scholarly journals Suppression of connexin 43 phosphorylation promotes astrocyte survival and vascular regeneration in proliferative retinopathy

2018 ◽  
Vol 115 (26) ◽  
pp. E5934-E5943 ◽  
Author(s):  
Nefeli Slavi ◽  
Abduqodir H. Toychiev ◽  
Stylianos Kosmidis ◽  
Jessica Ackert ◽  
Stewart A. Bloomfield ◽  
...  
Keyword(s):  
Connexin 43 ◽  
Transmembrane Protein ◽  
Critical Role ◽  
Oxygen Induced Retinopathy ◽  
Retinal Astrocytes ◽  
Conditional Deletion ◽  
Vascular Regeneration ◽  
Molecular Events ◽  
Proliferative Retinopathies

Degeneration of retinal astrocytes precedes hypoxia-driven pathologic neovascularization and vascular leakage in ischemic retinopathies. However, the molecular events that underlie astrocyte loss remain unclear. Astrocytes abundantly express connexin 43 (Cx43), a transmembrane protein that forms gap junction (GJ) channels and hemichannels. Cx channels can transfer toxic signals from dying cells to healthy neighbors under pathologic conditions. Here we show that Cx43 plays a critical role in astrocyte apoptosis and the resulting preretinal neovascularization in a mouse model of oxygen-induced retinopathy. Opening of Cx43 hemichannels was not observed following hypoxia. In contrast, GJ coupling between astrocytes increased, which could lead to amplification of injury. Accordingly, conditional deletion of Cx43 maintained a higher density of astrocytes in the hypoxic retina. We also identify a role for Cx43 phosphorylation in mediating these processes. Increased coupling in response to hypoxia is due to phosphorylation of Cx43 by casein kinase 1δ (CK1δ). Suppression of this phosphorylation using an inhibitor of CK1δ or in site-specific phosphorylation-deficient mice similarly protected astrocytes from hypoxic damage. Rescue of astrocytes led to restoration of a functional retinal vasculature and lowered the hypoxic burden, thereby curtailing neovascularization and neuroretinal dysfunction. We also find that absence of astrocytic Cx43 does not affect developmental angiogenesis or neuronal function in normoxic retinas. Our in vivo work directly links phosphorylation of Cx43 to astrocytic coupling and apoptosis and ultimately to vascular regeneration in retinal ischemia. This study reveals that targeting Cx43 phosphorylation in astrocytes is a potential direction for the treatment of proliferative retinopathies.

scholarly journals Integrin-α7 signaling regulates connexin 43, M-cadherin, and myoblast fusion

2019 ◽  
Vol 316 (6) ◽  
pp. C876-C887 ◽  
Author(s):  
Michael J. McClure ◽  
Allison N. Ramey ◽  
Mashaba Rashid ◽  
Barbara D. Boyan ◽  
Zvi Schwartz
Keyword(s):  
Connexin 43 ◽  
Ex Vivo ◽  
Myogenic Differentiation ◽  
Transmembrane Protein ◽  
Critical Role ◽  
Cell Communication ◽  
Myoblast Fusion ◽  
Functional Improvement ◽  
Muscle Injuries

Regenerative medicine treatments for severe skeletal muscle injuries are limited, resulting in persistent functional deficits. Clinical options include neglecting the wound with the expectation that fibrosis will develop or using an autologous muscle graft with minimal functional improvement. A regenerative matrix can be used, but muscle fiber development on these matrices remains a challenge in vivo. Here, we explored the fundamental mechanisms that mediate cell-substrate signaling and its effect on cell-cell communication during myoblast fusion and tube formation to improve outcomes following implantation of matrices used to stimulate muscle regeneration. We previously reported that integrin-α7 was increased on anisotropic biomaterials, suggesting a role for α7β1 signaling in myoblast communication via connexin 43 and M-cadherin. Our results demonstrated that α7 silencing blocked expression of myogenic differentiation factor 1 (Myod), myogenin (Myog), myogenic factor 6 (Myf6), myosin heavy chain type 1 (Myh1), and transmembrane protein 8c (Tmem8c), indicating that myoblast fusion was inhibited. Expression of α5 and M-cadherin decreased but β1 and connexin 43 increased. We examined protein production and observed reduced extracellular-signal regulated kinase 1/2 (ERK) in α7-silenced cells that correlated with upregulation of connexin 43 and M-cadherin, suggesting a compensatory pathway. These results indicate that α7 signaling plays a critical role in ex vivo fusion and implicates a relationship with connexin 43 and M-cadherin.

scholarly journals ADAM9 Is Involved in Pathological Retinal Neovascularization

2009 ◽  
Vol 29 (10) ◽  
pp. 2694-2703 ◽  
Author(s):  
Victor Guaiquil ◽  
Steven Swendeman ◽  
Tsunehiko Yoshida ◽  
Sai Chavala ◽  
Peter A. Campochiaro ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Critical Role ◽  
Age Related Macular Degeneration ◽  
Ectodomain Shedding ◽  
Ocular Neovascularization ◽  
Oxygen Induced Retinopathy ◽  
Age Related ◽  
Enhanced Expression ◽  
Underlying Causes ◽  
Proliferative Retinopathies

ABSTRACT Pathological ocular neovascularization, caused by diabetic retinopathy, age-related macular degeneration, or retinopathy of prematurity, is a leading cause of blindness, yet much remains to be learned about its underlying causes. Here we used oxygen-induced retinopathy (OIR) and laser-induced choroidal neovascularization (CNV) to assess the contribution of the metalloprotease-disintegrin ADAM9 to ocular neovascularization in mice. Pathological neovascularization in both the OIR and CNV models was significantly reduced in Adam9 − / − mice compared to wild-type controls. In addition, the level of ADAM9 expression was strongly increased in endothelial cells in pathological vascular tufts in the OIR model. Moreover, tumor growth from heterotopically injected B16F0 melanoma cells was reduced in Adam9 − / − mice compared to controls. In cell-based assays, the overexpression of ADAM9 enhanced the ectodomain shedding of EphB4, Tie-2, Flk-1, CD40, VCAM, and VE-cadherin, so the enhanced expression of ADAM9 could potentially affect pathological neovascularization by increasing the shedding of these and other membrane proteins from endothelial cells. Finally, we provide the first evidence for the upregulation of ADAM9-dependent shedding by reactive oxygen species, which in turn are known to play a critical role in OIR. Collectively, these results suggest that ADAM9 could be an attractive target for the prevention of proliferative retinopathies, CNV, and cancer.

scholarly journals The conditional deletion of steroidogenic factor 1 (Nr5a1) in Sox9-Cre mice compromises testis differentiation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yayoi Ikeda ◽  
Ayako Tagami ◽  
Mamiko Maekawa ◽  
Akiko Nagai
Keyword(s):  
Sertoli Cells ◽  
Sex Differentiation ◽  
Critical Role ◽  
Gonadal Development ◽  
Conditional Knockout ◽  
Double Immunostaining ◽  
Steroidogenic Factor 1 ◽  
Conditional Deletion ◽  
Male To Female

AbstractSteroidogenic factor 1 (NR5A1) is essential for gonadal development. To study the importance of NR5A1 during early gonadal sex differentiation, we generated Sox9-Cre-Nr5a1 conditional knockout (cKO) mice: Sox9-Cre;Nr5a1flox/flox and Sox9-Cre;Nr5a1flox/− mice. Double-immunostaining for NR5A1 and AMH revealed silenced NR5A1 in Sertoli cells and reduced AMH+ cells in the gonads of XY Sox9-Cre-Nr5a1 cKO mice between embryonic days 12.5 (E12.5) and E14.5. Double-immunostaining for SOX9 and FOXL2 further indicated an early block in Sertoli cells and ectopic granulosa cell differentiation. The number of cells expressing the Leydig cell marker 3βHSD obviously reduced in the gonads of XY Sox9-Cre;Nr5a1flox/− but not Sox9-Cre;Nr5a1flox/flox mice at E15.5. The presence of STRA8+ cells indicated that germ cells entered meiosis in the gonads of XY Sox9-Cre-Nr5a1 cKO mice. The results of qRT-PCR revealed remarkably reduced and elevated levels of testis and ovary markers, respectively, in the gonads of XY Sox9-Cre-Nr5a1 cKO mice at E12.5‒E13.5. These data suggested that the loss of Nr5a1 abrogates the testicular pathway and induces the ectopic ovarian pathway, resulting in postnatal partial/complete male-to-female gonadal sex reversal. Our findings provide evidence for the critical role of NR5A1 in murine gonadal sex determination in vivo.

scholarly journals Clarin-1 acts as a modulator of mechanotransduction activity and presynaptic ribbon assembly

2014 ◽  
Vol 207 (3) ◽  
pp. 375-391 ◽  
Author(s):  
Oluwatobi Ogun ◽  
Marisa Zallocchi
Keyword(s):  
Hair Cells ◽  
Vision Loss ◽  
Late Onset ◽  
Transmembrane Protein ◽  
Usher Syndrome ◽  
Critical Role ◽  
Synapse Maturation ◽  
And Function ◽  
Type 3

Clarin-1 is a four-transmembrane protein expressed by hair cells and photoreceptors. Mutations in its corresponding gene are associated with Usher syndrome type 3, characterized by late-onset and progressive hearing and vision loss in humans. Mice carrying mutations in the clarin-1 gene have hair bundle dysmorphology and a delay in synapse maturation. In this paper, we examined the expression and function of clarin-1 in zebrafish hair cells. We observed protein expression as early as 1 d postfertilization. Knockdown of clarin-1 resulted in inhibition of FM1-43 incorporation, shortening of the kinocilia, and mislocalization of ribeye b clusters. These phenotypes were fully prevented by co-injection with clarin-1 transcript, requiring its C-terminal tail. We also observed an in vivo interaction between clarin-1 and Pcdh15a. Altogether, our results suggest that clarin-1 is functionally important for mechanotransduction channel activity and for proper localization of synaptic components, establishing a critical role for clarin-1 at the apical and basal poles of hair cells.

scholarly journals VPS35 Protects Against TMEM230-Mutation-Induced Progressive Locomotor Deficits in Drosophila

2021 ◽  
Author(s):  
Chao Ma ◽  
Xiaobo Wang ◽  
Wanli W Smith ◽  
Zhaohui Liu
Keyword(s):  
Protein Trafficking ◽  
Molecular Mechanisms ◽  
Caspase 3 ◽  
Transmembrane Protein ◽  
Critical Role ◽  
In Vivo Studies ◽  
Wild Type ◽  
Dopaminergic Neurodegeneration ◽  
Locomotor Deficits

Abstract BackgroundRecently, four Parkinson’s disease (PD)-linked mutations (Y92C, R141L, 184PGext*5 and 184Wext*5) in transmembrane protein 230 (TMEM230) were identified in PD patients, and these mutations have implications in protein trafficking and neurodegeneration. However, there is a lack of in vivo studies on the roles of PD-related variants of TMEM230 in PD pathogenesis.MethodsIn this study, we generated human wild-type (WT) and mutant TMEM230 (Y92C, R141L, 184PGext*5 and 184Wext*5) transgenic Drosophila using isoform Ⅱ cDNA. ResultsWe found that the expression of TMEM230 184PGext*5 in pan-neurons or dopaminergic neurons in Drosophila induced PD-like phenotypes, which included impaired locomotor ability, a shortened lifespan, reduced TH levels, and increased phosphorylated JNK and cleaved caspase-3 levels. Moreover, rotenone, a common pesticide, enhanced TMEM230-184PGext*5-induced PD-like phenotypes. In contrast, the overexpression of wild-type (WT) VPS35 rescued TMEM230-184PGext*5-induced PD-like phenotypes, while the knockdown of VPS35 by RNA interference (RNAi) or the expression of mutant VPS35 D620N worsened PD-like phenotypes. ConclusionThese results indicate that VPS35, as a downstream effector of TMEM230, plays a critical role in TMEM230-linked JNK/caspase-3 signalling pathways and that mutations in TMEM230 and VPS35 disrupt these pathways, resulting in dopaminergic neurodegeneration and PD-like phenotypes. These findings provide novel insight into the molecular mechanisms of mutant TME230- and VPS35-induced abnormalities underlying the pathogenesis of PD.

scholarly journals Natriuretic Peptides Attenuate Retinal Pathological Neovascularization Via Cyclic Guanosine Monophosphate Signaling in Pericytes and Astrocytes

2020 ◽  
Vol 40 (1) ◽  
pp. 159-174 ◽  
Author(s):  
Katarina Špiranec Spes ◽  
Sabrina Hupp ◽  
Franziska Werner ◽  
Franziska Koch ◽  
Katharina Völker ◽  
...  
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Vascular Development ◽  
Cyclic Guanosine Monophosphate ◽  
Guanosine Monophosphate ◽  
Oxygen Induced Retinopathy ◽  
Proliferative Retinopathies

Objective: In proliferative retinopathies, complications derived from neovascularization cause blindness. During early disease, pericyte’s apoptosis contributes to endothelial dysfunction and leakage. Hypoxia then drives VEGF (vascular endothelial growth factor) secretion and pathological neoangiogenesis. Cardiac ANP (atrial natriuretic peptide) contributes to systemic microcirculatory homeostasis. ANP is also formed in the retina, with unclear functions. Here, we characterized whether endogenously formed ANP regulates retinal (neo)angiogenesis. Approach and Results: Retinal vascular development and ischemia-driven neovascularization were studied in mice with global deletion of GC-A (guanylyl cyclase-A), the cGMP (cyclic guanosine monophosphate)-forming ANP receptor. Mice with a floxed GC-A gene were interbred with Tie2-Cre, GFAP-Cre, or PDGF-Rβ-Cre ERT2 lines to dissect the endothelial, astrocyte versus pericyte-mediated actions of ANP in vivo. In neonates with global GC-A deletion (KO), vascular development was mildly delayed. Moreover, such KO mice showed augmented vascular regression and exacerbated ischemia-driven neovascularization in the model of oxygen-induced retinopathy. Notably, absence of GC-A in endothelial cells did not impact retinal vascular development or pathological neovascularization. In vitro ANP/GC-A/cGMP signaling, via activation of cGMP-dependent protein kinase I, inhibited hypoxia-driven astrocyte’s VEGF secretion and TGF-β (transforming growth factor beta)–induced pericyte apoptosis. In neonates lacking ANP/GC-A signaling in astrocytes, vascular development and hyperoxia-driven vascular regression were unaltered; ischemia-induced neovascularization was modestly increased. Remarkably, inactivation of GC-A in pericytes retarded physiological retinal vascularization and markedly enhanced cell apoptosis, vascular regression, and subsequent neovascularization in oxygen-induced retinopathy. Conclusions: Protective pericyte effects of the ANP/GC-A/cGMP pathway counterregulate the initiation and progression of experimental proliferative retinopathy. Our observations indicate augmentation of endogenous pericyte ANP signaling as target for treatment of retinopathies associated with neovascularization.

scholarly journals A Microtiter Assay for Quantifying Protein-Protein Interactions Associated with Cell-Cell Adhesion

2007 ◽  
Vol 12 (5) ◽  
pp. 683-693 ◽  
Author(s):  
Nicholas A. Graham ◽  
Melissa D. Pope ◽  
Tharathorn Rimchala ◽  
Beijing K. Huang ◽  
Anand R. Asthagiri
Keyword(s):  
Protein Complex ◽  
Crucial Role ◽  
Cell Biology ◽  
Transmembrane Protein ◽  
Critical Role ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dramatic Improvement ◽  
E Cadherin ◽  
Cell Cell

Cell-cell adhesions are a hallmark of epithelial tissues, and the disruption of these contacts plays a critical role in both the early and late stages of oncogenesis. The interaction between the transmembrane protein E-cadherin and the intracellular protein β-catenin plays a crucial role in the formation and maintenance of epithelial cell-cell contacts and is known to be downregulated in many cancers. The authors have developed a protein complex enzyme-linked immunosorbent assay (ELISA) that can quantify the amount of β-catenin bound to E-cadherin in unpurified whole-cell lysates with a Z′ factor of 0.74. The quantitative nature of the E-cadherin:β-catenin ELISA represents a dramatic improvement over the low-throughput assays currently used to characterize endogenous E-cadherin:β-catenin complexes. In addition, the protein complex ELISA format is compatible with standard sandwich ELISAs for parallel measurements of total levels of endogenous E-cadherin and β-catenin. In 2 case studies closely related to cancer cell biology, the authors use the protein complex ELISA and traditional sandwich ELISAs to provide a detailed, quantitative picture of the molecular changes occurring within adherens junctions in vivo. Because the E-cadherin: β-catenin protein complex plays a crucial role in oncogenesis, this protein complex ELISA may prove to be a valuable quantitative prognostic marker of tumor progression. ( Journal of Biomolecular Screening 2007:683-693)

The Natural Flavonoid Naringenin Inhibits the Cell Growth of WilmsTumorinChildren by Suppressing TLR4/NF-κB Signaling

2020 ◽  
Vol 20 ◽  
Author(s):  
Hongtao Li ◽  
Peng Chen ◽  
Lei Chen ◽  
Xinning Wang
Keyword(s):  
Cell Growth ◽  
Western Blot ◽  
Wilms Tumor ◽  
Critical Role ◽  
Time Dependent ◽  
Luciferase Assay ◽  
Dependent Manner ◽  
Tlr4 Expression ◽  
Protein Levels

Background: Nuclear factor kappa B (NF-κB) is usually activated in Wilms tumor (WT) cells and plays a critical role in WT development. Objective: The study purpose was to screen a NF-κB inhibitor from natural product library and explore its effects on WT development. Methods: Luciferase assay was employed to assess the effects of natural chemical son NF-κB activity. CCK-8 assay was conducted to assess cell growth in response to naringenin. WT xenograft model was established to analyze the effect of naringenin in vivo. Quantitative real-time PCR and Western blot were performed to examine the mRNA and protein levels of relative genes, respectively. Results: Naringenin displayed significant inhibitory effect on NF-κB activation in SK-NEP-1 cells. In SK-NEP-1 and G-401 cells, naringenin inhibited p65 phosphorylation. Moreover, naringenin suppressed TNF-α-induced p65 phosphorylation in WT cells. Naringenin inhibited TLR4 expression at both mRNA and protein levels in WT cells. CCK-8 staining showed that naringenin inhibited cell growth of the two above WT cells in dose-and time-dependent manner, whereas Toll-like receptor 4 (TLR4) over expression partially reversed the above phenomena. Besides, naringenin suppressed WT tumor growth in dose-and time-dependent manner in vivo. Western blot found that naringenin inhibited TLR4 expression and p65 phosphorylation in WT xenograft tumors. Conclusion: Naringenin inhibits WT development viasuppressing TLR4/NF-κB signaling

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