The liver injury following ischemia and reperfusion is worse in experimental knockout heterozygote mouse model for expression of connexin 43

Purpose:To evaluate that Connexin (Cx43) plays a role in lesions after hepatic ischemia/reperfusion (IR) injury.Methods:We use Cx43 deficient model (heterozygotes mice) and compared to a wild group. The groups underwent 1 hour ischemia and 24 hours reperfusion. The heterozygote genotype was confirmed by PCR. We analyzed the hepatic enzymes (AST, ALT, GGT) and histology.Results:The mice with Cx43 deficiency showed an ALT mean value of 4166 vs. 307 in the control group (p<0.001); AST mean value of 7231 vs. 471 in the control group (p<0.001); GGT mean value of 9.4 vs. 1.7 in the control group (p=0.001); histology showed necrosis and inflammation in the knockout group.Conclusions:This research demonstrated that the deficiency of Cx43 worses the prognosis for liver injury. The topic is a promising target for therapeutics advancements in liver diseases and procedures.(AU)

Large-scale chromatin structure and function changes during oogenesis: theinterplay between oocyte and companioncumulus cell

The process of chromatin configuration remodeling within the mammalian oocyte nucleus or germinal vesicle (GV), which occurs towards the end of its differentiation phase before meiotic resumption, has received much attention and has been studied in several mammals. This review is aimed to highlight the relationship between changes in chromatin configurations and to both functional and structural modifications occurring in the oocyte nuclear compartment. During the extensive phase of meiotic arrest at the diplotene stage, the chromatin enclosed within the GV is subjected to several levels of regulation. Morphologically, the chromosomes lose their individuality and form a loose chromatin mass. Then the decondensed chromatin undergoes profound rearrangements during the final stages of oocyte growth in tight association with the acquisition of meiotic and developmental competence. Functionally, the discrete stages of chromatin condensation are characterized by different level of transcriptional activity, DNA methylation and covalent histone modifications. Interestingly, the program of chromatin rearrangement is not completely intrinsic to the oocyte, but follicular cells exert their regulatory actions through gap junction mediated communications and intracellular messenger dependent mechanism(s). With this in mind and since oocyte growth mostly relies on the bidirectional crosstalk with the follicular cells, experimental manipulation of large-scale chromatin configuration is discussed. Besides providing tools to determine the key cellular pathways involved in genome-wide chromatin modifications , the present findings will aid to the refinement of physiological culture systems that can have important implications in treating human infertility as well as managing breeding schemes in animal husband .

Large-scale chromatin structure and function changes during oogenesis: theinterplay between oocyte and companioncumulus cell

The process of chromatin configuration remodeling within the mammalian oocyte nucleus or germinal vesicle (GV), which occurs towards the end of its differentiation phase before meiotic resumption, has received much attention and has been studied in several mammals. This review is aimed to highlight the relationship between changes in chromatin configurations and to both functional and structural modifications occurring in the oocyte nuclear compartment. During the extensive phase of meiotic arrest at the diplotene stage, the chromatin enclosed within the GV is subjected to several levels of regulation. Morphologically, the chromosomes lose their individuality and form a loose chromatin mass. Then the decondensed chromatin undergoes profound rearrangements during the final stages of oocyte growth in tight association with the acquisition of meiotic and developmental competence. Functionally, the discrete stages of chromatin condensation are characterized by different level of transcriptional activity, DNA methylation and covalent histone modifications. Interestingly, the program of chromatin rearrangement is not completely intrinsic to the oocyte, but follicular cells exert their regulatory actions through gap junction mediated communications and intracellular messenger dependent mechanism(s). With this in mind and since oocyte growth mostly relies on the bidirectional crosstalk with the follicular cells, experimental manipulation of large-scale chromatin configuration is discussed. Besides providing tools to determine the key cellular pathways involved in genome-wide chromatin modifications , the present findings will aid to the refinement of physiological culture systems that can have important implications in treating human infertility as well as managing breeding schemes in animal husband .(AU)

Avaliação imuno-histoquímica da conexina 43 no carcinoma mamário em felinos

As junções do tipo GAP, formadas por proteínas denominadas conexinas (Cx), são junções comunicantes responsáveis pelo fluxo intercelular de moléculas e íons, desempenhando importante funções no controle da homeostasia tecidual. Ainda, participam no controle da proliferação celular, apoptose e de diversos mecanismos envolvidos na carcinogênese em diferentes tecidos. Nas neoplasias mamárias em humanos e cães, a Cx43 apresenta funções contraditórias, dependendo da fase do desenvolvimento tumoral. Considerando a importância da Cx43 nos processos de carcinogênese e os dados contraditórios sobre sua expressão em tumores mamários, este trabalho teve como principal objetivo avaliar a imunoexpressão da Cx43 nos carcinomas mamários em felinos, correlacionando-a com os dados clínico-patológicos e de sobrevida destes animais. Neste estudo, foram incluídas amostras tumorais de 23 gatas diagnosticadas com carcinomas mamários, as quais foram submetidas a análises histopatológicas e imuno-histoquímicas para detecção de marcadores moleculares e imunoexpressão da Cx43. Os parâmetros clinico-patológicos foram correlacionados com a sobrevida pelo teste de Log-rank (P<0,05). A presença de metástase à distância e a realização de mastectomia unilateral correlacionaram-se a uma menor sobrevida nestes animais. A maioria dos carcinomas mamários (78,3%) apresentou baixa imunoexpressão da Cx43, porém sem correlação com a sobrevida. Os tumores com maior graduação histológica, assim com os subtipos histológicos e moleculares mais agressivos, apresentaram maior expressão da Cx43 quando comparados aos demais subtipos. Estes dados indicam uma correlação da Cx43 com o grau de malignidade tumoral, sugerindo sua participação na progressão dos carcinomas mamários em felinos.

The GAP junctions, are formed by proteins called connexins (Cx), are communicating junctions responsible for the intercellular flow of molecules and ions, performing important functions in the control of tissue homeostasis. They also participate in the control of cell proliferation, apoptosis and various mechanisms involved in carcinogenesis in different tissues. In human and dog mammary neoplasms, Cx43 has contradictory functions, depending on the stage of tumor development. Considering the importance of Cx43 in carcinogenesis processes and contradictory data on its expression in mammary tumors, this study aimed to evaluate the immunoexpression of Cx43 in feline mammary carcinomas, correlating it with clinical and pathological survival data. animals. In this study, tumor samples from 23 cats diagnosed with mammary carcinomas were included and submitted to histopathological and immunohistochemical analyzes to detect molecular markers and immunoexpression of Cx43. Clinical-pathological parameters were correlated with survival by the Log-rank test (P <0.05). The presence of distant metastasis and unilateral mastectomy were correlated with lower survival in these animals. Most breast carcinomas (78.3%) presented low immunoexpression of Cx43, but without correlation with survival. The tumors with higher histological grading, as well as the more aggressive histological and molecular subtypes, presented higher expression of Cx43 when compared to the other subtypes. These data indicate a correlation of Cx43 with the degree of tumor malignancy, suggesting its participation in the progression of feline mammary carcinomas.

Expression of Connexins 43, 26 and 32 in normal, hyperplastic and neoplastic perianal dog glands

Connexin (Cx) expression is reportedly altered in neoplasms. This study aimed to investigate the expression of Cx43, 26 and 32 in normal and pathological canine perianal glands. Thirty perianal glands bearing pathological processes and ten normal canine perianal glands were submitted to immunohistochemistry to search for presence of Cx43, Cx26 and Cx32. Both Cx43 and Cx26 expressions were observed in normal, hyperplastic glands, and in well and moderately differentiated adenomas. However, in poorly differentiated adenomas, expressions were reduced, and they were absent in carcinomas. Cx26 was located in the cytoplasm of normal, hyperplastic perianal gland cells, and in well and moderately differentiated adenomas. Cx32 was not observed in any neoplasm neither in normal or hyperplastic glands. Our results show that Cx43 and Cx26 expressions are altered in more aggressive canine perianal gland neoplasms, and we conclude that they may be related to the perianal gland carcinogenesis process

Expression of Connexins 43, 26 and 32 in normal, hyperplastic and neoplastic perianal dog glands

Connexin (Cx) expression is reportedly altered in neoplasms. This study aimed to investigate the expression of Cx43, 26 and 32 in normal and pathological canine perianal glands. Thirty perianal glands bearing pathological processes and ten normal canine perianal glands were submitted to immunohistochemistry to search for presence of Cx43, Cx26 and Cx32. Both Cx43 and Cx26 expressions were observed in normal, hyperplastic glands, and in well and moderately differentiated adenomas. However, in poorly differentiated adenomas, expressions were reduced, and they were absent in carcinomas. Cx26 was located in the cytoplasm of normal, hyperplastic perianal gland cells, and in well and moderately differentiated adenomas. Cx32 was not observed in any neoplasm neither in normal or hyperplastic glands. Our results show that Cx43 and Cx26 expressions are altered in more aggressive canine perianal gland neoplasms, and we conclude that they may be related to the perianal gland carcinogenesis process (AU)

EXPRESSÃO DAS CONEXINAS 37 E 43 EM FOLÍCULOS OVARIANOS OVINOS, FRESCOS, VITRIFICADOS OU CULTIVADOS IN VITRO

Alguns estudos têm mostrado que crioinjúrias observadas durante a vitrificação levam à perda da integridade de proteínas membranárias que constituem as comunicações intercelulares. Dentre as proteínas de membranas que formam essas comunicações, destacam-se as conexinas 37 (Cx37) e 43 (Cx43), as quais são importantes na interação entre oócito e células foliculares. Este estudo teve como principal objetivo avaliar o efeito da vitrificação do tecido ovariano ovino utilizando o ovarian tissue cryosystem (OTC), associado ao cultivo in vitro de folículos secundários isolados, sobre o padrão de expressão gênica e protéica das Cx37 e Cx43. Para isso, seis diferentes tratamentos foram avaliados: 1) tecido ovariano fresco (FOT); 2) tecido ovariano vitrificado (VOT); 3) folículos secundários frescos isolados de tecido ovariano fresco (FIF); 4) folículos secundários cultivados in vitro, isolados do tecido ovariano fresco (CIF); 5) folículos secundários isolados do tecido ovariano vitrificado (VIF) e 6) folículos secundários cultivados in vitro, isolados de tecido ovariano vitrificado (CVIF). O tecido ovariano fresco ou vitrificado, bem como os folículos isolados de todos os tratamentos foram avaliados quanto à expressão gênica e protéica para as Cx37 e Cx43. Adicionalmente, folículos secundários foram analisados para a integridade e crescimento folicular, morte por apoptose e proliferação celular, e folículos secundários somente cultivados in vitro (CIF e CVIF) foram avaliados para morfologia (folículos extrusos), formação de antro e viabilidade. O percentual de folículos intactos no tratamento CVIF foi significativamente superior (P < 0,05), enquanto que a formação de antro, taxa de extrusão e viabilidade folicular foram inferiores (P < 0,05) aos folículos do tratamento CIF. O teste TUNEL mostrou que folículos frescos (FIF) não apresentaram apoptose, enquanto os folículos nos demais tratamentos (CIF, VIF e CVIF) mostraram marcação positiva. A proliferação celular nos tratamentos VIF e CVIF foi mais intensa do que nos folículos do FIF. Em relação à expressão gênica, nos folículos secundários apenas a Cx43 apresentou alterações nos níveis de expressão de mRNA, sendo que os folículos do tratamento CVIF apresentaram níveis de RNAm significativamente inferiores, comparados aos folículos dos demais tratamentos. A Cx37 e Cx43 foram predominantemente imunolocalizadas nas células da granulosa e oócitos, respectivamente. Em conclusão, folículos secundários ovinos podem ser isolados com sucesso após a vitrificação do tecido ovariano e são capazes de manter a integridade da membrana após o cultivo in vitro. Embora a expressão gênica e protéica da Cx37 não varie após a vitrificação do tecido ovariano, a Cx43 é alterada nos folículos secundários após vitrificação e cultivo in vitro.

Previous studies have demonstrated that cryoinjuries showed through vitrification leads to a loss of integrity of membrane proteins that constitutes the intercellular communications. Among these membrane proteins, it is prominent the role of connexins 37 (Cx 37) and 43 (Cx 43). Thus, this study aimed evaluate the effect of vitrification of ovine ovarian tissue using ovarian tissue cryosystem (OTC), associated to in vitro culture of isolated secondary follicles, under genetic and protein expression pattern of Cx 37 and Cx 43. Ovarian fragments were distributed into six different treatments: 1) fresh ovarian tissue (FOT); 2) vitrified ovarian tissue (VOT); 3) isolated secondary follicles of fresh ovarian tissue (FIF); 4) secondary follicles cultured in vitro, follow by isolation of ovarian tissue (CIF); 5) isolated secondary follicles of vitrified ovarian tissue (VIF) and 6) secondary follicles cultured in vitro, and then isolated of vitrified ovarian tissue (CVIF). Fresh or vitrified ovarian tissue as well as isolated follicles of all treatments were evaluated to genetic and protein expression for Cx 37 and Cx 43. Additionally, secondary follicles were analyzed to integrity, follicular growth, apoptosis, and cell proliferation, while only cultured secondary follicles (CIF and CVIF) were evaluated by morphology (extruded follicles), antrum formation and viability. The percentage of intact follicles on CVIF treatment had higher (P < 0.05) while antrum formation, extruded rate and follicle viability were lower (P < 0.05) to follicles on treatment CIF. TUNEL assay demonstrates that in fresh follicles (FIF) did not show apoptosis, while follicles from other treatments had a positive labelling. A cell proliferation on VIF and CVIF treatments had more intensity of follicles from FIF. In relation to genetic expression on secondary follicles, only Cx43 alters mRNA levels, and follicles of CVIF treatment had lower (P < 0.05) mRNA levels when compared to follicles of other treatments. Cx37 and Cx43 had an immunolabelling mainly on granulosa cells and oocytes, respectively. In conclusion, the isolation of ovine secondary follicles occurs successfully after vitrification of ovarian tissue and be able to maintain the integrity of membrane after in vitro culture. Although the genetic and protein expression of Cx37 did not varies after vitrification of ovarian tissue, Cx 43 is altered on secondary follicles after vitrification and in vitro culture. Keywords:

Gap junctions and communication within the nervous system

Gap junctions are sites on the cellular membrane with intercellular channels build up by twelve protein subunits called connexins. Each connected cell contributes with a hemichannel made up by six connexins subunits. This kind of connection represents and efficient way of intercellular communication in most tissues, including the nervous system. It works as a passage for ions, secondary messenger and metabolites exchange between the cells. In a complex tissue like the nervous tissue they are particularly important because they connect the various cellular types composing a panglial syncytium that performs neuronal protection and tissue homeostasis. The expression of connexins and the intercellular communication through gap junctions are crucial to regulate vital functions as cellular motility, proliferations and survival; changes in the conformational expression of connexins may be involved in diseases as Alzheimer's disease, neoplasms, bacterial and parasitic infections, or even affect cellular groups when they occur as genetic mutations leading to functional defects of the nervous system as demyelination in the PNS (Charcot-Marie-Tooth disease), hereditary epilepsy, non-syndromic deafness and senile cataract.

Gap junctions and communication within the nervous system

Gap junctions are sites on the cellular membrane with intercellular channels build up by twelve protein subunits called connexins. Each connected cell contributes with a hemichannel made up by six connexins subunits. This kind of connection represents and efficient way of intercellular communication in most tissues, including the nervous system. It works as a passage for ions, secondary messenger and metabolites exchange between the cells. In a complex tissue like the nervous tissue they are particularly important because they connect the various cellular types composing a panglial syncytium that performs neuronal protection and tissue homeostasis. The expression of connexins and the intercellular communication through gap junctions are crucial to regulate vital functions as cellular motility, proliferations and survival; changes in the conformational expression of connexins may be involved in diseases as Alzheimer´s disease, neoplasms, bacterial and parasitic infections, or even affect cellular groups when they occur as genetic mutations leading to functional defects of the nervous system as demyelination in the PNS (Charcot-Marie-Tooth disease), hereditary epilepsy, nonsyndromic deafness and senile cataract.