Protein kinase casein kinase II (Ck2) is a cyclic-AMP and calcium-independent serine-threonine kinase that is composed of two catalytic subunits (alpha and alpha') and two regulatory beta-subunits. Ck2 is not a casein kinase in vivo, but over 100 substrates are known. The highly conserved amino acid sequences of its subunits and their broad expression suggest that Ck2 may have a fundamental role in cell function. Ck2 has been implicated in DNA replication, regulation of basal and inducible transcription, translation and control of metabolism. The Ck2alpha and Ck2alpha' isoforms (products of the genes Csnk2a1 and Csnk2a2, respectively) are highly homologous, but the reason for their redundancy and evolutionary conservation is unknown. We find here that Csnk2a2 is preferentially expressed in late stages of spermatogenesis, and male mice in which Csnk2a2 has been disrupted are infertile, with oligospermia and globozoospermia ('round-headed' spermatozoa). This is the first demonstration of a unique role for a Ck2 isoform in development. The primary spermatogenic defect in Csnk2a2-/- testis is a specific abnormality of anterior head shaping of elongating spermatids; this is the first defined gene that regulates sperm head morphogenesis. As the germ cells differentiate, they are capable of undergoing chromatin condensation, although many abnormal cells are deleted through apoptosis or Sertoli cell phagocytosis. The few that survive to populate the epididymis exhibit head abnormalities similar to those described in human globozoospermia, thus Csnk2a2 may be a candidate gene for these inherited syndromes.

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An aerolysin-related cytotoxic enterotoxin (Act) of Aeromonas hydrophila possesses multiple biological activities, which include its ability to lyse red blood cells, destroy tissue culture cell lines, evoke a fluid secretory response in ligated intestinal loop models, and induce lethality in mice. The role of Act in the virulence of the organism has been demonstrated. In this study, we evaluated the potential of Act to induce production of proinflammatory cytokines associated with Act-induced tissue injury and Act's capacity to activate in macrophages arachidonic acid (AA) metabolism that leads to production of eicosanoids (e.g., prostaglandin E 2 [PGE 2 ]). Our data indicated that Act stimulated the production of tumor necrosis factor alpha and upregulated the expression of genes encoding interleukin-1␤ (IL-1␤) and IL-6 in the murine macrophage cell line RAW264.7. Act also activated transcription of the gene encoding inducible nitric oxide synthase. Act evoked the production of PGE 2 coupled to the cyclooxygenase-2 (COX-2) pathway. AA is a substrate for PGE 2 , and Act produced AA from phospholipids by inducing group V secretory phospholipase A 2 . We also demonstrated that Act increased cyclic AMP (cAMP) production in macrophages. cAMP, along with PGE 2 , could potentiate fluid secretion in animal models because of infiltration and activation of macrophages resulting from Act-induced tissue injury. After Act treatment of RAW cells, we detected an increased translocation of NF-B and cAMP-responsive element binding protein (CREB) to the nucleus using gel shift assays. Act also upregulated production of antiapoptotic protein Bcl-2 in macrophages, suggesting a protective role for Bcl-2 against cell death induced by proinflammatory cytokines. The increased expression of genes encoding the proinflammatory cytokines, COX-2, and Bcl-2 appeared correlated with the activation of NF-B and CREB. This is the first report of the detailed mechanisms of action of Act from A. hydrophila.Aeromonas spp. recently have been placed in the family Aeromonadaceae. They cause both intestinal and nonintestinal infections in humans (12), and, unlike gastroenteritis, which generally occurs in young children, these nonintestinal infections are often fatal and involve adults (36). Aeromonas spp. have been cultured from both freshwater and salt water and from many foods. These bacteria have emerged as important human pathogens and are being isolated in an increased incidence from patients with traveler's diarrhea (3,11,28,29,41,44,70). Aeromonas spp. produce an array of virulence factors, and the pathogenesis of Aeromonas infections is therefore complex and multifactorial (2). These virulence factors include hemolysins, cytotoxins, enterotoxins, proteases, lipases/phospholipases, leucocidin, endotoxin, fimbriae or adhesins, and the capacity to form an S-layer (17,45,47). Aeromonas hydrophila has been shown to be invasive for HEp-2 cell monolayers, and the bacterial cells adhere to human erythrocytes (6, 26). Two distinct families of type IV ...

In addition to the POR1 gene, which encodes the well-characterized voltage dependent anion-selective channel (YVDAC1) of the mitochondrial outer membrane, the yeast Saccharomyces cerevisiae contains a second gene (POR2) encoding a protein (YVDAC2) with 50% sequence identity to YVDAC1. Mitochondria isolated from yeast cells deleted for the POR1 gene (delta por1) had a profoundly reduced outer membrane permeability as measured by the ability of an intermembrane space dehydrogenase to oxidize exogenously added NADH. Mitochondria missing either YVDAC1 or both YVDAC1 and YVDAC2 showed a 2-fold increase in the rate of NADH oxidation when the outer membrane was deliberately damaged. Mitochondria from parental cells showed only a 10% increase indicating that the outer membrane is highly permeable to NADH. In the absence of YVDAC1, we calculate that the outer membrane permeability to NADH is reduced 20-fold. The low NADH permeability in the presence of YVDAC2 was not due to the low levels of YVDAC2 expression as mitochondria from cells expressing levels of YVDAC2 comparable to those of YVDAC1 in parental cells showed no substantial increase in NADH permeability, indicating a minimal role of YVDAC2 in this permeability. The residual permeability may be due to other pathways because cells missing both genes can still grow on nonfermentable carbon sources. However, YVDAC1 is clearly the major pathway for NADH flux through the outer membrane in these mitochondria.