scholarly journals The Role of pkc-3 and Genetic Suppressors in Caenorhabditis elegans Epithelial Cell Junction Formation

Genetics ◽  
2020 ◽  
Vol 214 (4) ◽  
pp. 941-959 ◽  
Author(s):  
José G. Montoyo-Rosario ◽  
Stephen T. Armenti ◽  
Yuliya Zilberman ◽  
Jeremy Nance
Keyword(s):  
Caenorhabditis Elegans ◽  
Epithelial Cells ◽  
Matrix Protein ◽  
Extracellular Matrix Protein ◽  
Cell Junction ◽  
Loss Of Function ◽  
Link Type ◽  
Junction Formation ◽  
Extragenic Suppressors

Epithelial cells form intercellular junctions to strengthen cell–cell adhesion and limit diffusion, allowing epithelia to function as dynamic tissues and barriers separating internal and external environments. Junctions form as epithelial cells differentiate; clusters of junction proteins first concentrate apically, then mature into continuous junctional belts that encircle and connect each cell. In mammals and Drosophila, atypical protein kinase C (aPKC) is required for junction maturation, although how it contributes to this process is poorly understood. A role for the Caenorhabditis elegans aPKC homolog PKC-3 in junction formation has not been described previously. Here, we show that PKC-3 is essential for junction maturation as epithelia first differentiate. Using a temperature-sensitive allele of pkc-3 that causes junction breaks in the spermatheca and leads to sterility, we identify intragenic and extragenic suppressors that render pkc-3 mutants fertile. Intragenic suppressors include an unanticipated stop-to-stop mutation in the pkc-3 gene, providing evidence for the importance of stop codon identity in gene activity. One extragenic pkc-3 suppressor is a loss-of-function allele of the lethal(2) giant larvae homolog lgl-1, which antagonizes aPKC within epithelia of Drosophila and mammals, but was not known previously to function in C. elegans epithelia. Finally, two extragenic suppressors are loss-of-function alleles of sups-1—a previously uncharacterized gene. We show that SUPS-1 is an apical extracellular matrix protein expressed in epidermal cells, suggesting that it nonautonomously regulates junction formation in the spermatheca. These findings establish a foundation for dissecting the role of PKC-3 and interacting genes in epithelial junction maturation.

scholarly journals LTBP1 promotes fibrillin incorporation into the extracellular matrix

2021 ◽  
Author(s):  
Matthias Przyklenk ◽  
Veronika Georgieva ◽  
Fabian Metzen ◽  
Sebastian Mostert ◽  
Birgit Kobbe ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Matrix Protein ◽  
Wide Spectrum ◽  
Extracellular Matrix Protein ◽  
Connective Tissues ◽  
Pathogenic Variants ◽  
Human Pathology ◽  
Fibrillin 1

LTBP1 is a large extracellular matrix protein and an associated ligand of fibrillin-microfibrils. Knowledge of LTBP1 functions is largely limited to its role in targeting and sequestering TGFβ growth factors within the extracellular matrix, thereby regulating their bioavailability. However, the recent description of a wide spectrum of phenotypes in multiple tissues in patients harboring LTBP1 pathogenic variants suggests a multifaceted role of the protein in the homeostasis of connective tissues. To better understand the human pathology caused by LTBP1 deficiency it is important to investigate its functional role in extracellular matrix formation. In this study, we show that LTBP1 coordinates the incorporation of fibrillin-1 and -2 into the extracellular matrix in vitro. We also demonstrate that this function is differentially exerted by the two isoforms, the short and long forms of LTBP1. Thereby our findings uncover a novel TGFβ-independent LTBP1 function potentially contributing to the development of connective tissue disorders.

Abstract 474: ERK4-deficiency Potentiates the TAC-induced Increase in Collagen1-α 1 Messenger RNA in Mice

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Joelle Trepanier ◽  
Dharmendra D Dingar ◽  
Marc-Antoine Gillis ◽  
Pramod Sahadevan ◽  
Yan Fen Shi ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Messenger Rna ◽  
Matrix Protein ◽  
Interstitial Fibrosis ◽  
Cardiac Fibroblasts ◽  
Primary Source ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Matrix Protein ◽  
Systolic And Diastolic Function

Cardiac hypertrophy, a common consequence of cardiopathologies such as hypertension and myocardial infarcts, involves formation of excessive interstitial fibrosis, which may impair cardiac function. Fibroblasts are the primary source of extracellular matrix protein. Extracellular-regulated kinase 4 (ERK4) is an atypical mitogen-activated protein kinase (MAPK). The regulation and role of ERK4 in the heart are currently unidentified and its only known target is MAP kinase-activated protein kinase 5 (MK5), a kinase involved in regulating fibroblast function. Following constriction of the transverse aorta (TAC), MK5 haplodeficient mice showed an attenuation of the TAC-induced increase in collagen 1-α 1 mRNA at 2-wk post-TAC and reduced hypertrophy 8-wk post-TAC. Further studies revealed MK5 immunoreactivity in cardiac fibroblasts but not myocytes. MK5 immunoprecipitates from whole heart contain ERK3 immunoreactivity, but not that of ERK4 or p38 MAPK. This study was to examine the role of ERK4 in myocardial structure, function, and remodeling 3-wk post-TAC. At 12 wk of age, echocardiographic imaging revealed systolic and diastolic function in male ERK4 -/- mice were similar to wild-type littermates (ERK4 +/+ ). Three weeks post-TAC, hypertrophy was similar in ERK4 +/+ and ERK4 -/- mice. Transcripts for BNP and βMHC increased to similar extent in TAC- ERK4 +/+ and TAC- ERK4 -/- mice. Two-way ANOVA indicated that ERK4 deficiency altered the effect of TAC on TGFβ 1 and collagen 1-α 1 transcript levels with each being higher in TAC-ERK4 -/- mice. Furthermore, MK5 immunoprecipitates from cardiac fibroblast lysates did not contain ERK4 immunoreactivity. Additional experiments revealed the presence of ERK4 immunoreactivity in myocytes but not fibroblasts. These results suggest 1) ERK4 may be involved in myocyte - fibroblast communication during myocardial remodeling and 2) in cardiac myocytes, ERK4 is part of a novel signaling cascade that does not involve MK5.

Role of mesenchymal nidogen for epithelial morphogenesis in vitro

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 2003-2014 ◽  
Author(s):  
P. Ekblom ◽  
M. Ekblom ◽  
L. Fecker ◽  
G. Klein ◽  
H.Y. Zhang ◽  
...  
Keyword(s):  
Matrix Protein ◽  
Northern Blotting ◽  
Epithelial Morphogenesis ◽  
Extracellular Matrix Protein ◽  
Epithelial Development ◽  
Morphogenesis In Vitro ◽  
Development In Vitro ◽  
Membrane Components

Recent biochemical studies suggested that the extracellular matrix protein nidogen is a binding molecule linking together basement membrane components. We studied its expression and role during development. By immunofluorescence and northern blotting, nidogen was found early during epithelial cell development of kidney and lung. Yet, in situ hybridization revealed that nidogen was not produced by epithelium but by the adjacent mesenchyme in both organs. Binding of mesenchymal nidogen to epithelial laminin may thus be a key event during epithelial development. This is supported by antibody perturbation experiments. Antibodies against the nidogen binding site on laminin B2 chain perturbed epithelial development in vitro in embryonic kidney and lung. Mesenchymal nidogen could be important for early stages of epithelial morphogenesis.

scholarly journals The clinical spectrum of the congenital myasthenic syndrome resulting from COL13A1 mutations

Brain ◽  
2019 ◽  
Vol 142 (6) ◽  
pp. 1547-1560 ◽  
Author(s):  
Pedro M. Rodríguez Cruz ◽  
Judith Cossins ◽  
Eduardo de Paula Estephan ◽  
Francina Munell ◽  
Kathryn Selby ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Matrix Protein ◽  
Neuromuscular Synapse ◽  
Extracellular Matrix Protein ◽  
Congenital Myasthenic Syndrome ◽  
Facial Dysmorphism ◽  
Feeding Difficulties ◽  
Myasthenic Syndrome ◽  
Over Time

Abstract Next generation sequencing techniques were recently used to show mutations in COL13A1 cause synaptic basal lamina-associated congenital myasthenic syndrome type 19. Animal studies showed COL13A1, a synaptic extracellular-matrix protein, is involved in the formation and maintenance of the neuromuscular synapse that appears independent of the Agrin-LRP4-MuSK-DOK7 acetylcholine receptor clustering pathway. Here, we report the phenotypic spectrum of 16 patients from 11 kinships harbouring homozygous or heteroallelic mutations in COL13A1. Clinical presentation was mostly at birth with hypotonia and breathing and feeding difficulties often requiring ventilation and artificial feeding. Respiratory crisis related to recurrent apnoeas, sometimes triggered by chest infections, were common early in life but resolved over time. The predominant pattern of muscle weakness included bilateral ptosis (non-fatigable in adulthood), myopathic facies and marked axial weakness, especially of neck flexion, while limb muscles were less involved. Other features included facial dysmorphism, skeletal abnormalities and mild learning difficulties. All patients tested had results consistent with abnormal neuromuscular transmission. Muscle biopsies were within normal limits or showed non-specific changes. Muscle MRI and serum creatine kinase levels were normal. In keeping with COL13A1 mutations affecting both synaptic structure and presynaptic function, treatment with 3,4-diaminopyridine and salbutamol resulted in motor and respiratory function improvement. In non-treated cases, disease severity and muscle strength improved gradually over time and several adults recovered normal muscle strength in the limbs. In summary, patients with COL13A1 mutations present mostly with severe early-onset myasthenic syndrome with feeding and breathing difficulties. Axial weakness is greater than limb weakness. Disease course improves gradually over time, which could be consistent with the less prominent role of COL13A1 once the neuromuscular junction is mature. This report emphasizes the role of collagens at the human muscle endplate and should facilitate the recognition of this disorder, which can benefit from pharmacological treatment.

Role of the Crumbs complex in the regulation of junction formation in Drosophila and mammalian epithelial cells

2002 ◽  
Vol 94 (6) ◽  
pp. 305-313 ◽  
Author(s):  
Emmanuelle Médina ◽  
Céline Lemmers ◽  
Lydie Lane-Guermonprez ◽  
André Bivic
Keyword(s):  
Epithelial Cells ◽  
Junction Formation ◽  
Crumbs Complex

scholarly journals Role and Molecular Mechanisms of Pericytes in Regulation of Leukocyte Diapedesis in Inflamed Tissues

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Paulina Rudziak ◽  
Christopher G. Ellis ◽  
Paulina M. Kowalewska
Keyword(s):  
Basement Membrane ◽  
Matrix Protein ◽  
Molecular Mechanisms ◽  
Leukocyte Recruitment ◽  
Extracellular Matrix Protein ◽  
Chemotactic Migration ◽  
Blood Vessel Formation ◽  
Vascular Basement Membrane ◽  
Leukocyte Extravasation

Leukocyte recruitment is a hallmark of the inflammatory response. Migrating leukocytes breach the endothelium along with the vascular basement membrane and associated pericytes. While much is known about leukocyte-endothelial cell interactions, the mechanisms and role of pericytes in extravasation are poorly understood and the classical paradigm of leukocyte recruitment in the microvasculature seldom adequately discusses the involvement of pericytes. Emerging evidence shows that pericytes are essential players in the regulation of leukocyte extravasation in addition to their functions in blood vessel formation and blood-brain barrier maintenance. Junctions between venular endothelial cells are closely aligned with extracellular matrix protein low expression regions (LERs) in the basement membrane, which in turn are aligned with gaps between pericytes. This forms preferential paths for leukocyte extravasation. Breaching of the layer formed by pericytes and the basement membrane entails remodelling of LERs, leukocyte-pericyte adhesion, crawling of leukocytes on pericyte processes, and enlargement of gaps between pericytes to form channels for migrating leukocytes. Furthermore, inflamed arteriolar and capillary pericytes induce chemotactic migration of leukocytes that exit postcapillary venules, and through direct pericyte-leukocyte contact, they induce efficient interstitial migration to enhance the immunosurveillance capacity of leukocytes. Given their role as regulators of leukocyte extravasation, proper pericyte function is imperative in inflammatory disease contexts such as diabetic retinopathy and sepsis. This review summarizes research on the molecular mechanisms by which pericytes mediate leukocyte diapedesis in inflamed tissues.

scholarly journals Integrin α5β1, as a Receptor of Fibronectin, Binds the FbaA Protein of Group A Streptococcus To Initiate Autophagy during Infection

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Jiachao Wang ◽  
Meiqi Meng ◽  
Miao Li ◽  
Xiaofei Guan ◽  
Jianguo Liu ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cell Surface ◽  
Matrix Protein ◽  
Beclin 1 ◽  
Extracellular Matrix Protein ◽  
Critical Surface ◽  
Structural Protein ◽  
Integrin Α5β1 ◽  
Potent Inducer ◽  
Group A

ABSTRACT Group A Streptococcus (GAS), one of the most common extracellular pathogens, has been reported to invade epithelial and endothelial cells. Our results reveal that M1 GAS strain SF370 can be effectively eliminated by respiratory epithelial cells. Emerging evidence indicates that autophagy is an important strategy for nonphagocytes to eliminate intracellular bacteria. Upon pathogen recognition, cell surface receptors can directly trigger autophagy, which is a critical step in controlling infection. However, the mechanisms of how cells sense invading bacteria and use this information specifically to trigger autophagy remain unclear. In this study, we stimulated cells and infected mice with M and FbaA mutants of M1 GAS strain SF370 or with purified M and FbaA proteins (two critical surface structural proteins of GAS), and found that only FbaA protein was involved in autophagy induction. Furthermore, the FbaA protein induced autophagy independent of common pattern recognition receptors (such as Toll-like receptors); rather, it relies on binding to integrin α5β1 expressed on the cell surface, which is mediated by extracellular matrix protein fibronectin (Fn). The FbaA-Fn-integrin α5β1 complex activates Beclin-1 through the mTOR-ULK1–Beclin-1 pathway, which enables the Beclin-1/Vps34 complex to recruit Rab7 and, ultimately, to promote the formation of autophagosomes. By knocking down integrin α5β1, Fn, Atg5, Beclin-1, and ULK1 in Hep2 cells and deleting Atg5 or integrin α5β1 in mice, we reveal a novel role for integrin α5β1 in inducing autophagy. Our study demonstrates that integrin α5β1, through interacting with pathogen components, initiates effective host innate immunity against invading intracellular pathogens. IMPORTANCE Autophagy is generally considered a strategy used by the innate immune system to eliminate invasive pathogens through capturing and transferring them to lysosomes. Currently, researchers pay more attention to how virulence factors secreted by GAS regulate the autophagic process. Here, we provide the first evidence that the structural protein FbaA of M1 GAS strain SF370 is a potent inducer of autophagy in epithelial cells. Furthermore, we demonstrate that integrin α5β1 in epithelial cells in vitro and in vivo acts as a receptor to initiate the signaling for inducing autophagy by binding to FbaA of M1 GAS strain SF370 via Fn. Our study reveals the underlying mechanisms by which pathogens induce Fn-integrin α5β1 to trigger autophagy in a conserved pattern in epithelial cells.

Extracellular Matrix Protein Matrilin-4 Regulates HSC Stress Response

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 601-601
Author(s):  
Hannah Uckelmann ◽  
Sandra Blaszkiewicz ◽  
Marieke Essers
Keyword(s):  
Cell Cycle ◽  
Bone Marrow ◽  
Extracellular Matrix ◽  
Matrix Protein ◽  
Bone Marrow Cells ◽  
Blood System ◽  
Extracellular Matrix Protein

Abstract The life-long maintenance of the blood system is accomplished by a pool of self-renewing multipotent hematopoietic stem cells (HSCs). Adult HSCs are found in a dormant state for most of their lifetime, entering cell cycle only to maintain homeostatic blood supply. Under stress conditions such as infection or chemotherapy, the loss of mature blood cells leads to an activation of dormant HSCs to replenish the blood system. Gene expression analysis performed by our group now revealed that Matrilin-4 is highly expressed in long-term HSCs (LT-HSCs) compared to short-term HSCs or committed progenitors, suggesting a potential role of Matrilin-4 in HSC function. Matrilin-4 is a member of the von Willebrand factor A-containing family of extracellular adapter proteins, which form filamentous structures outside of cells. Using mice lacking the entire family of Matrilins (1-4) we have investigated the role of Matrilins in HSC function. Constitutive Matrilin 1-4 KO mice exhibit normal hematopoiesis with a mild reduction in bone marrow cellularity and LSK numbers. However, when Matrilin KO bone marrow cells are pushed to proliferate in competitive transplantation assays with wildtype (WT) cells, they show a striking growth advantage. In a competitive transplant setting, where bone marrow cells of Matrilin KO versus WT mice are transplanted in a 1:1 ratio, the KO cells outcompete WT cells within four weeks, reaching a 90% chimerism at 16 weeks. This competitive advantage of Matrilin KO cells is evident in the long-term stem cell level as well as progenitors and is consistent in secondary transplants. To explore this remarkable phenotype, we performed single cell transplantation experiments of LT-HSCs and observed a more rapid reconstitution of peripheral blood cell levels of KO HSCs compared to WT controls. Confirming this growth advantage, Matrilin KO LSK cells show higher colony forming and serial replating potential in vitro, which can be rescued by the addition of recombinant or overexpressed Matrilin-4. While Matrilin-4 is highly expressed in homeostatic HSCs, in vivo treatment with IFNα or other inflammatory agents, such as LPS or G-CSF result in a dramatic downregulation (25-fold) of Matrilin-4 on the transcript as well as the protein level. Moreover, Matrilin KO HSCs are more sensitive to inflammatory stress, as they show a 2-fold stronger cell cycle activation in response to IFNα in vivo. Critically, Matrilin-4 KO HSCs return to the G0 state of the cell cycle normally after stress-induced activation and transplantation, thereby preventing their exhaustion. In summary, we show that the extracellular matrix protein Matrilin-4 is a novel component of the HSC niche, regulating HSC stress response. Surprisingly, HSCs lacking this extracellular matrix protein show a higher HSC potential due to an accelerated response to stress. Our data suggest that high expression of Matrilin-4 in LT-HSCs confers a resistance to stress stimuli. In situations of acute stress such as infection or transplantation however, this protection is rapidly lost to allow HSCs to efficiently replenish the blood system. Disclosures No relevant conflicts of interest to declare.

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