Nuclear actin and nuclear myosins have been implicated in the regulation of gene expression in vertebrate cells. Myosin V is a class of actin-based motor proteins involved in cytoplasmic vesicle transport and anchorage, spindle-pole alignment and mRNA translocation. In this study, myosin-Va, phosphorylated on a conserved serine in the tail domain (phospho-ser(1650) MVa), was localized to subnuclear compartments. A monoclonal antibody, 9E6, raised against a peptide corresponding to phosphoserine(1650) and flanking regions of the murine myosin Va sequence, was immunoreactive to myosin Va heavy chain in cellular and nuclear extracts of HeLa cells, PC12 cells and B16-F10 melanocytes. Immunofluorescence microscopy with this antibody revealed discrete irregular spots within the nucleoplasm that colocalized with SC35, a splicing factor that earmarks nuclear speckles. Phospho-ser(1650) MVa was not detected in other nuclear compartments, such as condensed chromatin, Cajal bodies, gems and perinucleolar caps. Although nucleoli also were not labeled by 9E6 under normal conditions, inhibition of transcription in HeLa cells by actinomycin D caused the redistribution of phospho-ser(1650) MVa to nucleoli, as well as separating a fraction of phospho-ser(1650) MVa from SC35 into near-neighboring particles. These observations indicate a novel role for myosin Va in nuclear compartmentalization and offer a new lead towards the understanding of actomyosin-based gene regulation.

Myosin-Va is a Ca(2+)/calmodulin-regulated unconventional myosin involved in the transport of vesicles, membranous organelles, and macromolecular complexes composed of proteins and mRNA. The cellular localization of myosin-Va has been described in great detail in several vertebrate cell types, including neurons, melanocytes, lymphocytes, auditory tissues, and a number of cultured cells. Here, we provide an immunohistochemical view of the tissue distribution of myosin-Va in the major endocrine organs. Myosin-Va is highly expressed in the pineal and pituitary glands and in specific cell populations of other endocrine glands, especially the parafollicular cells of the thyroid, the principal cells of the parathyroid, the islets of Langerhans of the pancreas, the chromaffin cells of the adrenal medulla, and a subpopulation of interstitial testicular cells. Weak to moderate staining has been detected in steroidogenic cells of the adrenal cortex, ovary, and Leydig cells. Myosin-Va has also been localized to non-endocrine cells, such as the germ cells of the seminiferous epithelium and maturing oocytes and in the intercalated ducts of the exocrine pancreas. These data provide the first systematic description of myosin-Va localization in the major endocrine organs of rat.

A daily dose of 50 mg/kg body weight of Ginkgo biloba extract has a significant neuroprotector effect on the myenteric plexus of the ileum during the aging process in rats.

Endoplasmic Reticulum Membrane Complex protein 1 (EMC1), also named KIAA0090, was recently identified as part of a complex with six proteins (EMC1-EMC6) proposed to participate in the folding/maturation of membrane proteins, but the mechanisms remains unclear. High throughput studies reveal that EMC1 gene is up-regulated in many types of cancer and up-regulation correlates to poor survival rates. It has been known that there is a close relationship between proteins involved in the unfolded protein response (UPR) and tumor maintenance. Here, we investigated the involvement of EMC1 in breast cancer cell proliferation and migration. We showed by qPCR that EMC1 gene is overexpressed in breast cancer cell lines in comparison to immortalized epithelial breast cells. Next, we stably overexpressed EMC1 in MCF-7 and SKBR-3 cell lines. Overexpression led to an increase in proliferation rates, clonogenic capacity, and migration in wound-healing assays. Consistently, EMC1 knockdown in SKBR-3 cells led to a decrease of cell migration and clonogenic capacity. Furthermore, we assessed by Fluo3 the involvement of EMC1 in the regulation of intracellular calcium levels in SKBR-3 cells in response to thapsigargin treatment, which inhibits the endoplasmic reticulum Ca2+ ATPase. SKBR-3 control cells showed an expected increment in cytosolic calcium levels following thapsigargin addition. Interestingly, cytosolic calcium increments were about 50% higher in EMC1 overexpressing cells and nearly 10-fold lower in knockdown cells, suggesting a role for EMC1 in the control of cellular calcium homeostasis. EMC1 could function in the maturation/assembly of calcium channels or calcium pumps, thereby promoting breast cancer cell migration and maintenance. Citation Format: Roberto Augusto Silva Molina, Rodrigo Ribeiro Silva, Roberta Ribeiro Costa, Silmara Reis Banzi, Enilza Maria Espreafico. EMC1 influences cellular calcium homeostasis and promotes breast cancer cell migration and proliferation. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B41.