ABSTRACT
In recent years, it has been recognized that mechanical forces play an important regulative role in living organisms and possess a direct impact on crucial cell functions, ranging from cell growth to maintenance of tissue homeostasis. Advancements in mechanobiology have revealed the profound impact of mechanical signals on diverse cellular responses that are cell type specific. Notably, numerous studies have elucidated the pivotal role of different mechanical cues as regulatory factors influencing various cellular processes, including cell spreading, locomotion, differentiation, and proliferation. Given these insights, it is unsurprising that the responses of cells regulated by physical forces are intricately linked to the modulation of nanoparticle uptake kinetics and processing. This complex interplay underscores the significance of understanding the mechanical microenvironment in shaping cellular behaviors and, consequently, influencing how cells interact with and process nanoparticles. Nevertheless, our knowledge on how localized physical forces affect the internalization and processing of nanoparticles by cells remains rather limited. A significant gap exists in the literature concerning a systematic analysis of how mechanical cues might bias the interactions between nanoparticles and cells. Hence, our aim in this review is to provide a comprehensive and critical analysis of the existing knowledge regarding the influence of mechanical cues on the complicated dynamics of cell-nanoparticle interactions. By addressing this gap, we would like to contribute to a detailed understanding of the role that mechanical forces play in shaping the complex interplay between cells and nanoparticles.
ABSTRACT
Recently, it has been recognized that physical abnormalities (e.g. elevated solid stress, elevated interstitial fluid pressure, increased stiffness) are associated with tumor progression and development. Additionally, these mechanical forces originating from tumor cell environment through mechanotransduction pathways can affect metabolism. On the other hand, mitochondria are well-known as bioenergetic, biosynthetic, and signaling organelles crucial for sensing stress and facilitating cellular adaptation to the environment and physical stimuli. Disruptions in mitochondrial dynamics and function have been found to play a role in the initiation and advancement of cancer. Consequently, it is logical to hypothesize that mitochondria dynamics subjected to physical cues may play a pivotal role in mediating tumorigenesis. Recently mitochondrial biogenesis and turnover, fission and fusion dynamics was linked to mechanotransduction in cancer. However, how cancer cell mechanics and mitochondria functions are connected, still remain poorly understood. Here, we discuss recent studies that link mechanical stimuli exerted by the tumor cell environment and mitochondria dynamics and functions. This interplay between mechanics and mitochondria functions may shed light on how mitochondria regulate tumorigenesis.
ABSTRACT
Iron oxide nanoparticles (IONPs) are being actively researched in various biomedical applications, particularly as magnetic resonance imaging (MRI) contrast agents for diagnosing various liver pathologies like nonalcoholic fatty liver diseases, nonalcoholic steatohepatitis, and cirrhosis. Emerging evidence suggests that IONPs may exacerbate hepatic steatosis and liver injury in susceptible livers such as those with nonalcoholic fatty liver disease. However, our understanding of how IONPs may affect steatotic cells at the sub-cellular level is still fragmented. Generally, there is a lack of studies identifying the molecular mechanisms of potential toxic and/or adverse effects of IONPs on "non-heathy" in vitro models. In this study, we demonstrate that IONPs, at a dose that does not cause general toxicity in hepatic cells (Alexander and HepG2), induce significant toxicity in steatotic cells (cells loaded with non-toxic doses of palmitic acid). Mechanistically, co-treatment with PA and IONPs resulted in endoplasmic reticulum (ER) stress, accompanied by the release of cathepsin B from lysosomes to the cytosol. The release of cathepsin B, along with ER stress, led to the activation of apoptotic cell death. Our results suggest that it is necessary to consider the interaction between IONPs and the liver, especially in susceptible livers. This study provides important basic knowledge for the future optimization of IONPs as MRI contrast agents for various biomedical applications.
ABSTRACT
BACKGROUND AND AIM: Gene defects contribute to the aetiology of intrahepatic cholestasis. We aimed to explore the outcome of whole-exome sequencing (WES) in a cohort of 51 patients with this diagnosis. PATIENTS AND METHODS: Both paediatric (n = 33) and adult (n = 18) patients with cholestatic liver disease of unknown aetiology were eligible. WES was used for reassessment of 34 patients (23 children) without diagnostic genotypes in ABCB11, ATP8B1, ABCB4 or JAG1 demonstrable by previous Sanger sequencing, and for primary assessment of additional 17 patients (10 children). Nasopharyngeal swab mRNA was analysed to address variant pathogenicity in two families. RESULTS: WES revealed biallelic variation in 3 ciliopathy genes (PKHD1, TMEM67 and IFT172) in 4 clinically unrelated index subjects (3 children and 1 adult), heterozygosity for a known variant in PPOX in one adult index subject, and homozygosity for an unreported splice-site variation in F11R in one child. Whereas phenotypes of the index patients with mutated PKHD1, TMEM67, and PPOX corresponded with those elsewhere reported, how F11R variation underlies liver disease remains unclear. Two unrelated patients harboured different novel biallelic variants in IFT172, a gene implicated in short-rib thoracic dysplasia 10 and Bardet-Biedl syndrome 20. One patient, a homozygote for IFT172 rs780205001 c.167A>C p.(Lys56Thr) born to first cousins, had liver disease, interpreted on biopsy aged 4y as glycogen storage disease, followed by adult-onset nephronophthisis at 25y. The other, a compound heterozygote for novel frameshift variant IFT172 NM_015662.3 c.2070del p.(Met690Ilefs*11) and 2 syntenic missense variants IFT172 rs776310391 c.157T>A p.(Phe53Ile) and rs746462745 c.164C>G p.(Thr55Ser), had a severe 8mo cholestatic episode in early infancy, with persisting hyperbilirubinemia and fibrosis on imaging studies at 17y. No patient had skeletal malformations. CONCLUSION: Our findings suggest association of IFT172 variants with non-syndromic cholestatic liver disease.
Subject(s)
Cholestasis, Intrahepatic , Cholestasis , Humans , Mutation , Exome Sequencing , Cholestasis/genetics , Genotype , Cholestasis, Intrahepatic/genetics , Cholestasis, Intrahepatic/diagnosis , Flavoproteins/genetics , Mitochondrial Proteins/genetics , Protoporphyrinogen Oxidase/genetics , Cytoskeletal Proteins/genetics , Adaptor Proteins, Signal Transducing/geneticsABSTRACT
Although several nanomedicines got clinical approval over the past two decades, the clinical translation rate is relatively small so far. There are many post-surveillance withdrawals of nanomedicines caused by various safety issues. For successful clinical advancement of nanotechnology, it is of unmet need to realize cellular and molecular foundation of nanotoxicity. Current data suggest that lysosomal dysfunction caused by nanoparticles is emerging as the most common intracellular trigger of nanotoxicity. This review analyzes prospect mechanisms of lysosomal dysfunction-mediated toxicity induced by nanoparticles. We summarized and critically assessed adverse drug reactions of current clinically approved nanomedicines. Importantly, we show that physicochemical properties have great impact on nanoparticles interaction with cells, excretion route and kinetics, and subsequently on toxicity. We analyzed literature on adverse reactions of current nanomedicines and hypothesized that adverse reactions might be linked with lysosomal dysfunction caused by nanomedicines. Finally, from our analysis it becomes clear that it is unjustifiable to generalize safety and toxicity of nanoparticles, since different particles possess distinct toxicological properties. We propose that the biological mechanism of the disease progression and treatment should be central in the optimization of nanoparticle design.
Subject(s)
Nanomedicine , Nanoparticles , Humans , Nanomedicine/methods , Nanotechnology/methods , Nanoparticles/toxicity , Nanoparticles/chemistry , LysosomesABSTRACT
It has become evident that physical stimuli of the cellular microenvironment transmit mechanical cues regulating key cellular functions, such as proliferation, migration, and malignant transformation. Accumulating evidence suggests that tumor cells face variable mechanical stimuli that may induce metabolic rewiring of tumor cells. However, the knowledge of how tumor cells adapt metabolism to external mechanical cues is still limited. We therefore designed soft 3D collagen scaffolds mimicking a pathological mechanical environment to decipher how liver tumor cells would adapt their metabolic activity to physical stimuli of the cellular microenvironment. Here, we report that the soft 3D microenvironment upregulates the glycolysis of HepG2 and Alexander cells. Both cell lines adapt their mitochondrial activity and function under growth in the soft 3D microenvironment. Cells grown in the soft 3D microenvironment exhibit marked mitochondrial depolarization, downregulation of mitochondrially encoded cytochrome c oxidase I, and slow proliferation rate in comparison with stiff monolayer cultures. Our data reveal the coupling of liver tumor glycolysis to mechanical cues. It is proposed here that soft 3D collagen scaffolds can serve as a useful model for future studies of mechanically regulated cellular functions of various liver (potentially other tissues as well) tumor cells.
Subject(s)
Liver Neoplasms , Tumor Microenvironment , Humans , Mitochondrial Dynamics , CollagenABSTRACT
DNA nanotechnology has yielded remarkable advances in composite materials with diverse applications in biomedicine. The specificity and predictability of building 3D structures at the nanometer scale make DNA nanotechnology a promising tool for uses in biosensing, drug delivery, cell modulation, and bioimaging. However, for successful translation of DNA nanostructures to real-world applications, it is crucial to understand how they interact with living cells, and the consequences of such interactions. In this review, we summarize the current state of knowledge on the interactions of DNA nanostructures with cells. We identify key challenges, from a cell biology perspective, that influence progress towards the clinical translation of DNA nanostructures. We close by providing an outlook on what questions must be addressed to accelerate the clinical translation of DNA nanostructures. STATEMENT OF SIGNIFICANCE: Self-assembled DNA nanostructures (DNs) offers unique opportunities to overcome persistent challenges in the nanobiotechnology field. However, the interactions between engineered DNs and living cells are still not well defined. Critical systematization of current cellular models and biological responses triggered by DNs is a crucial foundation for the successful clinical translation of DNA nanostructures. Moreover, such an analysis will identify the pitfalls and challenges that are present in the field, and provide a basis for overcoming those challenges.
Subject(s)
Nanostructures , DNA/chemistry , Drug Delivery Systems/methods , Nanostructures/chemistry , Nanotechnology/methodsABSTRACT
Amyloid A amyloidosis is a serious clinical condition resulting from the systemic deposition of amyloid A originating from serum amyloid A proteins with the kidneys being the most commonly and earliest affected organ. Previously described amyloid A amyloidosis is linked to increased production and deposition of serum amyloid A proteins secondary to inflammatory conditions arising from infectious, metabolic, or genetic causes. Here we describe a family with primary amyloid A amyloidosis due to a chr11:18287683 T>C (human genome version19) mutation in the SAA1 promoter linked to the amyloidogenic SAA1.1 haplotype. This condition leads to a doubling of the basal SAA1 promoter activity and sustained elevation of serum amyloid A levels that segregated in an autosomal dominant pattern in 12 genetically affected and in none of six genetically unaffected relatives, yielding a statistically significant logarithm of odds (LOD) score over 5. Affected individuals developed proteinuria, chronic kidney disease and systemic deposition of amyloid composed specifically of the SAA1.1 isoform. Tocilizumab (a monoclonal antibody against the interleukin-6 receptor) had a beneficial effect when prescribed early in the disease course. Idiopathic forms represent a significant and increasing proportion (15-20%) of all diagnosed cases of amyloid A amyloidosis. Thus, genetic screening of the SAA1 promoter should be pursued in individuals with amyloid A amyloidosis and no systemic inflammation, especially if there is a positive family history.
Subject(s)
Amyloidosis , Amyloidosis/complications , Humans , Mutation , Promoter Regions, Genetic , Serum Amyloid A Protein/genetics , Serum Amyloid A Protein/metabolismABSTRACT
Hepatocellular carcinoma (HCC) mainly stems from liver cirrhosis and its genetic predisposition is believed to be rare. However, two recent studies describe pathogenic/likely pathogenic germline variants (PV) in cancer-predisposition genes (CPG). As the risk of de novo tumors might be increased in PV carriers, especially in immunosuppressed patients after a liver transplantation, we analyzed the prevalence of germline CPG variants in HCC patients considered for liver transplantation. Using the panel NGS targeting 226 CPGs, we analyzed germline DNA from 334 Czech HCC patients and 1662 population-matched controls. We identified 48 PVs in 35 genes in 47/334 patients (14.1%). However, only 7/334 (2.1%) patients carried a PV in an established CPG (PMS2, 4×NBN, FH or RET). Only the PV carriers in two MRN complex genes (NBN and RAD50) were significantly more frequent among patients over controls. We found no differences in clinicopathological characteristics between carriers and non-carriers. Our study indicated that the genetic component of HCC is rare. The HCC diagnosis itself does not meet criteria for routine germline CPG genetic testing. However, a low proportion of PV carriers may benefit from a tailored follow-up or targeted therapy and germline testing could be considered in liver transplant recipients.
ABSTRACT
Heterozygotes for Z or S alleles of alpha-1-antrypsin (AAT) have low serum AAT levels. Our aim was to compare the risk of hepatocellular carcinoma (HCC) in patients with liver cirrhosis carrying the SERPINA1 MM, MZ and MS genotypes. The study groups consisted of 1119 patients with liver cirrhosis of various aetiologies, and 3240 healthy individuals served as population controls. The MZ genotype was significantly more frequent in the study group (55/1119 vs. 87/3240, p < 0.0001). The MS genotype frequency was comparable in controls (32/119 vs. 101/3240, p = 0.84). MZ and MS heterozygotes had lower serum AAT level than MM homozygotes (medians: 0.90 g/L; 1.40 g/L and 1.67 g/L; p < 0.001 for both). There were significantly fewer patients with HCC in the cirrhosis group among MZ and MS heterozygotes than in MM homozygotes (5/55 and 1/32 respectively, vs. 243/1022, p < 0.01 for both). The risk of HCC was lower in MZ and MS heterozygotes than in MM homozygotes (OR 0.3202; 95% CI 0.1361-0.7719 and OR 0.1522; 95% CI 0.02941-0.7882, respectively). Multivariate analysis of HCC risk factors identified MZ or MS genotype carriage as a protective factor, whereas age, male sex, BMI and viral aetiology of cirrhosis increased HCC risk.
Subject(s)
Carcinoma, Hepatocellular/genetics , Liver Cirrhosis/genetics , Liver Neoplasms/genetics , alpha 1-Antitrypsin/genetics , Alleles , Body Mass Index , Carcinoma, Hepatocellular/complications , Female , Gene Frequency , Genotype , Humans , Liver Cirrhosis/complications , Liver Neoplasms/complications , Male , Middle Aged , Multivariate Analysis , Risk Factors , Sex Factors , alpha 1-Antitrypsin/bloodABSTRACT
Lambda interferons mediate antiviral immunity by inducing interferon-stimulated genes (ISGs) in epithelial tissues. A common variant rs368234815TT/∆G creating functional gene from an IFNL4 pseudogene is associated with the expression of major ISGs in the liver but impaired clearance of hepatitis C. To explain this, we compared Halo-tagged and non-tagged IFNL3 and IFNL4 signaling in liver-derived cell lines. Transfection with non-tagged IFNL3, non-tagged IFNL4 and Halo-tagged IFNL4 led to a similar degree of JAK-STAT activation and ISG induction; however, the response to transfection with Halo-tagged IFNL3 was lower and delayed. Transfection with non-tagged IFNL3 or IFNL4 induced no transcriptome change in the cells lacking either IL10R2 or IFNLR1 receptor subunits. Cytosolic overexpression of signal peptide-lacking IFNL3 or IFNL4 in wild type cells did not interfere with JAK-STAT signaling triggered by interferons in the medium. Finally, expression profile changes induced by transfection with non-tagged IFNL3 and IFNL4 were highly similar. These data do not support the hypothesis about IFNL4-specific non-canonical signaling and point out that functional studies conducted with tagged interferons should be interpreted with caution.
Subject(s)
Hepatocytes/immunology , Hepatocytes/metabolism , Interferons/genetics , Interferons/metabolism , Interleukins/genetics , Interleukins/metabolism , Cell Line , Gene Expression , Gene Knockout Techniques , Hep G2 Cells , Humans , Interferon Regulatory Factors/genetics , Interferon Regulatory Factors/metabolism , Interferons/deficiency , Interleukin-10 Receptor beta Subunit/deficiency , Interleukin-10 Receptor beta Subunit/genetics , Interleukin-10 Receptor beta Subunit/metabolism , Interleukins/deficiency , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, Interferon/deficiency , Receptors, Interferon/genetics , Receptors, Interferon/metabolism , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Signal Transduction , TransfectionABSTRACT
Liver stiffness is a reliable non-invasive predictor of Hepatic Venous Pressure Gradient (HVPG) above 10 mm Hg. However, it failed to predict higher thresholds of HVPG. Our aim was to investigate whether liver stiffness and selected previously published non-invasive blood biomarkers could predict higher HVPG thresholds in liver transplant candidates without ongoing alcohol use. One hundred and nine liver transplant candidates with liver cirrhosis of various aetiologies underwent direct HVPG measurement, liver stiffness measurement by 2D shear-wave elastography (Aixplorer Multiwave, Supersonic Imagine, France) and assessment of blood HVPG biomarkers (osteopontin, VCAM-1, IL-6, TNF-α, IL-1ra/IL-1F3 and ELF score). The correlation between liver stiffness and HVPG was linear up to 30 mm Hg of HVPG (r = 0.765, p < 0.0001). The regression lines had similar slopes for HVPG values below and above 16 mm Hg (p > 0.05) and the correlation in patients with HVPG <16 mm Hg (r = 0.456, p = 0.01) was similar to patients with HVPG ≥ 16 mm Hg (r = 0.499, p < 0.0001). The correlation was similar in the subgroup patients with alcoholic (r = 0.718, p < 0.0001), NASH (r = 0.740, p = 0.008), cryptogenic (r = 0.648, p = 0,0377), cholestatic and autoimmune (r = 0.706, p < 0.0001) and viral cirrhosis (r = 0.756, p < 0.0001). Liver stiffness distinguished patients with HVPG above 16, and 20 mm Hg with AUROCs 0.90243, and 0.86824, sensitivity 0.7656, and 0.7027, and specificity 0.9333, and 0.8750. All studied blood biomarkers correlated better with liver stiffness than with HVPG and their AUROCs did not exceed 0.8 at both HVPG thresholds. Therefore, a composite predictor superior to liver stiffness could not be established. We conclude that liver stiffness is a clinically reliable predictor of higher HVPG thresholds in non-drinking subjects with advanced liver cirrhosis.
Subject(s)
Elasticity Imaging Techniques/methods , Elasticity/physiology , Liver/pathology , Adult , Aged , Aged, 80 and over , Biomarkers/blood , Czech Republic , Female , Fibrosis/pathology , Hepatic Veins/pathology , Humans , Hypertension, Portal/pathology , Linear Models , Liver Cirrhosis/pathology , Male , Middle Aged , Portal Pressure/physiology , Prospective Studies , Sensitivity and Specificity , Venous Pressure/physiologyABSTRACT
Recent studies undoubtedly show that the mammalian target of rapamycin (mTOR) and the Hippo-Yes-associated protein 1 (YAP) pathways are important mediators of mechanical cues. The crosstalk between these pathways as well as de-regulation of their signaling has been implicated in multiple tumor types, including liver tumors. Additionally, physical cues from 3D microenvironments have been identified to alter gene expression and differentiation of different cell lineages. However, it remains incompletely understood how physical constraints originated in 3D cultures affect cell plasticity and what the key mediators are of such process. In this work, we use collagen scaffolds as a model of a soft 3D microenvironment to alter cellular size and study the mechanotransduction that regulates that process. We show that the YAP-mTOR axis is a downstream effector of 3D cellular culture-driven mechanotransduction. Indeed, we found that cell mechanics, dictated by the physical constraints of 3D collagen scaffolds, profoundly affect cellular proliferation in a YAP-mTOR-mediated manner. Functionally, the YAP-mTOR connection is key to mediate cell plasticity in hepatic tumor cell lines. These findings expand the role of YAP-mTOR-driven mechanotransduction to the control hepatic tumor cellular responses under physical constraints in 3D cultures. We suggest a tentative mechanism, which coordinates signaling rewiring with cytoplasmic restructuring during cell growth in 3D microenvironments.
ABSTRACT
Iron oxide nanoparticles (IONPs) were the first generation of nanomaterials that reached real clinic use. Particularly, several IONPs-based magnetic resonance imaging contrast agents gained approval by US Food and Drug Administration (FDA). However, latter body of evidence revealed the overlooked side effects of IONPs, resulting in their withdrawal. Emerging evidence suggests that this happened due to poor understanding of the mechanisms by which IONPs act at the cellular and sub-cellular levels. Recent studies indicate that better understanding of fundamental signal modulations induced by nanomaterials is essential to overcome the clinical problems with nanoparticles. Therefore, in this article we critically review potential mechanisms of IONPs-cell interactions and challenges related with their identification. We describe mechanisms of IONPs-induced toxicity. Ultimately, we demonstrate that knowledge of cellular mechanisms of IONPs action helped to overcome certain translation problems in nanomedicine - we explore potential causes and challenges associated with poor clinical performance of IONPs and propose outlook of how to overcome problems in the field. Our critical analysis implies that a clear understanding of molecular mechanisms of IONPs-cell interactions will provide a basement to increase the likelihood for clinical success of IONPs.
Subject(s)
Magnetite Nanoparticles , Nanoparticles , Contrast Media , Ferric Compounds , Magnetic Iron Oxide Nanoparticles , Magnetic Resonance ImagingABSTRACT
Iron oxide nanoparticles (IONs) are frequently used in various biomedical applications, in particular as magnetic resonance imaging contrast agents in liver imaging. Indeed, number of IONs have been withdrawn due to their poor clinical performance. Yet comprehensive understanding of their interactions with hepatocytes remains relatively limited. Here we investigated how iron oxide nanocubes (IO-cubes) and clusters of nanocubes (IO-clusters) affect distinct human hepatic cell lines. The viability of HepG2, Huh7 and Alexander cells was concentration-dependently decreased after exposure to either IO-cubes or IO-clusters. We found similar cytotoxicity levels in three cell lines triggered by both nanoparticle formulations. Our data indicate that different expression levels of Bcl-2 predispose cell death signaling mediated by nanoparticles. Both nanoparticles induced rather apoptosis than autophagy in HepG2. Contrary, IO-cubes and IO-clusters trigger distinct cell death signaling events in Alexander and Huh7 cells. Our data clarifies the mechanism by which cubic nanoparticles induce autophagic flux and the mechanism of subsequent toxicity. These findings imply that the cytotoxicity of ION-based contrast agents should be carefully considered, particularly in patients with liver diseases.
ABSTRACT
Iron oxide-based nanoparticles have been repeatedly shown to affect lysosomal-mediated signaling. Recently, nanoparticles have demonstrated an ability to modulate autophagic flux via lysosome-dependent signaling. However, the precise underlying mechanisms of such modulation as well as the impact of cellular genetic background remain enigmatic. In this study, we investigated how lysosomal-mediated signaling is affected by iron oxide nanoparticle uptake in three distinct hepatic cell lines. We found that nanoparticle-induced lysosomal dysfunction alters sub-cellular localization of pmTOR and p53 proteins. Our data indicate that alterations in the sub-cellular localization of p53 protein induced by nanoparticle greatly affect the autophagic flux. We found that cells with high levels of Bcl-2 are insensitive to autophagy initiated by nanoparticles. Altogether, our data identify lysosomes as a central hub that control nanoparticle-mediated responses in hepatic cells. Our results provide an important fundamental background for the future development of targeted nanoparticle-based therapies.
Subject(s)
Hepatocytes/metabolism , Lysosomes/metabolism , Magnetic Iron Oxide Nanoparticles , Proto-Oncogene Proteins c-bcl-2/metabolism , Tumor Suppressor Protein p53/metabolism , Autophagy/genetics , Cell Line , Humans , TOR Serine-Threonine Kinases/metabolismABSTRACT
BACKGROUND: Niemann-Pick type C (NP-C) is a rare neurovisceral genetic disorder caused by mutations in the NPC1 or the NPC2 gene. NPC1 is a multipass-transmembrane protein essential for egress of cholesterol from late endosomes/lysosomes. To evaluate impacts of NPC1 mutations, we examined fibroblast cultures from 26 NP-C1 patients with clinical phenotypes ranging from infantile to adult neurologic onset forms. The cells were tested with multiple assays including NPC1 mRNA expression levels and allele expression ratios, assessment of NPC1 promoter haplotypes, NPC1 protein levels, cellular cholesterol staining, localization of the mutant NPC1 proteins to lysosomes, and cholesterol/cholesteryl ester ratios. These results were correlated with phenotypes of the individual patients. RESULTS: Overall we identified 5 variant promoter haplotypes. Three of them showed reporter activity decreased down to 70% of the control sequence. None of the haplotypes were consistently associated with more severe clinical presentation of NP-C. Levels of transcripts carrying null NPC1 alleles were profoundly lower than levels of the missense variants. Low levels of the mutant NPC1 protein were identified in most samples. The protein localised to lysosomes in cultures expressing medium to normal NPC1 levels. Fibroblasts from patients with severe infantile phenotypes had higher cholesterol levels and higher cholesterol/cholesteryl ester ratios. On the contrary, cell lines from patients with juvenile and adolescent/adult phenotypes showed values comparable to controls. CONCLUSION: No single assay fully correlated with the disease severity. However, low residual levels of NPC1 protein and high cholesterol/cholesteryl ester ratios associated with severe disease. The results suggest not only low NPC1 expression due to non-sense mediated decay or low mutant protein stability, but also dysfunction of the stable mutant NPC1 as contributors to the intracellular lipid transport defect.
Subject(s)
Carrier Proteins , Membrane Glycoproteins , Adolescent , Carrier Proteins/genetics , Fibroblasts/metabolism , Humans , Intracellular Signaling Peptides and Proteins , Membrane Glycoproteins/genetics , Membrane Glycoproteins/metabolism , Mutation/genetics , Niemann-Pick C1 ProteinABSTRACT
Rotor syndrome is defined as a self-limiting hyperbilirubinemia characterized by jaundice that does not need treatment, cause any morbidity or affect life expectancy. As far as the literature is evaluated, the number of patients with Rotor syndrome diagnosed at the molecular level is less than 20 until today. In this case presentation, we aimed to present two siblings with Rotor syndrome who were diagnosed at the molecular level. To the nest of our knowledge, these patients are the first Turkish patients with Rotor syndrome diagnosed at the molecular level.
ABSTRACT
ATP-binding cassette (ABC) subfamily B member 4 (ABCB4), also known as multidrug resistance protein 3 (MDR3), encoded by ABCB4, is involved in biliary phospholipid secretion, protecting hepatobiliary system from deleterious detergent and lithogenic properties of the bile. ABCB4 mutations altering canalicular ABCB4 protein function and expression may have variable clinical presentation and predispose to several human liver diseases. Well-established phenotypes of ABCB4 deficit are: progressive familial intrahepatic cholestasis type 3, gallbladder disease 1 (syn. low phospholipid associated cholelithiasis syndrome), high ɣ-glutamyl transferase intrahepatic cholestasis of pregnancy, chronic cholangiopathy, and adult biliary fibrosis/cirrhosis. Moreover, ABCB4 aberrations may be involved in some cases of drug induced cholestasis, transient neonatal cholestasis, and parenteral nutrition-associated liver disease. Recently, genome-wide association studies have documented occurrence of malignant tumours, predominantly hepatobiliary malignancies, in patients with ABCB4/MDR3 deficit. The patient's age at the time of the first presentation of cholestatic disease, as well as the severity of liver disorder and response to treatment are related to the ABCB4 allelic status. Mutational analysis of ABCB4 in patients and their families should be considered in all individuals with cholestasis of unknown aetiology, regardless of age and/or time of onset of the first symptoms.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B/deficiency , Chemical and Drug Induced Liver Injury/genetics , Cholelithiasis/genetics , Cholestasis, Intrahepatic/genetics , Liver Cirrhosis, Biliary/genetics , Pregnancy Complications/genetics , ATP Binding Cassette Transporter, Subfamily B/genetics , ATP Binding Cassette Transporter, Subfamily B/metabolism , Age of Onset , Alleles , Bile Duct Diseases/genetics , Cholagogues and Choleretics/therapeutic use , Cholestasis/genetics , Gallbladder Diseases/genetics , Humans , Liver Diseases/etiology , Liver Diseases/genetics , Parenteral Nutrition/adverse effects , Ursodeoxycholic Acid/therapeutic useABSTRACT
BACKGROUND: The rs58542926 polymorphism in transmembrane 6 superfamily member 2 (TM6SF2) is a genetic factor predisposing to nonalcoholic fatty liver disease. We aimed to explore the effect of recipient and donor TM6SF2 rs58542926 genotypes on liver graft fat content after liver transplantation. METHODS: Steatosis was evaluated in liver biopsies from 268 adult recipients. The influence of recipient and donor TM6SF2 genotypes, patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 genotypes, and nongenetic factors on the steatosis grade assessed 6-30 months after transplantation was analyzed by ordinal logistic regression. RESULTS: The presence of the TM6SF2 c.499A allele in the donor (P = 0.014), PNPLA3 c.444G allele in the donor (P < 0.001), posttransplant body mass index (P < 0.001), and serum triglycerides (P = 0.047) independently predicted increased liver fat content on multivariable analysis, whereas noncirrhotic liver disease, as an indication for liver transplantation, was associated with lower risk of steatosis (P = 0.003). The effects of the donor TM6SF2 A and PNPLA3 G alleles were additive, with an odds ratio of 4.90 (95% confidence interval, 2.01-13.00; P < 0.001), when both minor alleles were present compared with an odds ratio of 2.22 (95% confidence interval, 1.42-3.61; P = 0.002) when only one of these alleles was present. CONCLUSIONS: The donor TM6SF2 c.499A allele is an independent risk factor of liver graft steatosis after liver transplantation that is additive to the effects of donor PNPLA3 c.444G allele.