Aberrant UBR4 expressions in Hirschsprung disease patients.

BACKGROUND: Recently, pathogenic alleles within ubiquitin N-recognin domain-containing E3 ligase 4 (UBR4) gene have been shown to be associated with Hirschsprung disease (HSCR). We determined the UBR4 expressions in Indonesian HSCR patients. METHODS: We analyzed the UBR4 expressions in the colons of HSCR patient and anorectal malformation (ARM) patient as control by real-time polymerase chain reaction (qPCR). RESULTS: Thirty-seven patients with non-syndromic HSCR and eighteen controls were involved in this study. qPCR revealed that the UBR4 expression was strongly decreased (0.77-fold) in the ganglionic group of patients with HSCR compared to the control group with ARM (ΔCT 2.43 ± 0.36 vs. 2.05 ± 0.69; p = 0.009), whereas the UBR4 expression was also significantly reduced (0.79-fold) in the aganglionic group of patients with HSCR compared to the control group with ARM (ΔCT 2.39 ± 0.46 vs. 2.05 ± 0.69; p = 0.044). However, the UBR4 expression change was not associated with gender (p = 0.35 and 0.80), nor with degree of aganglionosis both in ganglionic and aganglionic colons (p = 0.72 and 0.73), respectively. CONCLUSION: Our study demonstrates that expression of UBR4 is decreased in both aganglionic and ganglionic colon of HSCR patients.

Determination of dendritic spine morphology by the striatin scaffold protein STRN4 through interaction with the phosphatase PP2A.

Dendritic spines are heterogeneous and exist with various morphologies. Altered spine morphology might underlie the cognitive deficits in neurodevelopmental disorders such as autism, but how different subtypes of dendritic spines are selectively maintained along development is still poorly understood. Spine maturation requires spontaneous activity of N-methyl-d-aspartate (NMDA) receptor and local dendritic protein synthesis. STRN4 (also called zinedin) belongs to the striatin family of scaffold proteins, and some of the potential striatin-interacting proteins are encoded by autism risk genes. Although previous studies have demonstrated their localization in dendritic spines, the function of various striatin family members in the neuron remains unknown. Here, we demonstrate that Strn4 mRNA is present in neuronal dendrites, and the local expression of STRN4 protein depends on NMDA receptor activation. Notably, STRN4 is preferentially expressed in mushroom spines, and STRN4 specifically maintains mushroom spines but not thin spines and filopodia through interaction with the phosphatase PP2A. Our findings have therefore unraveled the local expression of STRN4 as a novel mechanism for the control of dendritic spine morphology.

Early hepatocellular carcinoma with high-grade atypia in small vaguely nodular lesions.

Multistep hepatocarcinogenesis progresses from dysplastic nodules to early hepatocellular carcinoma (eHCC) and to advanced HCC. The aim of the present study was to investigate the detailed histopathological features of eHCC. We investigated 66 small vaguely nodular lesions resected from 40 patients. The degree of cellular and structural atypia and stromal invasion were assessed. The immunohistochemical expression of HCC-related markers adenylate cyclase-associated protein 2 (CAP2), heat shock protein 70 (HSP70), Bmi-1, CD34 and h-caldesmon were evaluated. Of the 66 nodules, 10 were diagnosed as low-grade dysplastic nodules (LGDN), 10 as high-grade dysplastic nodules (HGDN) and 46 as eHCC. Among the 46 eHCC, 18 nodules (39.1%) showed marked stromal invasion and/or the presence of the scirrhous component and were subclassified as high-grade eHCC (HGeHCC). The remaining 28 eHCC, which lacked these features, were subclassified as low-grade eHCC (LGeHCC) and were examined further. HGeHCC showed high levels of cellular and structural atypia and large tumor size. The immunohistochemical expression of CAP2 and the area of sinusoidal vascularization showed increases from LGDN to HGeHCC. The density of arterial tumor vessels was high in HGeHCC compared with other nodule types. Cluster analysis of these parameters subclassified 65 nodules into HGeHCC-dominant, LGeHCC and HGDN-dominant, and LGDN-dominant groups. These results indicate the increased malignant potential of HGeHCC and suggest that it is already a transitional stage to advanced HCC. We consider that our grading classification system may be valuable for considering treatment strategies for eHCC around 2 cm in diameter.

Genome-wide analysis of the IQD gene family in maize.

IQD gene family plays important roles in plant developmental processes and stress responses. To date, no systematic characterization of this gene family has been carried out in maize. In this study, 26 IQD genes, from ZmIQD1 to ZmIQD26, were identified using Blast search tools. The phylogenetic analysis showed these genes were divided into four subfamilies (IQD I-IV) and members within the same subfamily shared conserved exon/intron distribution and motif composition. The 26 ZmIQD genes are distributed unevenly on 8 of the 10 chromosomes, with 9 segmental duplication events, suggesting that the expansion of IQDs in maize was due to the segmental duplication. The analysis of Ka/Ks ratios showed that the duplicated ZmIQDs had primarily undergone strong purifying selection. In addition, the 26 ZmIQDs displayed different expression patterns at different developmental stages of maize based on transcriptome analysis. Further, quantitative real-time PCR analysis showed that all 26 ZmIQD genes were responsive to drought treatment, suggesting their crucial roles in drought stress response. Yeast two-hybrid assay proved that ZmIQD2 and ZmIQD15 can interact with ZmCaM2 and IQ or I in IQ motif is required for ZmIQD15 to combine with CaM2. Our results present a comprehensive overview of the maize IQD gene family and lay an important foundation for further analysis aimed at uncovering the biological functions of ZmIQDs in growth and development.

Genome-wide analysis of the oxyntic proliferative isthmus zone reveals ASPM as a possible gastric stem/progenitor cell marker over-expressed in cancer.

The oxyntic proliferative isthmus zone contains the main stem/progenitor cells that provide for physiological renewal of the distinct mature cell lineages in the oxyntic epithelium of the stomach. These cells are also proposed to be the potential cells-of-origin of gastric cancer, although little is known about their molecular characteristics and specific biological markers are lacking. In this study, we developed a method for serial section-navigated laser microdissection to isolate cells from the proliferative isthmus zone of rat gastric oxyntic mucosa for genome-wide microarray gene expression analysis. Enrichment analysis showed a distinct gene expression profile for the isthmus zone, with genes regulating intracellular processes such as the cell cycle and ribosomal activity. The profile was also related to stem cell transcriptional networks and stomach neoplasia. Genes expressed uniquely in the isthmus zone were associated with E2F transcription factor 1 (E2F1), which participates in the self-renewal of stem cells and in gastric carcinogenesis. One of the unique genes was Aspm [Asp (abnormal spindle) homologue, microcephaly-associated (Drosophila)]. Here we show ASPM in single scattered epithelial cells located in the proliferative isthmus zone of rat, mouse and human oxyntic mucosa, which do not seem to be actively dividing. The ASPM-expressing cells are mainly mature cell marker-deficient, except for a limited overlap with cells with neuroendocrine and tuft cell features. Further, both ASPM and E2F1 were expressed in human gastric cancer cell lines and increased and correlated in human gastric adenocarcinomas compared to non-tumour mucosa, as shown by expression profile analyses and immunohistochemistry. The association between ASPM and the transcription factor E2F1 in gastric tissue is relevant, due to their common involvement in crucial cell fate-regulatory mechanisms. Our results thus introduce ASPM as a novel possible oxyntic stem/progenitor cell marker that may be involved in both normal gastric physiology and gastric carcinogenesis.

Sox4-mediated caldesmon expression facilitates differentiation of skeletal myoblasts.

Caldesmon (CaD), which was originally identified as an actin-regulatory protein, is involved in the regulation of diverse actin-related signaling processes, including cell migration and proliferation, in various cells. The cellular function of CaD has been studied primarily in the smooth muscle system; nothing is known about its function in skeletal muscle differentiation. In this study, we found that the expression of CaD gradually increased as differentiation of C2C12 myoblasts progressed. Silencing of CaD inhibited cell spreading and migration, resulting in a decrease in myoblast differentiation. Promoter analysis of the caldesmon gene (Cald1) and gel mobility shift assays identified Sox4 as a major trans-acting factor for the regulation of Cald1 expression during myoblast differentiation. Silencing of Sox4 decreased not only CaD protein synthesis but also myoblast fusion in C2C12 cells and myofibril formation in mouse embryonic muscle. Overexpression of CaD in Sox4-silenced C2C12 cells rescued the differentiation process. These results clearly demonstrate that CaD, regulated by Sox4 transcriptional activity, contributes to skeletal muscle differentiation.

Glucocorticoid suppresses dendritic spine development mediated by down-regulation of caldesmon expression.

Glucocorticoids (GCs) mediate the effects of stress to cause structural plasticity in brain regions such as the hippocampus, including simplification of dendrites and shrinkage of dendritic spines. However, the molecular mechanics linking stress and GCs to these effects remain largely unclear. Here, we demonstrated that corticosterone (CORT) reduces the expression levels of caldesmon (CaD), causing dendritic spines to become vulnerable. CaD regulates cell motility by modulating the actin-myosin system and actin filament stability. In cultured rat hippocampal neurons, CaD localized to dendritic spines by binding to filamentous actin (F-actin), and CaD expression levels increased during spine development. CaD stabilized the F-actin dynamics in spines, thereby enlarging the spine heads, whereas CaD knockdown decreased the spine-head size via destabilization of the F-actin dynamics. CaD was also required for chemical LTP-induced actin stabilization. The CaD expression levels were markedly decreased by exposure to CORT mediated by suppression of serum response factor-dependent transcription. High CORT levels reduced both the spine-head size and F-actin stability similarly to CaD knockdown, and overexpressing CaD abolished the detrimental effect of CORT on dendritic spine development. These results indicate that CaD enlarges the spine-head size by stabilizing F-actin dynamics, and that CaD is a critical target in the GC-induced detrimental effects on dendritic spine development.

Androglobin: a chimeric globin in metazoans that is preferentially expressed in Mammalian testes.

Comparative genomic studies have led to the recent identification of several novel globin types in the Metazoa. They have revealed a surprising evolutionary diversity of functions beyond the familiar O(2) supply roles of hemoglobin and myoglobin. Here we report the discovery of a hitherto unrecognized family of proteins with a unique modular architecture, possessing an N-terminal calpain-like domain, an internal, circular permuted globin domain, and an IQ calmodulin-binding motif. Putative orthologs are present in the genomes of many metazoan taxa, including vertebrates. The calpain-like region is homologous to the catalytic domain II of the large subunit of human calpain-7. The globin domain satisfies the criteria of a myoglobin-like fold but is rearranged and split into two parts. The recombinantly expressed human globin domain exhibits an absorption spectrum characteristic of hexacoordination of the heme iron atom. Molecular evolutionary analyses indicate that this chimeric globin family is phylogenetically ancient and originated in the common ancestor to animals and choanoflagellates. In humans and mice, the gene is predominantly expressed in testis tissue, and we propose the name "androglobin" (Adgb). Expression is associated with postmeiotic stages of spermatogenesis and is insensitive to experimental hypoxia. Evidence exists for increased gene expression in fertile compared with infertile males.

Overexpression of caldesmon is associated with lymph node metastasis and poorer prognosis in patients with oral cavity squamous cell carcinoma.

BACKGROUND: A previous comparative tissue proteomics study by the authors of the current study led to the identification of caldesmon (CaD) as one of the proteins associated with cervical metastasis of oral cavity squamous cell carcinoma (OSCC). In the current investigation, the authors focused on the potential functions of CaD in patients with OSCC. METHODS: CaD expression was examined in tissue samples from 155 patients using immunohistochemical analysis. The expression of CaD variants was determined by Western blot analysis and reverse transcriptase-polymerase chain reaction. In addition, the specific effects of CaD gene overexpression and silence were determined in OSCC cell lines. RESULTS: CaD expression was found to be significantly higher in tumor cells from metastatic lymph nodes compared with primary tumor cells, and was nearly absent in normal oral epithelia. Higher CaD expression was found to be correlated with positive N classification, poor differentiation, perineural invasion, and tumor depth (P = .001, P = .029, P = .001, and P = .031, respectively). In survival analyses, OSCC patients with higher CaD expression were found to have poorer prognosis with regard to disease-specific survival and disease-free survival (P = .003 and P = .014, respectively). Multivariate analyses further indicated that higher CaD expression was an independent predictor of disease-specific survival (P = .043). Serum CaD levels were found to be significantly higher in patients with OSCC, but this finding was not associated with clinicopathological manifestations. Data obtained from in vitro suppression, rescue, and overexpression of CaD in OEC-M1 cells indicated that CaD promotes migration and invasive processes in OSCC cells. CONCLUSIONS: The findings of the current study collectively suggest that the low-molecular-weight CaD expression in OSCC tumors is associated with tumor metastasis and patient survival.

mRNA and protein levels of FUS, EWSR1, and TAF15 are upregulated in liposarcoma.

Translocations or mutations of FUS, EWSR1, and TAF15 (FET) result in distinct genetic diseases. N-terminal translocations of any FET protein to a series of transcription factors yields chimeric proteins that contribute to sarcomagenesis, whereas mutations in the conserved COOH-terminal domain of wild-type FUS were recently shown to cause familial amyotrophic lateral sclerosis. We thus investigated whether the loss of one FUS allele by translocation in liposarcoma may be followed by mutations in either the remaining FUS allele or the paralogous EWSR1. Furthermore, we investigated the strength of the FET promoters and their contributions to sarcomagenesis given the proteins' frequent involvement in oncogenic translocations. We sequenced the respective genomic regions of both FUS and EWSR1 in 96 liposarcoma samples. Additionally, we determined FET transcript and protein levels in several liposarcoma cell lines. We did not observe sequence variations in either FUS or EWSR1. However, protein copy numbers reached an impressive 0.9 and 5.5 Mio of FUS and EWSR1 per tumor cell, respectively. Compared with adipose-derived stem cells, FUS and EWSR1 protein expression levels were elevated on average 28.6-fold and 7.3-fold, respectively. TAF15 mRNA levels were elevated on average 3.9-fold, although with a larger variation between samples. Interestingly, elevated TAF15 mRNA levels did not translate to strongly elevated protein levels, consistent with its infrequent occurrence as translocation partner in tumors. These results suggest that the powerful promoters of FET genes are predominantly responsible for the oncogenic effect of transcription factor translocations in sarcomas.

Epigenetic modifications precede molecular alterations and drive human hepatocarcinogenesis.

Development of primary liver cancer is a multistage process. Detailed understanding of sequential epigenetic alterations is largely missing. Here, we performed Infinium Human Methylation 450k BeadChips and RNA-Seq analyses for genome-wide methylome and transcriptome profiling of cirrhotic liver (n = 7), low- (n = 4) and high-grade (n = 9) dysplastic lesions, and early (n = 5) and progressed (n = 3) hepatocellular carcinomas (HCC) synchronously detected in 8 patients with HCC with chronic hepatitis B infection. Integrative analyses of epigenetically driven molecular changes were identified and validated in 2 independent cohorts comprising 887 HCCs. Mitochondrial DNA sequencing was further employed for clonality analyses, indicating multiclonal origin in the majority of investigated HCCs. Alterations in DNA methylation progressively increased from liver cirrhosis (CL) to dysplastic lesions and reached a maximum in early HCCs. Associated early alterations identified by Ingenuity Pathway Analysis (IPA) involved apoptosis, immune regulation, and stemness pathways, while late changes centered on cell survival, proliferation, and invasion. We further validated 23 putative epidrivers with concomitant expression changes and associated with overall survival. Functionally, Striatin 4 (STRN4) was demonstrated to be epigenetically regulated, and inhibition of STRN4 significantly suppressed tumorigenicity of HCC cell lines. Overall, application of integrative genomic analyses defines epigenetic driver alterations and provides promising targets for potentially novel therapeutic approaches.

Prostaglandin E2 and other cyclic AMP elevating agents inhibit interleukin 2 gene transcription by counteracting calcineurin-dependent pathways.

We have previously shown that prostaglandin E2 and other cAMP elevating agents inhibit the nuclear transcription of the human IL-2 gene by interfering with a Ca(2+)-sensitive T cell signal transduction pathway. Calcineurin, a Ca2+/calmodulin-dependent 2B protein phosphatase, is an essential component of the T cell receptor signal transduction pathway leading to IL-2 gene expression. We have therefore tested the hypothesis that this phosphatase may be a target for the inhibitory effects of cAMP on IL-2 gene transcription. We report here that PGE2 markedly reduces the IL-2 promoter activity that is induced by a constitutively active form of calcineurin. In contrast to the complete inhibition of promoter activity produced by the immunosuppressants cyclosporin A and FK-506, this partial block suggests that PGE2 modulates downstream events needed for lymphokine gene activation. Overexpression of calcineurin in Jurkat cells decreases their apparent sensitivity to the inhibitory effects of PGE2 consistent with the fact that this enzyme plays a physiological role in dephosphorylating substrates of cAMP-dependent kinases in several tissues. These results provide evidence that cAMP-dependent pathways may antagonize calcineurin-regulated cascades for T cell activation in vivo, and suggest crosstalk between the Ca2+ and the cAMP signaling pathways during T cell activation.

Adding myofibroblasts to the lacrimal pump.

The lacrimal sac (LS) empties in the nasolacrimal duct to drain the tears in the inferior nasal meatus. Different studies indicated the role of the lacrimal pump in the lacrimal drainage. Although controversial, the lacrimal pump mechanism is an extrinsic one, either active, or passive. An intrinsic contractile potential of the LS was not documented previously. We thus aimed a retrospective immunohistochemical study to test the alpha-smooth muscle actin (α-SMA) and h-caldesmon expression in the LS wall. We used archived paraffin-embedded samples of LS from ten adult patients. The α-SMA + phenotype was detected in basal epithelial cells, in subepithelial ribbons of stromal cells, in vascular smooth muscle cells, as well as in pericytes. H-caldesmon was exclusively expressed in pericytes, vascular smooth muscle cells and myoepithelial cells of the subepithelial glands. The most striking feature we found in all samples was a consistent stromal network of α-SMA+/h-caldesmon- myofibroblasts. This finding supports an intrinsic scaffold useful for the lacrimal pump.

Assessing the effects of transforming growth factor-beta1 on bladder smooth muscle cell phenotype. I. Modulation of in vitro contractility.

PURPOSE: Modulation of the bladder smooth muscle cell phenotype contributes to the resulting bladder dysfunction in many pathological bladder conditions. Transforming growth factor-beta1 is an important regulator of cellular phenotype in fibrotic diseases that has specific effects on bladder smooth muscle cells associated with phenotypic changes. We verified transforming growth factor-beta1 expression in neurogenic bladder tissue and investigated its effects on bladder smooth muscle cell collagen gel contraction. MATERIALS AND METHODS: Transforming growth factor-beta1 immunostaining was performed on tissue sections from spinalized rats and quantified based on the ratio of fluorescence to total detrusor area. Rat bladder smooth muscle cells were seeded at different densities on anchored collagen gels and the effect of transforming growth factor-beta1 on contractility was assessed by measuring changes in the collagen gel area with time. Phenotypic changes induced by transforming growth factor-beta1 were detected by immunostaining for caldesmon and the specific isoform high molecular weight caldesmon. RESULTS: Transforming growth factor-beta1 immunostaining revealed increased levels specifically in the detrusor of spinal cord injured rats. Rat bladder smooth muscle cell contraction increased with larger cell populations and was inhibited by transforming growth factor-beta1. Transforming growth factor-beta1 induced a decrease in high molecular weight caldesmon expression in bladder smooth muscle cells. CONCLUSIONS: Increased transforming growth factor-beta1 expression in the detrusor of spinal cord injured rats implies up-regulation and localized signaling in response to injury. Bladder smooth muscle cells showed a loss of contractility in response to transforming growth factor-beta1 in all cell populations. A shift in phenotype was confirmed by high molecular weight caldesmon immunostaining. These results suggest that transforming growth factor-beta1 can modulate bladder smooth muscle cell function and may be a crucial regulator of bladder smooth muscle cell phenotype in pathological bladder conditions.

[Mesenchymal uterine tumors. Leiomyomas]. / Mesenchymale Uterustumoren. Leiomyogene Tumoren.

Leiomyomas are by far the most frequent mesenchymal uterine neoplasms. Leiomyoma variants refer to a particular histological differentiation and growth pattern, respectively. To assess malignancy, an algorithm is used based on the presence or absence of cellular atypia, tumor cell necrosis and mitosis. In addition, vascular invasion is a criterion for malignancy. Ischemic or infarct type necrosis is not considered a criterion for malignancy. The differential diagnosis of leiomyosarcoma includes cellular and mitotically active leiomyoma and leiomyoma with extensive infarct type necrosis (apoplectic leiomyoma). The term smooth muscle tumor of uncertain malignant potential (STUMP) should be reserved for tumors with uncertainty regarding cell type, type of necrosis and mitotic index, as well as for special cases of myxoid and epithelioid smooth muscle neoplasms. Immunohistochemically, the expression of desmin and caldesmon is indicative of smooth muscle tumors, while stromal tumors can express smooth muscle actin and, rarely, desmin in addition to CD10.

MicroRNA Expression Profiling Screen miR-3557/324-Targeted CaMK/mTOR in the Rat Striatum of Parkinson's Disease in Regular Aerobic Exercise.

This study aimed to screen the target miRNAs and to investigate the differential miR-3557/324-targeted signal mechanisms in the rats' model of Parkinson's disease (PD) with regular aerobic exercise. Rats were divided into sedentary control PD group (SED-PD, n = 18) and aerobic exercise PD group (EX-PD, n = 22). After 8 weeks of regular aerobic exercise, a 6-hydroxydopamine- (6-OHDA-) induced PD lesion model was constructed. Preregular aerobic exercises enhanced the injury resistance of rats with 6-OHDA-induced PD. The rotational behavior after injection of apomorphine hydrochloride was alleviated. Under the scanning electron microscopy, we found the neurons, axons, and villi of the striatum were clearly and tightly arranged, and neurons and axons significantly becoming larger. Tyrosine hydroxylase (TH) was increased significantly and α-synuclein protein expression was reduced in the EX-PD group compared to the SED-PD group. Screening from miRNA microarray chip, we further found upregulation of miR-3557 and downregulation of miR-324 were closely related to the calcium-modulating signaling pathway, remitting the progress of Parkinson's disease on aerobic exercise. Compared to the SED-PD group, Ca2+/calmodulin dependent protein kinase II (CaMK2α) was upregulated, but CaMKV and voltage-dependent anion-selective channel protein 1 (Vdac1) were significantly downregulated in the EX-PD group. Additionally, phosphatidylinositol-3-kinase (PI3K)/mammalian target of rapamycin (mTOR) expression were activated, and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) expression was upregulated in the EX-PD group. Conclusions: the adaptive mechanism of regular aerobic exercise delaying neurodegenerative diseases and lesions was that miR-3557/324 was activated to regulate one of its targets CaMKs signaling pathways. CaMKs, coordinated with mTOR pathway-related gene expression, improved UCH-L1 level to favor for delaying neurodegeneration or improving the pathogenesis of PD lesions.

Adducins inhibit lung cancer cell migration through mechanisms involving regulation of cell-matrix adhesion and cadherin-11 expression.

Cell migration is a critical mechanism controlling tissue morphogenesis, epithelial wound healing and tumor metastasis. Migrating cells depend on orchestrated remodeling of the plasma membrane and the underlying actin cytoskeleton, which is regulated by the spectrin-adducin-based membrane skeleton. Expression of adducins is altered during tumorigenesis, however, their involvement in metastatic dissemination of tumor cells remains poorly characterized. This study investigated the roles of α-adducin (ADD1) and γ-adducin (ADD3) in regulating migration and invasion of non-small cell lung cancer (NSCLC) cells. ADD1 was mislocalized, whereas ADD3 was markedly downregulated in NSCLC cells with the invasive mesenchymal phenotype. CRISPR/Cas9-mediated knockout of ADD1 and ADD3 in epithelial-type NSCLC and normal bronchial epithelial cells promoted their Boyden chamber migration and Matrigel invasion. Furthermore, overexpression of ADD1, but not ADD3, in mesenchymal-type NSCLC cells decreased cell migration and invasion. ADD1-overexpressing NSCLC cells demonstrated increased adhesion to the extracellular matrix (ECM), accompanied by enhanced assembly of focal adhesions and hyperphosphorylation of Src and paxillin. The increased adhesiveness and decreased motility of ADD1-overexpressing cells were reversed by siRNA-mediated knockdown of Src. By contrast, the accelerated migration of ADD1 and ADD3-depleted NSCLC cells was ECM adhesion-independent and was driven by the upregulated expression of pro-motile cadherin-11. Overall, our findings reveal a novel function of adducins as negative regulators of NSCLC cell migration and invasion, which could be essential for limiting lung cancer progression and metastasis.

[Caldesmon changes the structure of actin at the leading edge and suppresses cell migration].

The effect of the suppression of expression of the actin-binding protein caldesmon on the motility of nonmuscle cells has been studied. A more than fivefold decrease in the content of this protein in cells by RNA interference led to the disturbance of the formation of actin stress fibrils and acceleration of cell migration to the zone of injury of the monolayer. A stimulation of stationary cells by serum induced a more than 1.5-fold accumulation of stress fibrils only in control cells but not in caldesmon-deficient cells. Similarly, the accumulation of actin filaments was observed in actively migrating cells of only wild type but not in cells with a low caldesmon content. These changes occurred mainly at the leading edge of the migrating cell where the distinct structure of actin filaments was not seen in the absence of caldesmon. It was assumed that caldesmon inhibits cell migration due to the stabilization of actin in filaments and a decrease in the dynamics of monomeric actin at the leading edge of the migrating cell.

TGFß1-induced expression of caldesmon mediates epithelial-mesenchymal transition.

Epithelial-mesenchymal transition (EMT) is an important process that mediates organ development and wound healing, and in pathological contexts, it can contribute to the progression of fibrosis and cancer. During EMT, cells exhibit marked changes in cytoskeletal organization and increased expression of a variety of actin associated proteins. Here, we sought to determine the role of caldesmon in mediating EMT in response to transforming growth factor (TGF)-ß1. We find that the expression level and phosphorylation state of caldesmon increase as a function of time following induction of EMT by TGFß1 and these changes in caldesmon correlate with increased focal adhesion number and size and increased cell contractility. Knockdown and forced expression of caldesmon in epithelial cells reveals that caldesmon expression plays an important role in regulating the expression of the myofibroblast marker alpha smooth muscle actin. Results from these studies provide insight into the role of cytoskeletal associated proteins in the regulation of EMT and may suggest ways to target the cell cytoskeleton for regulating EMT processes.