Metabolic Engineering of Glycofusion Bispecific Antibodies for α-Dystroglycanopathies

Background: α-dystroglycanopathies are congenital muscular dystrophies in which genetic mutations cause the decrease or absence of a unique and complex O-linked glycan called matriglycan. This hypoglycosylation of O-linked matriglycan on the α-dystroglycan (α-DG) protein subunit abolishes or reduces the protein binding to extracellular ligands such as laminins in skeletal muscles, leading to compromised survival of muscle cells after contraction. Methods: Surrogate molecular linkers reconnecting laminin-211 and the dystroglycan β-subunit through bispecific antibodies can be engineered to improve muscle function in the α-dystroglycanopathies. This study reports the metabolic engineering of a novel glycofusion bispecific (GBi) antibody that fuses the mucin-like domain of the α-DG to the light chain of an anti-β-DG subunit antibody. Results: Transient HEK production with the co-transfection of LARGE1, the glycoenzyme responsible for the matriglycan modification, produced the GBi antibody only with a light matriglycan modification and a weak laminin-211 binding activity. However, when a sugar feed mixture of uridine, galactose, and manganese ion (Mn2+) was added to the culture medium, the GBi antibody produced exhibited a dramatically enhanced matriglycan modification and a much stronger laminin-binding activity. Conclusions: Further investigation has revealed that Mn2+ in the sugar feeds played a critical role in increasing the matriglycan modification of the GBi antibody, key for the function of the resulting bispecific antibody.

Laminin Beta 2 Is Localized at the Sites of Blood-Brain Barrier and Its Disruption Is Associated With Increased Vascular Permeability, Histochemical, and Transcriptomic Study

Heterotrimeric extracellular matrix proteins laminins are mostly deposited at basal membranes and are important in repair and neoplasia. Here, we localize laminin beta 2 (LAMB2) at the sites of blood-brain barrier (BBB). Microvasculature (MV) of normal brain is endowed with complete LAMB2 coverage. In contrast, its cognate protein laminin beta 1 (LAMB1) is absent in MV of normal brain but emerges at the sprouting tip of a growing vessels. Similarly, vascular proliferation in high-grade gliomas (HGG) is accompanied by marked overexpression of LAMB1, whereas LAMB2 shows deficient deposition. We find that many brain pathologies with presence of post-gadolinium enhancement (PGE) on magnetic resonance imaging (MRI) show disruption of LAMB2 vascular ensheathment. Inhibition of vascular endothelial growth factor signaling in HGG blocks angiogenesis, suppresses PGE in HGG, prevents expression of LAMB1, and restores LAMB2 vascular coverage. Analysis of single-cell RNA sequencing (scRNA-seq) databases shows that in quiescent brain LAMB2 is predominantly expressed by BBB-associated pericytes (PCs) and endothelial cells (ECs), whereas neither cell types produce LAMB1. In contrast, in HGG, both LAMB1 and 2 are overexpressed by endothelial precursor cells, a phenotypically unique immature group, specific to proliferating hyperplastic MV.

An atypical basement membrane forms a midline barrier during left-right asymmetric gut development in the chicken embryo

Correct intestinal morphogenesis depends on the early embryonic process of gut rotation, an evolutionarily conserved program in which a straight gut tube elongates and forms into its first loops. However, the gut tube requires guidance to loop in a reproducible manner. The dorsal mesentery (DM) connects the gut tube to the body and directs the lengthening gut into stereotypical loops via left-right (LR) asymmetric cellular and extracellular behavior. The LR asymmetry of the DM also governs blood and lymphatic vessel formation for the digestive tract, which is essential for prenatal organ development and postnatal vital functions including nutrient absorption. Although the genetic LR asymmetry of the DM has been extensively studied, a divider between the left and right DM has yet to be identified. Setting up LR asymmetry for the entire body requires a Lefty1+ midline barrier to separate the two sides of the embryo, without it, embryos have lethal or congenital LR patterning defects. Individual organs including the brain, heart, and gut also have LR asymmetry, and while the consequences of left and right signals mixing are severe or even lethal, organ-specific mechanisms for separating these signals are poorly understood. Here, we uncover a midline structure composed of a transient double basement membrane, which separates the left and right halves of the embryonic chick DM during the establishment of intestinal and vascular asymmetries. Unlike other basement membranes of the DM, the midline is resistant to disruption by intercalation of Netrin4 (Ntn4). We propose that this atypical midline forms the boundary between left and right sides and functions as a barrier necessary to establish and protect organ asymmetry.

Efficient Generation of Skin Organoids from Pluripotent Cells via Defined Extracellular Matrix Cues and Morphogen Gradients in a Spindle-Shaped Microfluidic Device

Pluripotent stem cell-derived skin organoids (PSOs) emerge as a developmental skin model that is self-organized into multiple components, such as hair follicles. Despite their impressive complexity, PSOs are currently generated in the absence of 3D extracellular matrix (ECM) signals and have several major limitations, including an inverted anatomy (e.g., epidermis inside/dermis outside). In this work, a method is established to generate PSOs effectively in a chemically-defined 3D ECM environment. After examining various dermal ECM molecules, it is found that PSOs generated in collagen -type I (COLI) supplemented with laminin 511 (LAM511) exhibit increased growth compared to conventional free-floating conditions, but fail to induce complete skin differentiation due in part to necrosis. This problem is addressed by generating the PSOs in a 3D bioprinted spindle-shaped hydrogel device, which constrains organoid growth longitudinally. This culture system significantly reduces organoid necrosis and leads to a twofold increase in keratinocyte differentiation and an eightfold increase in hair follicle formation. Finally, the system is adapted as a microfluidic device to create asymmetrical gradients of differentiation factors and improves the spatial organization of dermal and epidermal cells. This study highlights the pivotal role of ECM and morphogen gradients in promoting and spatially-controlling skin differentiation in the PSO framework.

Non-integrin laminin receptor (LamR) plays a role in axonal outgrowth from chicken DRG via modulating the Akt and Erk signaling

37/67 kDa laminin receptor (LamR)/ribosomal protein SA exhibits dual function as both a ribosomal protein and cell surface receptor for laminin. LamR influences critical cellular processes such as invasion, adhesion, and migration when acting as a receptor. Despite the acknowledged importance of LamR/67LR in various cellular processes, its contribution to the peripheral nervous system development is obscure. Thus, this study investigated the biological activity of LamR in peripheral axonal outgrowth in the presence of laminin-1 or Ile-Lys-Val-Ala-Val (IKVAV) peptide, whose important role in dorsal root ganglia (DRG) axonal outgrowth we recently showed. Unexpectedly, we did not observe LamR on the surface of DRG cells or in a conditioned medium, suggesting its intracellular action in the negative regulation of DRG axonal outgrowth. Using C-terminus LamR-targeting IgG, we demonstrated the role of LamR in that process, which is independent of the presence of Schwann cell precursors (SCPs) and is mediated by extracellular signal-regulated kinase (Erk) and Protein kinase B (Akt1/2/3) signaling pathways. Additionally, we show that the action of LamR towards laminin-1-dependent axonal outgrowth is unmasked only when the activity of integrin β1 is perturbed. We believe that modulation of LamR activity provides the basis for its use for inhibiting axon growth as a potential therapeutic agent for regulating abnormal or excessive neurite growth during neurodevelopmental diseases or pathological nerve regeneration.

Extracellular matrix substrates differentially influence enteric glial cell homeostasis and immune reactivity

Introduction

Enteric glial cells are important players in the control of motility, intestinal barrier integrity and inflammation. During inflammation, they switch into a reactive phenotype enabling them to release inflammatory mediators, thereby shaping the inflammatory environment. While a plethora of well-established in vivo models exist, cell culture models necessary to decipher the mechanistic pathways of enteric glial reactivity are less well standardized. In particular, the composition of extracellular matrices (ECM) can massively affect the experimental outcome. Considering the growing number of studies involving primary enteric glial cells, a better understanding of their homeostatic and inflammatory in vitro culture conditions is needed.

Methods

We examined the impact of different ECMs on enteric glial culture purity, network morphology and immune responsiveness. Therefore, we used immunofluorescence and brightfield microscopy, as well as 3' bulk mRNA sequencing. Additionally, we compared cultured cells with in vivo enteric glial transcriptomes isolated from Sox10iCreERT2Rpl22HA/+ mice.

Results

We identified Matrigel and laminin as superior over other coatings, including poly-L-ornithine, different lysines, collagens, and fibronectin, gaining the highest enteric glial purity and most extended glial networks expressing connexin-43 hemichannels allowing intercellular communication. Transcriptional analysis revealed strong similarities between enteric glia on Matrigel and laminin with enrichment of gene sets supporting neuronal differentiation, while cells on poly-L-ornithine showed enrichment related to cell proliferation. Comparing cultured and in vivo enteric glial transcriptomes revealed a 50% overlap independent of the used coating substrates. Inflammatory activation of enteric glia by IL-1β treatment showed distinct coating-dependent gene expression signatures, with an enrichment of genes related to myeloid and epithelial cell differentiation on Matrigel and laminin coatings, while poly-L-ornithine induced more gene sets related to lymphocyte differentiation.

Discussion

Together, changes in morphology, differentiation and immune activation of primary enteric glial cells proved a strong effect of the ECM. We identified Matrigel and laminin as pre-eminent substrates for murine enteric glial cultures. These new insights will help to standardize and improve enteric glial culture quality and reproducibility between in vitro studies in the future, allowing a better comparison of their functional role in enteric neuroinflammation.

C. elegans touch receptor neurons direct mechanosensory complex organization via repurposing conserved basal lamina proteins

The sense of touch is conferred by the conjoint function of somatosensory neurons and skin cells. These cells meet across a gap filled by a basal lamina, an ancient structure found in metazoans. Using Caenorhabditis elegans, we investigate the composition and ultrastructure of the extracellular matrix at the epidermis and touch receptor neuron (TRN) interface. We show that membrane-matrix complexes containing laminin, nidogen, and the MEC-4 mechano-electrical transduction channel reside at this interface and are central to proper touch sensation. Interestingly, the dimensions and spacing of these complexes correspond with the discontinuous beam-like extracellular matrix structures observed in serial-section transmission electron micrographs. These complexes fail to coalesce in touch-insensitive extracellular matrix mutants and in dissociated neurons. Loss of nidogen reduces the density of mechanoreceptor complexes and the amplitude of the touch-evoked currents they carry. Thus, neuron-epithelium cell interfaces are instrumental in mechanosensory complex assembly and function. Unlike the basal lamina ensheathing the pharynx and body wall muscle, nidogen recruitment to the puncta along TRNs is not dependent upon laminin binding. MEC-4, but not laminin or nidogen, is destabilized by point mutations in the C-terminal Kunitz domain of the extracellular matrix component, MEC-1. These findings imply that somatosensory neurons secrete proteins that actively repurpose the basal lamina to generate special-purpose mechanosensory complexes responsible for vibrotactile sensing.

The expression of intermediate filaments in the abomasum of ruminants: A comparative study

Intermediate filaments (IFs) are key molecular factors of the cell and have been reported to play an important role in maintaining the structural integrity and functionality of the abomasum. This study was designed to determine the regional distribution, cellular localization and expression of several IFs, including CK8, CK18, CK19, vimentin, desmin, peripherin and nestin, as well as the connective tissue component laminin, in the bovine, ovine and caprine abomasa. Immunohistochemical analyses demonstrated varying levels of expression of CK8, CK18, CK19, vimentin, desmin, nestin, peripherin and laminin in the bovine, ovine and caprine abomasa. CK8 immunoreactions were particularly evident in the luminal and glandular epithelia of the glands found in the abomasal cardia, fundus and pylorus in all three species. In the bovine abomasum, CK18 immunoreactions were stronger in the parietal cells, compared to the chief cells. In the abomasum of all three species, the smooth muscle as well as the smooth muscle cells of the vascular media in the cardiac, fundic and pyloric regions showed strong immunoreactivity. In all three species, the cardiac, fundic and pyloric regions of the abomasum showed strong peripherin and nestin immunoreactions in the luminal and glandular epithelial cells, stromal and smooth muscle cells, nervous plexuses and blood vessels. The expression patterns of IFs and laminin in the ruminant abomasum suggest that these proteins play a structural role in the cytoskeleton and are effective in maintaining abomasal tissue integrity and stability.

The correlation between serum levels of laminin, type IV collagen, type III procollagen N-terminal peptide and hyaluronic acid with the progression of post-COVID-19 pulmonary fibrosis

COVID-19 patients often suffer from post-COVID-19 acute sequelae (PASC). Pulmonary fibrosis has the most significant long-term impact on the respiratory health of patients, known as post-COVID-19 pulmonary fibrosis (PC19-PF). PC19-PF can be caused by acute respiratory distress syndrome (ARDS) or COVID-19-induced pneumonia. Individuals who experience COVID-19 pneumonia symptoms (including cough, shortness of breath, dyspnea on exertion, and desaturation) for at least 12 weeks after diagnosis, almost all develop PC19-PF. Extracellular matrix molecules: laminin (LN), type IV collagen (IV Col), procollagen III N-terminal peptide (PIIINP), and hyaluronic acid (HA) are involved in the development and progression of PC19-PF. This study aimed to investigate the relationship between the progression of PC19-PF and serum levels of laminin, IV COL, PIIINP, and hyaluronic acid. This retrospective study included 162 PC19-PF patients treated and 160 healthy controls who received treatment at Shenzhen Longgang District Third People's Hospital, Hebei PetroChina Central Hospital and Changzhi People's Hospital from January 2021 to December 2023. Serum levels of LN, IV COL, PIIINP, and HA were detected by chemiluminescence immunoassay using commercial kits. Predicted forced vital capacity percentage (FVC% pred), predicted carbon monoxide lung diffusion capacity percentage (DLCO% pred), high-resolution computed tomography (HRCT) scores were assessed, and patient mortality was compared with healthy controls. Serum levels of LN, IV Col, PIIINP, and HA were significantly higher in PC19-PF or CTD-ILD patients than in healthy controls (all p < 0.05), and they were further elevated in acute exacerbation cases (all p < 0.01). In patients, HA was positively associated with HRCT scores and negatively associated with FVC% pred and DLCO% pred (all p < 0.05). Serum levels of LN, IV COL, PIIINP, and HA were significantly lower in surviving patients than in those who deceased (all p > 0.05). Serum levels of LN, IV C, PIIINP, and HA may affect the progression of PC19-PF and may serve as indicators of PC19-PF severity.

Unlocking Clinical Insights: Lymphocyte-Specific Protein Tyrosine Kinase Candidates as Promising Therapeutic Targets for Pancreatic Cancer Risk Stratification

Background: Uncover the pivotal link between lymphocyte-specific protein tyrosine kinase (Lck)-related genes and clinical risk stratification in pancreatic cancer. Methods: This study identifies shared genes between differentially expressed genes (DEGs) and Lck-related genes in pancreatic cancer using a methodological framework rooted in The Cancer Genome Atlas database. Feature gene selection is accomplished and a signature model is constructed. Statistical significant clinical endpoints such as overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) were defined. Results: After performing random survival forest, Lasso regression, and multivariate Cox regression model, 7 trait genes out of 272 Lck-associated DEGs are selected to create a signature model that is independent of other clinical factors and can predict OS and DSS. It appears that high-risk patients have activated the TP53 signaling pathway and the cell cycle signaling pathway. LAMA3 turned out to be the hub gene of the signature with high expression in pancreatic cancer. Patients with increased expression of LAMA3 had a short OS, DSS, and PFI in comparison. The candidate competing endogenous RNA network of LAMA3 turned out to be OPI5-AS1/hsa-miR-186-5p/LAMA3 axis. Conclusions: A characteristic signature of seven Lck-related genes, especially LAMA3, has been shown to be a key factor in clinical risk stratification for pancreatic cancer.

Laminin-Augmented Decellularized Extracellular Matrix Ameliorating Neural Differentiation and Neuroinflammation in Human Mini-Brains

Non-neural extracellular matrix (ECM) has limited application in humanized physiological neural modeling due to insufficient brain-specificity and safety concerns. Although brain-derived ECM contains enriched neural components, certain essential components are partially lost during the decellularization process, necessitating augmentation. Here, it is demonstrated that the laminin-augmented porcine brain-decellularized ECM (P-BdECM) is xenogeneic factor-depleted as well as favorable for the regulation of human neurons, astrocytes, and microglia. P-BdECM composition is comparable to human BdECM regarding brain-specificity through the matrisome and gene ontology-biological process analysis. As augmenting strategy, laminin 111 supplement promotes neural function by synergic effect with laminin 521 in P-BdECM. Annexin A1(ANXA1) and Peroxiredoxin(PRDX) in P-BdECM stabilized microglial and astrocytic behavior under normal while promoting active neuroinflammation in response to neuropathological factors. Further, supplementation of the brain-specific molecule to non-neural matrix also ameliorated glial cell inflammation as in P-BdECM. In conclusion, P-BdECM-augmentation strategy can be used to recapitulate humanized pathophysiological cerebral environments for neurological study.

Continuous protein-density gradients: A new approach to correlate physical cues with cell response

To assess cellular behavior within heterogeneous tissues, such as bone, skin, and nerves, scaffolds with biophysical gradients are required to adequately replicate the in vivo interaction between cells and their native microenvironment. In this study, we introduce a strategy for depositing ultrathin films comprised of laminin-111 with precisely controlled biophysical gradients onto planar substrates using the Langmuir-Blodgett (LB) technique. The gradient is created by controlled desynchronization of the barrier compression and substrate withdrawal speed during the LB deposition process. Characterization of the films was performed using techniques such as atomic force microscopy and confocal fluorescence microscopy, enabling the comprehensive analysis of biophysical parameters along the gradient direction. Furthermore, human adipose-derived stem cells were seeded onto the gradient films to investigate the influence of protein density on cell attachment, showing that the distribution of the cells can be modulated by the arrangement of the laminin at the air-water interface. The presented approach not only allowed us to gain insights into the intricate interplay between biophysical cues and cell behavior within complex tissue environments, but it is also suited as a screening approach to determine optimal protein concentrations to achieve a target cellular output.

Oligodendrocyte-derived laminin-γ1 regulates the blood-brain barrier and CNS myelination in mice

Although oligodendrocytes (OLs) synthesize laminin-γ1, the most widely used γ subunit, its functional significance in the CNS remains unknown. To answer this important question, we generated a conditional knockout mouse line with laminin-γ1 deficiency in OL lineage cells (γ1-OKO). γ1-OKO mice exhibit weakness/paralysis and die by post-natal day 33. Additionally, they develop blood-brain barrier (BBB) disruption in the cortex and striatum. Subsequent studies reveal decreased major facilitator superfamily domain containing 2a expression and increased endothelial caveolae vesicles, but unaltered tight junction protein expression and tight junction ultrastructure, indicating a transcellular, rather than a paracellular, mechanism of BBB breakdown. Furthermore, significantly reduced OL lineage cells, OL precursor cells (OPCs), proliferating OPCs, and mature OLs are observed in γ1-OKO brains in a region-specific manner. Consistent with this finding, various defects in myelination are detected in γ1-OKO brains at biochemical and ultrastructural levels. Overall, these results highlight important roles of OL-derived laminin-γ1 in BBB maintenance and OL biology (proliferation, differentiation, and myelination).

Development of a chemically disclosed serum-free medium for mouse pluripotent stem cells

Mouse embryonic stem cells (mESCs) have been widely used as a model system to study the basic biology of pluripotency and to develop cell-based therapies. Traditionally, mESCs have been cultured in a medium supplemented with fetal bovine serum (FBS). However, serum with its inconsistent chemical composition has been problematic for reproducibility and for studying the role of specific components. While some serum-free media have been reported, these media contain commercial additives whose detailed components have not been disclosed. Recently, we developed a serum-free medium, DA-X medium, which can maintain a wide variety of adherent cancer lines. In this study, we modified the DA-X medium and established a novel serum-free condition for both naïve mESCs in which all components are chemically defined and disclosed (DA-X-modified medium for robust growth of pluripotent stem cells: DARP medium). The DARP medium fully supports the normal transcriptome and differentiation potential in teratoma and the establishment of mESCs from blastocysts that retain the developmental potential in all three germ layers, including germ cells in chimeric embryos. Utility of chemically defined DA-X medium for primed mouse epiblast stem cells (mEpiSCs) revealed that an optimal amount of cholesterol is required for the robust growth of naïve-state mESCs, but is dispensable for the maintenance of primed-state mEpiSCs. Thus, this study provides reliable and reproducible culture methods to investigate the role of specific components regulating self-renewal and pluripotency in a wide range of pluripotent states.

Laminin as a Key Extracellular Matrix for Proliferation, Differentiation, and Maturation of Porcine Muscle Stem Cell Cultivation

Extracellular matrix (ECM) proteins play a crucial role in culturing muscle stem cells (MuSCs). However, there is a lack of extensive research on how each of these proteins influences proliferation and differentiation of MuSCs from livestock animals. Therefore, we investigated the effects of various ECM coatings-collagen, fibronectin, gelatin, and laminin-on the proliferation, differentiation, and maturation of porcine MuSCs. Porcine MuSCs, isolated from 14-day-old Berkshire piglets, were cultured on ECM-coated plates, undergoing three days of proliferation followed by three days of differentiation. MuSCs on laminin showed higher proliferation rate than others (p<0.05). There was no significant difference in the mRNA expression levels of PAX7, MYF5, and MYOD among MuSCs on laminin, collagen, and fibronectin (p>0.05). During the differentiation period, MuSCs cultured on laminin exhibited a significantly higher differentiation rate, resulting in thicker myotubes compared to those on other ECMs (p<0.05). Also, MuSCs on laminin showed higher expression of mRNA related with maturated muscle fiber such as MYH1 and MYH4 corresponding to muscle fiber type IIx and muscle fiber type IIb, respectively, compared with MuSCs on other ECM coatings (p<0.05). In summary, our comparison of ECMs revealed that laminin significantly enhances MuSC proliferation and differentiation, outperforming other ECMs. Specifically, muscle fibers cultured on laminin exhibited a more mature phenotype. These findings underscore laminin's potential to advance in vitro muscle research and cultured meat production, highlighting its role in supporting rapid cell proliferation, higher differentiation rates, and the development of mature muscle fibers.

Focal Traumatic Brain Injury Impairs the Integrity of the Basement Membrane of Hindlimb Muscle Fibers Revealed by Extracellular Matrix Immunoreactivity

Traumatic brain injury (TBI) stands as a prominent global cause of disability, with motor deficits being a common consequence. Despite its widespread impact, the precise pathological mechanisms underlying motor deficits after TBI remain elusive. In this study, hindlimb postural asymmetry (HL-PA) development in rats subjected to focal TBI was investigated to explore the potential roles of collagen IV and laminin within the extracellular matrix (ECM) of selected hindlimb muscles in the emergence of motor deficits following TBI. A focal TBI was induced by ablating the left sensorimotor cortex in rats and motor deficits were assessed by measuring HL-PA. The expression of laminin and collagen IV in eight selected muscles on each side of the hindlimbs from both TBI- and sham-operated rats were studied using immunohistochemistry and semi-quantitatively analyzed. The results indicated that the TBI rats exhibited HL-PA, characterized by flexion of the contralateral (right) hindlimb. In the sham-operated rats, the immunoreactive components of laminin and collagen IV were evenly and smoothly distributed along the border of the muscle fibers in all the investigated muscles. In contrast, in the TBI rats, the pattern was broken into aggregated, granule-like, immunoreactive components. Such a labeling pattern was detected in all the investigated muscles both from the contra- and ipsilateral sides of the TBI rats. However, in TBI rats, most of the muscles from the contralateral hindlimb showed a significantly increased expression of these two proteins in comparison with those from the ipsilateral hindlimb. In comparison to sham-operated rats, there was a significant increase in laminin and collagen IV expression in various contralateral hindlimb muscles in the TBI rats. These findings suggest potential implications of laminin and collagen IV in the development of motor deficits following a focal TBI.

Exploring a Solvent Dependent Strategy to Control Self-Assembling Behavior and Cellular Interaction in Laminin-Mimetic Short Peptide based Supramolecular Hydrogels

Self-assembled hydrogels, fabricated through diverse non-covalent interactions, have been extensively studied in regenerative medicines. Inspired from bioactive functional motifs of ECM protein, short peptide sequences have shown remarkable abilities to replicate the intrinsic features of the natural extracellular milieu. In this direction, we have fabricated two short hydrophobic bioactive sequences derived from the laminin protein i. e., IKVAV and YIGSR. Based on the substantial hydrophobicity of these peptides, we selected a co-solvent approach as a suitable gelation technique that included different concentrations of DMSO as an organic phase along with an aqueous solution containing 0.1 % TFA. These hydrophobic laminin-based bioactive peptides with limited solubility in aqueous physiological environment showed significantly enhanced solubility with higher DMSO content in water. The enhanced solubility resulted in extensive intermolecular interactions that led to the formation of hydrogels with a higher-order entangled network along with improved mechanical properties. Interestingly, by simply modulating DMSO content, highly tunable gels were accessed in the same gelator domain that displayed differential physicochemical properties. Further, the cellular studies substantiated the potential of these laminin-derived hydrogels in enhancing cell-matrix interactions, thereby reinforcing their applications in tissue engineering.

Cardiac arrhythmia in individuals with steroid sulfatase deficiency (X-linked ichthyosis): candidate anatomical and biochemical pathways

Circulating steroids, including sex hormones, can affect cardiac development and function. In mammals, steroid sulfatase (STS) is the enzyme solely responsible for cleaving sulfate groups from various steroid molecules, thereby altering their activity and water solubility. Recent studies have indicated that Xp22.31 genetic deletions encompassing STS (associated with the rare dermatological condition X-linked ichthyosis), and common variants within the STS gene, are associated with a markedly elevated risk of cardiac arrhythmias, notably atrial fibrillation/flutter. Here, we consider emerging basic science and clinical findings which implicate structural heart abnormalities (notably septal defects) as a mediator of this heightened risk, and propose candidate cellular and biochemical mechanisms. Finally, we consider how the biological link between STS activity and heart structure/function might be investigated further and the clinical implications of work in this area.

A dispensable role of oligodendrocyte-derived laminin-α5 in brain homeostasis and intracerebral hemorrhage

Laminin, a major component of the basal lamina in the CNS, is also expressed in oligodendrocytes (OLs). However, the function of OL-derived laminin remains largely unknown. Here, we performed loss-of-function studies using two OL-specific laminin-α5 conditional knockout mouse lines. Both mutants were grossly normal and displayed intact blood-brain barrier (BBB) integrity. In a mouse model of intracerebral hemorrhage (ICH), control mice and both mutants exhibited comparable hematoma size and neurological dysfunction. In addition, similar levels of hemoglobin and IgG leakage were detected in the mutant brains compared to the controls, indicating comparable BBB damage. Consistent with this finding, subsequent studies revealed no differences in tight junction protein (TJP) and caveolin-1 expression among control and knockout mice, suggesting that neither paracellular nor transcellular mechanism was affected in the mutants. Furthermore, compared to the controls, both mutant lines showed comparable oligodendrocyte number, oligodendrocyte proliferation rate, MBP/MAG levels, and SMI-32 expression, highlighting a minimal role of OL-derived laminin-α5 in OL biology. Together, these findings highlight a dispensable role of OL-derived laminin-α5 in both brain homeostasis and ICH pathogenesis.

YAP/TAZ-mediated regulation of laminin 332 is enabled by β4 integrin repression of ZEB1 to promote ferroptosis resistance

We are interested in the contribution of integrins and the extracellular matrix to epithelial differentiation in carcinomas. This study was motivated by our finding that the Hippo effectors YAP and TAZ can sustain the expression of laminin 332 (LM332), the predominant ECM ligand for the integrin β4, in breast carcinoma cells with epithelial differentiation. More specifically, we observed that YAP and TAZ regulate the transcription of the LAMC2 subunit of LM332. Given that the β4-LM332 axis is associated with epithelial differentiation and YAP/TAZ have been implicated in carcinoma de-differentiation, we sought to resolve this paradox. Here, we observed that the β4 integrin sustains the expression of miR-200s that target the transcription factor ZEB1 and that ZEB1 has a pivotal role in determining the nature of YAP/TAZ-mediated transcription. In the presence of β4, ZEB1 expression is repressed enabling YAP/TAZ/TEAD-mediated transcription of LAMC2. The absence of β4, however, induces ZEB1, and ZEB1 binds to the LAMC2 promoter to inhibit LAMC2 transcription. YAP/TAZ-mediated regulation of LAMC2 has important functional consequences because we provide evidence that LM332 enables carcinoma cells to resist ferroptosis in concert with the β4 integrin.

Leucine-Rich Repeat in Polycystin-1 Suppresses Cystogenesis in a Zebrafish (Danio rerio) Model of Autosomal-Dominant Polycystic Kidney Disease

Mutations of PKD1 coding for polycystin-1 (PC1) account for most cases of autosomal-dominant polycystic kidney disease (ADPKD). The extracellular region of PC1 contains many evolutionarily conserved domains for ligand interactions. Among these are the leucine-rich repeats (LRRs) in the far N-terminus of PC1. Using zebrafish (Danio rerio) as an in vivo model system, we explored the role of LRRs in the function of PC1. Zebrafish expresses two human PKD1 paralogs, pkd1a and pkd1b. Knockdown of both genes in zebrafish by morpholino antisense oligonucleotides produced phenotypes of dorsal-axis curvature and pronephric cyst formation. We found that overexpression of LRRs suppressed both phenotypes in pkd1-morphant zebrafish. Purified recombinant LRR domain inhibited proliferation of HEK cells in culture and interacted with the heterotrimeric basement membrane protein laminin-511 (α5β1γ1) in vitro. Mutations of amino acid residues in LRRs structurally predicted to bind laminin-511 disrupted LRR-laminin interaction in vitro and neutralized the ability of LRRs to inhibit cell proliferation and cystogenesis. Our data support the hypothesis that the extracellular region of PC1 plays a role in modulating PC1 interaction with the extracellular matrix and contributes to cystogenesis of PC1 deficiency.

Ramipril therapy in integrin α1-null, autosomal recessive Alport mice triples lifespan: mechanistic clues from RNA-seq analysis

The standard of care for patients with Alport syndrome (AS) is angiotensin-converting enzyme (ACE) inhibitors. In autosomal recessive Alport (ARAS) mice, ACE inhibitors double lifespan. We previously showed that deletion of Itga1 in Alport mice [double-knockout (DKO) mice] increased lifespan by 50%. This effect seemed dependent on the prevention of laminin 211-mediated podocyte injury. Here, we treated DKO mice with vehicle or ramipril starting at 4 weeks of age. Proteinuria and glomerular filtration rates were measured at 5-week intervals. Glomeruli were analyzed for laminin 211 deposition in the glomerular basement membrane (GBM) and GBM ultrastructure was analyzed using transmission electron microscopy (TEM). RNA sequencing (RNA-seq) was performed on isolated glomeruli at all time points and the results were compared with cultured podocytes overlaid (or not) with recombinant laminin 211. Glomerular filtration rate declined in ramipril-treated DKO mice between 30 and 35 weeks. Proteinuria followed these same patterns with normalization of foot process architecture in ramipril-treated DKO mice. RNA-seq revealed a decline in the expression of Foxc2, nephrin (Nphs1), and podocin (Nphs2) mRNAs, which was delayed in the ramipril-treated DKO mice. GBM accumulation of laminin 211 was delayed in ramipril-treated DKO mice, likely due to a role for α1β1 integrin in CDC42 activation in Alport mesangial cells, which is required for mesangial filopodial invasion of the subendothelial spaces of the glomerular capillary loops. Ramipril synergized with Itga1 knockout, tripling lifespan compared with untreated ARAS mice. © 2023 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Advanced Glycation End Products Upregulate CD40 in Human Retinal Endothelial and Müller Cells: Relevance to Diabetic Retinopathy

CD40 induces pro-inflammatory responses in endothelial and Müller cells and is required for the development of diabetic retinopathy (DR). CD40 is upregulated in these cells in patients with DR. CD40 upregulation is a central feature of CD40-driven inflammatory disorders. What drives CD40 upregulation in the diabetic retina remains unknown. We examined the role of advanced glycation end products (AGEs) in CD40 upregulation in endothelial cells and Müller cells. Human endothelial cells and Müller cells were incubated with unmodified or methylglyoxal (MGO)-modified fibronectin. CD40 expression was assessed by flow cytometry. The expression of ICAM-1 and CCL2 was examined by flow cytometry or ELISA after stimulation with CD154 (CD40 ligand). The expression of carboxymethyl lysine (CML), fibronectin, and laminin as well as CD40 in endothelial and Müller cells from patients with DR was examined by confocal microscopy. Fibronectin modified by MGO upregulated CD40 in endothelial and Müller cells. CD40 upregulation was functionally relevant. MGO-modified fibronectin enhanced CD154-driven upregulation of ICAM-1 and CCL2 in endothelial and Müller cells. Increased CD40 expression in endothelial and Müller cells from patients with DR was associated with increased CML expression in fibronectin and laminin. These findings identify AGEs as inducers of CD40 upregulation in endothelial and Müller cells and enhancers of CD40-dependent pro-inflammatory responses. CD40 upregulation in these cells is associated with higher CML expression in fibronectin and laminin in patients with DR. This study revealed that CD40 and AGEs, two important drivers of DR, are interconnected.

T-Cell Receptor Sequences Identify Combined Coxsackievirus-Streptococci Infections as Triggers for Autoimmune Myocarditis and Coxsackievirus-Clostridia Infections for Type 1 Diabetes

Recent research suggests that T-cell receptor (TCR) sequences expanded during human immunodeficiency virus and SARS-CoV-2 infections unexpectedly mimic these viruses. The hypothesis tested here is that TCR sequences expanded in patients with type 1 diabetes mellitus (T1DM) and autoimmune myocarditis (AM) mimic the infectious triggers of these diseases. Indeed, TCR sequences mimicking coxsackieviruses, which are implicated as triggers of both diseases, are statistically significantly increased in both T1DM and AM patients. However, TCRs mimicking Clostridia antigens are significantly expanded in T1DM, whereas TCRs mimicking Streptococcal antigens are expanded in AM. Notably, Clostridia antigens mimic T1DM autoantigens, such as insulin and glutamic acid decarboxylase, whereas Streptococcal antigens mimic cardiac autoantigens, such as myosin and laminins. Thus, T1DM may be triggered by combined infections of coxsackieviruses with Clostridia bacteria, while AM may be triggered by coxsackieviruses with Streptococci. These TCR results are consistent with both epidemiological and clinical data and recent experimental studies of cross-reactivities of coxsackievirus, Clostridial, and Streptococcal antibodies with T1DM and AM antigens. These data provide the basis for developing novel animal models of AM and T1DM and may provide a generalizable method for revealing the etiologies of other autoimmune diseases. Theories to explain these results are explored.

The biophysical and compositional properties of human basement membranes

Basement membranes are among the most widespread, non-cellular functional materials in metazoan organisms. Despite this ubiquity, the links between their compositional and biophysical properties are often difficult to establish due to their thin and delicate nature. In this article, we examine these features on a molecular level by combining results from proteomics, elastic, and nanomechanical analyses across a selection of human basement membranes. Comparing results between these different membranes connects certain compositional attributes to distinct nanomechanical signatures and further demonstrates to what extent water defines these properties. In all, these data underline BMs as stiff yet highly elastic connective tissue layers and highlight how the interplay between composition, mechanics and hydration yields such exceptionally adaptable materials.