Background: Three genes encode human nonmuscle myosin II (NM II) heavy chains, and the proteins have different intracellular roles and localizations. Results: NM II paralogs form bipolar filaments, but there are important differences in filament structure, enzymatic, and actin binding behavior. Conclusion: NM II filaments show diverse interactions with actin. Significance: NM II filaments are adapted to work in cytoskeletal networks.

No abstract

Abstract. microRNAs are involved in different cancer-related processes. miR-195, one of the miR-16/15/195/424/497 family members, has been shown to act as a tumor suppressor during tumorigenesis. However, the function of miR-195 in osteosarcoma is still unclear. In our study, the miR-195 expression level was upregulated in osteosarcoma cells, by transfection with miR-195, and the fatty acid synthase (FASN) mRNA and protein expression levels were measured by RT-PCR and western blotting. Cell migration and invasion was measured using wound healing migration and Transwell invasion assays. We found that the upregulation of miR-195 greatly decreased cell invasion and the migration of U2OS. We also identified that FASN may be a direct target of miR-195 by the luciferase activity assay. These findings provide evidence that miR-195 plays a key role in inhibiting osteosarcoma cell migration and invasion through targeting FASN, and strongly suggest that exogenous miR-195 may have therapeutic value in treating osteosarcoma.

Mesenchymal stem cells (MSCs) have been demonstrated to be involved in tumor progression and the modulation of the tumor microenvironment, partly through their secretome. Extracellular vesicles (EVs) are membranous nanovesicles secreted by multiple types of cells and have been demonstrated to mediate intercellular communication in both physiological and pathological conditions. However, numerous questions still remain regarding the underlying mechanisms and functional consequences of these interactions. The purpose of this study was to investigate the effects of human umbilical cord mesenchymal stem cell-derived EVs (hUC-MSC-EVs) on the proliferation, migration and invasion of human breast cancer cells. We successfully generated and identified hUC-MSCs and hUC-MSC-EVs which were used in this study. The results revealed that treatment of the MDA-MB-231 and MCF-7 human breast cancer cells with medium containing hUC-MSC-EVs significantly enhanced the proliferation, migration and invasion of the cells in vitro. Treatment of the cells with medium containing hUC-MSC-EVs also reduced E-cadherin expression and increased N-cadherin expression, thus promoting the epithelial-mesenchymal transition (EMT) of the breast cancer cells. Treatment of the breast cancer cells with extracellular signal-regulated kinase (ERK) inhibitor prior to the interaction with hUC-MSC-EVs significantly reversed the enhanced proliferation, migration and invasion, as well as the EMT of the breast cancer cells induced by the hUC-MSC-EVs. On the whole, these data indicate that hUC-MSC-EVs promote the invasive and migratory potential of breast cancer cells through the induction of EMT via the ERK pathway, leading to malignant tumor progression and metastasis. Taken together, the findings of this study suggest that targeting pathways to reverse EMT may lead to the development of novel therapeutic approaches with which to combat breast cancer.

Numerous studies have recently suggested that miRNAs contribute to the development of various types of human cancer as well as to their invasive and metastatic capacities. The aim of this study was to investigate the functional significance of miR-424 and to identify its possible target genes in osteosarcoma (OS) cells. Previously, inhibition of fatty acid synthase (FASN) has been shown to suppress OS cell proliferation, invasion and migration. The prediction was made using the microRNA.org and TargetScan.human6.0.database. The results showed that FASN is a promising target gene of miR-424. FASN may be a direct target of miR-424 as shown by the luciferase reporter assays. Furthermore, miR-424 expression was increased in osteosarcoma cells by transfection with has-miR-424. FASN mRNA and protein expression levels were measured by RT-PCR and western blot analysis. Cell migration and invasion was measured using Transwell migration and Transwell invasion assays. Expression levels of FASN mRNA and protein were greatly decreased in U2OS cells transfected with has-miR-424. The migration and invasion of cells was significantly decreased by the upregulation of miR-424. These findings suggested that miR-424 plays a key role in inhibiting OS cell migration and invasion through targeting FASN.

Female germline or oogonial stem cells transiently residing in fetal ovaries are analogous to the spermatogonial stem cells or germline stem cells (GSCs) in adult testes where GSCs and meiosis continuously renew. Oocytes can be generated in vitro from embryonic stem cells and induced pluripotent stem cells, but the existence of GSCs and neo-oogenesis in adult mammalian ovaries is less clear. Preliminary findings of GSCs and neo-oogenesis in mice and humans have not been consistently reproducible. Monkeys provide the most relevant model of human ovarian biology. We searched for GSCs and neo-meiosis in ovaries of adult monkeys at various ages, and compared them with GSCs from adult monkey testis, which are characterized by cytoplasmic staining for the germ cell marker DAZL and nuclear expression of the proliferative markers PCNA and KI67, and pluripotencyassociated genes LIN28 and SOX2, and lack of nuclear LAMIN A, a marker for cell differentiation. Early meiocytes undergo homologous pairing at prophase I distinguished by synaptonemal complex lateral filaments with telomere perinuclear distribution. By exhaustive searching using comprehensive experimental approaches, we show that proliferative GSCs and neo-meiocytes by these specific criteria were undetectable in adult mouse and monkey ovaries. However, we found proliferative nongermline somatic stem cells that do not express LAMIN A and germ cell markers in the adult ovaries, notably in the cortex and granulosa cells of growing follicles. These data support the paradigm that adult ovaries do not undergo germ cell renewal, which may contribute significantly to ovarian senescence that occurs with age.

We report a novel isoform of non-muscle myosin II-C (NM II- Mammalian non-muscle myosin IIs (NM IIs)2 belong to the conventional Class II myosins and are hexameric proteins composed of two heavy chains and two pairs of light chains, referred as the 20-kDa regulatory myosin light chain (MLC 20 ) and the 17-kDa essential myosin light chain (MLC 17 ). These myosins self-associate through their tail regions to form bipolar filaments that pull on actin filaments to produce force to drive important cellular functions such as cytokinesis, cell polarity, and cell migration (1-4). Three isoforms of the non-muscle myosin heavy chain (NMHC), II-A, II-B, and II-C, have been identified in vertebrates. They are products of three different genes, MYH9 (5, 6), MYH10 (6), and MYH14 (7, 8), respectively, in humans. It is well established that the enzymatic activity of these myosins is regulated by phosphorylation of MLC 20 , which is catalyzed by a number of enzymes, including myosin light chain kinase (MLCK), and Rho kinase (9 -14).Alternative splicing of pre-mRNA of NMHC II genes generates multiple mRNAs to enhance protein diversity in the NM II family. Work from this laboratory and others (8,(15)(16)(17)(18) has established that both NMHC II-B and II-C undergo alternative splicing to generate several isoforms. In the case of NMHC II-B, 10 amino acids are incorporated into loop 1 at amino acid 212 (NMHC II-B1), and 21 amino acids are inserted into loop 2 at amino acid 622 (NMHC II-B2; see Ref. 15). These isoforms have been expressed as proteins, and their biochemical and functional importance has been studied extensively (19 -22). Recently, it has been reported that baculovirus-expressed heavy meromyosin (HMM) II-B2 lacks actin-activated MgATPase activity and cannot propel actin filaments in an in vitro motility assay following MLC 20 phosphorylation (22) even though HMM II-B0 and II-B1 show normal phosphorylation-dependent activities (21). These two inserted isoforms (NM II-B1 and NM II-B2) are only expressed in neuronal tissues, and the results of ablating each of them and NM II-B in mice have been reported (23)(24)(25).For NMHC II-C, an alternative exon encoding 8 amino acids is incorporated into loop 1 at amino acid 227 (NMHC II-C1) at a location homologous to that of the B1 insert. Unlike NMHC II-B1, which is only expressed in neuronal tissue, NMHC II-C1 is found in a variety of tissues such as liver, kidney, testes, brain, and lung (8). The presence of the C1 insert in baculovirusexpressed HMM II-C1 increases both the actin-activated MgATPase activity and in vitro motility of HMM II-C1 compared with HMM II-C0, the noninserted form. The activity of both HMM II-C0 and HMM II-C1 is dependent on MLC 20 phosphorylation (26). NM II-C1 has been shown to be expressed in a number of tumor cell lines, and decreasing its expression using small interfering RNA delays a late step in cytokinesis in the lung tumor cell line A549 (27).In this study, we report that an exon encoding 41 amino acids can be incorporated into loop 2 near the ...

No abstract