Loss of connectin novex-3 leads to heart dysfunction associated with impaired cardiomyocyte proliferation and abnormal nuclear mechanics.

Connectin (also known as titin) is a giant striated muscle protein that functions as a molecular spring by providing elasticity to the sarcomere. Novex-3 is a short splice variant of connectin whose physiological function remains unknown. We have recently demonstrated using in vitro analyses that in addition to sarcomere expression, novex-3 was also expressed in cardiomyocyte nuclei exclusively during fetal life, where it provides elasticity/compliance to cardiomyocyte nuclei and promotes cardiomyocyte proliferation in the fetus, suggesting a non-sarcomeric function. Here, we analyzed novex-3 knockout mice to assess the involvement of this function in cardiac pathophysiology in vivo. Deficiency of novex-3 compromised fetal cardiomyocyte proliferation and induced the enlargement of individual cardiomyocytes in neonates. In adults, novex-3 deficiency resulted in chamber dilation and systolic dysfunction, associated with Ca2+ dysregulation, resulting in a reduced life span. Mechanistic analyses revealed a possible association between impaired proliferation and abnormal nuclear mechanics, including stiffer nuclei positioned peripherally with stabilized circumnuclear microtubules in knockout cardiomyocytes. Although the underlying causal relationships were not fully elucidated, these data show that novex-3 has a vital non-sarcomeric function in cardiac pathophysiology and serves as an early contributor to cardiomyocyte proliferation.

Juvenile hormone identification in the cabbage bug Eurydema rugosa.

Juvenile hormone (JH) plays a pivotal role in almost every aspect of insect development and reproduction. The chemical structure of the JH in heteropteran species has long remained elusive until methyl (2R,3S,10R)-2,3;10,11-bisepoxyfarnesoate, commonly named as juvenile hormone III skipped bisepoxide (JHSB3), was isolated from Plautia stali (Hemiptera: Heteroptera: Pentatomidae). Recently, several groups reported the presence of JHSB3 in other heteropteran species. However, most of the studies paid no attention to the determination of the relative and absolute structure of the JH. In this study, we investigated the JH of the cabbage bug Eurydema rugosa (Hemiptera: Heteroptera: Pentatomidae), known as a pest for wild and cultivated crucifers. JHSB3 was detected in the hexane extract from the corpus allatum (CA) product using a chiral ultraperformance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) which can inform the absolute stereochemistry of the JH. Its stereoisomers were not detected. Topical application of the synthetic JHSB3 to the last instar nymphs inhibited their metamorphosis and induced nymphal-type colouration of the dorsal abdomen in a dose-dependent manner. Additionally, the topical application of JHSB3 effectively terminated summer and winter diapauses in females. These results indicate that the JH of E. rugosa is JHSB3. Although individuals in summer and winter diapauses are physiologically distinct in E. rugosa, the results suggest that the physiological differences between these diapauses are based, not on the responsiveness to JH, but on the processes governing activation of the CA or on its upstream cascades.

Postnatal expression of cell cycle promoter Fam64a causes heart dysfunction by inhibiting cardiomyocyte differentiation through repression of Klf15.

Introduction of fetal cell cycle genes into damaged adult hearts has emerged as a promising strategy for stimulating proliferation and regeneration of postmitotic adult cardiomyocytes. We have recently identified Fam64a as a fetal-specific cell cycle promoter in cardiomyocytes. Here, we analyzed transgenic mice maintaining cardiomyocyte-specific postnatal expression of Fam64a when endogenous expression was abolished. Despite an enhancement of cardiomyocyte proliferation, these mice showed impaired cardiomyocyte differentiation during postnatal development, resulting in cardiac dysfunction in later life. Mechanistically, Fam64a inhibited cardiomyocyte differentiation by repressing Klf15, leading to the accumulation of undifferentiated cardiomyocytes. In contrast, introduction of Fam64a in differentiated adult wildtype hearts improved functional recovery upon injury with augmented cell cycle and no dedifferentiation in cardiomyocytes. These data demonstrate that Fam64a inhibits cardiomyocyte differentiation during early development, but does not induce de-differentiation in once differentiated cardiomyocytes, illustrating a promising potential of Fam64a as a cell cycle promoter to attain heart regeneration.

Nuclear connectin novex-3 promotes proliferation of hypoxic foetal cardiomyocytes.

Loss of cardiomyocyte proliferative capacity after birth is a major obstacle for therapeutic heart regeneration in adult mammals. We and others have recently shown the importance of hypoxic in utero environments for active foetal cardiomyocyte proliferation. Here, we report the unexpected expression of novex-3, the short splice variant of the giant sarcomeric protein connectin (titin), in the cardiomyocyte nucleus specifically during the hypoxic foetal stage in mice. This nuclear localisation appeared to be regulated by the N-terminal region of novex-3, which contains the nuclear localisation signal. Importantly, the nuclear expression of novex-3 in hypoxic foetal cardiomyocytes was repressed at the postnatal stage following the onset of breathing and the resulting elevation of oxygen tension, whereas the sarcomeric expression remained unchanged. Novex-3 knockdown in foetal cardiomyocytes repressed cell cycle-promoting genes and proliferation, whereas novex-3 overexpression enhanced proliferation. Mechanical analysis by atomic force microscopy and microneedle-based tensile tests demonstrated that novex-3 expression in hypoxic foetal cardiomyocytes contributes to the elasticity/compliance of the nucleus at interphase and facilitates proliferation, by promoting phosphorylation-induced disassembly of multimer structures of nuclear lamins. We propose that novex-3 has a previously unrecognised role in promoting cardiomyocyte proliferation specifically at the hypoxic foetal stage.

Fam64a is a novel cell cycle promoter of hypoxic fetal cardiomyocytes in mice.

Fetal cardiomyocytes actively proliferate to form the primitive heart in utero in mammals, but they stop dividing shortly after birth. The identification of essential molecules maintaining this active cardiomyocyte proliferation is indispensable for potential adult heart regeneration. A recent study has shown that this proliferation depends on a low fetal oxygen condition before the onset of breathing at birth. We have established an isolation protocol for mouse fetal cardiomyocytes, performed under strict low oxygen conditions to mimic the intrauterine environment, that gives the highest proliferative activities thus far reported. Oxygen exposure during isolation/culture markedly inhibited cell division and repressed cell cycle-promoting genes, and subsequent genome-wide analysis identified Fam64a as a novel regulatory molecule. Fam64a was abundantly expressed in hypoxic fetal cardiomyocyte nuclei, but this expression was drastically repressed by oxygen exposure, and in postnatal cardiomyocytes following the onset of breathing and the resulting elevation of oxygen tension. Fam64a knockdown inhibited and its overexpression enhanced cardiomyocyte proliferation. Expression of a non-degradable Fam64a mutant suggested that optimum Fam64a expression and subsequent degradation by anaphase-promoting complex/cyclosome (APC/C) during the metaphase-to-anaphase transition are required for fetal cardiomyocyte division. We propose that Fam64a is a novel cell cycle promoter of hypoxic fetal cardiomyocytes in mice.

Complete primary structure of the I-band region of connectin at which mechanical property is modulated in zebrafish heart and skeletal muscle.

Connectin, also called titin, is the largest protein with a critical function as a molecular spring during contraction and relaxation of striated muscle; its mutation leads to severe myopathy and cardiomyopathy. To uncover the cause of this pathogenesis, zebrafish have recently been used as disease models because they are easier to genetically modify than mice. Although the gene structures and putative primary structures of zebrafish connectin have been determined, the actual primary structures of zebrafish connectin in heart and skeletal muscles remain unclear because of its large size and the PCR amplification-associated difficulties. In this research, using RT-PCR amplification from zebrafish heart and skeletal muscles, we determined the complete primary structures of zebrafish connectin in the I-band region at which mechanical property is modulated by alternative splicing. Our results showed that the domain structures of zebrafish connectins were largely similar to those of human connectins; however, the splicing pathways in the middle-Ig segment and the PEVK segment were highly diverse in every isoform. We also found that a set of 10 Ig domains in the middle-Ig segment of zebrafish connectin had been triplicated in human connectin. Because these triplicate regions are expressed in human leg and diaphragm, our findings may provide insight into the establishment of walking with limbs and lung respiration during tetrapod evolution.

Cosmetic Cleansing Oil Absorption by Soft Contact Lenses in Dry and Wet Conditions.

OBJECTIVES: Previous reports showed that cosmetic cleansing oil for removing makeup, which contains mineral oil and surfactant, can deform some silicone hydrogel contact lenses (SHCLs) when applied directly to the lenses, although plasma-coated SHCLs (lotrafilcon A and B) were not affected. In the present study, we investigated hydrogel lenses and SHCLs in both wet and dry conditions. METHODS: Several brands of hydrogel and SHCLs were immersed in a cleansing oil solution containing Sudan Black B for 5 min under wet and dry conditions. The lenses under the wet condition were simply picked up from the saline, whereas those under the dry condition were blotted with paper wipes. After immersing, the excess solution remaining on the lenses was removed by finger rubbing with a multipurpose solution. The lenses were then examined using a stereomicroscope, and their mean brightness was measured and compared. RESULTS: The cosmetic cleansing oil was not absorbed by the hydrogel lenses under wet or dry conditions. However, four of seven brands of SHCLs absorbed the cosmetic cleansing oil under both conditions (dry and wet), whereas asmofilcon A absorbed it only under the dry condition. Lotrafilcon B and delefilcon A did not absorb cleansing oil even under the dry condition. CONCLUSIONS: Hydrogel lenses resist cosmetic cleansing oil. However, SHCLs have different degrees of resistance depending on the lens material. Some SHCLs absorbed cosmetic cleansing oil more under dry conditions than under wet conditions.

Regulatory Mechanism of Collagen Degradation by Keratocytes and Corneal Inflammation: The Role of Urokinase-Type Plasminogen Activator.

Keratocytes, corneal resident cells in the corneal stroma, exist between collagen lamellae and maintain the corneal stromal structure. When the corneal stroma is damaged, keratocytes are transformed to myofibroblasts to aid corneal wound healing by phagocytizing debris. Keratocytes and extracellular collagen influence each other because keratocytes cultured in a 3D collagen gel undergo morphological changes and keratocytes produce metalloproteases that degrade extracellular collagen. IL-1 and plasminogen are critical mediators for collagen degradation. The plasminogen system contributes to tissue repair by activating matrix metalloproteinases (MMPs), releasing growth factors from the extracellular matrix and extracellular matrix degradation. Urokinase-type plasminogen activator (uPA) is thought to be involved in corneal disorders and regulates corneal wound healing. uPA is a serine protease synthesized by various cells such as corneal epithelial cells, corneal fibroblasts, vascular endothelial cells, smooth muscle cells, monocytes, macrophages, and malignant tumor cells of different origins. Here, we review the role of uPA in corneal stromal wound healing. uPA is expressed in leukocytes and corneal fibroblasts in the corneas of patients with corneal ulcerations suggesting it is a key regulator of corneal stromal wound healing. uPA is directly involved in plasmin-mediated collagen degradation induced by IL-1. Moreover, uPA is critically involved in promoting leukocyte infiltration in corneal inflammation by activating MMP-9. This activation is presumably directly and indirectly mediated by the plasminogen/plasmin cascade. Moreover, uPA mediates the release of inflammatory cytokines from corneal fibroblasts to promote leukocyte infiltration.

The roles of urokinase-type plasminogen activator in leukocyte infiltration and inflammatory responses in mice corneas treated with lipopolysaccharide.

PURPOSE: Urokinase-type plasminogen activator (u-PA) plays an important role in corneal wound healing, yet its role in corneal inflammation remains poorly understood. We investigated the role of u-PA in a murine model of lipopolysaccharide (LPS)-induced corneal inflammation. METHODS: The corneal epithelium was scraped and LPS was applied to u-PA wild-type (u-PA(+/+)) and u-PA-deficient (u-PA(-/-)) mice. Corneal re-epithelialization and opacity were measured by stereomicroscopy. Fibrin zymography was performed to detect plasminogen activators in corneas from u-PA(+/+) and u-PA(-/-) mice. Neutrophil, macrophage, and u-PA receptor (u-PAR) expression were determined by immunohistochemistry. Gene expression of corneal macrophage chemoattractant protein (MCP)-1 and macrophage inflammatory protein (MIP)-2 was assessed with reverse transcription-polymerase chain reaction. The in vitro effects of endogenous u-PA on MCP-1, MIP-2, matrix metalloproteinase (MMP)-2, and MMP-9 expression, and macrophage migration activity in mouse ocular fibroblasts stimulated by LPS, were examined. RESULTS: The u-PA(+/+) mice showed enhanced corneal inflammation as compared with u-PA(-/-) mice. The u-PA expression was increased by LPS stimulation. Immunohistochemical analyses indicated that more neutrophils and macrophages were present in corneas from u-PA(+/+) mice than u-PA(-/-) mice. The u-PAR expression was detected in inflammatory cells and in the leading edges of the epithelial migrating cells. Enhanced mRNA expression of MCP-1 and MIP-2 was observed in corneas from u-PA(+/+) mice compared to u-PA(-/-) mice. Macrophage chemoattractant protein-1, MIP-2, and MMP-9, but not MMP-2, significantly increased in corneal fibroblasts from u-PA(+/+) mice compared with u-PA(-/-) mice. CONCLUSIONS: These data indicate that u-PA promotes LPS-induced leukocyte infiltration in cornea and that u-PA is an important component in LPS-induced corneal inflammatory responses.

Combined treatment for Coats' disease: retinal laser photocoagulation combined with intravitreal bevacizumab injection was effective in two cases.

BACKGROUND: The exact pathogenetic mechanisms of Coats' disease remain unknown. In this report, we show two cases of Coats' disease that achieved a favorable prognosis with the combined treatment of intravitreal bevacizumab (IVB) injection prior to photocoagulation, although both initially resisted photocoagulation therapy. CASE PRESENTATIONS: Case 1 was a 15-year-old boy with initial visual acuity of 0.4 OD. At the temporal retina, aneurysms and abnormal telangiectatic vessels were observed. Hard exudates and an exudative retinal detachment extended to the fovea. He was diagnosed as having Coats' disease at stage 3A and we performed laser photocoagulation as an initial approach to treat peripheral aneurysms and telangiectatic vessels. After the treatment, the exudative retinal detachment was eased and visual acuity improved to 1.0; however, recurrence occurred after 5 months. The exudative change was resistant against laser photocoagulation therapy and we therefore added IVB as an adjuvant before photocoagulation. Fourteen days after IVB injection phased laser photocoagulation was given to cover the abnormal capillaries, aneurysms and the leakage area spotted in FA. A good prognosis was obtained with decreased exudation and improved visual acuity.Case 2 was an 11-year-old boy with decreased visual acuity of 0.15 OS at the initial visit. Hard exudates, retinal edema and serous retinal detachment were seen at the macula and peripheral retina. Fluorescein angiography revealed telangiectatic capillaries at the temporal retina. Our diagnosis was Coats' disease at stage 3A. Extensive photocoagulation was performed as an initial treatment to the lesion. However, the exudative change was severe and resistant against the photocoagulation treatment. Therefore, we added IVB as an adjuvant before photocoagulation. Exudative change in the retina seemed to be eased 7 days after IVB injection, therefore, phased laser phototherapy was added to cover the abnormal capillaries. After the combination therapy, exudative change was remarkably ameliorated and better visual acuity was achieved. CONCLUSION: Bevacizumab is considered an effective adjuvant for Coats' disease with exudative change resistant to retinal photocoagulation therapy.

TGF-ß2 promotes RPE cell invasion into a collagen gel by mediating urokinase-type plasminogen activator (uPA) expression.

Transforming growth factor-beta (TGF-ß) is one of the main epithelial-mesenchymal transition (EMT)-inducing factors. In general, TGF-ß-induced EMT promotes cell migration and invasion. TGF-ß also acts as a potent regulator of pericellular proteolysis by regulating the expression and secretion of plasminogen activators. Urokinase-type plasminogen activator (uPA) is a serine protease that binds to its cell surface receptor (uPAR) with high affinity. uPA binding to uPAR stimulates uPAR's interaction with transmembrane proteins, such as integrins, to regulate cytoskeletal reorganization and cell migration, differentiation and proliferation. However, the influence of TGF-ß and the uPA/uPAR system on EMT in retinal pigment epithelial (RPE) cells is still unclear. The purpose of this study was to determine the effect of TGF-ß2, which is the predominant isoform in the retina, and the uPA/uPAR system on RPE cells. In this study, we first examined the effect of TGF-ß2 and/or the inhibitor of uPA (u-PA-STOP(®)) on the proliferation of a human retinal pigment epithelial cell line (ARPE-19 cells). Treatment with TGF-ß2 or u-PA-STOP(®) suppressed cell proliferation. Combination treatment of TGF-ß2 and u-PA-STOP(®) enhanced cell growth suppression. Furthermore, western blot analysis, fibrin zymography and real-time reverse transcription PCR showed that that TGF-ß2 induced EMT in ARPE-19 cells and that the expression of uPA and uPAR expression was up-regulated during EMT. The TGF-ß inhibitor SB431542 suppressed TGF-ß2-stimulated uPA expression and secretion but did not suppress uPAR expression. Furthermore, we seeded ARPE-19 cells onto Transwell chambers and allowed them to invade the collagen matrix in the presence of TGF-ß2 alone or with TGF-ß2 and u-PA-STOP(®). TGF-ß2 treatment induced ARPE-19 cell invasion into the collagen gel. Treatment with a combination of TGF-ß2 and the uPA inhibitor strongly inhibited ARPE-19 cell invasion compared with treatment with TGF-ß2 alone. Furthermore, the interaction between uPA and ARPE-19 cells was analyzed using a surface plasmon biosensor system. The binding of uPA to ARPE-19 cells was observed. In addition, TGF-ß2 significantly promoted the binding activity of uPA to ARPE-19 cells in a time-dependent or cell-number-dependent fashion. These results indicate that TGF-ß-induced EMT-associated phenotype changes in ARPE-19 cells and the invasiveness of ARPE-19 cells into a collagen gel matrix are mediated, at least in part, by uPA.

Immunohistochemical localization of urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor and α2-antiplasmin in human corneal perforation: a case report.

BACKGROUND: Corneal ulceration leading to perforation is associated with infectious and non-infectious destructive conditions in the cornea. The fibrinolytic (plasminogen/plasmin) system is considered to contribute to tissue remodeling in the wound healing process and it is believed to play an important role in proteolysis and fibrosis. To determine the localization of urokinase-type plasminogen activator (u-PA), u-PA receptor (u-PAR) and α2-antiplasmin (α2AP) in the tissue of a corneal perforation, we investigated immunohistochemical expressions of u-PA, u-PAR, α2AP, CD68, and α-smooth muscle actin (α-SMA) in a patient with corneal perforation that developed from an ulcer of no clear cause. CASE PRESENTATION: The patient was a 77-year-old woman who presented with a perforated corneal ulcer in her right eye. The cause of her corneal ulcer was unknown. Double immunohistochemistry was performed for the combinations of u-PA with u-PAR, CD68 or α-SMA and α2AP with CD68 or α-SMA to detect the localization of u-PA and α2AP. u-PA and u-PAR co-localization was seen in the corneal ulceration area. u-PA was mainly observed in CD68-positive cells and in some α-SMA positive cells. On the other hand, α2AP was not expressed in CD68-positive cells, but was expressed in α-SMA positive cells. CONCLUSION: We identified expression of the u-PA/u-PAR complex and α2AP in a patient with a corneal ulcer. These two molecules are believed to play a crucial role in inflammatory cell recruitment, ECM synthesis and degradation during corneal wound healing.

Slug is upregulated during wound healing and regulates cellular phenotypes in corneal epithelial cells.

PURPOSE: The involvement of the epithelial mesenchymal transition (EMT) in the process of corneal wound healing remains largely unclear. The purpose of the present study was to gain insight into Slug expression and corneal wound healing. METHODS: Slug expression during wound healing in the murine cornea was evaluated using fluorescence staining in vivo. Slug or Snail was stably introduced into human corneal epithelial cells (HCECs). These stable transfectants were evaluated for the induction of the EMT, cellular growth, migration activity, and expression changes in differentiation-related molecules. RESULTS: Slug, but not Snail, was clearly expressed in the nuclei of corneal epithelial cells in basal lesion of the corneal epithelium during wound healing in vivo. The overexpression of Slug or Snail induced an EMT-like cellular morphology and cadherin switching in HCECs, indicating that these transcription factors were able to mediate the typical EMT in HCECs. The overexpression of Slug or Snail suppressed cellular proliferation but enhanced the migration activity. Furthermore, ABCG2, TP63, and keratin 19, which are known as stemness-related molecules, were downregulated in these transfectants. CONCLUSIONS: It was found that Slug is upregulated during corneal wound healing in vivo. The overexpression of Slug mediated a change in the cellular phenotype affecting proliferation, migration, and expression levels of differentiation-related molecules. This is the first evidence that Slug is regulated during the process of corneal wound healing in the corneal epithelium in vivo, providing a novel insight into the EMT and Slug expression in corneal wound healing.

Intravitreal bevacizumab injection and carotid artery stent replacement for neovascular glaucoma in internal carotid artery occlusion.

Neovascular glaucoma (NVG) secondary to internal carotid artery (ICA) occlusion is usually resistant to treatment. We report a case of NVG with ICA occlusion improved by intravitreal bevacizumab (IVB) injection and carotid artery stent replacement (CAS), even though we did not perform panretinal photocoagulation. A 67-year-old male with NVG noted visual loss in his left eye. Magnetic resonance angiography showed left ICA occlusion. He was diagnosed with NVG secondary to ICA occlusion. The next day, we carried out IVB injection in his left eye, following which the iris and angle neovascularization regressed, and the intraocular pressure decreased to normal within a day after the injection. CAS was performed on his left ICA at a month post injection. Two months later, we reinjected bevacizumab in his left eye. His condition remained stable with no recurrence over two years. This case indicates that IVB injection and CAS are useful for early-stage NVG secondary to ICA occlusion.

Connective tissue growth factor cooperates with fibronectin in enhancing attachment and migration of corneal epithelial cells.

Corneal wound healing is a complex process involving the integrated actions of various growth factors, cytokines and extracellular matrix produced by corneal cells and inflammatory cells. Connective tissue growth factor (CTGF) has been linked to wound healing, and fibronectin (FN) is a major component of the extracellular matrix. However, the functions of CTGF and FN in corneal epithelial cells are not well understood. We therefore investigated the coordinated function of CTGF and FN in the attachment and migration of corneal epithelial cells. Treatment of human corneal epithelial cells (HCECs) with transforming growth factor (TGF) beta1 up-regulated the expression of CTGF, but did not noticeably affect FN expression, as judged by immunoblot analysis of cell lysates. In contrast, the amount of FN accumulated in the cultured media was increased in a time-dependent manner, but CTGF was undetectable in the cultured media. The expression level of FN was decreased by the knockdown of CTGF expression with a specific short hairpin RNA, indicating that CTGF acts as an upstream mediator of FN expression. CTGF augmented the FN-mediated increase in the attachment of HCEC by about twofold, although CTGF alone did not influence the attachment. Moreover, the migration assay with rabbit corneal blocks revealed that CTGF (390 nM) alone or in combination of FN (10 microg/mL) promoted corneal epithelial migration; the mean migration distances of control, CTGF, and CTGF + FN were 272, 325, and 626, microm, respectively. In conclusion, CTGF cooperates with FN in enhancing the attachment and migration of corneal epithelial cells.