Characterization of the fast skeletal troponin C (<i>TNNC2</i>) gene in three Chinese native sheep breeds

Abstract. Fast skeletal muscle troponin C (TNNC2) protein plays a critical role in skeletal muscle contraction and has been proposed to be involved in meat quality traits in farm animals. Here, we report the cloning of the gene TNNC2 from native Chinese sheep. Sequence analysis indicated that the gene TNNC2 contains a putative open reading frame of 483 base pair, encoding a protein of 160 amino acids. We employed the polymerase chain reaction-single strand conformation polymorphism analysis to study the relationship between the TNNC2 gene polymorphisms and meat quality traits. A single site mutation (T/ −) was detected in the first intron, which created three genotypes TT (T/ T), TD (T/ −) and DD (−/ −). Compared with the DD and TD genotypes, the genotype TT conferred lower in carcass weight (P<0.05), longissimus thoracis et lumborum shear force (P<0.05) and drip loss rate (P<0.05), and higher in pH value (P<0.01) and marbling score (P<0.01). The results indicated that the allele T had positive effects on tenderness and marbling score, and suggest that the allele could be used as a molecular marker to study the meat quality in sheep.

Assessment of wall shear stress in the common carotid artery of healthy subjects using 3.0-tesla magnetic resonance

BACKGROUND

Wall shear stress (WSS) has been proven to play a critical role in the formation and development of atherosclerotic plaques. Measurement of WSS in vivo is significant for the clinical assessment of atherosclerosis.

PURPOSE

To assess the magnitude and distribution of local WSS in the common carotid artery (CCA) in vivo using 3.0T magnetic resonance (MR).

MATERIAL AND METHODS

The common carotid artery of eight healthy volunteers was studied using a cine phase-contrast MR sequence. A three-dimensional paraboloid model was applied to fit the velocity profiles, and the WSS values were calculated. The cross-sectional area, average flow velocity, maximum velocity, and flow rate were also obtained.

RESULTS

Mean WSS was 0.850 +/- 0.195 (range 0.132-3.464) N/m(2) for the common carotid arteries; the spatial and temporal distribution and change of WSS were displayed. During a cardiac cycle, the mean velocity was 22.8 +/- 3.5 (16.9-28.3) cm/s, blood flow rate 8.03+/-1.45 (5.73-10.72) ml/s, and luminal vessel area 34.94+/-7.06 (24.25-49.01) mm(2).

CONCLUSION

Local WSS values in CCAs can be measured using 3.0T MR imaging combined with image-processing techniques. Intersubject variations were found in the distribution and magnitude of wall shear stress as well as in the flow profile pattern in CCAs, which may be caused by different vessel morphologies.

Structural kinetics of cardiac troponin C mutants linked to familial hypertrophic and dilated cardiomyopathy in troponin complexes

The key events in regulating cardiac muscle contraction involve Ca(2+) binding to and release from cTnC (troponin C) and structural changes in cTnC and other thin filament proteins triggered by Ca(2+) movement. Single mutations L29Q and G159D in human cTnC have been reported to associate with familial hypertrophic and dilated cardiomyopathy, respectively. We have examined the effects of these individual mutations on structural transitions in the regulatory N-domain of cTnC triggered by Ca(2+) binding and dissociation. This study was carried out with a double mutant or triple mutants of cTnC, reconstituted into troponin with tryptophanless cTnI and cTnT. The double mutant, cTnC(L12W/N51C) labeled with 1,5-IAEDANS at Cys-51, served as a control to monitor Ca(2+)-induced opening and closing of the N-domain by Förster resonance energy transfer (FRET). The triple mutants contained both L12W and N51C labeled with 1,5-IAEDANS, and either L29Q or G159D. Both mutations had minimal effects on the equilibrium distance between Trp-12 and Cys-51-AEDANS in the absence or presence of bound Ca(2+). L29Q had no effect on the closing rate of the N-domain triggered by release of Ca(2+), but reduced the Ca(2+)-induced opening rate. G159D reduced both the closing and opening rates. Previous results showed that the closing rate of cTnC N-domain triggered by Ca(2+) dissociation was substantially enhanced by PKA phosphorylation of cTnI. This rate enhancement was abolished by L29Q or G159D. These mutations alter the kinetics of structural transitions in the regulatory N-domain of cTnC that are involved in either activation (L29Q) or deactivation (G159D). Both mutations appear to be antagonistic toward phosphorylation signaling between cTnI and cTnC.

Chronic but not acute treatment with caffeine attenuates traumatic brain injury in the mouse cortical impact model

Caffeine, the most consumed psychoactive drug and non-specific adenosine receptor antagonist, has recently been shown to exert a neuroprotective effect against brain injury in animal models of Parkinson's disease (PD) and stroke. However, the effects of caffeine on traumatic brain injury (TBI) are not known. In this study, we investigated the effects of acute and chronic caffeine treatment on brain injury in a cortical-impact model of TBI in mice. Following TBI, neurological deficits, cerebral edema, as well as inflammatory cell infiltration were all significantly attenuated in mice pretreated chronically (for 3 weeks) with caffeine in drinking water compared with the mice pretreated with saline. Furthermore, we found that chronic caffeine treatment attenuated glutamate release and inflammatory cytokine production, effects that were correlated with an upregulation of brain A1 receptor mRNA. By contrast, acute treatment with caffeine (i.p. injection, 30 min before TBI) was not effective in protecting against TBI-induced brain injury. These results suggest that chronic (but not acute) caffeine treatment attenuates brain injury, possibly by A1 receptor-mediated suppression of glutamate release and inhibition of excessive inflammatory cytokine production. These results highlight the potential benefit of chronic caffeine intake for preventing TBI and provide a rationale for the epidemiological investigation of the potential association between TBI and human caffeine intake.

Effects of PKA phosphorylation of cardiac troponin I and strong crossbridge on conformational transitions of the N-domain of cardiac troponin C in regulated thin filaments

Regulation of cardiac muscle function is initiated by binding of Ca2+ to troponin C (cTnC) which induces a series of structural changes in cTnC and other thin filament proteins. These structural changes are further modulated by crossbridge formation and fine-tuned by phosphorylation of cTnI. The objective of the present study is to use a new Förster resonance energy transfer-based structural marker to distinguish structural and kinetic effects of Ca2+ binding, crossbridge interaction, and protein kinase A phosphorylation of cTnI on the conformational changes of the cTnC N-domain. The FRET-based structural marker was generated by attaching AEDANS to one cysteine of a double-cysteine mutant cTnC(13C/51C) as a FRET donor and attaching DDPM to the other cysteine as the acceptor. The doubly labeled cTnC mutant was reconstituted into the thin filament by adding cTnI, cTnT, tropomyosin, and actin. Changes in the distance between Cys13 and Cys51 induced by Ca2+ binding/dissociation were determined by FRET-sensed Ca2+ titration and stopped-flow studies, and time-resolved fluorescence measurements. The results showed that the presence of both Ca2+ and strong binding of myosin head to actin was required to achieve a fully open structure of the cTnC N-domain in regulated thin filaments. Equilibrium and stopped-flow studies suggested that strongly bound myosin head significantly increased the Ca2+ sensitivity and changed the kinetics of the structural transition of the cTnC N-domain. PKA phosphorylation of cTnI impacted the Ca2+ sensitivity and kinetics of the structural transition of the cTnC N-domain but showed no global structural effect on cTnC opening. These results provide an insight into the modulation mechanism of strong crossbridge and cTnI phosphorylation in cardiac thin filament activation/relaxation processes.

Grating-less, fiber-based oscillator that generates 25 nJ pulses at 80 MHz, compressible to 150 fs

We report a passively mode-locked fiber-based oscillator that has no internal dispersion-compensating gratings. This design, which we believe to be the first of its kind, produces 25 nJ pulses at 80 MHz with the pulses compressible to 150 fs. The pulses appear to be self-similar and initial data imply that their energy is further scalable.

Structural transition of the inhibitory region of troponin I within the regulated cardiac thin filament

Contraction and relaxation of cardiac muscle are regulated by the inhibitory and regulatory regions of troponin I (cTnI). Our previous FRET studies showed that the inhibitory region of cTnI in isolated troponin experiences a structural transition from a beta-turn/coil motif to an extended conformation upon Ca(2+) activation. During the relaxation process, the kinetics of the reversal of this conformation is coupled to the closing of the Ca(2+)-induced open conformation of the N-domain of troponin C (cTnC) and an interaction between cTnC and cTnI in their interface. We have since extended the structural kinetic study of the inhibitory region to fully regulated thin filament. Single-tryptophan and single-cysteine mutant cTnI(L129W/S151C) was labeled with 1,5-IAEDANS at Cys151, and the tryptophan-AEDANS pair served as a donor-acceptor pair. Labeled cTnI mutant was used to prepare regulated thin filaments. Ca(2+)-induced conformational changes in the segment of Trp129-Cys151 of cTnI were monitored by FRET sensitized acceptor (AEDANS) emission in Ca(2+) titration and stopped-flow measurements. Control experiments suggested energy transfer from endogenous tryptophan residues of actin and myosin S1 to AEDANS attached to Cys151 of cTnI was very small and Ca(2+) independent. The present results show that the rate of Ca(2+)-induced structural transition and Ca(2+) sensitivity of the inhibitory region of cTnI were modified by (1) thin filament formation, (2) the presence of strongly bound S1, and (3) PKA phosphorylation of the N-terminus of cTnI. Ca(2+) sensitivity was not significantly changed by the presence of cTm and actin. However, the cTn-cTm interaction decreased the cooperativity and kinetics of the structural transition within cTnI, while actin filaments elicited opposite effects. The strongly bound S1 significantly increased the Ca(2+) sensitivity and slowed down the kinetics of structural transition. In contrast, PKA phosphorylation of cTnI decreased the Ca(2+) sensitivity and accelerated the structural transition rate of the inhibitory region of cTnI on thin filaments. These results support the idea of a feedback mechanism by strong cross-bridge interaction with actin and provide insights on the molecular basis for the fine tuning of cardiac function by beta-adrenergic stimulation.

Overcoming the radioresistance of prostate cancer cells with a novel Bcl-2 inhibitor

Bcl-2 overexpression is an important mechanism underlying the aggressive behavior of prostate cancer cells and their resistance to radio- or chemotherapy. HA14-1, a recently discovered organic Bcl-2 inhibitor, potently induces apoptosis in various human cancer cells. Sequential exposure of radioresistant LNCaP (wild-type (wt) p53), LNCaP/Bcl-2 (wt p53) and PC3 (mutant p53) prostate cancer cells to a minimally cytotoxic concentration of 10 microM HA14-1 for 1 h followed by 1-6 Gy gamma radiation, resulted in a highly synergistic (combination index <1.0) induction of cell death as determined by an apoptosis assay at 72 h, and a clonogenicity assay at 12 days, after the initial treatment. The reverse treatment sequence did not cause a synergistic induction of cell death. When compared to individual treatments, cell death induced by the combined treatment was associated with dramatically increased reactive oxygen species (ROS) generation, c-Jun N-terminal kinase (JNK) activation, Bcl-2 phosphorylation, cytochrome c release, caspase-3 activation and DNA fragmentation. Exposure to either 200 microg/ml of the antioxidant alpha-tocopherol or 10 microM JNK inhibitor SP600125 before the combined treatment resulted in decreased activation of JNK and caspase-3 as well as decreased DNA fragmentation. However, treatment with the pancaspase inhibitor carbobenzoxyl-valyl-alanyl-aspartyl-[O-methyl]-fluoromethylketone before the combined treatment inhibited apoptosis without affecting JNK activation, and this inhibitory effect was enhanced in the presence of alpha-tocopherol or SP600125. Taken together, our results indicate that HA14-1 potently sensitizes radioresistant LNCaP and PC3 cells to gamma radiation, regardless of the status of p53. ROS and JNK are important early signals that trigger both caspase-dependent and -independent cell death pathways and contribute to the apoptotic synergy induced by the combined treatments.

Spindle checkpoint and apoptotic response in alpha-particle transformed human bronchial epithelial cells

The mitotic spindle checkpoint and apoptosis in response to nocodazole, a microtubule-disrupting agent, were investigated in the alpha-particle transformed human bronchial epithelial cell lines BERP35T1, BERP35T4 and the parental BEP2D cell line. When treated with 0.2 microg/ml of nocodazole, BEP2D and BERP35T1 cells were efficiently arrested in the mitotic phase, whilst BERP35T4, a transformed cell line showing chromosomal instability, failed to be arrested as evidenced by a low G2/M fraction. BERP35T4 cells also showed a higher proportion of aneuploids when treated with nocodazole or not. Thus, the BERP35T4 cell line has a defect in spindle checkpoint function. The extent of apoptosis induced by nocodazole (0.3 microg/ml) was significantly higher (2-fold to 2.5-fold) in BEP2D cells than in the two transformed cell lines. Furthermore, the induced apoptosis was found to occur predominantly before mitotic division in BEP2D cells. In BERP35T4 cells, however, 50% of induced apoptosis occurred before mitotic division and 50% occurred after division in binucleated cells when co-treated with cytochalasin B. The 5'-CpG island of the Chfr gene, a mitotic checkpoint gene that functions in entry into metaphase, was found to be methylated in BERP35T4 cells but not in BEP2D cells. Consistent with methylation, the expression of the Chfr gene was markedly suppressed in BERP35T4 cells. Our results suggest that the impaired spindle checkpoint and abnormal apoptotic response may be related to the oncogenic progression of human bronchial epithelial cells initiated by exposure to alpha-particles.

Antitumor effects of bortezomib (PS-341) on primary effusion lymphomas

Primary effusion lymphomas (PELs) are a rare type of non-Hodgkin's lymphoma that are resistant to cytotoxic chemotherapy. PELs manifest constitutive activation of nuclear factor kappa B (NF-kappaB), and inhibition of NF-kappaB induces apoptosis of PELs and sensitizes to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced death. Bortezomib (PS-341), a peptidyl boronic acid inhibitor of the proteasome, is a potent agent against a wide range of hematologic malignancies and has been shown to inhibit NF-kappaB. Thus, we examined the cytotoxic effects of bortezomib alone and in combination with various drugs. Bortezomib potently inhibited NF-kappaB in PEL cells in a dose-dependent manner. In addition, bortezomib inhibited growth and induced apoptosis of PEL cell lines (IC(50) values of 3.4-5.0 nM). Results of drug interactions between bortezomib and chemotherapy (doxorubicin and Taxol) were schedule-dependent: synergistic interactions were generally observed when PEL cells were pretreated with bortezomib prior to chemotherapy, whereas additive or even antagonistic interactions occurred with chemotherapy pretreatment or simultaneous treatment with bortezomib and chemotherapy. Most schedules of bortezomib and dexamethasone were synergistic, although pretreatment with dexamethasone resulted in additive interactions. Effects of combinations of bortezomib and TRAIL were generally additive. Thus, bortezomib represents a promising potential therapy for the treatment of PEL.

Protein preparation, crystallization and preliminary X-ray analysis of human adrenal gland protein AD-004

The adrenal gland protein AD-004 was identified in the human adrenal gland. Full-length AD-004 contains 172 amino acids, with a predicted molecular weight of about 20 kDa. In attempts to crystallize human AD-004, the gene was subcloned into a modified pET vector, pET21-DEST, with an N-terminal His(5) tag using the Gateway cloning system, followed by protein expression in Escherichia coli strain BL21(DE3). The protein was purified in two steps to near-homogeneity and was crystallized. The crystals belong to space group P6(1) or P6(5), with unit-cell parameters a = b = 99.56, c = 57.19 A. A complete 2.0 A data set has been collected at a rotating-anode X-ray source and structure determination is under way.

Comparison of hyperkalemic cardioplegia with altered [CaCl2] and [MgCl2] on [Ca2+]i transients and function after warm global ischemia in isolated hearts

AIM

[MgCl(2)] and [CaCl(2)] may modify the cardioprotective effects of hyperkalemic cardioplegia (CP). We changed [MgCl(2)] and [CaCl(2)] in a CP solution to examine their effects on [Ca(2+)]i transients and cardiac function before and after global normothermic ischemia.

METHODS

After stabilization and loading of indo 1-AM in Kreb's solution (KR), each heart was perfused with either KR or 1 of 4 CP solutions before 37 degrees C, 30 min ischemia followed by reperfusion with KR. The KR solution contained, in mM, 4.5 KCl, 2.4 MgCl(2) and 2.5 CaCl(2); the CP solutions had in addition to 18 KCl: CP 1 (control CP): 2.4 MgCl(2), 2.5 CaCl(2); CP 2: 7.2 MgCl(2), 2.5 CaCl(2); CP 3, 7.2 MgCl(2), 1.25 CaCl(2); CP 4: 2.4 MgCl(2), 1.25 CaCl(2).

RESULTS

In the KR group [Ca(2+)]i markedly increased on early reperfusion while functional return (LVP, dLVP/dt((max and min))) was much reduced; each CP group led to reduced [Ca(2+)]i loading and improved function. The rates of cytosolic Ca(2+) fluxes (d[Ca(2+)]/dt(max) and d[Ca(2+)]/dt(min)) increased significantly compared to baseline in the KR group, but were mostly suppressed in the CP groups, and d[Ca(2+)]/dt(min) was lower after CP 4 compared to CP 1 on reperfusion. At 60 min reperfusion, LVP area to [Ca(2+)] area and cardiac efficiency to phasic [Ca(2+)] relationships were shifted after KR, but not after CP 1-4. With similar functional recovery, [Ca(2+)] transient and [Ca(2+)] area were significantly lower after CP 4 than after CP 1.

CONCLUSION

Increasing [MgCl(2)] (CP 2 and 3) did not improve cardiac function or reduce Ca(2+) transients on reperfusion better than the other CP groups, but reducing [CaCl(2)] (CP 3 and 4) was more effective in reducing [Ca(2+)] transients on reperfusion after global ischemia.

Protein preparation, crystallization and preliminary X-ray crystallographic studies of a thermostable hypoxanthine–guanine phosphoribosyltransferase fromThermoanaerobacter tengcongensis

Native and His-tagged mutant (L160I) hypoxanthine-guanine phosphoribosyltransferase (HGPRT) from Thermoanaerobacter tengcongensis were cloned, expressed in Escherichia coli and purified. Both proteins were crystallized with polyethylene glycol as the main precipitant at 293 K using the hanging-drop vapour-diffusion method. The crystal of native HGPRT belongs to space group C222(1), with unit-cell parameters a = 65.77, b = 137.73, c = 95.27 A, and diffracted to 2.2 A resolution on an in-house X-ray generator. The crystal of the His-tagged mutant (L160I) HGPRT belongs to the space group I222, with unit-cell parameters a = 52.21, b = 88.36, c = 93.03 A, and diffracted to 1.7 A resolution in-house.

Thermodynamic databases for proteins and protein-nucleic acid interactions

Thermodynamic data regarding proteins and their interactions are important for understanding the mechanisms of protein folding, protein stability, and molecular recognition. Although there are several structural databases available for proteins and their complexes with other molecules, databases for experimental thermodynamic data on protein stability and interactions are rather scarce. Thus, we have developed two electronically accessible thermodynamic databases. ProTherm, Thermodynamic Database for Proteins and Mutants, contains numerical data of several thermodynamic parameters of protein stability, experimental methods and conditions, along with structural, functional, and literature information. ProNIT, Thermodynamic Database for Protein-Nucleic Acid Interactions, contains thermodynamic data for protein-nucleic acid binding, experimental conditions, structural information of proteins, nucleic acids and the complex, and literature information. These data have been incorporated into 3DinSight, an integrated database for structure, function, and properties of biomolecules. A WWW interface allows users to search for data based on various conditions, with different display and sorting options, and to visualize molecular structures and their interactions. These thermodynamic databases, together with structural databases, help researchers gain insight into the relationship among structure, function, and thermodynamics of proteins and their interactions, and will become useful resources for studying proteins in the postgenomic era.

Using an enzyme linked immunosorbent assay (ELISA) and a protein phosphatase inhibition assay (PPIA) for the detection of microcystins and nodularins

Cyanotoxins produced by cyanobacteria (blue-green algae) include potent neurotoxins and hepatotoxins. The hepatotoxins include cyclic peptide microcystins and nodularins plus the alkaloid cylindrospermopsins. Among the cyanotoxins the microcystins have proven to be the most widespread, and are most often implicated in animal and human poisonings. This paper presents a practical guide to two widely used methods for detecting and quantifying microcystins and nodularins in environmental samples-the enzyme linked immunosorbant assay (ELISA) and the protein phosphatase inhibition assay (PPIA).

Variable-temperature scanning tunneling microscopy and scanning tunneling spectroscopy study on copper phthalocyanine ultrathin films on a Au(111) surface

Variable-temperature high-resolution scanning tunneling microscopy (STM) images reveal that well-ordered copper phthalocyanine (CuPc) strips can be self-assembled by depositing CuPc molecules on a Au(111) surface. The self-assembled strips are supposed to result from the balance of the intermolecular interaction and the interaction between the molecules and substrate during annealing. The energy band (approximately 1.9-2.1 eV) of CuPc, measured by scanning tunneling spectroscopy (STS), is comparable to the optical band gap (approximately 1.7 eV). Spectroscopic measurements confirm that a dipole layer and/or an effect of image force exist at the CuPc/Au(111) interface.

Preliminary X-ray crystallographic analysis of ciliate Euplotes octocarinatus release factor eRF1a

eRF1a, one of the class-I release factors from ciliate Euplotes octocarinatus, has been crystallized by the vapor-diffusion method using polyethylene glycol 4000 as the precipitant at pH 7.5. The crystal belongs to space group P2(1) and the unit-cell parameters are a=90.4, b=107.9, c=114.8A, beta=94.2 degrees. There appear to be four eRF1a molecules in the asymmetric unit.

Blocking Na(+)/H(+) exchange reduces [Na(+)](i) and [Ca(2+)](i) load after ischemia and improves function in intact hearts

We determined in intact hearts whether inhibition of Na(+)/H(+) exchange (NHE) decreases intracellular Na(+) and Ca(2+) during ischemia and reperfusion, improves function during reperfusion, and reduces infarct size. Guinea pig isolated hearts were perfused with Krebs-Ringer solution at 37 degrees C. Left ventricular (LV) free wall intracellular Na(+) concentration ([Na(+)](i)) and intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured using fluorescence dyes. Hearts were exposed to 30 min of ischemia with or without 10 microM of benzamide (BIIB-513), a selective NHE-1 inhibitor, infused for 10 min just before ischemia or for 10 min immediately on reperfusion. At 2 min of reperfusion, BIIB-513 given before ischemia decreased peak increases in [Na(+)](i) and [Ca(2+)](i), respectively, from 2.5 and 2.3 times (controls) to 1.6 and 1.3 times pre-ischemia values. At 30 min of reperfusion, BIIB-513 increased systolic-diastolic LV pressure (LVP) from 49 +/- 2% (controls) to 80 +/- 2% of pre-ischemia values. BIIB-513 reduced ventricular fibrillation by 54% and reduced infarct size from 64 +/- 1% to 20 +/- 3%. First derivative of the LVP, O(2) consumption, and cardiac efficiency were also improved by BIIB-513. Similar results were obtained with BIIB-513 given on reperfusion. These data show that Na(+) loading is a marker of reperfusion injury in intact hearts in that inhibiting NHE reduces Na(+) and Ca(2+) loading during reperfusion while improving function. These results clearly implicate the ionic basis by which inhibiting NHE protects the guinea pig intact heart from ischemia-reperfusion injury.

Thermodynamic database for protein-nucleic acid interactions (ProNIT)

MOTIVATION

Protein-nucleic acid interactions are fundamental to the regulation of gene expression. In order to elucidate the molecular mechanism of protein-nucleic acid recognition and analyze the gene regulation network, not only structural data but also quantitative binding data are necessary. Although there are structural databases for proteins and nucleic acids, there exists no database for their experimental binding data. Thus, we have developed a Thermodynamic Database for Protein-Nucleic Acid Interactions (ProNIT).

RESULTS

We have collected experimentally observed binding data from the literature. ProNIT contains several important thermodynamic data for protein-nucleic acid binding, such as dissociation constant (K(d)), association constant (K(a)), Gibbs free energy change (DeltaG), enthalpy change (DeltaH), heat capacity change (DeltaC(p)), experimental conditions, structural information of proteins, nucleic acids and the complex, and literature information. These data are integrated into a relational database system together with structural and functional information to provide flexible searching facilities by using combinations of various terms and parameters. A www interface allows users to search for data based on various conditions, with different display and sorting options, and to visualize molecular structures and their interactions.

AVAILABILITY

ProNIT is freely accessible at the URL http://www.rtc.riken.go.jp/jouhou/pronit/pronit.html.

[Analysis of structural motifs of proteins using sets of codes, describing local structures]

An amino acid sequence pattern conserved among a family of proteins is called motif. It is usually related to the specific function of the family. On the other hand, functions of proteins are achieved by their 3D structures. Specific local structures, called structural motifs, are considered related to their functions. However, searching for common structural motifs in different proteins is much more difficult than for common sequence motifs. We are attempting in this study to convert the information about the structural motifs into a set of one-dimensional digital strings, i.e., a set of codes, to compare them more easily by computer and to investigate their relationship to functions more quantitatively. By applying the Delaunay tessellation to a 3D structure of a protein, we can assign each local structure to a unique code that is defined so as to reflect its structural feature. Since a structural motif is defined as a set of the local structures in this paper, the structural motif is represented by a set of the codes. In order to examine the ability of the set of the codes to distinguish differences among the sets of local structures with a given PROSITE pattern that contain both true and false positives, we clustered them by introducing a similarity measure among the set of the codes. The obtained clustering shows a good agreement with other results by direct structural comparison methods such as a superposition method. The structural motifs in homologous proteins are also properly clustered according to their sources. These results suggest that the structural motifs can be well characterized by these sets of the codes, and that the method can be utilized in comparing structural motifs and relating them with function.

Ischemic and anesthetic preconditioning reduces cytosolic [Ca2+] and improves Ca(2+) responses in intact hearts

Ca(+) loading during reperfusion after myocardial ischemia is linked to reduced cardiac function. Like ischemic preconditioning (IPC), a volatile anesthetic given briefly before ischemia can reduce reperfusion injury. We determined whether IPC and sevoflurane preconditioning (SPC) before ischemia equivalently improve mechanical and metabolic function, reduce cytosolic Ca(2+) loading, and improve myocardial Ca(2+) responsiveness. Four groups of guinea pig isolated hearts were perfused: no ischemia, no treatment before 30-min global ischemia and 60-min reperfusion (control), IPC (two 2-min occlusions) before ischemia, and SPC (3.5 vol%, two 2-min exposures) before ischemia. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured at the left ventricular (LV) free wall with the fluorescent probe indo 1. Ca(2+) responsiveness was assessed by changing extracellular [Ca(2+)]. In control hearts, initial reperfusion increased diastolic [Ca(2+)] and diastolic LV pressure (LVP), and the maximal and minimal derivatives of LVP (dLVP/dt(max) and dLVP/dt(min), respectively), O(2) consumption, and cardiac efficiency (CE). Throughout reperfusion, IPC and SPC similarly reduced ischemic contracture, ventricular fibrillation, and enzyme release, attenuated rises in systolic and diastolic [Ca(2+)], improved contractile and relaxation indexes, O(2) consumption, and CE, and reduced infarct size. Diastolic [Ca(2+)] at 50% dLVP/dt(min) was right shifted by 32-53 +/- 8 nM after 30-min reperfusion for all groups. Phasic [Ca(2+)] at 50% dLVP/dt(max) was not altered in control but was left shifted by -235 +/- 40 nM [Ca(2+)] after IPC and by -135 +/- 20 nM [Ca(2+)] after SPC. Both SPC and IPC similarly reduce Ca(2+) loading, while augmenting contractile responsiveness to Ca(2+), improving postischemia cardiac function and attenuating permanent damage.

Estrogen receptor beta-selective transcriptional activity and recruitment of coregulators by phytoestrogens

Estrogens used in hormone replacement therapy regimens may increase the risk of developing breast cancer. Paradoxically, high consumption of plant-derived phytoestrogens, particularly soybean isoflavones, is associated with a low incidence of breast cancer. To explore the molecular basis for these potential different clinical outcomes, we investigated whether soybean isoflavones elicit distinct transcriptional actions from estrogens. Our results demonstrate that the estrogen 17beta-estradiol effectively triggers the transcriptional activation and repression pathways with both estrogen receptors (ERs) ERalpha and ERbeta. In contrast, soybean isoflavones (genistein, daidzein, and biochanin A) are ERbeta-selective agonists of transcriptional repression and activation at physiological levels. The molecular mechanism for ERbeta selectivity by isoflavones involves their capacity to create an activation function-2 surface of ERbeta that has a greater affinity for coregulators than ERalpha. Phytoestrogens may act as natural selective estrogen receptor modulators that elicit distinct clinical effects from estrogens used for hormone replacement by selectively recruiting coregulatory proteins to ERbeta that trigger transcriptional pathways.

Overexpression of the P46 (T1) translocase component of the glucose-6-phosphatase complex in hepatocytes impairs glycogen accumulation via hydrolysis of glucose 1-phosphate

The final step of gluconeogenesis and glycogenolysis is catalyzed by the glucose-6-phosphatase (Glc-6-Pase) enzyme complex, located in the endoplasmic reticulum. The complex consists of a 36-kDa catalytic subunit (P36), a 46-kDa glucose 6-phosphate translocase (P46), and putative glucose and inorganic phosphate transporters. Mutations in the genes encoding P36 or P46 have been linked to glycogen storage diseases type Ia and type Ib, respectively. However, the relative roles of these two proteins in control of the rate of glucose 6-phosphate hydrolysis have not been defined. To gain insight into this area, we have constructed a recombinant adenovirus containing the cDNA encoding human P46 (AdCMV-P46) and treated rat hepatocytes with this virus, or a virus encoding P36 (AdCMV-P36), or the combination of both viruses, resulting in large and equivalent increases in expression of the transgenes within 8-24 h of viral treatment. The overexpressed P46 protein was appropriately targeted to hepatocyte microsomes and caused a 58% increase in glucose 6-phosphate hydrolysis in nondetergent-treated (intact) microsomal preparations relative to controls, whereas overexpression of P36 caused a 3.6-fold increase. Overexpression of P46 caused a 50% inhibition of glycogen accumulation in hepatocytes from fasted rats incubated at 25 mm glucose relative to cells treated with a control virus (AdCMV-betaGAL). Furthermore, in hepatocytes from fed rats cultured at 25 mm glucose and then exposed to 15 mm glucose, AdCMV-P46 treatment activated glycogenolysis, as indicated by a 50% reduction in glycogen content relative to AdCMV-betaGAL-treated controls. In contrast, overexpression of P46 had only small effects on glycolysis, whereas overexpression of P36 had large effects on both glycogen metabolism and glycolysis, even in the presence of co-overexpressed glucokinase. Finally, P46 overexpression enhanced glucose 1-phosphate but not fructose 6-phosphate hydrolysis in intact microsomes, providing a mechanism by which P46 overexpression may exert its preferential effects on glycogen metabolism.

Overexpression of a modified human malonyl-CoA decarboxylase blocks the glucose-induced increase in malonyl-CoA level but has no impact on insulin secretion in INS-1-derived (832/13) beta-cells

The long-chain acyl-CoA (LC-CoA) model of glucose-stimulated insulin secretion (GSIS) holds that secretion is linked to a glucose-induced increase in malonyl-CoA level and accumulation of LC-CoA in the cytosol. We have previously tested the validity of this proposal by overexpressing goose malonyl-CoA decarboxylase (MCD) in INS-1 cells, but these studies have been criticized due to: 1) the small insulin secretion response (2-4-fold) of the INS-1 cells used; 2) unknown contribution of the ATP-sensitive K(+) (K(ATP)) channel-independent pathway of GSIS in INS-1 cells, which has been implicated as the site at which lipids regulate insulin granule exocytosis; and 3) deletion of the N-terminal mitochondrial targeting sequence, but not the C-terminal peroxisomal targeting sequence in the goose MCD construct, raising the possibility that a significant fraction of the overexpressed enzyme was localized to peroxisomes. To address these outstanding concerns, INS-1-derived 832/13 cells, which exhibit robust K(ATP) channel-dependent and -independent pathways of GSIS, were treated with a new adenovirus encoding human MCD lacking both its mitochondrial and peroxisomal targeting sequences (AdCMV-MCD Delta 5), resulting in large increases in cytosolic MCD activity. Treatment of 832/13 cells with AdCMV-MCD Delta 5 completely blocked the glucose-induced rise in malonyl-CoA and attenuated the inhibitory effect of glucose on fatty acid oxidation. However, MCD overexpression had no effect on K(ATP) channel-dependent or -independent GSIS in 832/13 cells. Furthermore, combined treatment of 832/13 cells with AdCMV-MCD Delta 5 and triacsin C, an inhibitor of long chain acyl-CoA synthetase that reduces LC-CoA levels, did not impair GSIS. These findings extend our previous observations and are not consistent with the LC-CoA hypothesis as originally set forth.

Changes in [Na(+)](i), compartmental [Ca(2+)], and NADH with dysfunction after global ischemia in intact hearts

We measured the effects of global ischemia and reperfusion on intracellular Na(+), NADH, cytosolic and mitochondrial (subscript mito) Ca(2+), relaxation, metabolism, contractility, and Ca(2+) sensitivity in the intact heart. Langendorff-prepared guinea pig hearts were crystalloid perfused, and the left ventricular (LV) pressure (LVP), first derivative of LVP (LV dP/dt), coronary flow, and O(2) extraction and consumption were measured before, during, and after 30-min global ischemia and 60-min reperfusion. Ca(2+), Na(+), and NADH were measured by luminescence spectrophotometry at the LV free wall using indo 1 and sodium benzofuran isophthalate, respectively, after subtracting changes in tissue autofluorescence (NADH). Mitochondrial Ca(2+) was assessed by quenching cytosolic indo 1 with MnCl(2). Mechanical responses to changes in cytosolic-systolic (subscript sys), diastolic (subscript dia), and mitochondrial Ca(2+) were tested over a range of extracellular [Ca(2+)] before and after ischemia-reperfusion. Both [Ca(2+)](sys) and [Ca(2+)](dia) doubled at 1-min reperfusion but returned to preischemia values within 10 min, whereas [Ca(2+)](mito) was elevated over 60-min reperfusion. Reperfusion dissociated [Ca(2+)](dia) and [Ca(2+)](sys) from contractile function as LVP(sys-dia) and the rise in LV dP/dt (LV dP/dt(max)) were depressed by one-third and the fall in LV dP/dt (LV dP/dt(min)) was depressed by one-half at 30-min reperfusion, whereas LVP(dia) remained markedly elevated. [Ca(2+)](sys-dia) sensitivity at 100% LV dP/dt(max) was not altered after reperfusion, but [Ca(2+)](dia) at 100% LV dP/dt(min) and [Ca(2+)](mito) at 100% LV dP/dt(max) were markedly shifted right on reperfusion (ED(50) +36 and +125 nM [Ca(2+)], respectively) with no change in slope. NADH doubled during ischemia but returned to normal on initial reperfusion. The intracellular [Na(+)] ([Na(+)](i)) increased minimally during ischemia but doubled on reperfusion and remained elevated at 60-min reperfusion. Thus Na(+) and Ca(2+) temporally accumulate during initial reperfusion, and cytosolic Ca(2+) returns toward normal, whereas [Na(+)](i) and [Ca(2+)](mito) remain elevated on later reperfusion. Na(+) loading likely contributes to Ca(2+) overload and contractile dysfunction during reperfusion.

Utility of the Arabidopsis FAE1 and yeast SLC1-1 genes for improvements in erucic acid and oil content in rapeseed

High-erucic acid (HEA) Brassica napus cultivars are regaining interest in industrial contexts. Erucic acid and its derivatives are important renewable raw materials utilized in the manufacture of plastic films, in the synthesis of Nylon 13,13, and in the lubricant and emollient industries. Theoretically, the highest level of erucic acid that can be achieved by means of classical breeding is 66 mol%; however, using new approaches on the basis of genetic engineering, it might be possible to develop a B. napus cultivar containing levels of erucic acid significantly above 66 mol% (>80 mol%). In an attempt to increase the amounts of very-long-chain fatty acids (VLCFAs), and erucic acid in particular, in Canadian HEA B. napus cultivars, we have focused on two targets using a transgenic approach. We examined both the role/function of the Arabidopsis thaliana FAE1 (fatty acid elongase) gene by expressing it under the control of the seed-specific napin promoter in B. napus germplasm with analysis of the changes in VLCFA content in the seed oil of transgenic lines, and the performance of the yeast SLC1-1 (sphingolipid compensation mutant) in B. napus cv. Hero transgenic progeny in the field. Here, we report analyses of the contents of 22:1, total VLCFAand oil in the seed oil, as well as seed yield of the field-grown FAE1 and SLC1-1 B. napus cv. Hero progeny.

Reduced cytosolic Ca(2+) loading and improved cardiac function after cardioplegic cold storage of guinea pig isolated hearts

BACKGROUND

Hypothermia is cardioprotective, but it causes Ca(2+) loading and reduced function on rewarming. The aim was to associate changes in cytosolic Ca(2+) with function in intact hearts before, during, and after cold storage with or without cardioplegia (CP).

METHODS AND RESULTS

Guinea pig hearts were initially perfused at 37 degrees C with Krebs-Ringer's (KR) solution (in mmol/L: Ca(2+) 2.5, K(+) 5, Mg(2+) 2.4). One group was perfused with CP solution (Ca(2+) 2.5, K(+) 18, Mg(2+) 7.2) during cooling and storage at 3 degrees C for 4 hours; another was perfused with KR. LV pressure (LVP), dP/dt, O(2) consumption, and cardiac efficiency were monitored. Cytosolic phasic [Ca(2+)] was calculated from indo 1 fluorescence signals obtained at the LV free wall. Cooling with KR increased diastolic and phasic [Ca(2+)], whereas cooling with CP suppressed phasic [Ca(2+)] and reduced the rise in diastolic [Ca(2+)]. Reperfusion with warm KR increased phasic [Ca(2+)] 86% more after CP at 20 minutes and did not increase diastolic [Ca(2+)] at 60 minutes, compared with a 20% increase in phasic [Ca(2+)] after KR. During early and later reperfusion after CP, there was a 126% and 50% better return of LVP than after KR; during later reperfusion, O(2) consumption was 23% higher and cardiac efficiency was 38% higher after CP than after KR.

CONCLUSIONS

CP decreases the rise in cardiac diastolic [Ca(2+)] observed during cold storage in KR. Decreased diastolic [Ca(2+)] and increased systolic [Ca(2+)] after CP improves function on reperfusion because of reduced Ca(2+) loading during and immediately after cold CP storage.

Linkage of the genes controlling natural killer cell activity to HLA-B

OBJECTIVE

To study whether there is a relationship between HLA-B alleles and low natural killer(NK) cell activity in Chinese.

METHODS

The subjects were 34 unrelated healthy individuals (10 males and 24 females), aged 25-60 years, and 31 individuals (17 males and 14 females) from 11 families, aged 22-70 years, previously genotyped for HLA class I, II, complotypes and haplotypes that were assigned based on family studies. The unrelated individuals were typed for HLA-A, -B antigen by a microcytotoxicity assay and all the subjects were tested for NK cell activity by lactate dehydrogenase (LDH) enzyme-release assay.

RESULTS

Statistical analysis showed that 30 lysis unit(LU) was the cutoff value of low and high NK reactors. The frequency of low reactor individuals homozygous for HLA-B was significantly higher than that for those for HLA-DR(P< 0. 05). The associated genes included HLA-B13, B40, B46, B7, B57, defined as NKB1 genes, and HLA-B44 as NKB2 gene. Family studies provide further evidence that the genes controlling low NK cell activity were located in the MHC region and it was a recessive trait.

CONCLUSION

There were recessive genes associated with HLA-B controlling low NK cell activity in Chinese. The NKB alleles were partly different from those found in Caucasian.

ProTherm, version 2.0: thermodynamic database for proteins and mutants

ProTherm 2.0 is the second release of the Thermo-dynamic Database for Proteins and Mutants that includes numerical data for several thermodynamic parameters, structural information, experimental methods and conditions, functional and literature information. The present release contains >5500 entries, an approximately 67% increase over the previous version. In addition, we have included information about reversibility of data, details about buffer and ion concentrations and the surrounding residues in space for all mutants. A WWW interface enables users to search data based on various conditions with different sorting options for outputs. Further, ProTherm has links with other structural and literature databases, and the mutation sites and surrounding residues are automatically mapped on the structures and can be directly viewed through 3DinSight developed in our laboratory. The ProTherm database is freely available through the WWW at http://www.rtc.riken.go.jp/protherm.html

Estradiol repression of tumor necrosis factor-alpha transcription requires estrogen receptor activation function-2 and is enhanced by coactivators

The tumor necrosis factor-alpha (TNF-alpha) promoter was used to explore the molecular mechanisms of estradiol (E(2))-dependent repression of gene transcription. E(2) inhibited basal activity and abolished TNF-alpha activation of the TNF-alpha promoter. The E(2)-inhibitory element was mapped to the -125 to -82 region of the TNF-alpha promoter, known as the TNF-responsive element (TNF-RE). An AP-1-like site in the TNF-RE is essential for repression activity. Estrogen receptor (ER) beta is more potent than ERalpha at repressing the -1044 TNF-alpha promoter and the TNF-RE upstream of the herpes simplex virus thymidine kinase promoter, but weaker at activating transcription through an estrogen response element. The activation function-2 (AF-2) surface in the ligand-binding domain is required for repression, because anti-estrogens and AF-2 mutations impair repression. The requirement of the AF-2 surface for repression is probably due to its capacity to recruit p160 coactivators or related coregulators, because overexpressing the coactivator glucocorticoid receptor interacting protein-1 enhances repression, whereas a glucocorticoid receptor interacting protein-1 mutant unable to interact with the AF-2 surface is ineffective. Furthermore, receptor interacting protein 140 prevents repression by ERbeta, probably by interacting with the AF-2 surface and blocking the binding of endogenous coactivators. These studies demonstrate that E(2)-mediated repression requires the AF-2 surface and the participation of coactivators or other coregulatory proteins.

Modulation of myocardial function and [Ca2+] sensitivity by moderate hypothermia in guinea pig isolated hearts

Cardiac hypothermia alters contractility and intracellular Ca2+ concentration ([Ca2+]i) homeostasis. We examined how left ventricular pressure (LVP) is altered as a function of cytosolic [Ca2+]i over a range of extracellular CaCl2 concentration ([CaCl2]e) during perfusion of isolated, paced guinea pig hearts at 37 degrees C, 27 degrees C, and 17 degrees C. Transmural LV phasic [Ca2+] was measured using the Ca2+ indicator indo 1 and calibrated (in nM) after correction was made for autofluorescence, temperature, and noncytosolic Ca2+. Noncytosolic [Ca2+]i, cytosolic diastolic and systolic [Ca2+]i, phasic [Ca2+]i, and systolic Ca2+ released per beat (area Ca2+) were plotted as a function of 0.3-4.5 mM [CaCl2]e, and indexes of contractility [LVP, maximal rates of LVP development (+dLVP/dt) and relaxation (-dLVP/dt), and the integral of the LVP curve per beat (LVParea)] were plotted as a function of [Ca2+]i. Hypothermia increased systolic [Ca2+]i and slightly changed systolic LVP but increased diastolic LVP and [Ca2+]i. The relationship of diastolic and noncytosolic [Ca2+] to [CaCl2]e was shifted upward at 17 degrees C and 27 degrees C, whereas that of phasic [Ca2+]) to [CaCl2]e was shifted upward at 17 degrees C but not at 27 degrees C. The relationships of phasic [Ca2+]i to developed LVP, +dLVP/dt, and LVP(area) were progressively reduced by hypothermia so that maximal Ca2+-activated LVP decreased and hearts were desensitized to Ca2+. Thus mild hypothermia modestly increases diastolic and noncytosolic Ca2+ with little effect on systolic Ca2+ or released (area) Ca2+, whereas moderate hypothermia markedly increases diastolic, noncytosolic, peak systolic, and released Ca2+ and results in reduced maximal Ca2+-activated LVP and myocardial sensitivity to systolic Ca2+.

Threonine phosphorylations induced by RX-871024 and insulin secretagogues in betaTC6-F7 cells

Treatment of the pancreatic beta-cell line betaTC6-F7 with an imidazoline compound, RX-871024, KCl, or tolbutamide resulted in increased threonine phosphorylation of a 220-kDa protein (p220) concurrent with enhanced insulin secretion, which can be partially antagonized by diazoxide, an ATP-sensitive potassium (K(ATP)) channel activator. Although phosphorylation of p220 was regulated by cytoplasmic free calcium concentration ([Ca(2+)](i)), membrane depolarization alone was not sufficient to induce phosphorylation. Phosphorylation of p220 also was not directly mediated by protein kinase A, protein kinase C, or insulin exocytosis. Analysis of subcellular fractions indicated that p220 is a hydrophilic protein localized exclusively in the cytosol. Subsequently, p220 was purified to homogeneity, sequenced, and identified as nonmuscle myosin heavy chain-A (MHC-A). Stimulation of threonine phosphorylation of nonmuscle MHC-A by KCl treatment also resulted in increased phosphorylation of a 40-kDa protein, which was coimmunoprecipitated by antibody to MHC-A. Our results suggest that both nonmuscle MHC-A and the 40-kDa protein may play roles in regulating signal transduction, leading to insulin secretion.

ESR evidence of the photogeneration of free radicals (GDHB*-, O2*-) and singlet oxygen ((1)O2) by 15-deacetyl-13-glycine-substituted hypocrellin B

15-Deacetyl-13-glycine-substituted hypocrellin B (GDHB) is a new type of hypocrellin derivative with an enhanced red absorption longer than 600 nm and water solubility. Visible light (> 470 nm) irradiation of an anaerobic aqueous solution of GDHB, the formation of GDHB*- was detected by an ESR method in the absence or presence of electron donor. When exposed to oxygen, superoxide anion radical and singlet oxygen were formed. The superoxide anion radical was generated by GDHB*- via electron transfer to oxygen and this process was significantly enhanced by the presence of electron donors. Singlet oxygen ((1)O2) was also formed in the photosensitization of GDHB in aerobic solution and 1,4-diazabicyclo [2,2,2] octane (DABCO), sodium azide (NaN3) and histidine inhibited the generation of (1)O2. A 9,10-diphenyl antracene (DPA)-bleaching method was used to determine the quantum yield of (1)O2 generated from GDHB photosensitization. The (1)O2 quantum yield was estimated to be 0.65. With the depletion of oxygen, the accumulation of GDHB*- would replace that of (1)O2. Evidence accumulated that the photodynamic action of GDHB may proceed via both type I and type II mechanisms and that a type II mechanism will be transformed into a type I mechanism as oxygen gets depleted.

Development of a novel mouse model for dengue virus infection

In the present study, we established an animal model for dengue virus infection using severe combined immunodeficient mice transplanted with a human hepatocarcinoma cell line (HepG2). At 7-8 weeks after transplantation, the HepG2-grafted mice were infected intraperitoneally with dengue virus type 2 (DEN-2). A higher titer of the virus was detected in the liver and serum but not in the brain in the early stage of postinfection. When the mice showed paralysis, the highest titer of virus was detected in the serum and brain. DEN-2 antigens were also found in HepG2 cells of the liver in the early stage and some neurons of the brain in the late stage. Upon clinical examination, thrombocytopenia, prolonged partial thromboplastin time, and increased hematocrit, blood urea nitrogen, and tumor necrosis factor alpha were seen in the paralyzed mice. Moreover, mild hemorrhage in the liver and tarry stool in the small intestine were observed in some mice. Our results show some similarities to human DEN infection and this mouse model might be valuable for studying some aspects of pathogenesis of this disease.

[The development of mouse bioreactor expressing human tissue plasminogen activator (tPA) in mammary gland by transfecting spermatozoa in testicular duct]

The most established methods for development of transgenic animals are the microinjection of DNA into the fertilized eggs, but it is still a procedure of certain complexity and high cost. Therefore, the idea of using sperm as a vehicle to carry exogenous DNA into eggs is very attractive, and there have been some successful reports. Though the methods are rather simple they sometimes have low reproducibility. To improve the technique we transinfected the spermatozoa in testicular duct, not in vitro, to produce mice which expressed human tissue plasminogen activator (tPA) in mammary gland. The results demonstrated that: (1) 5 transinfected mice mated 10 female mice in 10 days after operation, (2) 79 founders were developed and 42 survived, (3) using PCR to detect foreign DNA integrated into the genome of founders, 7 out of 42 founders were positive (16.67%), (4) The expression level of tPA was 48-80 ng/ml in the milk of 5 PCR positive founders and (5) the foreign DNA integrated into the genome was detected in 2 out of 4 1st offspring by PCR technique.

Fibrin microbeads (FMB) as biodegradable carriers for culturing cells and for accelerating wound healing

We have developed biodegradable fibrin-derived microbeads as potent cell carriers. The fibrin-derived microbeads, 50-200 microm in diameter, were tested for their attachment to a wide range of cell types. Fibrin-derived microbeads were shown to be greatly haptotactic to cells (such as endothelial cells, smooth muscle cells and fibroblasts), which respond to fibrinogen in contrast to keratinocytes and different cell lines derived from leukocytic lineage. The cells on fibrin-derived microbeads could be maintained for more than 10 d and achieved a high density. 31P-nuclear magnetic resonance was employed to monitor phosphate metabolism in cells, with densities on the order of 100 million cells per g of fibrin-derived microbeads. The 31P-nuclear magnetic resonance adenosine triphosphate and phosphocreatine signals, equivalent to the signal obtained with perfused normal skin, indicated that metabolism of cells on fibrin-derived microbeads was responsive to oxygenation and nutrients. Light, fluorescent, and confocal laser microscopy revealed that the porous fibrin-derived microbeads accommodate up to 200-300 cells due to their high surface area which minimized contact inhibition. Cells could degrade the fibrin-derived microbeads and be transferred to seed culture flasks without trypsinization. In a pig skin wound healing model, fibrin-derived microbeads + fibroblasts were transplanted into full thickness punch wounds. This procedure was compared with other treatment modalities, such as the addition of human platelet-derived growth factor BB or fibrin-derived microbeads alone. By the third day after wounding, only the wounds in which fibroblasts on fibrin-derived microbeads were added showed significant formation of granulation tissue. Based on the above, we project many uses of our novel fibrin-derived microbead technology for cell culturing, wound healing and tissue engineering.

Characterization of a mutant pancreatic eIF-2alpha kinase, PEK, and co-localization with somatostatin in islet delta cells

Phosphorylation of eukaryotic translation initiation factor-2alpha (eIF-2alpha) is one of the key steps where protein synthesis is regulated in response to changes in environmental conditions. The phosphorylation is carried out in part by three distinct eIF-2alpha kinases including mammalian double-stranded RNA-dependent eIF-2alpha kinase (PKR) and heme-regulated inhibitor kinase (HRI), and yeast GCN2. We report the identification and characterization of a related kinase, PEK, which shares common features with other eIF-2alpha kinases including phosphorylation of eIF-2alpha in vitro. We show that human PEK is regulated by different mechanisms than PKR or HRI. In contrast to PKR or HRI, which are dependent on autophosphorylation for their kinase activity, a point mutation that replaced the conserved Lys-614 with an alanine completely abolished the eIF-2alpha kinase activity, whereas the mutant PEK was still autophosphorylated when expressed in Sf-9 cells. Northern blot analysis indicates that PEK mRNA was predominantly expressed in pancreas, though low expression was also present in several tissues. Consistent with the high levels of mRNA in pancreas, the PEK protein was only detected in human pancreatic islets, and the kinase co-localized with somatostatin, a pancreatic delta cell-specific hormone. Thus PEK is believed to play an important role in regulating protein synthesis in the pancreatic islet, especially in islet delta cells.