Potent and selective small-molecule MCL-1 inhibitors demonstrate on-target cancer cell killing activity as single agents and in combination with ABT-263 (navitoclax)

The anti-apoptotic protein MCL-1 is a key regulator of cancer cell survival and a known resistance factor for small-molecule BCL-2 family inhibitors such as ABT-263 (navitoclax), making it an attractive therapeutic target. However, directly inhibiting this target requires the disruption of high-affinity protein-protein interactions, and therefore designing small molecules potent enough to inhibit MCL-1 in cells has proven extremely challenging. Here, we describe a series of indole-2-carboxylic acids, exemplified by the compound A-1210477, that bind to MCL-1 selectively and with sufficient affinity to disrupt MCL-1-BIM complexes in living cells. A-1210477 induces the hallmarks of intrinsic apoptosis and demonstrates single agent killing of multiple myeloma and non-small cell lung cancer cell lines demonstrated to be MCL-1 dependent by BH3 profiling or siRNA rescue experiments. As predicted, A-1210477 synergizes with the BCL-2/BCL-XL inhibitor navitoclax to kill a variety of cancer cell lines. This work represents the first description of small-molecule MCL-1 inhibitors with sufficient potency to induce clear on-target cellular activity. It also demonstrates the utility of these molecules as chemical tools for dissecting the basic biology of MCL-1 and the promise of small-molecule MCL-1 inhibitors as potential therapeutics for the treatment of cancer.

Human thioredoxin reductase directly reduces lipid hydroperoxides by NADPH and selenocystine strongly stimulates the reaction via catalytically generated selenols

Human placenta thioredoxin reductase (HP-TR) in the presence of NADPH-catalyzed reduction of (15S)-hydroperoxy-(5Z),(8Z),11(Z),13(E)-eicosatetraenoic acid ((15S)-HPETE) into the corresponding alcohol ((15S)-HETE). Incubation of 50 nM HP-TR and 0.5 mM NADPH with 300 microM 15-HPETE for 5 min resulted in formation of 16.5 microM 15-HETE. After 60 min, 74.7 microM 15-HPETE was reduced. The rate of the reduction of 15-HPETE by the HP-TR/NADPH peroxidase system was increased 8-fold by the presence of 2.5 microM selenocystine, a diselenide amino acid. In this case, 15-HPETE was catalytically reduced by the selenol amino acid, selenocysteine, generated from the diselenide by the HP-TR/NADPH system. To a smaller extent, selenodiglutathione or human thioredoxin also potentiated the reduction of 15-HPETE by HP-TR. Hydrogen peroxide and 15-HPETE were reduced at approximately the same rate by HP-TR, thioredoxin, and selenocystine. In contrast, t-butyl hydroperoxide was reduced at a 10-fold lower rate. Our data suggest two novel pathways for the reduction and detoxification of lipid hydroperoxides, hydrogen peroxide, and organic hydroperoxides, i.e. the human thioredoxin reductase-dependent pathway and a coupled reduction in the presence of selenols or selenide resulting from the reduction of selenocystine or selenodiglutathione.

Molecular cloning and mRNA tissue distribution of a novel matrix metalloproteinase isolated from porcine enamel organ

A cDNA encoding a novel matrix metalloproteinase (MMP) was isolated from a porcine enamel organ-specific cDNA library. Multiple tissue northern blot analysis revealed the presence of two mRNA transcripts which were expressed only in the enamel organ. The transcripts were 1968 bp or 3420 bp in length and resulted from the utilization of alternative polyadenylation sites. The open reading frame of the cloned mRNA encodes a protein composed of 483 amino acids. The MMP has a predicted molecular mass of 54.1 kDa, which is similar to that of the stromelysins or collagenases, although it is not a member of either of these two classes of MMPs. A motif analysis revealed that the cloned MMP does not contain a consensus hemopexin-like domain because it lacks a critical tryptophan and proline residue at the appropriate positions. Since the cloned MMP is a new member of the MMP gene family and its expression appears limited to the enamel organ, we have named it enamelysin.

Increased transcript level of RBM3, a member of the glycine-rich RNA-binding protein family, in human cells in response to cold stress

Although the cold-shock responses of microorganisms have been extensively investigated, those of mammalian cells are just beginning to be understood. Recently, CIRP, a member of the glycine-rich RNA-binding protein (GRP) family, has been identified as the first cold-shock protein in mammalian cells. Here, we report that RBM3, another member of the GRP family, is induced in human cells in response to cold stress (32 degrees C). RBM3 transcripts were constitutively expressed in all cell lines examined including K562, HepG2, NC65, HeLa, and T24 cells. In all of them, the transcript levels of RBM3 were increased at 24 h after the 37 to 32 degrees C temperature down-shift. In NC65 cells, the kinetics of RBM3 induction was different from that of CIRP. Protein synthesis inhibitors cycloheximide and puromycin induced RBM3 transcripts, but cadmium chloride, H2O2, ethanol, and osmotic shock had no effect. Combined with the different tissue distribution of expression, these results suggest that RBM3 and CIRP play distinct roles in cold responses of human cells.

Purification, characterization, and cloning of enamel matrix serine proteinase 1

The maturation of dental enamel succeeds the degradation of organic matrix. Inhibition studies have shown that this degradation is accomplished by a serine-type proteinase. To isolate and characterize cDNA clones encoding this proteinase, we used two degenerate primer approaches to amplify part of the coding region using polymerase chain-reaction (PCR). First, we purified the proteinase from porcine transition-stage enamel matrix and characterized it by partial protein sequencing. The enzyme was isolated from the neutral soluble enamel extract by successive ammonium sulfate precipitations, hydroxyapatite HPLC, reverse-phase HPLC, DEAE ion exchange, and affinity chromatography with a Benzamidine Sepharose 6B column. The intact protein and lysylendopeptidase-generated cleavage products were characterized by amino acid sequence analyses. Degenerate oligonucleotide primers encoding two of the polypeptide sequences were synthesized. In a complementary strategy, degenerate oligonucleotide primers were designed against highly conserved active-site regions of chymotrypsin-like proteinases. Both approaches yielded PCR amplification products that served as probes for screening a porcine enamel organ epithelia-specific cDNA library. The longest full-length clone is 1133 nucleotides and encodes a preproprotein of 254 amino acids. We designate this protein enamel matrix serine proteinase 1 or EMSP1. The active protein has 224 amino acids, an isotope-averaged molecular mass of 24.1 kDa, and an isoelectric point of 6.0. Multiple-tissue Northern analysis indicates that EMSP1 is a tooth-specific protein. Gelatin enzymography shows a dramatic increase in EMSP1 activity in the transition-stage enamel matrix. EMSP1 is most homologous to kallikriens and trypsins.

Differential gene expression of adenosine A1, A2a, A2b, and A3 receptors in the human enteric nervous system

Adenosine receptors (ADORs) in the enteric nervous system may be of importance in the control of motor and secretomotor functions. Gene expression and distribution of neural adenosine A1, A2a, A2b, or A3 receptors (Rs) in the human intestine was investigated using immunochemical, Western blotting, RT-PCR, and short-circuit current (I(sc)) studies. Adenosine A1R, A2aR, A2bR, or A3R mRNAs were differentially expressed in neural and nonneural layers of the jejunum, ileum, colon, and cecum and in HT-29, T-84, T98G, and Bon cell lines. A1R, A2aR, A2bR, and A3R immunoreactivities (IRs) were differentially expressed in PGP 9.5-immunoreactive neurons. A2bR IR occurs exclusively in 50% of submucosal vasoactive intestinal peptide (VIP) neurons (interneurons, secretomotor or motor neurons) in jejunum, but not colon; A2aR is also found in other neurons. A3R IR occurs in 57% of substance P-positive jejunal submucosal neurons (putative intrinsic primary afferent neurons) and less than 10% of VIP neurons. Western blots revealed bands for A3R at 44 kDa, 52 kDa, and 66 kDa. A2aR and A2bR are coexpressed in enteric neurons and epithelial cells. 5'-N-methylcarboxamidoadenosine or carbachol evoked an increase in I(sc). A2bR IR is more prominent than A2aR IR in myenteric neurons, nerve fibers, or glia. A1R is expressed in jejunal myenteric neurons and colonic submucosal neurons. Regional differences also exist in smooth muscle expression of ADOR IR(s). It is concluded that neural and nonneural A1, A2a, A2b, and A3Rs may participate in the regulation of neural reflexes in the human gut. Clear cell and regional differences exist in ADOR gene expression, distribution, localization, and coexpression.

Incomplete embryonic lethality and fatal neonatal hemorrhage caused by prothrombin deficiency in mice

Deficiency of blood coagulation factor V or tissue factor causes the death of mouse embryos by 10.5 days of gestation, suggesting that part of the blood coagulation system is necessary for development. This function is proposed to require either generation of the serine protease thrombin and cell signaling through protease-activated receptors or an activity of tissue factor that is distinct from blood clotting. We find that murine deficiency of prothrombin clotting factor 2 (Cf2) was associated with the death of approximately 50% of Cf2(-/-) embryos by embryonic day 10.5 (E10.5), and surviving embryos had characteristic defects in yolk sac vasculature. Most of the remaining Cf2(-/-) embryos died by E15.5, but those surviving to E18.5 appeared normal. The rare Cf2(-/-) neonates died of hemorrhage on the first postnatal day. These studies suggest that a part of the blood coagulation system is adapted to perform a developmental function. Other mouse models show that the absence of platelets or of fibrinogen does not cause fetal wastage. Therefore, the role of thrombin in development may be independent of its effects on blood coagulation and instead may involve signal transduction on cells other than platelets.

Architecture of the mouse utricle: macular organization and hair bundle heights

Hair bundles are critical to mechanotransduction by vestibular hair cells, but quantitative data are lacking on vestibular bundles in mice or other mammals. Here we quantify bundle heights and their variation with macular locus and hair cell type in adult mouse utricular macula. We also determined that macular organization differs from previous reports. The utricle has approximately 3,600 hair cells, half on each side of the line of polarity reversal (LPR). A band of low hair cell density corresponds to a band of calretinin-positive calyces, i.e., the striola. The relation between the LPR and the striola differs from previous reports in two ways. First, the LPR lies lateral to the striola instead of bisecting it. Second, the LPR follows the striolar trajectory anteriorly, but posteriorly it veers from the edge of the striola to reach the posterior margin of the macula. Consequently, more utricular bundles are oriented mediolaterally than previously supposed. Three hair cell classes are distinguished in calretinin-stained material: type II hair cells, type ID hair cells contacting calretinin-negative (dimorphic) afferents, and type IC hair cells contacting calretinin-positive (calyceal) afferents. They differ significantly on most bundle measures. Type II bundles have short stereocilia. Type IC bundles have kinocilia and stereocilia of similar heights, i.e., KS ratios (ratio of kinocilium to stereocilia heights) approximately 1, unlike other receptor classes. In contrast to these class-specific differences, bundles show little regional variation except that KS ratios are lowest in the striola. These low KS ratios suggest that bundle stiffness is greater in the striola than in the extrastriola.

Genome-wide screening for components of small interfering RNA (siRNA) and micro-RNA (miRNA) pathways in the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae)

The brown planthopper (BPH), Nilaparvata lugens, is a major rice pest in Asia, and accumulated evidence indicates that this species is susceptible to RNA interference (RNAi); however, the mechanism underlying RNAi and parental RNAi has not yet been determined. We comprehensively investigated the repertoire of core genes involved in small interfering RNA (siRNA) and micro-RNA (miRNA) pathways in the BPH by comparing its newly assembled transcriptome and genome with those of Drosophila melanogaster, Tribolium castaneum and Caenorhabditis elegans. Our analysis showed that the BPH possesses one drosha and two Dicer (dcr) genes, three dsRNA-binding motif protein genes, two Argonaute (ago) genes, two Eri-1-like genes (eri-1), and a Sid-1-like gene (sid-1). Additionally, we report for first time that parental RNAi might occur in this species, and siRNA pathway and Sid-1 were required for high efficiency of systemic RNAi triggered by exogenous dsRNA. Furthermore, our results also demonstrated that the miRNA pathway was involved in BPH metamorphosis as depletion of the ago1 or dcr1 gene severely impaired ecdysis. The BPH might be a good model system to study the molecular mechanism of systemic RNAi in hemimetabolous insects, and RNAi has potential to be developed to control this pest in agricultural settings.

Prolonged mild hypothermia therapy protects the brain against permanent focal ischemia

BACKGROUND AND PURPOSE

The efficacy of hypothermic intervention for permanent focal ischemia has yet to be clarified. This study investigated the effect of a prolonged moderate or mild hypothermia on permanent focal ischemia in rats.

METHODS

Two permanent focal ischemia models in male Sprague-Dawley rats were used. Moderate (30 degrees C, in experiment 1) or mild (33 degrees C, in experiment 2) hypothermia was achieved at the time of the induction of focal ischemia and was maintained for 2 hours under general anesthesia. Thereafter, the hypothermic condition was maintained by means of a cold room for a total of 24 hours. The infarct volume and neurological function were analyzed for a maximum of 21 days and compared with that of the normothermia group. Regional cerebral blood flow was monitored for 6 hours in the ischemic core and penumbra region.

RESULTS

In experiment 1, the total infarct volume in the normothermic group was 368+/-59 mm(3); in contrast, it was significantly smaller in the hypothermia group: 169+/-33 mm(3) at 48 hours (mean+/-SEM, P:<0.05). In experiment 2, the infarct volume was 211+/-19 mm(3) in the normothermia group and 88+/-15 mm(3) in the hypothermia group at 21 days (P:<0.05). There were significant differences in neurological function from days 2 through 21 between the two groups. Mean regional cerebral blood flow in the penumbra region increased to a level >50% of baseline.

CONCLUSIONS

Prolonged mild hypothermia suppressed the development of cerebral infarct and neurological deficit chronically after the induction of permanent focal ischemia.

Phosphorylation of splicing factor SF1 on Ser20 by cGMP-dependent protein kinase regulates spliceosome assembly

Splicing factor 1 (SF1) functions at early stages of pre-mRNA splicing and contributes to splice site recognition by interacting with the essential splicing factor U2AF65 and binding to the intron branch site. We have identified an 80 kDa substrate of cGMP-dependent protein kinase-I (PKG-I) isolated from rat brain, which is identical to SF1. PKG phosphorylates SF1 at Ser20, which inhibits the SF1-U2AF65 interaction leading to a block of pre-spliceosome assembly. Mutation of Ser20 to Ala or Thr also inhibits the interaction with U2AF65, indicating that Ser20 is essential for binding. SF1 is phosphorylated in vitro by PKG, but not by cAMP-dependent protein kinase A (PKA). Phosphorylation of SF1 also occurs in cultured neuronal cells and is increased on Ser20 in response to a cGMP analogue. These results suggest a new role for PKG in mammalian pre-mRNA splicing by regulating in a phosphorylation-dependent manner the association of SF1 with U2AF65 and spliceosome assembly.

Effects of ischemia and H2O2 on the cold stress protein CIRP expression in rat neuronal cells

Expression of CIRP (cold-inducible RNA-binding protein) is inducible at 32 degrees C in cultured fibroblasts. Because ischemia is known to induce expression of heat shock proteins, its effect on the CIRP expression was examined using the rat transient forebrain ischemia model. The isolated rat CIRP cDNA encoded amino acids 100% identical in its sequence to mouse CIRP. Northern blot analysis revealed that the CIRP transcripts were ubiquitously expressed in various tissues. In situ hybridization histochemistry of normal rat brain revealed the expression of CIRP in neurons in the hippocampus and the cerebral cortex among others. In the hippocampus of postischemic rats, CIRP mRNA level decreased from 3-6 h after the onset of reperfusion, while it did not change in the cerebral cortex. When PC12 pheochromocytoma cells were cultured at 32 degrees C, the CIRP mRNA level was increased. The presence of H2O2 in the culture media inhibited dose dependently this induction as well as constitutive expression, suggesting that the effect of brain ischemia on CIRP expression is related to generation of reactive oxygen species. Further studies are necessary to clarify the roles played by cold shock proteins in the hypothermic therapy of brain damages.

Breed differences in boar taint: relationship between tissue levels boar taint compounds and sensory analysis of taint

A total of 228 intact male pigs form Duroc, Hampshire, Landrace, and Yorkshire breeds were used in the experiment. Samples of salivary gland and backfat were collected at slaughter for colorimetric assay of salivary and fat 16-androstene levels and fat skatole levels. Fat levels also were tested by a sensory panel using an R-index technique for detecting the presence of boar taint. The proportion of tainted carcasses determined by the sensory panel was 5.0% for androstenone and 11.4% for skatole, with a combined total of 15.0% tainted from either source. Sensory analysis of taint showed a lower proportion (P < .05) of tainted carcasses in Hampshire, with no difference in taint across the other three breeds. Analysis of taint compounds indicated that overall 14.5% of pigs had salivary gland 16-androstene levels and 20.9% had fat 16-androstene levels above acceptable limits. There was a higher (P < .05) proportion of Duroc pigs above the threshold levels for 16-androstenes in both salivary gland and fat. Landrace pigs had the lowest (P < .05) average tissue concentrations of steroids and skatole. Across breeds, only 1.8% of pigs had fat skatole concentrations above .25 ppm, which has been suggested as threshold levels of skatole for taint. The canonical correlation coefficient between fat compound levels and the R-indices of fat 16-androstenes and skatole was .40 (P < .001). Our results indicate breed differences in tissue levels of taint compounds and in taint assessed by a sensory panel. Levels of 16-androstene steroids were highly associated with taint, but more pigs had measured levels above the threshold than those identified as tainted by sensory analysis. Levels of fat skatole were low overall and did not account for all the pigs judged as tainted from skatole by sensory analysis.

Brain tissue classification of magnetic resonance images using partial volume modeling

This paper presents a fully automatic three-dimensional classification of brain tissues for Magnetic Resonance (MR) images. An MR image volume may be composed of a mixture of several tissue types due to partial volume effects. Therefore, we consider that in a brain dataset there are not only the three main types of brain tissue: gray matter, white matter, and cerebro spinal fluid, called pure classes, but also mixtures, called mixclasses. A statistical model of the mixtures is proposed and studied by means of simulations. It is shown that it can be approximated by a Gaussian function under some conditions. The D'Agostino-Pearson normality test is used to assess the risk alpha of the approximation. In order to classify a brain into three types of brain tissue and deal with the problem of partial volume effects, the proposed algorithm uses two steps: 1) segmentation of the brain into pure and mixclasses using the mixture model; 2) reclassification of the mixclasses into the pure classes using knowledge about the obtained pure classes. Both steps use Markov random field (MRF) models. The multifractal dimension, describing the topology of the brain, is added to the MRFs to improve discrimination of the mixclasses. The algorithm is evaluated using both simulated images and real MR images with different T1-weighted acquisition sequences.

Enamelysin mRNA displays a developmentally defined pattern of expression and encodes a protein which degrades amelogenin

Previously, a cDNA encoding a novel matrix metalloproteinase (enamelysin) was isolated from a porcine enamel organ-specific cDNA library. The cloned mRNA is tooth-specific and contains an open reading frame encoding a protein composed of 483 amino acids (Gene, 183:(1-2), p123-128, 1996). Here, we show that: 1) The expression of enamelysin mRNA is not limited to the enamel organ as previously reported. The enamelysin message is also expressed at very low levels in the pulp organ. 2) Northern analysis reveals that the enamelysin mRNA displays a developmentally defined pattern of expression in the enamel organ. The message is expressed at relatively high levels during the presecretory and early transition stages of development. However, during late maturation, the quantity of enamelysin mRNA is greatly reduced. Conversely, the low message levels in the pulp organ remain relatively constant throughout these developmental stages. 3) The enamelysin cDNA was ligated into a prokaryotic expression vector and recombinant enamelysin containing a His tag was purified from E. coli. Zymographic analysis utilizing recombinant murine amelogenin as the substrate, reveals that the purified enamelysin degrades amelogenin. Since enamelysin is developmentally regulated and is capable of degrading amelogenin, it is likely to play a significant role during enamel biomineralization.

Amperometric ultramicrosensors for peroxynitrite detection and its application toward single myocardial cells

The research studied the concentration variation of peroxynitrite anion (O=N-O-O-) released from cultured neonatal myocardial cells induced by ischemia/reperfusion and studied the protective effect of melatonin on the injury. For this purpose, amperometry peroxynitrite ultramicrosensors (UMS) were fabricated and constructed by electropolymerizing inorganic macromolecular film of tetraaminophthalocyanine manganese(II) and coating chemically with poly(4-vinylpyridine). Under optimum conditions, the UMS showed high selectivity and sensitivity to peroxynitrite determination with a calculated detection limit of 1.8 x 10(-8) mol/L (S/N of 3). The detection of peroxynitrite was based on electrocatalytic reduction of peroxynitrite. The mechanism of catalysis was also discussed. The UMS should be promising for in vivo measurement of peroxynitrite without interference or fouling. Peroxynitrite released from myocardial cells both in the ischemic period and in the reperfusion period was measured directly. This approach may lead to important information for myocardial cells on the mechanism of injury and prospective treatments of medicine such as melatonin.

Diurnal change of the cold-inducible RNA-binding protein (Cirp) expression in mouse brain

RNA-binding proteins are believed to play important roles in regulation of neural functions. Recently, a mouse cDNA encoding the cold-inducible RNA-binding protein, Cirp, has been isolated, the amino acid sequence of which showed similarity to plant circadian rhythm proteins. In the present study, diurnal expression of Cirp in the mouse nervous system was examined. Northern blot analysis showed that the level of Cirp mRNA was diurnally regulated in the brain but not in the testis and liver. The level increased during the daytime and decreased during the nighttime. Immunohistochemistry using an anti-Cirp antibody showed that Cirp was expressed in the nucleus of neurons and that the level of Cirp was diurnally regulated in the suprachiasmatic nucleus and the cerebral cortex. The diurnal regulation was not observed in the brain of adult mice kept in constant darkness nor that of 3-day-old mice. These findings suggest that Cirp plays a role in biological rhythms as known for plant proteins and that expression of Cirp is regulated differentially in discrete brain regions.

Management factors associated with swine breeding-herd productivity in the United States

A database containing 24 key production measurements was created by abstracting data files of 673 U.S. farms which participated in the PigCHAMP data-share program in 1995. Summary statistics for breeding-herd performance data were presented for the Cornbelt and the South or Eastern regions. Eight models were built to assess the association between production system, operation management factors and productivity outcomes. Lactation length, percentage of multiple matings, parity of culled sows, percent gilts in the breeding-female inventory, and female culling rate were the management factors identified as having important associations with productivity outcomes. For example, shorter lactation length, higher percentage of multiple matings, and lower culling rate were associated with more pigs weaned per mated female per year. In addition, a lower percentage of gilts in the breeding-female inventory and a higher percentage of multiple matings were associated with fewer average non-productive female days. We recommend that producers change their management systems to decrease lactation length, the percentage of gilts in the breeding-female inventory, and female culling rate, and increase percentage of multiple matings in order to improve breeding-herd productivity on swine farms.

Stimuli-responsive multifunctional membranes of controllable morphology from poly(vinylidene fluoride)-graft-poly[2-(N,N-dimethylamino)ethyl methacrylate] prepared via atom transfer radical polymerization

Poly(vinylidene fluoride) (PVDF) with poly[2-(N,N-dimethylamino) ethyl methacrylate] (PDMAEMA) side chains were synthesized via vinylidene fluoride-initiated atom transfer radical polymerization (ATRP) of 2-(N,N-dimethylamino) ethyl methacrylate (DMAEMA). The graft copolymer can be readily cast into porous pH- and thermo-responsive microfiltration (MF) membranes with enriched "living" PDMAEMA graft chains on the surface (including the pore surfaces) by phase inversion in an aqueous medium. The morphology and surface composition of the membranes were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The pH and temperature of the aqueous media for phase inversion and the PDMAEMA content in the PVDF-g-PDMAEMA copolymers can be used to adjust the pore size of the membranes. In addition to having pH and temperature-responsive permeability, the PVDF-g-PDMAEMA MF membranes also exhibit both good antifouling and antibacterial properties, making the membrane potentially useful for biorelated applications. Furthermore, the dormant PDMAEMA chain ends on the PVDF-g-PDMAEMA membrane can be reactivated for the consecutive surface-initiated ATRP of other functional monomers, such as 2-naphthyl methacrylate (2NM), to produce fluorescent PDMAEMA-b-P2NM diblock copolymer brushes on the PVDF membrane.

Testicular protein Spag5 has similarity to mitotic spindle protein Deepest and binds outer dense fiber protein Odf1

Outer dense fibers (ODF) and the fibrous sheath (FS) are major cytoskeletal structures in the mammalian sperm tail. The molecular mechanisms underlying their morphogenesis along the axoneme or their function are poorly understood. Recently, we reported the cloning and characterization of Odf2, a major ODF protein, and Spag4, an axoneme-binding protein, by virtue of their strong interaction with Odf1, the 27 kDa major ODF protein. We proposed a crucial role for leucine zippers in molecular interactions during sperm tail morphogenesis. Here we report the cloning and characterization of a novel gene, Spag5, which encodes a 200 kDa testicular protein that interacts strongly with Odf1. Spag5 is transcribed and translated in pachytene spermatocytes and spermatids. It bears 73% similarity with the mitotic spindle protein Deepest of unknown function. We identified two putative leucine zippers in the C-terminal part of the Spag5 protein, the downstream one of which is involved in interaction with Odf1. Interestingly, these motifs are present in Deepest. These results highlight the importance of the leucine zipper in sperm tail protein interactions. Mol. Reprod. Dev. 59: 410-416, 2001.

Photoinduced reactions of 1-acetylisatin with phenylacetylenes

[reaction: see text]Photoinduced reactions of 1-acetylisatin 1 with diphenylacetylenes 2a-2c afforded the corresponding 3-methylene-2-indolones 4a-4e and 5a-5e in 80-90% yields via a spirooxetene intermediate. Similar irradiation of 1 with phenylacetylene, on the other hand, resulted in efficient formation of two diastereoisomeric dispiro[3H-indole-3,2'-furan-3',3"-(3H)-indole]-2,5',2"(2H,5'H,2"H )triones 6 and 7 via a reaction sequence with initial formation of the spirooxetene intermediate. The regioselectivity in the photocycloaddition of 1 with phenylacetylene and the reaction mechanism for the formation of 6 and 7 are discussed.