNA promoter, and chromatin immunoprecipitation (ChIP) and dual-luciferase report experiment verified the combination. Curcumin treatment made LSCC cells viability reduce, cell cycle retardant, angiogenesis decrease, metastasis inhibition and apoptosis increase. And curcumin treatment could downregulate the expression of E2F1, and E2F1 overexpression would reverse the influence of curcumin treatment in LSCC cells. Moreover, E2F1 could bind to FLAN promoter and promote FLNA expression. The expression level of FLNA was higher in LSCC tissue and cells compared with normal tissue and cells. E2F1 knockdown inhibited malignant phenotype of LSCC cells, which would be reversed by FLNA addition. In addition, FLNA had high level in LSCC tissue and cells. Curcumin regulated FLNA expression via inhibiting E2F1. Finally, in vivo assay showed that curcumin inhibition restrained LSCC tumor formation. Curcumin downregulated FLNA expression through inhibiting E2F1, thereby suppressing the malignant phenotype and angiogenesis of LSCC cells, which was a new regulatory pathway in LSCC.

FLNA overexpression promotes papillary thyroid cancer aggression via the FAK/AKT signaling pathway.

Background: Filamin A (FLNA) is a member of the filamin family and has been found to be critical for the progression of several cancers. However, its biological function in papillary thyroid cancer (PTC) remains largely unexplored. Methods: Data from The Cancer Genome Atlas (TCGA) databases were utilized to analyze the FLNA expression level and its influence on the clinical implications of patients with PTC. Gene Expression Omnibus (GEO) and qRT-PCR was used to verify the expression levels of FLNA in PTC. Kaplan-Meier survival analysis was conducted to evaluate the prognostic value of FLNA in PTC. Transwell assays and wound healing were performed to examine the biological function of FLNA knockdown in PTC cells. Gene set enrichment analysis (GSEA) and Western blotting were conducted to investigate the potential mechanisms underlying the role of FLNA in PTC progression. In addition, the relationship between FLNA expression and the tumor immune microenvironment (TME) in PTC was explored. Results: FLNA was significantly upregulated in PTC tissues. High expression levels of FLNA was correlated with advanced TNM stage, T stage, and N stage, as well as poor disease-free interval (DFI) and progression-free interval (PFI) time in PTC patients. Moreover, we found that FLNA knockdown inhibited the migration and invasion of PTC cells. Mechanistically, FLNA knockdown inhibited epithelial-mesenchymal transition (EMT) in PTC and affected the activation of the FAK/AKT signaling pathway. In addition, FLNA expression was associated with TME in PTC. Conclusion: FLNA may be regarded as a new therapeutic target for PTC patients.

Filamin A Is a Prognostic Serum Biomarker for Differentiating Benign Prostatic Hyperplasia from Prostate Cancer in Caucasian and African American Men.

Prostate cancer represents a significant health risk to aging men, in which diagnostic challenges to the identification of aggressive cancers remain unmet. Prostate cancer screening is driven by the prostate-specific antigen (PSA); however, in men with benign prostatic hyperplasia (BPH) due to an enlarged prostate and elevated PSA, PSA's screening utility is diminished, resulting in many unnecessary biopsies. To address this issue, we previously identified a cleaved fragment of Filamin A (FLNA) protein (as measured with IP-MRM mass spectrometry assessment as a prognostic biomarker for stratifying BPH from prostate cancer and subsequently evaluated its expanded utility in Caucasian (CA) and African American (AA) men. All men had a negative digital rectal examination (DRE) and PSA between 4 and 10 ng/mL and underwent prostate biopsy. In AA men, FLNA serum levels exhibited diagnostic utility for stratifying BPH from patients with aggressive prostate cancer (0.71 AUC and 12.2 OR in 48 men with BPH and 60 men with PCa) and outperformed PSA (0.50 AUC, 2.2 OR). In CA men, FLNA serum levels also exhibited diagnostic utility for stratifying BPH from patients with aggressive prostate cancer (0.74 AUC and 19.4 OR in 191 men with BPH and 109 men with PCa) and outperformed PSA (0.46 AUC, 0.32 OR). Herein, we established FLNA alone as a serum biomarker for stratifying men with BPH vs. those with high Gleason (7-10) prostate cancers compared to the current diagnostic paradigm of using PSA. This approach demonstrates clinical actionability of FLNA alone without the requirement of prostate volume measurement as a test with utility in AA and CA men and represents a significant opportunity to decrease the number of unnecessary biopsies in aggressive prostate cancer diagnoses.

Digenic FLNA and UCHL1 variants resulting in a complex phenotype.

AIM: X-linked variants in Filamin A (FLNA) are associated with the Ehlers-Danlos-syndrome-variant form of periventricular heterotopia, and autosomal dominant variants in ubiquitin C-terminal hydrolase L1 (UCHL1) are associated with a late-onset spastic ataxia, peripheral neuropathy and optic atrophy. Here we present a rare case involving both a novel heterozygous whole-gene deletion of UCHL1 and a heterozygous frameshift variant in the FLNA gene resulting in a complex phenotype. METHODS: A 67-year-old female with a confirmed pathogenic variant in the FLNA gene, resulting in an enlarged aorta and joint pains, presented with a 4-year history of severe sensory ataxia, upper motor neuron signs, eye movement abnormalities and severe sensory loss. RESULTS: Neurophysiology including Somatosensory-evoked potentials confirmed the sensory loss as predominantly preganglionic with denervation. Genetic testing revealed a digenic cause of her complex presentation, confirming a pathogenic frameshift variant in the FLNA gene and a heterozygous loss of function deletion in the UCHL1 gene. CONCLUSIONS: To the best of our knowledge, this is the first case with concomitant pathogenic variants in the FLNA and UCHL1 genes which explain the complex phenotype. The severe preganglionic sensory loss is also a rare finding and expands the phenotype of UCHL1 variants.

A new case of Melnick-Needles syndrome with skeletal manifestations: A case report.

INTRODUCTION AND IMPORTANCE: Melnick-Needles syndrome (MNS) is a rare skeletal dysplasia that affects skeletal and connective tissue. Less than 70 cases of MNS reported in the literature. MNS had various clinical manifestations such as skeletal deformity, cortical bony sclerosis, facial abnormality, and urogenital symptoms. CASE PRESENTATION: We presented a 5-year-old girl who referred to our orthopedic clinic with knee valgus deformity, spinal kyphoscoliosis, bilateral coxa valga, and humerus cortical irregularity. Based on some facial and skeletal feature, MNS was confirmed with genetic evaluation (heterozygote Filamin A genome). CLINICAL DISCUSSION: The diagnosis of MNS requires a thorough medical and family history, physical examination, and radiographic evaluation. Differential diagnoses for patients with skeletal and facial deformities like MNS include Camurati-Engelmann disease, cystinuria, Galloway-Mowat syndrome, Joubert syndrome, and mucopolysaccharidosis. Treatment for MNS patients with bony deformities without lethal conditions can be conservative, but corrective surgery may be necessary in some cases. CONCLUSIONS: MNS was a rare syndrome with common clinical manifestations such as limb and spine deformity. It is important to conduct a careful examination of any patient who presents with limb and skeletal deformity to the orthopedic clinic, as the disease may have some lethal clinical implications.

Periventricular nodular heterotopias is associated with mutation at the FLNA locus-a case history and a literature review.

BACKGROUND: Periventricular nodular heterotopia (PNH), associated with FLNA mutations, is a rare clinical condition potentially associated with multiple systemic conditions, including cardiac, pulmonary, skeletal, and cutaneous diseases. However, due to a paucity of information in the literature, accurate prognostic advice cannot be provided to patients with the disease. CASE PRESENTATION: We report a 2-year-old female whose PNH was associated with a nonsense mutation in the q28 region of the X chromosome, in exon 31 of FLNA (c.5159dupA). The patient is currently seizure-free and has no congenital heart disease, lung disease or skeletal or joint issues, and her development is normal. CONCLUSIONS: FLNA-associated PNH is a genetically-heterogeneous disease, and the FLNA mutation, c.5159dupA (p.Tyr1720*) is a newly identified pathogenic variant. FLNA characterization will help the clinical diagnosis and treatment of PNH and provide individualized genetic counseling for patients.

Bi-allelic variants of FILIP1 cause congenital myopathy, dysmorphism and neurological defects.

Filamin-A-interacting protein 1 (FILIP1) is a structural protein that is involved in neuronal and muscle function and integrity and interacts with FLNa and FLNc. Pathogenic variants in filamin-encoding genes have been linked to neurological disorders (FLNA) and muscle diseases characterized by myofibrillar perturbations (FLNC), but human diseases associated with FILIP1 variants have not yet been described. Here, we report on five patients from four unrelated consanguineous families with homozygous FILIP1 variants (two nonsense and two missense). Functional studies indicated altered stability of the FILIP1 protein carrying the p.[Pro1133Leu] variant. Patients exhibit a broad spectrum of neurological symptoms including brain malformations, neurodevelopmental delay, muscle weakness and pathology and dysmorphic features. Electron and immunofluorescence microscopy on the muscle biopsy derived from the patient harbouring the homozygous p.[Pro1133Leu] missense variant revealed core-like zones of myofibrillar disintegration, autophagic vacuoles and accumulation of FLNc. Proteomic studies on the fibroblasts derived from the same patient showed dysregulation of a variety of proteins including FLNc and alpha-B-crystallin, a finding (confirmed by immunofluorescence) which is in line with the manifestation of symptoms associated with the syndromic phenotype of FILIP1opathy. The combined findings of this study show that the loss of functional FILIP1 leads to a recessive disorder characterized by neurological and muscular manifestations as well as dysmorphic features accompanied by perturbed proteostasis and myopathology.

LINC01002 Targets miR-650/FLNA Pathway to Suppress Prostate Cancer Progression.

INTRODUCTION: In view of the vital implication of long noncoding RNAs in tumorigenesis, we possess the aim to determine the action effects and mechanisms of LINC01002 in prostate cancer (PCa). METHODS: Expression level of LINC01002, miR-650, or filamin A (FLNA) in PCa tissues and cells was assessed using quantitative real-time PCR or Western blotting. Cell proliferative and migratory capacities were investigated by Cell Counting Kit-8 (CCK-8) and wound healing assays. Cell apoptosis was investigated by the levels of Bax and Bcl-2. Xenograft models were constructed to testify the role of LINC01002 in vivo. The anticipated binding of miR-650 to LINC01002 or FLNA was confirmed by dual-luciferase reporter or RNA binding protein immunoprecipitation assays. RESULTS: Relatively poor expression of LINC01002 and FLNA, and high expression of miR-650 were identified in PCa tumor specimens and cells. Ectopic LINC01002 expression restrained PCa cell proliferation/migration and provoked apoptosis in vitro, and blocked solid tumor growth in Xenograft models. MiR-650 was directly targeted by LINC01002, and it also directly bound to FLNA. MiR-650 reintroduction in PCa cells overexpressing LINC01002 or FLNA partly reversed the anticancer effects of LINC01002 or FLNA overexpression, thus recovering PCa cell proliferation/migration and repressing apoptosis. CONCLUSION: LINC01002 deregulation was linked to PCa development. LINC01002 exerted potential anticancer effects in PCa via targeting the miR-650/FLNA pathway, which, at least in part, provided a basis for the involvement of LINC01002 as a therapeutic target in PCa.

Case report: Unruptured sinus of Valsalva aneurysms causing postural angina pectoris and false "pulmonary hypertension".

A 37-year-old woman presented with worsening intermittent chest pain and dyspnea in the previous year. Although the dyspnea was exertion-dependent, her chest pain was heavily dependent on her postural position, worsening in the supine position but alleviated by lying prone or by sitting up and leaning forward. She was cyanotic, and a diastolic murmur in the left third intercostal space was auscultated. An electrocardiogram recorded when she laid flat and had angina pectoris attacks showed ST-segment elevation in the aVR and depression in the II, III, aVF, and V3-V6 leads. However, when she sat up for a few minutes, her symptoms and ST-segment abnormalities disappeared. Echocardiography and cardiac computed tomography angiography revealed large unruptured aneurysms of the left and non-coronary sinuses, along with a dilated aortic root, severe aortic regurgitation, and right ventricular high pressure. Coronary angiography showed ∼90% pulsating stenosis of the left main coronary artery and ∼80% pulsating stenosis of the proximal left circumflex artery, presumably caused by pulsation of the dilated sinus of Valsalva aneurysm under blood pressure. Genetic testing revealed c.1781 C > G nonsense mutations in the FLNA gene. The patient underwent surgery, which confirmed dual unruptured left/non-coronary sinus of Valsalva aneurysms. Our case illustrates an unusual postural form of angina pectoris and false "pulmonary hypertension" caused by large dual unruptured left/non-coronary sinus of Valsalva aneurysms.

FLNA-filaminopathy skeletal phenotypes are not due to an osteoblast autonomous loss-of-function.

Mutations in FLNA, which encodes the cytoskeletal protein FLNA, cause a spectrum of sclerosing skeletal dysplasias. Although many of these genetic variants are recurrent and cluster within the gene, the pathogenic mechanism that underpins the development of these skeletal phenotypes is unknown. To determine if the skeletal dysplasia in FLNA-related conditions is due to a cell-autonomous loss-of-function localising to osteoblasts and/or osteocytes, we utilised mouse models to conditionally remove Flna from this cellular lineage. Flna was conditionally knocked out from mature osteocytes using the Dmp1-promoter driven Cre-recombinase expressing mouse, as well as the committed osteoblast lineage using the Osx-Cre or Col1a1-Cre expressing lines. We measured skeletal parameters with µCT and histological methods, as well as gene expression in the mineralised skeleton. We found no measureable differences between the conditional Flna knockout mice, and their control littermate counterparts. Moreover, all of the conditional Flna knockout mice, developed and aged normally. From this we concluded that the skeletal dysplasia phenotype associated with pathogenic variants in FLNA is not caused by a cell-autonomous loss-of-function in the osteoblast-osteocyte lineage, adding more evidence to the hypothesis that these phenotypes are due to gain-of-function in FLNA.

WTAP regulates autophagy in colon cancer cells by inhibiting FLNA through N6-methyladenosine.

Our study investigated the role of WTAP in colon cancer. We employed experiments including m6A dot blot hybridization, methylated RNA immunoprecipitation, dual-luciferase, and RNA immunoprecipitation to investigate the regulatory mechanism of WTAP. Western blot was performed to analyze the expression of WTAP, FLNA and autophagy-related proteins in cells. Our results confirmed the up-regulation of WTAP in colon cancer and its promoting effect on proliferation and inhibiting effect on apoptosis. FLNA was the downstream gene of WTAP and WTAP-regulated m6A modification led to post-transcriptional repression of FLNA. The rescue experiments showed that WTAP/FLNA could inhibit autophagy. WTAP-mediated m6A modification was confirmed to be crucial in colon cancer development, providing new insights into colon cancer therapy.

Mutation of FLNA attenuating the migration of abdominal muscles contributed to Melnick-Needles syndrome (MNS) in a family with recurrent miscarriage.

BACKGROUND: Filamin A, encoded by the X-linked gene FLNA, links the cell membrane with the cytoskeleton and acts as a regulator of the actin cytoskeleton. Mutations in FLNA cause a large spectrum of congenital malformations during embryonic development, including Melnick-Needles syndrome (MNS). However, reports of MNS, especially in males, are rare, and the pathogenesis molecular mechanisms are not well understood. METHODS: We found a family with two consecutive miscarriages of similar fetuses with multiple malformations. DNA was extracted from peripheral blood and tissues, and whole exome sequencing was performed for genetic analysis. Then, we created a C57BL/6 mouse with a point mutation by CRISPR/Cas-mediated genome engineering. The migration of primary abdominal muscle cell was detected by wound healing assay. RESULTS: The first fetus showed congenital hygroma colli and omphalocele identified by ultrasound at 12 wks; the second fetus showed hygroma colli and thoraco abdominoschisis at 12 wks, with a new hemizygous mutation c.4420G>A in exon 26 of the FLNA gene, which is predicted to cause an amino acid substitution (p.Asp1474Asn). The mother and grandmother were both present in the c.4420G>A heterozygous state, and the mother's healthy brother had wild-type FLNA. These FLNA-mutated mice exhibited a broader central gap between the rectus abdominis than the wild type (WT), similar to the midline structure dysplasia of the abdominal wall in the two fetuses. Wound healing assays showed the attenuated migration capacity of abdominal muscle cells in mice with mutated FLNA. Finally, we summarized the cases of MNS with FLNA mutation from the accessible published literature thus far. CONCLUSION: Our research revealed a mutation site of the FLNA for MNS and explored the mechanism of midline structure dysplasia in the abdominal wall of male patients, which could provide more evidence for the clinical diagnosis and genetic counseling of families with these disorders.

The force-dependent filamin A-G3BP1 interaction regulates phase-separated stress granule formation.

Filamin A (FLNA) is an actin crosslinking protein that mediates mechanotransduction. External and internal mechanical forces, through the actin cytoskeleton, can induce conformational changes of the FLNA molecule to expose cryptic binding sites for its binding partners. Here, we identified Ras GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) as a new FLNA mechanobinding partner. Unlike other FLNA binding partners to the mechanosensing domain repeat 21 (R21), G3BP1 requires an additional neighboring repeat R22 to interact. We demonstrated that their interaction occurs in the cytosol of living cells in an actin polymerization-dependent manner. We also mapped the FLNA-binding site on G3BP1 and found that a F360A point mutation in the RNA recognition motif disrupts the interaction. RNA interfered with the FLNA-G3BP1 interaction, and FLNA did not localize in RNA-rich stress granules (SGs). Disruption of the interaction was sufficient to promote phase-separated SG formation, and arsenite treatment further stimulated the formation of SGs. Taken together, these data identify G3BP1 as a new mechanobinding protein that interacts with the FLNA mechanosensing domain R21 and suggest that SG formation is partially regulated by mechanical force.

Direct and Indirect Effects of Filamin A on Tau Pathology in Neuronal Cells.

In Alzheimer disease (AD), Tau, an axonal microtubule-associated protein, becomes hyperphosphorylated, detaches from microtubules, accumulates, and self-aggregates in the somatodendritic (SD) compartment. The accumulation of hyperphosphorylated and aggregated Tau is also seen in other neurodegenerative diseases such as frontotemporal lobar degeneration (FTLD-Tau). Previous studies reported a link between filamin A (FLNA), an actin-binding protein found in the SD compartment, and Tau pathology. In the present study, we further explored this link. We confirmed the interaction of Tau with FLNA in neuroblastoma 2a (N2a) cells. This interaction was mediated by a domain located between the 157 and 383 amino acids (a.a.) of Tau. Our results also revealed that the overexpression of FLNA resulted in an intracellular accumulation of wild-type Tau and Tau mutants (P301L, V337M, and R406W) in N2a cells. Tau phosphorylation and cleavage by caspase-3 but not its aggregation were increased upon FLNA overexpression in N2a cells. In the parietal cortex of AD brain, insoluble FLNA was increased compared to control brain, but it did not correlate with Tau pathology. Interestingly, Tau binding to microtubules and F-actin was preserved upon FLNA overexpression in N2a cells. Lastly, our results revealed that FLNA also induced the accumulation of annexin A2, a Tau interacting partner involved in its axonal localization. Collectively, our data indicated that in Tauopathies, FLNA could contribute to Tau pathology by acting on Tau and annexin A2.

Case report: Filamin A mutation lung disease recognized in an 11-year-old child.

The loss of function (LOF) due to mutations in the Filamin A (FLNA) gene may result in abnormality of the FLNA protein. Of the many clinical syndromes, this condition may produce chronic lung disease, which usually presents and is diagnosed in the infant/toddler age group. Its clinical pattern may mimic broncho-pulmonary dysplasia. It is part of the entities included in childhood interstitial lung disease group of disorders. We are herein reporting a patient that was diagnosed with FLNA-associated lung disease at 11 years of age. This case provides a unique insight into the long-term course of lung disease in this illness and broadens our understanding of the spectrum of its presentation. Although the patient had symptoms early in life, the diagnosis was not entertained because of the rarity of the disorder, its atypical and clinically mild presentation, and discontinuous care due to parents moving to different cities for employment reasons. Her presentation to our institution was for pneumonia. Due to highly unusual chest X-ray images, asthenia, and early clubbing, an extensive workup included further imaging and a lung biopsy. The final diagnosis was confirmed by the detection of FLNA LOF gene mutation.