The role of SepF in cell division and diazotrophic growth in the multicellular cyanobacterium Anabaena sp. strain PCC 7120.

The cyanobacterium Anabaena forms filaments of cells that grow by intercalary cell division producing adjoined daughter cells connected by septal junction protein complexes that provide filament cohesion and intercellular communication, representing a genuine case of bacterial multicellularity. In spite of their diderm character, cyanobacterial genomes encode homologs of SepF, a protein normally found in Gram-positive bacteria. In Anabaena, SepF is an essential protein that localized to the cell division ring and the intercellular septa. Overexpression of sepF had detrimental effects on growth, provoking conspicuous alterations in cell morphology that resemble the phenotype of mutants impaired in cell division, and altered the localization of the division-ring. SepF interacted with FtsZ and with the essential FtsZ tether ZipN. Whereas SepF from unicellular bacteria generally induces the bundling of FtsZ filaments, Anabaena SepF inhibited FtsZ bundling, reducing the thickness of the toroidal aggregates formed by FtsZ alone and eventually preventing FtsZ polymerization. Thus, in Anabaena SepF appears to have an essential role in cell division by limiting the polymerization of FtsZ to allow the correct formation and localization of the Z-ring. Expression of sepF is downregulated during heterocyst differentiation, likely contributing to the inhibition of Z-ring formation in heterocysts. Finally, the localization of SepF in intercellular septa and its interaction with the septal-junction related proteins SepJ and SepI suggest a role of SepF in the formation or stability of the septal complexes that mediate cell-cell adhesion and communication, processes that are key for the multicellular behavior of Anabaena.

[Translated article] Prognosis of the contralateral hip after primary total hip replacement: Can it be predicted?

INTRODUCTION: Coxarthrosis is one of the most frequent and disabling pathologies. 20% of individuals over 60 years of age will develop symptomatic coxarthrosis and 10% of them will need a hip replacement; it is probably one of the orthopaedic procedures that most increases quality of life. When we recommend arthroplasty in clinical practice, patients often ask about the prognosis of their other hip. Will it deteriorate in the same way? Will it be necessary to replace it? When? The aim of the study is to determine if there is any variable or radiological sign that predicts the medium-term prognosis of the contralateral hip after total hip arthroplasty. MATERIAL AND METHODS: A retrospective review of patients who underwent total hip arthroplasty in our hospital during 2011 and 2012 was carried out, with a total of 543 patients. The coxarthrosis degree at X-ray was determined at the time of the first arthroplasty and at regular intervals during follow-up, according to the JOA and Tönnis classifications, analyzing each of the items included in these classifications. Its relation with the progression of osteoarthritis and the need of contralateral hip replacement was established. RESULTS AND CONCLUSIONS: A progression of osteoarthritis of the contralateral hip could be expected in the next 3 years in 10% of patients. This progression will be greater and faster in those with JOA grade III-IV/Tönnis grade II-III, especially, in those with greater joint narrowing and femoral head shape score, and can reach between 25 and 30% of patients. The initial JOA/Tönnis degree is a predictive factor for requiring a hip replacement on the contralateral side.

Prognosis of the contralateral hip after primary total hip replacement: Can it be predicted? / ¿Se puede predecir el pronóstico de la cadera contralateral tras una artroplastia total de cadera?

INTRODUCTION: Coxarthrosis is one of the most frequent and disabling pathologies. 20% of individuals over 60 years of age will develop symptomatic coxarthrosis and 10% of them will need a hip replacement; it is probably one of the orthopaedic procedures that most increases quality of life. When we recommend arthroplasty in clinical practice, patients often ask about the prognosis of their other hip. Will it deteriorate in the same way? Will it be necessary to replace it? When? The aim of the study is to determine if there is any variable or radiological sign that predicts the medium-term prognosis of the contralateral hip after total hip arthroplasty. MATERIAL AND METHODS: A retrospective review of patients who underwent total hip arthroplasty in our hospital during 2011 and 2012 was carried out, with a total of 543 patients. The coxarthrosis degree at X-ray was determined at the time of the first arthroplasty and at regular intervals during follow-up, according to the JOA and Tönnis classifications, analyzing each of the items included in these classifications. Its relation with the progression of osteoarthritis and the need of contralateral hip replacement was established. RESULTS AND CONCLUSIONS: A progression of osteoarthritis of the contralateral hip could be expected in the next 3 years in 10% of patients. This progression will be greater and faster in those with JOA grade III-IV/Tönnis grade II-III, especially, in those with greater joint narrowing and femoral head shape score, and can reach between 25 and 30% of patients. The initial JOA/Tönnis degree is a predictive factor for requiring a hip replacement on the contralateral side.

Combined excimer laser trabeculostomy and phacoemulsification: One year follow-up real world data of a laser-based MIGS.

PURPOSE: To evaluate the efficacy and complication profile of excimer laser trabeculostomy (ELT), an emerging laser-based trabecular minimally invasive glaucoma surgery (MIGS), combined with cataract surgery in routine clinical practice. PATIENTS AND METHODS: Single-site, retrospective, interventional study. Preoperative and postoperative clinical data of patients with cataract and open-angle glaucoma (OAG) who underwent combined phacoemulsification and ELT were collected and analyzed at preoperative day, one week postoperatively, and after one, two, three, six, nine and 12 months. Main outcome measure was intraocular pressure (IOP). Qualified and complete success were defined as an IOP less than 21mmHg and an IOP reduction ≥20% from preoperative medicated IOP with or without adjuvant medical treatment, respectively. RESULTS: Thirty-four eyes of 29 patients were included; 29 eyes completed 1-year follow-up. The mean preoperative IOP under medications was 20.9±2.6mmHg (±standard deviation, SD) and decreased significantly at one year (16.3±1.9; p<0.0001). The mean number of IOP-lowering medications decreased from 1.7±0.7 to 0.3±0.8 (p<0.0001) at the 12-month follow-up. At one year, 81% of eyes were medication free. Qualified and complete success was obtained in 62% and 58% of eyes, respectively. Two eyes had postoperative hyphema, three eyes had transient IOP spikes and one patient underwent a subsequent filtering surgery at three months. CONCLUSION: Combining ELT with phacoemulsification in eyes with cataract and mild to moderate OAG significantly reduced IOP and medication use without meaningful complications after one-year follow-up in a real world clinical practice setting.

Combined excimer laser trabeculostomy and phacoemulsification: one year follow-up real world data of a laser-based MIGS. / Cirugía combinada de trabeculostomía láser excímer y facoelmusificación: datos a un año en el mundo real de una MIGS de tipo láser.

PURPOSE: To evaluate the efficacy and complication profile of excimer laser trabeculostomy (ELT), an emerging laser-based trabecular minimally invasive glaucoma surgery (MIGS), combined with cataract surgery in routine clinical practice. PATIENTS AND METHODS: Single-site, retrospective, interventional study. Preoperative and postoperative clinical data of patients with cataract and open-angle glaucoma (OAG) who underwent combined phacoemulsification and ELT were collected and analyzed at preoperative day, one week postoperatively, and after one, two, three, six, nine and 12 months. Main outcome measure was intraocular pressure (IOP). Qualified and complete success were defined as an IOP less than 21 mmHg and an IOP reduction ≥ 20% from preoperative medicated IOP with or without adjuvant medical treatment, respectively. RESULTS: Thirty-four eyes of 29 patients were included; 29 eyes completed 1-year follow-up. The mean preoperative IOP under medications was 20.9 ± 2.6 mmHg (± standard deviation, SD) and decreased significantly at one year (16.3 ± 1.9; p < 0.0001). The mean number of IOP-lowering medications decreased from 1.7 ± 0.7 to 0.3 ± 0.8 (p < 0.0001) at the 12-month follow-up. At one year, 81% of eyes were medication free. Qualified and complete success was obtained in 62% and 58% of eyes, respectively. Two eyes had postoperative hyphema, three eyes had transient IOP spikes and one patient underwent a subsequent filtering surgery at three months. CONCLUSION: Combining ELT with phacoemulsification in eyes with cataract and mild to moderate OAG significantly reduced IOP and medication use without meaningful complications after one-year follow-up in a real world clinical practice setting.

About 3 cases of post-acute retinopathy of chikungunya fever. / A propósito de 3 casos con retinopatía posterior a fase aguda de fiebre por chikungunya.

A descriptive study is presented on a case series of 3 patients, with IgM an IgG serology diagnosis of Chikungunya in whom other metabolic, autoimmune and infectious diseases were ruled out. They presented with other ocular manifestations with vascular changes and inflammatory characteristics. They were treated at the Retinovascular and Retinal and Vitreous clinics at the "Dr. Rodolfo Robles Valverde Hospital" and "Benemérito Comité Pro-ciegos y Sordos" in Guatemala City during 2019. Guatemala is a country with a high prevalence of vector-borne diseases, including chikungunya. In recent years cases of this disease has increased in recent years, and complications are currently seen more frequently. Within these complications, there have been reports of cases of optic neuritis, iridocyclitis, episcleritis, retinitis, uveitis, and blood dyscrasia that can affect the retina. It is important to consider these as an important differential diagnosis of ocular vascular alterations.

New anesthetic approach in glaucoma surgery: "Underbleb" subtenonian anesthesia and its influence in medium term outcome. / Nuevo abordaje anestésico en la cirugía de glaucoma: anestesia subtenoniana ampular y su influencia en el resultado a medio plazo.

PURPOSE: To present a new anterior subtenonian anesthesia approach in the area of the future filtration bleb and its influence on medium term surgical success. MATERIAL AND METHODS: Retrospective study of 97 surgeries, deep sclerectomy (DE) or phaco-deep sclerectomy (PHACO-DS), were performed in patients with open angle glaucoma (OAG) comparing our modified "underbleb" subtenonian anesthesia (USA) (n=58) versus a control group under peribulbar anesthesia (PA) (n=38). Main outcomes were intraocular pressure (IOP), number of antiglaucomatous drugs and total and qualificated success, compared during 1, 3, 6, 12, 18 and 24 months follow up after glaucoma surgery. RESULTS: Both groups were comparable in terms of age, gender, surgical technique, number of antiglaucoma drugs and preoperative IOP. The IOP in the USA group decreased as in PA control group without statistical significant differences except at 24 months, where the IOP was 2mm lower (14.83 ± 2.87 vs. 17.61 ± 4.27 (P=.009). This happened for both, DS and PHACO-DS surgeries. The number of postoperative drugs was lower at 3, 6, and 18 months but without statistically significant diferences. Total success rate at 24 months was higher in the USA group respect AP control group (62.5% vs. 51.6) as well as partial success (100% vs. 71%). CONCLUSION: Our new USA anesthetic technique does not have a negative impact in DS medium-term surgical success, even it could contribute to a longer-term improvement.

[Antiangiogenic therapy in Sorsby's fundus dystrophy without a mutation in the TIMP-3 gene]. / Tratamiento antiangiogénico en fondo de distrofia de Sorsby sin mutación en gen de TIMP-3.

CASE REPORT: The case is presented of a 32-year-old man referring to metamorphopsia and blurred vision in both eyes for 3 days. Best corrected visual acuity of 20/32 in the right eye and 20/25 in the left eye. Fundus examination revealed the presence of drusen-like deposits, suggestive of Sorsby's fundus dystrophy (SFD) and choroidal neovascularization (CNV) bilaterally. The patient received intravitreal ranibizumab. Visual acuity improved to 20/20 in both eyes at 6-months follow-up, and results of fundus examination showed complete regression of neovascularization. No mutations were found in the TIMP-3 gene. DISCUSSION: The known mutations in TIMP-3 may not be extended to all patients with SFD. The use of intravitreal ranibizumab may be considered as a therapeutic option in CNV secondary to SFD.

First Report of Cymbidium mosaic virus and Odontoglossum ringspot virus in Orchids in Mexico.

In 2010, a survey for viral diseases in commercial, orchid-producing greenhouses was carried out in Morelos, Mexico. Many symptomatic plants were observed. The most common leaf symptoms were yellow mottle, yellow streaks, and chlorotic and necrotic ringspots. Leaf samples were collected from eight symptomatic plants from the following genera: Encyclia, Oncidium, Shomburghia, Brassia, Guarianthe, Cattleya, Epidendrum, Vanilla, Xilobium, Laelia, and Brassocattleya. Samples were tested using double-antibody sandwich (DAS)-ELISA (Agdia, Elkhart, IN) with antiserum for Cymbidium mosaic virus (CymMV), Odontoglossum ringspot virus (ORSV), Cymbidium ringspot mosaic virus, and Tobacco mosaic virus (TMV) and a general antiserum for potyviruses. At least one plant from each genus was positive to CymMV and ORSV as individual or mixed infections. Encyclia and Laelia plants were the most frequently found with mixed infections by both viruses. All genera were negative for TMV and potyviruses. Total RNA extracts were obtained from all ELISA-positive samples by a modified silica capture protocol (2). Reverse transcription (RT)-PCR was carried out with general polymerase (RdRp) gene primers corresponding to the Potexvirus group (3) and specific primers for the coat protein gene (CP) of CymMV and ORSV (1). The PCR amplification from a positive sample of each genus was resolved in agarose gels. Amplification products of the expected size were obtained for CymMV and ORSV. Five CymMV RdRp gene clones from five different plants of Laelia (GenBank Accession Nos. HQ393958, HQ393959, HQ393960, HQ393961, and HQ393962), two CP gene clones of CP gene of CymMV from two different plants of Oncidium (GenBank Accession Nos. HQ393956 and HQ393957), and three CP clones of CP of ORSV from three different plants of Encyclia (GenBank Accession Nos. HQ393953, HQ393954, and HQ393955) were sequenced. The nucleotide sequences of the Mexican orchid CymMV isolates were 96 to 97% identical to CymMV sequences in the GenBank, while those of ORSV were 99 to 100% identical to deposited ORSV sequences. To our knowledge, this is the first report of CymMV and ORSV in orchids in Mexico, which are two of the most important quarantine virus in orchids in Mexico. References: (1) P. Ajjikuttira et al. J. Gen. Virol. 86:1543, 2005. (2) J. R. Thompson et al. J. Virol. Methods 111:85, 2003. (3) R. A. A. van der Vlugt and M. Berendsen. Eur. J. Plant Pathol. 108:367, 2002.

Genome-wide association study of type 2 diabetes in a sample from Mexico City and a meta-analysis of a Mexican-American sample from Starr County, Texas.

AIMS/HYPOTHESIS: We report a genome-wide association study of type 2 diabetes in an admixed sample from Mexico City and describe the results of a meta-analysis of this study and another genome-wide scan in a Mexican-American sample from Starr County, TX, USA. The top signals observed in this meta-analysis were followed up in the Diabetes Genetics Replication and Meta-analysis Consortium (DIAGRAM) and DIAGRAM+ datasets. METHODS: We analysed 967 cases and 343 normoglycaemic controls. The samples were genotyped with the Affymetrix Genome-wide Human SNP array 5.0. Associations of genotyped and imputed markers with type 2 diabetes were tested using a missing data likelihood score test. A fixed-effects meta-analysis including 1,804 cases and 780 normoglycaemic controls was carried out by weighting the effect estimates by their inverse variances. RESULTS: In the meta-analysis of the two Hispanic studies, markers showing suggestive associations (p < 10(-5)) were identified in two known diabetes genes, HNF1A and KCNQ1, as well as in several additional regions. Meta-analysis of the two Hispanic studies and the recent DIAGRAM+ dataset identified genome-wide significant signals (p < 5 × 10(-8)) within or near the genes HNF1A and CDKN2A/CDKN2B, as well as suggestive associations in three additional regions, IGF2BP2, KCNQ1 and the previously unreported C14orf70. CONCLUSIONS/INTERPRETATION: We observed numerous regions with suggestive associations with type 2 diabetes. Some of these signals correspond to regions described in previous studies. However, many of these regions could not be replicated in the DIAGRAM datasets. It is critical to carry out additional studies in Hispanic and American Indian populations, which have a high prevalence of type 2 diabetes.

Isolation and characterization of new facultative alkaliphilic Bacillus flexus strains from maize processing waste water (nejayote).

AIMS: This work describes the isolation and characterization of two new alkaliphilic micro-organisms present in nejayote. METHODS AND RESULTS: Samples of fresh industrial nejayote were plated on nejayote medium and incubated for 4 days at 37 °C. Isolates were identified based on morphological and physiological characteristics, as well as 16S rDNA sequence analysis. Two gram-positive strains, NJY2 and NJY4, able to hydrolyse starch, xylan, and gelatin were isolated from nejayote. Comparative sequence analysis of 16S rDNA and phylogenetic studies indicate that the micro-organisms studied were closely related to members of the Bacillus flexus species. The strains were identified as facultative alkaliphilic salt tolerant bacteria. Isolate NJY2 produced cell associated phenolic acid esterases, able to release ferulic acid from nixtamalised corn bran and ethyl and methyl esters. CONCLUSIONS: The isolated strains of B. flexus NJY2 and NJY4 showed important physiological properties to produce high-value molecules from agroindustrial by-products. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report about the isolation of alkaliphilic micro-organisms from nejayote and the first report of phenolic acid esterases synthesised by alkaliphiles. The new alkaliphilic micro-organisms have potential application in the treatment and transformation of tortilla industry residues.

[Depression: a social mortgage. Latest advances in knowledge of the cost of the disease]. / La depresión: una hipoteca social. Ultimos avances en el conocimiento del coste de la enfermedad.

INTRODUCTION: Following the latest examination of the worldwide mental health situation, the World Health Organization has estimated that depression produces the greatest decrement in health compared with other chronic diseases, and has encouraged to all countries to increase investment and resources in this field. METHODOLOGY: On investing resources for the care of patients with depression, cost of illness studies are a complement to morbidity-mortality studies, and are of great relevance in defining health care policies. The present study describes the economic impact of depression in our setting, in the light of the most recent publications on this subject. RESULTS: The total cost of depression in Europe has been estimated to reach 118 billion euros, and most of this amount (61 %) is due to indirect costs associated with sick leave and productivity losses. The economic burden of depression in Spain could add up to 5.005 million euros a year, with a resource category distribution very similar to that found in Europe as a whole. CONCLUSIONS: Health care systems and society must cope with the important costs of depression, which implies intense resource utilization, fundamentally outside the health care sector as such. There are a number of areas in which improvements can be made in order to reduce this important burden associated with depression, though the incorporation of health economics to public health care policies must become a priority.

MGEA5-14 polymorphism and type 2 diabetes in Mexico City.

A family-based study has recently reported that a variant located in intron 10 of the gene MGEA5 increases susceptibility to Type 2 Diabetes (T2D). We evaluated the distribution of this SNP in a sample of T2D patients (N = 271) and controls (N = 244) from Mexico City. The frequency of the T allele was higher in the cases (2.6%) than in the controls (1.8%). After adjusting for age, sex, BMI, education, and individual ancestry the odds ratio was 1.60 but the 95% confidence interval was wide and overlapped 1 (0.52-4.86, P-value : 0.404). In order to characterize the distribution of the MGEA5-14 polymorphism in the relevant parental populations, we genotyped this variant in European (and European Americans), West African, and Native American samples. The T-allele was present at a frequency of 2.3% in Spain, 4.2% in European Americans, and 13% in Western Africans, but was absent in two Native American samples from Mexico and Peru. Given the low frequency of the T-allele, further studies using large sample sizes will be required to confirm the role of this variant in T2D.

Association of TCF7L2 polymorphisms with type 2 diabetes in Mexico City.

Polymorphisms within the transcription factor 7-like 2 gene (TCF7L2) have been associated with type 2 diabetes (T2D) in several recent studies. We characterized three of these polymorphisms (rs12255372, rs7903146 and the microsatellite DG10S478) in an admixed sample of 286 patients with T2D and 275 controls from Mexico City. We also analyzed three samples representative of the relevant parental populations: Native Americans from the state of Guerrero (Mexico), Spanish from Valencia and Nigerians (Bini from the Edo region). In order to minimize potential confounding because of the presence of population stratification in the sample, we evaluated the association of the three TCF7L2 polymorphisms with T2D by using the program admixmap to fit a logistic regression model incorporating individual ancestry, sex, age, body mass index and education. The markers rs12255372, rs7903146 and DG10S478 are in tight disequilibrium in the Mexican sample. We observed a significant association between the single-nucleotide polymorphism (SNP) rs12255372 and the microsatellite DG10S478 with T2D in the Mexican sample [rs12255372, odds ratio (OR) = 1.78, p = 0.017; DG10S478, OR = 1.62, p = 0.041]. The SNP rs7903146 shows similar trends, but its association with T2D is not as strong (OR = 1.39, p = 0.152). Analysis of the parental samples, as well as other available data, indicates that there are substantial population frequency differences for these polymorphisms: The frequencies of the T2D risk factors are more than 20% higher in European and West African populations than in East Asian and Native American populations.

Interaction of FurA from Anabaena sp. PCC 7120 with DNA: a reducing environment and the presence of Mn(2+) are positive effectors in the binding to isiB and furA promoters.

The Fur (ferric uptake regulator) protein is a global regulator in most prokaryotes that controls a large number of genes. Fur is a classical repressor that uses ferrous iron as co-repressor and binds to specific DNA sequences (iron boxes) as a dimer. Three different genes coding for Fur homologues have been identified in Anabaena sp. PCC 7120. FurA controls the transcription of flavodoxin, the product of the isiB gene, and is moderately autoregulated. In this work, the promoter of the furA gene was defined and the FurA protected regions in the furA and isiB promoters were identified, showing that the binding sites for Anabaena FurA contain A/T-rich sequences with a variable arrangement compared to the conventional 19-base pair Fur consensus. The influence of different factors on the interaction between FurA and the promoters was evaluated in vitro. The affinity of FurA for the DNA targets was significantly affected by the redox status of this regulator and the presence of Mn(2+). The optimal binding conditions were observed in the presence of both Mn(2+) and DTT. Those results suggest that, in addition to iron availability, FurA-DNA interaction is modulated by redox conditions.

The coxBAC operon encodes a cytochrome c oxidase required for heterotrophic growth in the cyanobacterium Anabaena variabilis strain ATCC 29413.

Three genes, coxB, coxA, and coxC, found in a clone from a gene library of the cyanobacterium Anabaena variabilis strain ATCC 29413, were identified by hybridization with an oligonucleotide specific for aa(3)-type cytochrome c oxidases. Deletion of these genes from the genome of A. variabilis strain ATCC 29413 FD yielded strain CSW1, which displayed no chemoheterotrophic growth and an impaired cytochrome c oxidase activity. Photoautotrophic growth of CSW1, however, was unchanged, even with dinitrogen as the nitrogen source. A higher cytochrome c oxidase activity was detected in membrane preparations from dinitrogen-grown CSW1 than from nitrate-grown CSW1, but comparable activities of respiratory oxygen uptake were found in the wild type and in CSW1. Our data indicate that the identified cox gene cluster is essential for fructose-dependent growth in the dark, but not for growth on dinitrogen, and that other terminal respiratory oxidases are expressed in this cyanobacterium. Transcription analysis showed that coxBAC constitutes an operon which is expressed from two transcriptional start points. The use of one of them was stimulated by fructose.

Activation of p38MAPK by TGF-beta in fetal rat hepatocytes requires radical oxygen production, but is dispensable for cell death.

We have previously found that transforming growth factor-beta (TGF-beta) induces an increase in radical oxygen species (ROS) production that mediates its apoptotic effects in fetal hepatocytes. In this paper we show that TGF-beta activates p38 mitogen-activated protein kinase (p38MAPK) and ROS may be responsible for this activation. Activation of p38MAPK occurs late, coincident with the maximal production of ROS, it is inhibited by radical scavengers and it is accentuated by the presence of glutathione synthesis inhibitors. However, p38MAPK does not appear to be involved in any of the apoptotic events: loss of Bcl-x(L) levels, cytochrome c release, cleavage of caspase substrates and loss of cell viability.

TNF-alpha inhibits UCP-1 expression in brown adipocytes via ERKs. Opposite effect of p38MAPK.

Tumor necrosis factor-alpha (TNF-alpha) activates extracellular-regulated kinases (ERKs) and p38 mitogen-activated protein kinase (p38MAPK), and inhibits the expression of uncoupling protein-1 (UCP-1) and adipocyte-specific genes in rat fetal brown adipocytes. MEK inhibition with PD98059 abolished the inhibitory effect of TNF-alpha on UCP-1, but not on adipogenic genes. In contrast, inhibition of p38MAPK with SB203580 potentiated the negative effect of TNF-alpha on UCP-1 and adipogenic genes. The inhibitory action of TNF-alpha was partially correlated with changes in C/EBPalpha and beta protein levels and in their DNA binding activity, suggesting a role for these transcription factors. However, other transcription factors might explain the different regulation of UCP-1 and adipogenic genes by ERKs.

p38 mitogen-activated protein kinase mediates tumor necrosis factor-alpha-induced apoptosis in rat fetal brown adipocytes.

Tumor necrosis factor-alpha (TNFalpha) induces apoptosis and cell growth inhibition in primary rat fetal brown adipocytes. Here, we examine the role played by some members of the mitogen-activated protein kinase (MAPK) superfamily. TNFalpha activates extracellular regulated kinase-1/2 (ERK1/2) and p38MAPK. Inhibition of p38MAPK by either SB203580 or SB202190 highly reduces apoptosis induced by TNFalpha, whereas ERK inhibition potentiates it. Moreover, cotransfection of an active MKK3 mutant and p38MAPK induces apoptosis. p38MAPK inhibition also prevents TNFalpha-induced cell cycle arrest, whereas MEK1 inhibition enhances this effect, which correlates with changes in proliferating cell nuclear antigen expression, but not in cyclin D1. c-Jun and activating transcription factor-1 are potential downstream effectors of p38MAPK and ERKs upon TNFalpha treatment. Thus, TNFalpha-induced c-Jun messenger RNA expression requires ERKs activation, whereas p38MAPK inhibition enhances its expression. In addition, TNFalpha-induced activating transcription factor-1 phosphorylation is extensively decreased by SB203580. However, TNFalpha-induced NF-kappaB DNA-binding activity is independent of p38MAPK and ERK activation. On the other hand, C/EBP homology protein does not appear to mediate the actions of TNFalpha, because its expression is almost undetectable and even reduced by TNFalpha. Finally, although TNFalpha induces c-Jun N-terminal kinase (JNK) activation, transfection of a dominant negative of either JNK1 or JNK2 had no effect on TNFalpha-induced apoptosis. These results suggest that p38MAPK mediates TNFalpha-induced apoptosis and cell cycle arrest, whereas ERKs do the opposite, and JNKs play no role in this process of apoptosis.