Human chromokinesin KIF4A functions in chromosome condensation and segregation

Accurate chromosome alignment at metaphase and subsequent segregation of condensed chromosomes is a complex process involving elaborate and only partially characterized molecular machinery. Although several spindle associated molecular motors have been shown to be essential for mitotic function, only a few chromosome arm--associated motors have been described. Here, we show that human chromokinesin human HKIF4A (HKIF4A) is an essential chromosome-associated molecular motor involved in faithful chromosome segregation. HKIF4A localizes in the nucleoplasm during interphase and on condensed chromosome arms during mitosis. It accumulates in the mid-zone from late anaphase and localizes to the cytokinetic ring during cytokinesis. RNA interference--mediated depletion of HKIF4A in human cells results in defective prometaphase organization, chromosome mis-alignment at metaphase, spindle defects, and chromosome mis-segregation. HKIF4A interacts with the condensin I and II complexes and HKIF4A depletion results in chromosome hypercondensation, suggesting that HKIF4A is required for maintaining normal chromosome architecture. Our results provide functional evidence that human KIF4A is a novel component of the chromosome condensation and segregation machinery functioning in multiple steps of mitotic division.     

Distinct Roles for Rho Versus Rac/Cdc42 GTPases Downstream of Vav2 in Regulating Mammary Epithelial Acinar Architecture

Non-malignant mammary epithelial cells (MECs) undergo acinar morphogenesis in three-dimensional Matrigel culture, a trait that is lost upon oncogenic transformation. Rho GTPases are thought to play important roles in regulating epithelial cell-cell junctions, but their contributions to acinar morphogenesis remain unclear. Here we report that the activity of Rho GTPases is down-regulated in non-malignant MECs in three-dimensional culture with particular suppression of Rac1 and Cdc42. Inducible expression of a constitutively active form of Vav2, a Rho GTPase guanine nucleotide exchange factor activated by receptor tyrosine kinases, in three-dimensional MEC culture activated Rac1 and Cdc42; Vav2 induction from early stages of culture impaired acinar morphogenesis, and induction in preformed acini disrupted the pre-established acinar architecture and led to cellular outgrowths. Knockdown studies demonstrated that Rac1 and Cdc42 mediate the constitutively active Vav2 phenotype, whereas in contrast, RhoA knockdown intensified the Vav2-induced disruption of acini, leading to more aggressive cell outgrowth and branching morphogenesis. These results indicate that RhoA plays an antagonistic role to Rac1/Cdc42 in the control of mammary epithelial acinar morphogenesis.     

Human digestive and metabolic lipases—a brief review

The major human lipases include the gastric, pancreatic and bile-salt-stimulated lipase that aid in the digestion and assimilation of dietary fats, and the hepatic, lipoprotein and endothelial lipase that function in the metabolism of lipoproteins. The triacylglycerol and phopholipase activities of these enzymes enable these varied functions. The lipase enzymes exhibit a high degree of sequence homology not only within but also across species. This and the diverse chromosomal location of their genes point to a multigenic family of enzymes involved in absorption and transport of lipids. Inactivation of lipolytic activity of microorganisms to control infection, inhibition of digestive lipase to control obesity, stimulation of metabolic lipase to reduce hyperlipidemia or procoagulant state, or use of pancreatic lipase supplement in the management of cystic fibrosis are examples of how lipase activity modulation can impact human health.     

Skin mucus proteins of lumpsucker (Cyclopterus lumpus)

Fish skin mucus serves as a first line of defense against pathogens and external stressors. In this study the proteomic profile of lumpsucker skin mucus was characterized using 2D gels coupled with tandem mass spectrometry. Mucosal proteins were identified by homology searches across the databases SwissProt, NCBInr and vertebrate EST. The identified proteins were clustered into ten groups based on their gene ontology biological process in PANTHER (www.patherdb.org). Calmodulin, cystatin-B, histone H2B, peroxiredoxin1, apolipoprotein A1, natterin-2, 14-3-3 protein, alfa enolase, pentraxin, warm temperature acclimation 65 kDa (WAP65kDa) and heat shock proteins were identified. Several of the proteins are known to be involved in immune and/or stress responses. Proteomic profile established in this study could be a benchmark for differential proteomics studies.     

Tumor formation via loss of a molecular motor protein

Aneuploidy has long been suggested to be causal in tumor formation. Direct testing of this hypothesis has been difficult because of the absence of methods to specifically induce aneuploidy. The chromosome-associated kinesin motor KIF4 plays multiple roles in mitosis, and its loss leads to multiple mitotic defects including aneuploidy. Here, we have taken advantage of the direct formation of aneuploidy in the absence of KIF4 to determine whether loss of a molecular motor and generation of aneuploidy during mitosis can trigger tumorigenesis. We find that embryonic stem cells genetically depleted of KIF4 support anchorage-independent growth and form tumors in nude mice. In cells lacking KIF4, mitotic spindle checkpoints and DNA-damage response pathways are activated. Down regulation or loss of KIF4 is physiologically relevant because reduced KIF4 levels are present in 35% of human cancers from several tissues. Our results support the notion that loss of a molecular motor leads to tumor formation and that aneuploidy can act as a primary trigger of tumorigenesis.     

Genome sequences of Salmonella enterica serovar typhimurium, Choleraesuis, Dublin, and Gallinarum strains of well- defined virulence in food-producing animals

Salmonella enterica is an animal and zoonotic pathogen of worldwide importance and may be classified into serovars differing in virulence and host range. We sequenced and annotated the genomes of serovar Typhimurium, Choleraesuis, Dublin, and Gallinarum strains of defined virulence in each of three food-producing animal hosts. This provides valuable measures of intraserovar diversity and opportunities to formally link genotypes to phenotypes in target animals.     

A single-nucleotide polymorphism in tumor necrosis factor-α (− 308 G/A) as a biomarker in chronic pancreatitis

Objective

Chronic pancreatitis is a gradual, long-term inflammation of the pancreas that results in alteration of its normal structure and function. The study aims to investigate the role of − 308 (G/A) polymorphism of TNF-α gene in chronic pancreatitis.

Material and methods

A total of 200 subjects were included in this case–control study. A total of 100 in patients admitted in the Gastroenterology Unit of Gandhi Hospital and Osmania General Hospital, Hyderabad were included in the present study. An equal number of healthy control subjects were randomly selected for the study. The genotyping of TNF-α gene was carried out by tetra-primer ARMS PCR followed by gel electrophoresis. The TNF-α levels were assayed by enzyme-linked immunosorbent assay.

Results

A significant variation with respect to the genotypic and allelic distribution in the disease group when compared to control subjects [OR = 2.001 (1.33–3.005), p < 0.0001**] was observed. Subjects homozygous for the A allele had higher TNF-α levels compared to G allele.

Conclusion

The present study revealed a significant association of the TNF-α gene promoter polymorphism with chronic pancreatitis. Thus, TNF-α genotype can be considered as one of the biological markers in the etiology of chronic pancreatitis.