Expression Of A7 Research Articles

Cadmium enhances root hair elongation through reactive oxygen species in Arabidopsis

We previously reported that Arabidopsis shows enhanced root hair density and length in response to cadmium (Cd). To understand how Cd stimulates root hair elongation, we examined the role of reactive oxygen species (ROS) and root hair elongation-related genes in root hair elongation/tip growth. In response to Cd, Arabidopsis displayed enhanced length and ROS levels in the root hairs, indicating ROS involvement. Furthermore, in response to Cd, ROS generation mutants, including root hair defective 2 ( rhd2/rbohc ), rbohh , rbohj , per1 , per44 and per73, which have shorter root hairs because of impaired ROS generation, also showed increased root hair length and ROS levels, suggesting the involvement of these genes in ROS production in Cd-induced root hair elongation. Supporting the participation of ROS, N-acetyl- L -cysteine (ROS scavenger) treatment reduced root hair elongation and ROS levels. Additionally, the expression of proline-rich extension-like receptor kinase (PERK)5 , PERK8, and root hair-specific 10 ( RHS10 ) , which are negative regulators of root hair elongation, was reduced by Cd and ROS (H 2 O 2 ). Furthermore, the expression of expansin A7 ( EXPA7 ) and expansin A18 ( EXPA18 ), which are involved in root hair elongation, was remarkably induced by Cd and H 2 O 2 in elongating root hairs and tips. Additionally, COBL9 , which is involved in cell wall formation, was highly expressed in root hairs and tips in response to Cd and H 2 O 2 . Furthermore, changes in auxin and ethylene levels showed a similar pattern to that of root hair elongation and ROS at various concentrations of Cd, suggesting the involvement of auxin and ethylene in Cd/ROS-induced root hair elongation. Combined, it appears that Cd enhances root hair elongation/tip growth by elevating the expression of EXPA7 , EXPA18 and COBL9 and by inhibiting the expression of PERK5 , PERK8, and RHS10 , which are ROS-mediated in Arabidopsis. Change of root hair elongation, ROS, auxin and ethylene at various concentrations of Cd in Col-0 Arabidopsis • Cd promotes root hair elongation by enhancing ROS level in Arabidopsis. • RBOHC, RBOHH, RBOHJ, PER1, PER44, and PER73 participate in Cd-induced ROS generation. • Auxin and ethylene may be involved in Cd-enhanced ROS and root hair elongation. • Cd-induced ROS elevates expressions of EXPA7 , EXPA18 and COBL9 . • Cd-enhanced ROS inhibits expressions of PERK5 , PERK8, and RHS10 .

Expression Characteristics of SODD and ALG-2 as Possible Biomarkers for Evaluating Lymphatic Metastasis Potential of Hepatocarcinoma in a Mouse Model.

Annexin A7 has been confirmed in our previous research to be an important factor in lymph node metastasis (LNM) of hepatocellular carcinoma (HCC). SODD and ALG-2 are the binding proteins of Annexin A7 and can work in protein complexes. The present study was carried out with the constructed cell lines in mouse model of metastasis for further elaboration of possible mechanisms and identification of associated genes in the LNM of HCC. This experiment used inbred Chinese 615 mice, as well as Hca-F and Hca-P cells. Quantification of the relative messenger RNA (mRNA) expression of SODD and ALG-2 was realized by using qRT-PCR. Quantification of the protein expressions of SODD and ALG-2 was achieved by using western blot. Experimental mice (n=160) (6-8weeks old, 18-22g, SCXK [LIAO] 2008-0002) were randomly classified into four groups equally, which were separately inoculated with Hca-F, Hca-P, FAnxa7-upregulated, and PAnxa7-upregulated cells. Serum levels of SODD and ALG-2 were measured by ELISA. Immunohistochemical analysis of SODD and ALG-2 was further conducted. Tumor LNM-related factors of SODD and ALG-2 showed the same tendency in their expression correspondingly with the up-regulated expression of Annexin A7. Our experiment further explored the roles of SODD and ALG-2 based on Annexin A7 up-regulation vectors construction and the establishment of corresponding controls in vivo. Furthermore, the mouse model of primary tumors was constructed by injecting Hca-F, FAnxa7-upregulated and Hca-P, PAnxa7-upregulated cells into the mouse footpad. Mice were sacrificed at the designated time points for detecting SODD and ALG-2 expression in tumor tissue and serum samples. Collectively, our work indicates SODD in tumors and in serum and ALG-2 in serum are valuable in evaluating LNM in mice with HCC.

RGC-32 Acts as a Hub to Regulate the Transcriptomic Changes Associated With Astrocyte Development and Reactive Astrocytosis.

Response Gene to Complement 32 (RGC-32) is an important mediator of the TGF-β signaling pathway, and an increasing amount of evidence implicates this protein in regulating astrocyte biology. We showed recently that spinal cord astrocytes in mice lacking RGC-32 display an immature phenotype reminiscent of progenitors and radial glia, with an overall elongated morphology, increased proliferative capacity, and increased expression of progenitor markers when compared to their wild-type (WT) counterparts that make them incapable of undergoing reactive changes during the acute phase of experimental autoimmune encephalomyelitis (EAE). Here, in order to decipher the molecular networks underlying RGC-32’s ability to regulate astrocytic maturation and reactivity, we performed next-generation sequencing of RNA from WT and RGC-32 knockout (KO) neonatal mouse brain astrocytes, either unstimulated or stimulated with the pleiotropic cytokine TGF-β. Pathway enrichment analysis showed that RGC-32 is critical for the TGF-β-induced up-regulation of transcripts encoding proteins involved in brain development and tissue remodeling, such as axonal guidance molecules, transcription factors, extracellular matrix (ECM)-related proteins, and proteoglycans. Our next-generation sequencing of RNA analysis also demonstrated that a lack of RGC-32 results in a significant induction of WD repeat and FYVE domain-containing protein 1 (Wdfy1) and stanniocalcin-1 (Stc1). Immunohistochemical analysis of spinal cords isolated from normal adult mice and mice with EAE at the peak of disease showed that RGC-32 is necessary for the in vivo expression of ephrin receptor type A7 in reactive astrocytes, and that the lack of RGC-32 results in a higher number of homeodomain-only protein homeobox (HOPX)+ and CD133+ radial glia cells. Collectively, these findings suggest that RGC-32 plays a major role in modulating the transcriptomic changes in astrocytes that ultimately lead to molecular programs involved in astrocytic differentiation and reactive changes during neuroinflammation.

Annexin A7 Levels Increase in Rats With Traumatic Brain Injury and Promote Secondary Brain Injury.

The incidence of traumatic brain injury (TBI) has been increasing annually. Annexin A7 is a calcium-dependent phospholipid binding protein. It can promote melting of the cell membrane. Recent studies have shown that it plays an important role in atherosclerosis, other cardiovascular diseases, and a variety of tumors. However, few studies of ANXA7 in TBI have been performed. We here observed how ANXA7 changes after TBI and discuss whether brain injury is associated with the use of ANXA7 antagonist intervention.Experimental Results: 1. After TBI, ANXA7 levels were higher than in the sham group, peaking 24 h after TBI. 2. The use of siA7 was found to reduce the expression of A7 in the injured brain tissue, and also brain edema, BBB damage, cell death, and apoptosis relative to the sham group.Conclusion: ANXA7 promotes the development of secondary brain injury (SBI) after TBI.

Dysregulated expression of homeobox family genes may influence survival outcomes of patients with epithelial ovarian cancer: analysis of data from The Cancer Genome Atlas.

Homeobox (HOX) family genes encode key transcription factors for embryogenesis and may be correlated with carcinogenesis. The aim of this study was to elucidate whether aberrant expression of HOX genes influences outcomes in epithelial ovarian cancer (EOC). Gene expression data and clinicopathologic information from 630 patients with EOC were downloaded from The Cancer Genome Atlas database. We explored correlations between expression levels of HOX gene family members and clinicopathological variables. Higher expression of HOXA1, A4, A5, A7, A10, A11, B13, C13, D1, and D3 was associated with advanced FIGO stage. Suboptimal residual disease after debulking surgery was significantly correlated with higher expression of HOXB9, B13, and C13. Additionally, patients with high expression of HOXC6 and C11 were significantly more likely to have poor performance status. Overall survival was significantly shorter in patients with high, rather than low, expression of two HOX genes (HOXA10 and B3), and significantly longer in patients with high rather than low HOXC5 expression. Dysregulated expression of the HOXA10, B3, and C5 was significantly correlated with overall survival in EOC patients. HOX gene expression levels are potentially useful as a prognostic indicator in EOC, and HOX genes may represent a novel and promising target for anticancer therapeutics.

Effect of annexin A7 suppression on the apoptosis of gastric cancer cells

Understanding the molecular mechanism of gastric cancer cell apoptosis is pivotal for the development of precise therapies targeting this disease. In the present study, we examined the effects of annexin A7 inhibition on the apoptosis of gastric cancer cells and the growth of tumour xenografts in vivo. Expression of annexin A7 in BGC823 cells was suppressed by small interference RNA, and cells apoptosis was assessed by flow cytometry. The mechanism by which annexin A7 mediates apoptosis in BGC823 cells was explored by determining the expression of key apoptosis regulators. In addition, by suppressing annexin A7 in BGC823 cells with small hairpin RNA, we studied the effects of annexin A7 inhibition on in vivo tumour growth. Our results showed that inhibiting annexin A7 expression induced more than fivefold increase in BGC823 cell apoptosis in vitro. This was in concord with a significant decrease of Bcl-2 expression and increases of Bax, Caspase-3, and Caspase-9. The activities of caspase-3 and caspase-9 were increased by 2.95 ± 0.18 and 3.70 ± 0.33 times, respectively, upon the annexin A7 downregulation in BGC823 cells. Importantly, suppressing annexin A7 showed the same apoptotic mechanism in vivo and significantly inhibited the growth of BGC823 xenografts in mice. These data suggest that annexin A7 likely protects gastric cells from apoptosis and targeting it may represent a valuable strategy in future therapeutic development.

Down-regulated expression of Annexin A7 induces apoptosis in mouse hepatocarcinoma cell line by the intrinsic mitochondrial pathway

Our previous studies have shown that decreased expression of Annexin A7 elevates apoptosis in Hca-P cells, a hepatocarcinoma cell line with lymphatic metastatic potential. In this study, RNA interference technique was used to down-regulate the expression of Annexin A7, and unmanipulated Hca-P cells and transfected nonspecific-sequence Hca-P cells as control. The down-regulation of Annexin A7 declined the cell viability after cisplatin exposure. And the reduced expression of Annexin A7 decreased the expression of Bcl2, increased the expression of Cytochrome-C in the cytoplasme, and then improved the expression of Caspase-3. However there was no significant effect on the expression of Bax, Caspase-12, Fas, FasL and Caspase-8. The results indicate that the decreased expression of Annexin A7 could inhibit the proliferation, and increase the apoptosis of Hca-P cells by affecting the expression of the apoptosis associated proteins by the mitochondrial pathway.

Clic1 plays a role in mouse hepatocarcinoma via modulating Annexin A7 and Gelsolin in vitro and in vivo

Clic1 is a member of the family of chloride intracellular ion channels. Previous studies suggest that Clic1 is involved in migration and invasion of the lymphatic metastasis in hepatocarcinoma, however, the mechanism is not fully understood. In the present study, we observed Clic1 is abundant in cytoplasm, higher expression in Hca-F cell than Hca-P cell, and we showed that downregulation of Clic1 by RNA interference was able to markedly enhance the expression of tumor metastasis genes Annexin A7 and Gelsolin in vitro, and downregulation of Annexin A7 and Gelsolin also enhanced the expression of Clic1 in vitro and in vivo. Our results provide novel insight that Clic1 have a role in migration and invasion in hepatocarcinoma maybe via modulating the expression of Annexin A7 and Gelsolin, and provide novel insight into the mechanisms of Clic1 for hepatocarcinoma treatment.

Evaluation of Annexin A7, Galectin-3 and Gelsolin as possible biomarkers of hepatocarcinoma lymphatic metastasis

We have previously demonstrated that Annexin A7 is involved in the lymphatic metastasis of hepatocarcinoma in vitro. The expression of Galectin-3 and Gelsolin, which were also relevant to tumor lymphatic metastasis, had shown the same tendency concordantly with the expression of Annexin A7 alteration by qRT-PCR and Western blot analysis. Here, we gain an insight into the role that Annexin A7 is playing in Hca-P, PAnxa7-upregulated and PAnxa7-downregulated cells in vivo. Then, Hca-P, PAnxa7-upregulated and PAnxa7-downregulated cells were injected into a mouse footpad to establish primary tumors in mice. On the fourth week after HCC cells inoculation, the mice were sacrificed for inspection the expression of Annexin A7, Galectin-3 and Gelsolin in primary tumors and in serum. Our work indicates that Annexin A7 and Gelsolin are both valuable in tumors and in serum evaluating lymph node metastasis in mice with hepatocarcinoma; Galectin-3 in tumors is significant but no much contribution in serum.

Ech1 is a potent suppressor of lymphatic metastasis in hepatocarcinoma

We have previously demonstrated that Ech1 is involved in the lymphatic metastasis of tumors in vitro. Here, we gain an insight into the role that Ech1 is playing in Hca-F cell. The expression of Annexin A7, Gelsolin and Clic1 genes, which were also relevant to tumor lymphatic metastasis, had been inhibited due to downregulation Ech1 gene by Western blot analysis. And downregulated of Ech1 inhibits the metastasic capability of Hca-F cells to peripheral lymph nodes in vivo. Our work indicates although the involvement of Ech1 in tumor metastasis development and progression, but the subcellular location of Ech1 has not much contribution to that.

Correlation of Histopathology, Urinary Biomarkers, and Gene Expression Responses Following Hexachloro-1:3-Butadiene–induced Acute Nephrotoxicity in Male Hanover Wistar Rats

Hexachloro-1:3-butadiene (HCBD) causes segment-specific injury to the proximal renal tubule. A time course study of traditional and more recently proposed urinary biomarkers was performed in male Hanover Wistar rats receiving a single intraperitoneal (ip) injection of 45 mg/kg HCBD. Animals were killed on days 1, 2, 3, 4, 5, 6, 7, 10, 14, and 28 postdosing and the temporal response of renal biomarkers was characterized using kidney histopathology, urinary and serum biochemistry, and gene expression. Histopathologic evidence of tubular degeneration was seen from day 1 until day 3 postdosing and correlated with increased urinary levels of α-glutathione S-transferase (α-GST), albumin, glucose, and kidney injury molecule-1 (KIM-1), and increased gene expression of KIM-1, NAD(P)H dehydrogenase, quinone 1, and heme oxygenase (decycling) 1. Histopathologic evidence of tubular regeneration was seen from day 2 postdosing and correlated with raised levels of urinary KIM-1 and osteopontin and increased gene expression of KIM-1 and annexin A7. Traditional renal biomarkers generally demonstrated low sensitivity. It is concluded that in rat proximal tubular injury, measurement of a range of renal biomarkers, in conjunction with gene expression analysis, provides an understanding of the extent of degenerative changes induced in the kidney and the process of regeneration.

Rapid and Efficient Generation of Functional Motor Neurons From Human Pluripotent Stem Cells Using Gene Delivered Transcription Factor Codes

Stem cell-derived motor neurons (MNs) are increasingly utilized for modeling disease in vitro and for developing cellular replacement strategies for spinal cord injury and diseases such as spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS). Human embryonic stem cell (hESC) differentiation into MNs, which involves retinoic acid (RA) and activation of the sonic hedgehog (SHH) pathway is inefficient and requires up to 60 days to develop MNs with electrophysiological properties. This prolonged differentiation process has hampered the use of hESCs, in particular for high-throughput screening. We evaluated the MN gene expression profile of RA/SHH-differentiated hESCs to identify rate-limiting factors involved in MN development. Based on this analysis, we developed an adenoviral gene delivery system encoding for MN inducing transcription factors: neurogenin 2 (Ngn2), islet-1 (Isl-1), and LIM/homeobox protein 3 (Lhx3). Strikingly, delivery of these factors induced functional MNs with mature electrophysiological properties, 11-days after gene delivery, with >60-70% efficiency from hESCs and human induced pluripotent stem cells (hiPSCs). This directed programming approach significantly reduces the time required to generate electrophysiologically-active MNs by approximately 30 days in comparison to conventional differentiation techniques. Our results further exemplify the potential to use transcriptional coding for rapid and efficient production of defined cell types from hESCs and hiPSCs.

Increased expression of annexin A7 in temporal lobe tissue of patients with refractory epilepsy.

Annexin A7 is a member of the family of annexins, which are thought to function in the regulation of calcium homeostasis and the fusion of vesicles. Refractory epilepsy may be related to the imbalance of calcium homeostasis. Our aims are to investigate the expression of Annexin A7 in epileptic brains in comparison with human controls and to explore Annexin A7's possible role in refractory epilepsy. We examined the expression of Annexin A7 via immunohistochemistry, double-label immunofluorescence and western blot. The expression of Annexin A7 was shown to be significantly increased in patients with refractory epilepsy. Double-label immunofluorescence and confocal microscopy disclosed Annexin A7 immunoreactivity in the neurons, which were recognized by the antibody of neuron specific enolase (NSE). The result showed that Annexin A7 may be involved in the pathophysiology of refractory epilepsy and may play a role in developing and maintaining the epilepsy.

Abstract 2028: HOX genes in oral cancer: Expression profile and functional characterization

Abstract Homeobox genes, specifically the HOX family, play an important role in the development by controlling cellular proliferation, differentiation and apoptosis. In the present study it was investigated whether genes of the HOX family play a role in oral cancer. Our results demonstrated that the expression of HOXA4, A5, A7, A10, B7, C4, C5, C6, C8, C9, C10, C11, D9, D10, D11 and D13 was statistically higher in oral squamous cell carcinoma (OSCC) samples when compared with those from normal oral mucosa. We further demonstrated that HOXA1 and HOXB7 overexpression in HaCAT human epithelial cell line promotes proliferation, whereas downregulation of HOXB7 endogenous levels in human oral carcinoma cells (SCC9 cells) decreases it. In OSCCs, expression of HOXB7 and Ki67, a marker of proliferation, correlate strongly with each other (rs=0.79, p<0.006). High immunohistochemical expression of HOXB7 was correlated with T stage (p=0.06), N stage (p=0.07), disease stage (p=0.09) and Ki67 expression (p=0.01), and patients with tumors showing high number of HOXB7-positive cells had shorter overall survival (p<0.08) and shorter disease-free survival after treatment (p<0.10) compared with patients with tumors exhibiting low amount of HOXB7-positive cells. No correlation between HOXA1 and clinicopathological parameters was observed. Our data suggest that HOXA1 and HOXB7 may contribute to oral carcinogenesis by increasing tumor cell proliferation, and imply that HOXB7 may be an important determinant of OSCC patient's prognosis. Thus, dysregulated expression of specific members of the HOX family of homeobox genes is related to the tumorigenesis of oral cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2028. doi:10.1158/1538-7445.AM2011-2028

Effect of Glytan on the Expression of the Nicotinic Acetylcholine Receptor a7 in Portal Hypertensive Rats

Abstract This study aimed to observe the expression of the nicotinic acetylcholine receptor nAchRa7 in liver tissue after portal hypertension (PHT). In the study, 40 male Sprague-Dawley rats, with weights between 240 g and 260 g, were randomly divided into sham-operated group, model group, and Glytan group according to their weights. Each group was observed at two time points, namely, two and four weeks after PHT. Common bile duct ligation was carried out on rats to induce PHT. The portal pressure of each group was measured, and the expression of nAchR a7 in the liver was detected by Western blotting at each time point. Results showed that the portal pressure and the expression of nAchRa7 in the model group increased significantly at two and four weeks after PHT. The portal pressure of the Glytan group was decreased compared to the model group, especially at four weeks after PHT. The expression of nAchRa7 in the liver of the Glytan group decreased significantly at four weeks after PHT. It is concluded that the change of portal pressure and the expression of nAchRa7 in the model and Glytan groups is consistent with the time sequence. Glytan may downregulate the portal pressure by affecting the nAchRa7 level in the liver.

Diabetes-related defects in sarcoplasmic Ca2+ release are prevented by inactivation of Gα11 and Gαq in murine cardiomyocytes

Neurohumoral stimulation of Gq-coupled receptors has been proposed as a central mechanism in the pathogenesis of diabetic heart disease. The resulting contractile dysfunction is closely related to abnormal intracellular Ca(2+) handling with functional defects of the sarcoplasmic reticulum (SR). The present study was therefore designed to determine the role of G(q)-protein signaling via G(alpha)(11) and G(alpha)(q) in diabetes for the induction of functional and structural changes in the Ca(2+) release complex of the SR. An experimental type 1-diabetes was induced in wild type, G(alpha)(11) knockout, and G(alpha)(11/q)-knockout mice by injection of streptozotocin. Cardiac morphology and function was assessed in vivo by echocardiography. SR Ca(2+) leak was tested in vitro based on a (45)Ca(2+) assay and protein densities as well as gene expression of ryanodine receptor (RyR2), FKBP12.6, sorcin, and annexin A7 were analyzed by immunoblot and RT-PCR. In wild type animals 8 weeks of diabetes resulted in cardiac hypertrophy and SR Ca(2+) leak was increased. In addition, diabetic wild type animals showed reduced protein levels of FKBP12.6 and annexin A7. In G(alpha)(11)- and G(alpha)(11/q)-knockout animals, however, SR Ca(2+) release and cardiac phenotype remained unchanged upon induction of diabetes. Densities of the proteins that we presently analyzed were also unaltered in G(alpha)(11)-knockout mice. G(alpha)(11/q)-knockout animals even showed increased expression of sorcin and annexin A7. Thus, based on the present study we suggest a signaling pathway via the G(q)-proteins, G(alpha)(11) and G(alpha)(q), that could link increased neurohumoral stimulation in diabetes with defective RyR2 channel function by regulating protein expression of FKBP12.6, annexin A7, and sorcin.

Establishment of mouse hepatic cancer cell line Hca-F with knockdown of annexin A7 gene

Objective:To establish a mouse hepatic cancer cell line Hca-F transfected with shRNA (small hairpin RNA) targeting annexin A7,so as to provide a basis for future study. Methods: Three shRNAs(shRNA1,2 and 3) were designed and inserted into the pSilencer vector to silence annexin A7 gene. The three pSilencer-shRNA vectors were transfected into Hca-F cells separately,and the most effective pSilencer-shRNA vector was selected based on the results of RT-PCR and Western blotting. The Hca-F cells were transfected with the most effective pSilencer-shRNA vector and the transfectants were selected by 400 μg/ml G418. The cells with annexin A7 stably knockdown were passaged and the expression of annexin A7 was confirmed by Western blotting,and the result was compared with those transfected with empty vector and normal controls.Results: The sequencing results confirmed that the sequences of the 3 shRNAs were correct,and shRNA1 was found to have the best inhibitory effect against annexin A7. Compared with normal Hca-F cells and those transfected with empty vectors,the annexin A7 protein expression was significantly down-regulated in cells transfected with pSilencer-shRNA(0.318 6 vs 0.824 3,0.798 7,P0.05),with no significant difference found between the former 2 groups. Conclusion: We have successfully established a Hca-F cell line with annexin A7 stably down-regulated using shRNA technique,paving a way for future study.

Annexins and Ca handling in the heart

Annexins are a family of 13 proteins known to bind phospholipids (PL) in a Ca(2+)-dependent way. They are ubiquitous proteins and share a similar structure characterized by a conserved C-terminal domain with Ca(2+) binding sites and a variable N-terminal domain. Depending on Ca(2+) concentration, they have been reported to participate in a variety of membrane-related events such as exocytosis, endocytosis, apoptosis and binding to cytoskeletal proteins. They have also been reported to regulate protein activities. This review will focus on annexins in the heart, and particularly on annexins A2, A5, A6 and A7. Annexin A2 has been found in endothelial cells and reported to play a central role in control of plasmin-mediated processes. Annexin A5 is mainly localized in cardiomyocytes. However, it could be relocated to interstitial tissue in ischemic and failing hearts or it could be externalized and exhibit a proapoptotic effect in cardiomyocytes. Annexin A6 is the most abundant annexin in the heart, and has been localized in various cell types including myocytes. Overexpression of annexin A6 has underlined physiological alterations in contractile mechanics leading to dilated cardiomyopathy, whereas knockout has been found to induce faster changes in Ca(2+) transient and increased contractility, suggesting a negative inotropic role for annexin A6. Annexin A7 is expressed in heart and skeletal muscle. In annexin A7 null mutant mice decreases in the force-frequency relationship were observed in adult cardiomyocytes, consistent with regulation of Ca(2+) handling. In conclusion, while annexin A2 was involved in regulation of fibrin homeostasis, alterations in expression and activity of annexins A5, A6 and A7 have been associated with regulation of Ca(2+) handling in the heart, but the target of each annexin has not yet been identified.

Three distinct lineages of mesenchymal cells in Ciona intestinalis embryos demonstrated by specific gene expression

The ascidian embryonic mesenchyme, comprising about 900 cells, forms mesodermal tissues or organs of the adult body after metamorphosis. The mesenchyme originates from the A7.6 [trunk lateral cells (TLCs)], B7.7, and B8.5 blastomeres of the 110-cell stage embryo. Previous studies showed that FGF9/16/20 is required for specification of the mesenchyme in Ciona embryos and that two different (A7.6 and B8.5/B7.7) but partially overlapping molecular mechanisms are associated with the expression of a basic helix-loop-helix (bHLH) transcription factor gene, Twist-like1, in the mesenchymal precursors, which triggers the differentiation process of mesenchyme cells. In the present study, we examined whether the three embryonic lineages express the same mesenchyme-specific structural genes under the control of a common mechanism or whether the three lineages are characterized by the expression of genes specific to each of the lineages. We characterized nine mesenchyme-specific genes in Ciona embryos and found that five were expressed in A7.6/B8.5/B7.7, two in B8.5/B7.7, and two in B7.7 only. FGF9/16/20 and Twist-like1 were required for the expression of all the mesenchyme-specific genes, except for three A7.6/B8.5/B7.7-specific genes in A7.6 progenitors. Overexpression of FGF9/16/20 or Twist-like1 upregulated the expression of A7.6/B8.5/B7.7- and B8.5/B7.7-specific genes, while it downregulated the expression of B7.7-specific genes. These results provide evidence that the differentiation of each of the three mesenchyme lineages of Ciona embryos is characterized by the expression of a specific set of genes, whose expression is controlled differentially.

Function, expression and localization of annexin A7 in platelets and red blood cells: Insights derived from an annexin A7 mutant mouse

BackgroundAnnexin A7 is a Ca2+- and phospholipid-binding protein expressed as a 47 and 51 kDa isoform, which is thought to be involved in membrane fusion processes. Recently the 47 kDa isoform has been identified in erythrocytes where it was proposed to be a key component in the process of the Ca2+-dependent vesicle release, a process with which red blood cells might protect themselves against an attack by for example complement components.ResultsThe role of annexin A7 in red blood cells was addressed in erythrocytes from anxA7-/- mice. Interestingly, the Ca2+-mediated vesiculation process was not impaired. Also, the membrane organization appeared not to be disturbed as assessed using gradient fractionation studies. Instead, lack of annexin A7 led to an altered cell shape and increased osmotic resistance of red blood cells. Annexin A7 was also identified in platelets. In these cells its loss led to a slightly slower aggregation velocity which seems to be compensated by an increased number of platelets. The results appear to rule out an important role of annexin A7 in membrane fusion processes occurring in red blood cells. Instead the protein might be involved in the organization of the membrane cytoskeleton. Red blood cells may represent an appropriate model to study the role of annexin A7 in cellular processes.ConclusionWe have demonstrated the presence of both annexin A7 isoforms in red blood cells and the presence of the small isoform in platelets. In both cell types the loss of annexin A7 impairs cellular functions. The defects observed are however not compatible with a crucial role for annexin A7 in membrane fusion processes in these cell types.