Expression pattern of an evolutionarily conserved splice variant in the rat Tacc2 gene

The transforming acidic coiled‐coil containing protein 2 (Tacc2) gene and its paralogs, Tacc1 and Tacc3 encode proteins that are associated with the centrosome and involved in microtubule assembly during the cell cycle. Tacc2 produces several splice variants, which are poorly characterized, especially in the rat. Characterization of the temporal/spatial expression patterns of these isoforms would be useful in understanding their distinct and overlapping functions. By comparative sequence analyses of Tacc2 in multiple species, we identified a third splice variant in rat, which is much shorter in size (1,021 aa) than the longest isoform (2,834 aa). This newly identified Tacc2 splice variant (isoform 3) uses a distinct first exon and generates a different open reading frame. Although Isoform 3 is expressed predominantly during developmental stages, the long Tacc2 isoform (isoform 1) is distributed mainly in adult tissues. Multiple protein sequence analyses revealed that Tacc2 Isoform 3 could be the ancient form, as it is conserved in mammals, birds, and amphibians; whereas the long Tacc2 isoforms may have evolved in the mammalian lineage by adding exons toward the 5′ region of the ancient isoform. genesis 52:378–386, 2014. © 2014 Wiley Periodicals, Inc.     

Overexpression of human CUTA isoform2 enhances the cytotoxicity of copper to HeLa cells

Copper, an essential transient element, can be toxic to cells when present in excess. Altered copper homeostasis is involved in pathological events of many diseases. Human CUTA isoform2 is a member of cation tolerance protein (CutA1) family. In this study, we examined the effect of CUTA isoform2 overexpression on copper toxicity. It was shown that overexpressed CUTA isoform2 sensitized HeLa cells to copper toxicity by promoting copper-induced apoptosis. The inhibition effect of excessive copper on cell proliferation was also enhanced by overexpressed CUTA isoform2. So CUTA isoform2 was implicated to be involved in the cytotoxicity of copper.     

Chromosomal assignment of two myosin alkali light-chain genes encoding the ventricular/slow skeletal muscle isoform and the atrial/fetal muscle isoform (MYL3, MYL4)

Summary In all eukaryotes, myosin plays a major role in the maintenance of cell shape and in cellular movement; in association with actin and other contractile proteins it is also a major structural component of the muscle sarcomere. Several isoforms of myosin alkali light chain have been identified, associated with different muscle types. We have recently localized the gene encoding the fast skeletal muscle alkali light-chain isoforms MLC1_F and MLC3_F (HGM symbol, MYL1) to human chromosome 2q32.1-qter (Cohen-Haguenauer 1988). We present here the chromosomal assignment of two loci encoding the ventricular muscle isoform MLC1_V (equivalent to the slow skeletal muscle isoform MLC1_Sb) and the atrial muscle isoform MLC1_A (equivalent to the fetal isoform MLC1_emb) using a panel of 25 independent man-rodent somatic cell hybrids. The MLC1_V gene (HGM symbol, MYL3) was mapped to human chromosome 3 using a human full-length cDNA probe that hybridizes to a single major human TaqI 2.8-kb fragment. The MLC1_A probe (HGM symbol, MYL4) was a 360-bp mouse cDNA fragment that gave a distinct signal with human DNA using low stringency conditions of hybridization and washings and after presaturation of the Southern blots with rodent DNA. A single PstI 7.8-kb fragment gives an intense signal, and its presence correlates with the presence of chromosome 17 among the hybrids. These data are in keeping with the localizations of the MLC1_V gene to mouse chromosome 9, and of the MLC1_A gene to mouse chromosome 11, which share some markers in common with human chromosomes 3 and 17 respectively.     

The C. elegans nck-1 gene encodes two isoforms and is required for neuronal guidance

The NCK adaptor proteins are composed entirely of SH3 and SH2 domains and serve as protein interaction bridges for several receptors during signal transduction events. Here we report the molecular and genetic analysis of the Caenorhabditis elegans nck-1 gene. C. elegans nck-1 encodes two isoforms: NCK-1A and a shorter isoform that lacks the first SH3 domain, NCK-1B. C. elegans nck-1 mutants exhibit defects in axon guidance and neuronal cell position, as well as defects in the excretory canal cell, gonad, and male mating. NCK-1 is broadly expressed in neurons and epithelial cells with NCK-1B being the most abundant isoform. NCK-1A and NCK-1B share a similar expression pattern in parts of the nervous system, but also have independent expression patterns in other tissues. Interestingly, NCK-1B is localized to the nuclei of many cells. Genetic rescue experiments show that NCK-1 functions cell autonomously and, in general, either NCK-1A or NCK-1B is sufficient to function in axon guidance. However, there appears to be specific roles for each isoform, for example NCK-1B is required for HSN cell migration while NCK-1A is required for efficient male mating. Genetic epistasis experiments show that NCK-1 functions redundantly with the LAR Receptor Tyrosine Phosphatase, PTP-3, and the Netrin receptor UNC-40.