Targeting AGTPBP1 inhibits pancreatic cancer progression via regulating microtubules and ERK signaling pathway.

BACKGROUND: AGTPBP1 is a cytosolic carboxypeptidase that cleaves poly-glutamic acids from the C terminus or side chains of α/ß tubulins. Although its dysregulated expression has been linked to the development of non-small cell lung cancer, the specific roles and mechanisms of AGTPBP1 in pancreatic cancer (PC) have yet to be fully understood. In this study, we examined the role of AGTPBP1 on PC in vitro and in vivo. METHODS: Immunohistochemistry was used to examine the expression of AGTPBP1 in PC and non-cancerous tissues. Additionally, we assessed the malignant behaviors of PC cells following siRNA-mediated AGTPBP1 knockdown both in vitro and in vivo. RNA sequencing and bioinformatics analysis were performed to identify the differentially expressed genes regulated by AGTPBP1. RESULTS: We determined that AGTPBP1 was overexpressed in PC tissues and the higher expression of AGTPBP1 was closely related to the location of tumors. AGTPBP1 inhibition can significantly decrease cell progression in vivo and in vitro. Moreover, the knockdown of AGTPBP1 inhibited the expression of ERK1/2, P-ERK1/2, MYLK, and TUBB4B proteins via the ERK signaling pathway. CONCLUSION: Our research indicates that AGTPBP1 may be a putative therapeutic target for PC.

The SNHG12/microRNA-15b-5p/MYLK axis regulates vascular smooth muscle cell phenotype to affect intracranial aneurysm formation.

OBJECTIVE: This research was dedicated to investigating the impact of the SNHG12/microRNA (miR)-15b-5p/MYLK axis on the modulation of vascular smooth muscle cell (VSMC) phenotype and the formation of intracranial aneurysm (IA). METHODS: SNHG12, miR-15b-5p and MYLK expression in IA tissue samples from IA patients were tested by RT-qPCR and western blot. Human aortic vascular smooth muscle cells (VSMCs) were cultivated with H2O2 to mimic IA-like conditions in vitro, and the cell proliferation and apoptosis were measured by MTT assay and Annexin V/PI staining. IA mouse models were established by induction with systemic hypertension combined with elastase injection. The blood pressure in the tail artery of mice in each group was assessed and the pathological changes in arterial tissues were observed by HE staining and TUNEL staining. The expression of TNF-α and IL-1ß, MCP-1, iNOS, caspase-3, and caspase-9 in the arterial tissues were tested by RT-qPCR and ELISA. The relationship among SNHG12, miR-15b-5p and MYLK was verified by bioinformatics, RIP, RNA pull-down, and luciferase reporter assays. RESULTS: The expression levels of MYLK and SNHG12 were down-regulated and that of miR-15b-5p was up-regulated in IA tissues and H2O2-treated human aortic VSMCs. Overexpressed MYLK or SNHG12 mitigated the decrease in proliferation and increase in apoptosis of VSMCs caused by H2O2 induction, and overexpression of miR-15b-5p exacerbated the decrease in proliferation and increase in apoptosis of VSMCs caused by H2O2 induction. Overexpression of miR-15b-5p reversed the H2O2-treated VSMC phenotypic changes caused by SNHG12 up-regulation, and overexpression of MYLK reversed the H2O2-treated VSMC phenotypic changes caused by up-regulation of miR-15b-5p. Overexpression of SNHG12 reduced blood pressure and ameliorated arterial histopathological damage and VSMC apoptosis in IA mice. The mechanical analysis uncovered that SNHG12 acted as an endogenous RNA that competed with miR-15b-5p, thus modulating the suppression of its endogenous target, MYLK. CONCLUSION: Decreased expression of SNHG12 in IA may contribute to the increasing VSMC apoptosis via increasing miR-15b-5p expression and subsequently decreasing MYLK expression. These findings provide potential new strategies for the clinical treatment of IA.

Oenothera biennis cell culture produce lignans activating Piezo1 triggering the Myosin Light Chain Kinase depending pathways.

Piezo1 and Piezo2 are mechanoreceptors involved in sensing both internal and external mechanical forces converting them in electrical signals to the brain. Piezo1 is mainly expressed in the endothelial system and in epidermis sensing shear stress and light touch. The internal traction forces generated by Myosin Light Chain Kinase (MYLK) activate Piezo1, regulating cell contraction. We observed Oenothera biennis cell culture hydro-soluble extract (ObHEx) activated MYLK regulating cell contraction ability. The aim of this work was to test the hypothesis that ObHEx activates Piezo1 through MYLK pathway using CHO cell overexpressing Piezo1, HUVEC and SHSY5Y cells endogenously expressing high levels of Piezo1. Results showed that ObHEx extracts were able to activate Piezo1 and the effect is due to Liriodendrin and Salvadoraside, the two most abundant lignans produced by the cell culture. The effect is lost in presence of MYLK specific inhibitors confirming the key role of this pathway and providing indication about the mechanism of action in Piezo1 activation by lignans. In summary, these results confirmed the connection between Piezo1 and MYLK, opening the possibility of using lignans-containing natural extracts to activate Piezo1.

Inhibition of UTX/KDM6A improves recovery of spinal cord injury by attenuating BSCB permeability and macrophage infiltration through the MLCK/p-MLC pathway.

Spinal cord injury (SCI) can prompt an immediate disruption to the blood-spinal cord barrier (BSCB). Restoring the integrity of this barrier is vital for the recovery of neurological function post-SCI. The UTX protein, a histone demethylase, has been shown in previous research to promote vascular regeneration and neurological recovery in mice with SCI. However, it is unclear whether UTX knockout could facilitate the recovery of the BSCB by reducing its permeability. In this study, we systematically studied BSCB disruption and permeability at different time points after SCI and found that conditional UTX deletion in endothelial cells (ECs) can reduce BSCB permeability, decrease inflammatory cell infiltration and ROS production, and improve neurological function recovery after SCI. Subsequently, we used RNA sequencing and ChIP-qPCR to confirm that conditional UTX knockout in ECs can down-regulate expression of myosin light chain kinase (MLCK), which specifically mediates myosin light chain (MLC) phosphorylation and is involved in actin contraction, cell retraction, and tight junctions (TJs) protein integrity. Moreover, we found that MLCK overexpression can increase the ratio of p-MLC/MLC, further break TJs, and exacerbate BSCB deterioration. Overall, our findings indicate that UTX knockout could inhibit the MLCK/p-MLC pathway, resulting in decreased BSCB permeability, and ultimately promoting neurological recovery in mice. These results suggest that UTX is a promising new target for treating SCI.

Multi-disciplinary Insights from the First European Forum on Visceral Myopathy 2022 Meeting.

Visceral myopathy is a rare, life-threatening disease linked to identified genetic mutations in 60% of cases. Mostly due to the dearth of knowledge regarding its pathogenesis, effective treatments are lacking. The disease is most commonly diagnosed in children with recurrent or persistent disabling episodes of functional intestinal obstruction, which can be life threatening, often requiring long-term parenteral or specialized enteral nutritional support. Although these interventions are undisputedly life-saving as they allow affected individuals to avoid malnutrition and related complications, they also seriously compromise their quality of life and can carry the risk of sepsis and thrombosis. Animal models for visceral myopathy, which could be crucial for advancing the scientific knowledge of this condition, are scarce. Clearly, a collaborative network is needed to develop research plans to clarify genotype-phenotype correlations and unravel molecular mechanisms to provide targeted therapeutic strategies. This paper represents a summary report of the first 'European Forum on Visceral Myopathy'. This forum was attended by an international interdisciplinary working group that met to better understand visceral myopathy and foster interaction among scientists actively involved in the field and clinicians who specialize in care of people with visceral myopathy.

Frail Silk: Is the Hughes-Stovin Syndrome a Behçet Syndrome Subtype with Aneurysm-Involved Gene Variants?

Hughes-Stovin syndrome is a rare disease characterized by thrombophlebitis and multiple pulmonary and/or bronchial aneurysms. The etiology and pathogenesis of HSS are incompletely known. The current consensus is that vasculitis underlies the pathogenic process, and pulmonary thrombosis follows arterial wall inflammation. As such, Hughes-Stovin syndrome may belong to the vascular cluster with lung involvement of Behçet syndrome, although oral aphtae, arthritis, and uveitis are rarely found. Behçet syndrome is a multifactorial polygenic disease with genetic, epigenetic, environmental, and mostly immunological contributors. The different Behçet syndrome phenotypes are presumably based upon different genetic determinants involving more than one pathogenic pathway. Hughes-Stovin syndrome may have common pathways with fibromuscular dysplasias and other diseases evolving with vascular aneurysms. We describe a Hughes-Stovin syndrome case fulfilling the Behçet syndrome criteria. A MYLK variant of unknown significance was detected, along with other heterozygous mutations in genes that may impact angiogenesis pathways. We discuss the possible involvement of these genetic findings, as well as other potential common determinants of Behçet/Hughes-Stovin syndrome and aneurysms in vascular Behçet syndrome. Recent advances in diagnostic techniques, including genetic testing, could help diagnose a specific Behçet syndrome subtype and other associated conditions to personalize the disease management.

Silencing of long noncoding RNA MYLK-AS1 suppresses nephroblastoma via down-regulation of CCNE1 through transcription factor TCF7L2.

Nephroblastoma, a pediatric kidney cancer, caused by pluripotent embryonic renal precursors. Long noncoding RNAs (lncRNAs) are commonly abnormal expressed in many cancers. In the present study, we fousced on one newly discrovered lncRNA, MYLK Antisense RNA 1 (MYLK-AS1), and its functional role in proliferation and cycle distribution of nephroblastoma cells. Micorarray-based analysis revealed the highly expressed Cyclin E1 (CCNE1) and MYLK-AS1 in nephroblastoma. After nephroblastoma tissue sample collection, RT-qPCR confirmed the upregulated expression of MYLK-AS1 and CCNE1 in nephroblastoma tissues and cells. Kaplan-Meier curve exhibited that patients with elevated CCNE1 had lower overall survival rate in follow-up study. RNA binding protein immunoprecipitation, chromatin immunoprecipitation, and dual-luciferase reporter gene assay were employed to determine the relationship among MYLK-AS1, TCF7L2, and CCNE1, which validated that transcription factor 7-like 2 (TCF7L2) could specifically bind to MYLK-AS1 and TCF7L2 could positively promote CCNE1. After gain- and loss-of function assays, the conclusion that silencing of MYLK-AS1 could inhibit expression of CCNE1 through the transcription factor TCF7L2 to regulate the cell proliferation and cell cycle distribution of nephroblastoma cells was obtained. Subsequently, the subcutaneous tumor formation ability of nephroblastoma cell in nude mice was observed and the silencing of MYLK-AS1 exerts suppressive role in the tumorigenic ability of nephroblastoma cells in vivo. Taken together, MYLK-AS1 constitutes a promising biomarker for the early detection and treatment of nephroblastoma.

Loeys-Dietz Syndrome.

Loeys-Dietz syndrome is an autosomal dominant aortic aneurysm syndrome characterized by multisystemic involvement. The most typical clinical triad includes hypertelorism, bifid uvula or cleft palate and aortic aneurysm with tortuosity. Natural history is significant for aortic dissection at smaller aortic diameter and arterial aneurysms throughout the arterial tree. The genetic cause is heterogeneous and includes mutations in genes encoding for components of the transforming growth factor beta (TGFß) signalling pathway: TGFBR1, TGFBR2, SMAD2, SMAD3, TGFB2 and TGFB3. Despite the loss of function nature of these mutations, the patient-derived aortic tissues show evidence of increased (rather than decreased) TGFß signalling. These insights offer new options for therapeutic interventions.

RPA1 binding to NRF2 switches ARE-dependent transcriptional activation to ARE-NRE-dependent repression.

NRF2 regulates cellular redox homeostasis, metabolic balance, and proteostasis by forming a dimer with small musculoaponeurotic fibrosarcoma proteins (sMAFs) and binding to antioxidant response elements (AREs) to activate target gene transcription. In contrast, NRF2-ARE-dependent transcriptional repression is unreported. Here, we describe NRF2-mediated gene repression via a specific seven-nucleotide sequence flanking the ARE, which we term the NRF2-replication protein A1 (RPA1) element (NRE). Mechanistically, RPA1 competes with sMAF for NRF2 binding, followed by interaction of NRF2-RPA1 with the ARE-NRE and eduction of promoter activity. Genome-wide in silico and RNA-seq analyses revealed this NRF2-RPA1-ARE-NRE complex mediates negative regulation of many genes with diverse functions, indicating that this mechanism is a fundamental cellular process. Notably, repression of MYLK, which encodes the nonmuscle myosin light chain kinase, by the NRF2-RPA1-ARE-NRE complex disrupts vascular integrity in preclinical inflammatory lung injury models, illustrating the translational significance of NRF2-mediated transcriptional repression. Our findings reveal a gene-suppressive function of NRF2 and a subset of negatively regulated NRF2 target genes, underscoring the broad impact of NRF2 in physiological and pathological settings.

Silencing of long noncoding RNA SRRM2-AS exerts suppressive effects on angiogenesis in nasopharyngeal carcinoma via activating MYLK-mediated cGMP-PKG signaling pathway.

Long noncoding RNAs (lncRNAs) play a crucial role in several malignances, involving nasopharyngeal carcinoma (NPC), a heterogeneous disease. This study investigated mechanism of serine/arginine repetitive matrix protein 2-alternative splicing (SRRM2-AS) in NPC cell proliferation, differentiation, and angiogenesis. Initially, differentially expressed lncRNAs were screened out via microarray analysis. Vascular endothelial growth factor (VEGF) protein positive rate and microvessel density (MVD) were determined in NPC and adjacent tissues. NPC CNE-2 cells were treated with a series of vector and small interfering RNA to explore the effect of SRRM2-AS in NPC. The target relationship between myosin light chain kinase (MYLK) and SRRM2-AS was verified. Levels of SRRM2-AS, MYLK, cGMP, PKG, VEGF, PCNA, Ki-67, B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), and Caspase 3 were determined after transfection. Finally, the effect of SRRM2-AS on cell proliferation, colony formation, angiogenesis, cell cycle, and apoptosis in NPC was evaluated. SRRM2-AS was highly expressed and MYLK was poorly expressed in NPC tissues. VEGF protein positive rate and MVD were elevated in NPC tissues. MYLK was confirmed to be a target gene of SRRM2-AS. Silencing of SRRM2-AS elevated levels of MYLK, cGMP, PKG, Bax, and Caspase 3, but decreased levels of VEGF, PCNA, Ki-67, and Bcl-2. Especially, silencing of SRRM2-AS suppressed cell proliferation, colony formation and angiogenesis, blocked cell cycle, and enhanced cell apoptosis in NPC. Our results suggested that silencing of SRRM2-AS protected against angiogenesis of NPC cells by upregulating MYLK and activating the cGMP-PKG signaling pathway, which provides a new target for NPC treatment.

Loss-of-Function Variants in MYLK Cause Recessive Megacystis Microcolon Intestinal Hypoperistalsis Syndrome.

Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a congenital disorder characterized by loss of smooth muscle contraction in the bladder and intestine. To date, three genes are known to be involved in MMIHS pathogenesis: ACTG2, MYH11, and LMOD1. However, for approximately 10% of affected individuals, the genetic cause of the disease is unknown, suggesting that other loci are most likely involved. Here, we report on three MMIHS-affected subjects from two consanguineous families with no variants in the known MMIHS-associated genes. By performing homozygosity mapping and whole-exome sequencing, we found homozygous variants in myosin light chain kinase (MYLK) in both families. We identified a 7 bp duplication (c.3838_3844dupGAAAGCG [p.Glu1282_Glyfs∗51]) in one family and a putative splice-site variant (c.3985+5C>A) in the other. Expression studies and splicing assays indicated that both variants affect normal MYLK expression. Because MYLK encodes an important kinase required for myosin activation and subsequent interaction with actin filaments, it is likely that in its absence, contraction of smooth muscle cells is impaired. The existence of a conditional-Mylk-knockout mouse model with severe gut dysmotility and abnormal function of the bladder supports the involvement of this gene in MMIHS pathogenesis. In aggregate, our findings implicate MYLK as a gene involved in the recessive form of MMIHS, confirming that this disease of the visceral organs is heterogeneous with a myopathic origin.

Androgen receptor variant 12 promotes migration and invasion by regulating MYLK in gastric cancer.

Androgen receptor (AR) and its variants (AR-Vs) promote tumorigenesis and metastasis in many hormone-related cancers, such as breast, prostate and hepatocellular cancers. However, the expression patterns and underlying molecular mechanisms of AR in gastric cancer (GC) are not fully understood. This study aimed to detect the expression of AR-Vs in GC and explored their role in metastasis of GC. Here, the AR expression form was identified in GC cell lines and tissues by RT-PCR and qPCR. Transwell assays and experimental lung metastasis animal models were used to assess the function of AR in cell migration and invasion. Downstream targets of AR were screened by bioinformatics, and identified by luciferase reporter assays and electrophoretic mobility shift assays. AR-v12 was identified as the main expression form in GC cell lines and tissues. Different from full length of AR, AR-v12 was localized to the nucleus independent of androgen. Upregulation of AR-v12 in primary GC tissues was significantly associated with metastasis. Overexpression of AR-v12 promoted migration and invasion independent of androgen. Knockdown of AR-v12 inhibited migration and invasion in vitro, as well as metastasis in vivo. Furthermore, AR-v12, serving as a transcription factor, promoted metastasis through regulating the promoter activity of MYLK. In AR-v12 overexpressing cells, knockdown of MYLK inhibited cell migration and invasion, while in AR-v12 knocked-down cells, overexpression of MYLK promoted cell migration and invasion. Collectively, our study demonstrates that AR-v12 is highly expressed in GC tissues and promotes migration and invasion through directly regulating MYLK. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Copy number variation of MYLK4 gene and its growth traits of Capra hircus (goat).

Copy number variation (CNV) is a form of genetic variation caused by genome rearrangement, with abnormal fragments ranging from 50 bp to Mb. And, CNV is closely related to disease, growth and reproductive shape of livestock. As a member of myosin light chain kinase (MYLK) family with serine/threonine specificity, MYLK4 belongs to an enzyme encoded by MYLK4 gene. Although MYLK4 is a recognized kinase, its function has yet to be revealed in subsequent studies. This study aims to analyze CNV and genetic effects of MYLK4 gene in goats. We used qPCR to detect CNV of MYLK4 gene in African Nubian goat (n = 32), Guizhou black goat (n = 196) and Guizhou white goat (n = 95), respectively, and correlated CNV data of MYLK4 gene with goat growth traits in Chinese goats. The results showed that the effect of MYLK4 gene CNV on body weight, body length and body height of goats had significantly different (p < 0.05, Q < 0.05), in which CNV showed better growth traits in type of deletion. Therefore, CNV of MYLK4 gene can be used as a molecular marker for assisted selection of goat growth traits, which provides a theoretical basis for the genetic improvement of goat breeds in China.

Association between MYLK4 gene polymorphism and growth traits at different age stages in Anatolian black cattle.

This study aims to find the association between MYLK4 gene polymorphism and growth traits at different ages, such as birth, 3rd-month, 6th-month and 12th-month ages in Anatolian black cattle. PCR-RFLP method was used to detect the polymorphism for MYLK4 gene in at G61595A locus. Allele and genotype frequencies were A: 0.34, G: 0.66 and AA: 0.17, AG: 0.34 and GG: 0.49. The chi-square χ2 test showed an agreement to Hardy-Weinberg equilibrium (p > .01). GLM and RRM models were used to estimate the association between MYLK4 gene polymorphism and growth traits. The results of the statistical analysis indicated an association between MYLK4 gene polymorphism and growth traits at different stage ages in Anatolian black cattle. Therefore, the G61595A mutation of MYLK4 gene can be used as a genetic marker for the selection of growth and development traits in the cattle breeding programs.

MYLK pathogenic variants aortic disease presentation, pregnancy risk, and characterization of pathogenic missense variants.

PURPOSE: Heritable thoracic aortic disease can result from null variants in MYLK, which encodes myosin light-chain kinase (MLCK). Data on which MYLK missense variants are pathogenic and information to guide aortic disease management are limited. METHODS: Clinical data from 60 cases with MYLK pathogenic variants were analyzed (five null and two missense variants), and the effect of missense variants on kinase activity was assessed. RESULTS: Twenty-three individuals (39%) experienced an aortic event (defined as aneurysm repair or dissection); the majority of these events (87%) were aortic dissections. Aortic diameters were minimally enlarged at the time of dissection in many cases. Time-to-aortic-event curves showed that missense pathogenic variant (PV) carriers have earlier-onset aortic events than null PV carriers. An MYLK missense variant segregated with aortic disease over five generations but decreases MYLK kinase acitivity marginally. Functional Assays fail to identify all pathogenic variants in MYLK. CONCLUSION: These data further define the aortic phenotype associated with MYLK pathogenic variants. Given minimal aortic enlargement before dissection, an alternative approach to guide the timing of aortic repair is proposed based on the probability of a dissection at a given age.

Circular RNA MYLK promotes hepatocellular carcinoma progression by increasing Rab23 expression by sponging miR-362-3p.

BACKGROUND: CircRNA myosin light chain kinase (circRNA MYLK) has been shown to promote the progression of various tumor diseases. The purpose of this study was to explore the potential molecular mechanism of circMYLK in hepatocellular carcinoma (HCC). METHODS: The quantitative Real-Time PCR (qRT-PCR) was used to measure the expressions of circMYLK, miR-362-3p and Rab23 in HCC tissues and cell lines. Huh7 and Hep3B cells were selected to explore the role of circMYLK in proliferation, invasion and migration of HCC cells in vitro. The interaction among circMYLK, miR-362-3p and Rab23 was investigated by biological information and dual luciferase gene reporter assay. The effect of circMYLK on HCC tumor growth in vivo was studied in a tumor xenograft model in mice. RESULTS: CircMYLK was highly expressed in HCC tissues and cell lines, which was associated with poor prognosis in HCC patients. In addition, knockdown of circMYLK remarkably inhibited the proliferation, invasion, and migration of Huh7 and Hep3B cells. MiR-362-3p was a direct target of circMYLK, and Rab23 was a direct target gene of miR-362-3p. Meanwhile, circMYLK was negatively correlated with the expression of miR-362-3p and positively correlated with Rab23 expression. Moreover, either overexpressed miR-362-3p or silencing Rab23 could observably suppress the enhanced proliferation, invasion, and migration induced by circMYLK in Huh7 and Hep3B cells. Finally, knockdown of circMYLK and overexpressed miR-362-3p could suppress the expression of Rab23, thus inhibiting the growth and proliferation of Hep3B cells in vivo. CONCLUSION: circMYLK promotes the occurrence and development of HCC by regulating the miR-362-3p/Rab23 axis, which provides a novel direction and theoretical basis for the early diagnosis and treatment of HCC.

The Splicing Factor hnRNPA1 Regulates Alternate Splicing of the MYLK Gene.

Profound lung vascular permeability is a cardinal feature of acute respiratory distress syndrome (ARDS) and ventilator-induced lung injury (VILI), two syndromes known to centrally involve the nonmuscle isoform of myosin light chain kinase (nmMLCK) in vascular barrier dysregulation. Two main splice variants, nmMLCK1 and nmMLCK2, are well represented in human lung endothelial cells and encoded by MYLK, and they differ only in the presence of exon 11 in nmMLCK1, which contains critical phosphorylation sites (Y464 and Y471) that influence nmMLCK enzymatic activity, cellular translocation, and localization in response to vascular agonists. We recently demonstrated the functional role of SNPs in altering MYLK splicing, and in the present study we sought to identify the role of splicing factors in the generation of nmMLCK1 and nmMLCK2 spliced variants. Using bioinformatic in silico approaches, we identified a putative binding site for heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1), a recognized splicing factor. We verified hnRNPA1 binding to MYLK by gel shift analyses and that hnRNPA1 gene and protein expression is upregulated in mouse lungs obtained from preclinical models of ARDS and VILI and in human endothelial cells exposed to 18% cyclic stretch, a model that reproduces the excessive mechanical stress observed in VILI. Using an MYLK minigene approach, we established a direct role of hnRNPA1 in MYLK splicing and in the context of 18% cyclic stretch. In summary, these data indicate an important regulatory role for hnRNPA1 in MYLK splicing, and they increase understanding of MYLK splicing in the regulation of lung vascular integrity during acute lung inflammation and excessive mechanical stress, such as that observed in ARDS and VILI.

A novel variant in MYLK causes thoracic aortic dissections: genotypic and phenotypic description.

BACKGROUND: Mutations in MYLK cause non-syndromic familial thoracic aortic aneurysms and dissections (FTAAD). Very little is known about the phenotype of affected families. We sought to characterize the aortic disease and the presence of other vascular abnormalities in FTAAD caused by a deletion in MYLK and to compare thoracic aortic diameter and stiffness in mutation carriers and non-carriers. METHODS: We studied FTAAD in a 5-generation family that included 19 living members. Exome sequencing was performed to identify the underlying gene defect. Aortic elastic properties measured by TTE, MRI and pulse wave velocity were then compared between mutation carriers and non-carriers. RESULTS: Exome sequencing led to the identification of a 2-bp deletion in MYLK (c3272_3273del, p.Ser1091*) that led to a premature stop codon and nonsense-mediated decay. Eleven people were mutation carriers and eight people were non-carriers. Five aortic ruptures or dissections occurred in this family, with two survivors. There were no differences in aortic diameter or stiffness between carriers and non-carriers of the mutation. CONCLUSIONS: Individuals carrying this deletion in MYLK have a high risk of presenting with an acute aortic dissection or rupture. Aortic events occur over a wide range of ages and are not always preceded by obvious aortic dilatation. Aortic elastic properties do not differ between carriers and non-carriers of this mutation, rendering it uncertain whether and when carriers should undergo elective prophylactic surgery.

Clinically relevant variants identified in thoracic aortic aneurysm patients by research exome sequencing.

Thoracic aortic aneurysm (TAA) is a genetically heterogeneous disease involving subclinical and progressive dilation of the thoracic aorta, which can lead to life-threatening complications such as dissection or rupture. Genetic testing is important for risk stratification and identification of at risk family members, and clinically available genetic testing panels have been expanding rapidly. However, when past testing results are normal, there is little evidence to guide decision-making about the indications and timing to pursue additional clinical genetic testing. Results from research based genetic testing can help inform this process. Here we present 10 TAA patients who have a family history of disease and who enrolled in research-based exome testing. Nine of these ten patients had previous clinical genetic testing that did not identify the cause of disease. We sought to determine the number of rare variants in 23 known TAA associated genes identified by research-based exome testing. In total, we found 10 rare variants in six patients. Likely pathogenic variants included a TGFB2 variant in one patient and a SMAD3 variant in another. These variants have been reported previously in individuals with similar phenotypes. Variants of uncertain significance of particular interest included novel variants in MYLK and MFAP5, which were identified in a third patient. In total, clinically reportable rare variants were found in 6/10 (60%) patients, with at least 2/10 (20%) patients having likely pathogenic variants identified. These data indicate that consideration of re-testing is important in TAA patients with previous negative or inconclusive results.

LncRNA MYLK antisense RNA 1 activates cell division cycle 42/Neutal Wiskott-Aldrich syndrome protein pathway via microRNA-101-5p to accelerate epithelial-to-mesenchymal transition of colon cancer cells.

Long noncoding RNA MYLK antisense RNA 1 (MYLK-AS1) is the crux in multiple diseases. Therefore, the purpose of this study was to investigate the possible mechanism of MYLK-AS1. A total of 62 colon cancer (CC) specimens and paired adjacent normal tissues were collected, and the expression of MYLK-AS1, microRNA (miR)-101-5p/cell division cycle 42 (CDC42) was detected. CC cell lines were transfected with MYLK-AS1, miR-101-5p, CDC42-related plasmids, and the biological functions and markers of epithelial-mesenchymal transition (EMT) were analyzed. The binding relationship between MYLK-AS1, miR-101-5p, and CDC42 was evaluated. In CC tissues and cell lines, MYLK-AS1 and CDC42 were highly expressed, and miR-101-5p was lowly expressed. Inhibition of MYLK-AS1 or upregulation of miR-101-5p can inhibit CC cell growth and EMT. miR-101-5p inhibited CDC42/N-wasp axis activation in CC cells by targeting CDC42. Knockdown of CDC42 or upregulation of miR-101-5p partially reversed the effects caused by upregulation of MYLK-AS1. MYLK-AS1, which is significantly upregulated in CC, may be a molecular sponge for miR-101-5p, and MYLK-AS1 promotes the activation of the CDC42/N-wasp axis in CC cells by targeting CDC42 through miR-101-5p, which in turn promotes tumor development. MYLK-AS1 may be a potential biomarker and target for CC therapy.