Type I interferon signaling pathway enhances immune-checkpoint inhibition in KRAS mutant lung tumors.

Lung cancer is the leading cause of cancer mortality worldwide. KRAS oncogenes are responsible for at least a quarter of lung adenocarcinomas, the main subtype of lung cancer. After four decades of intense research, selective inhibitors of KRAS oncoproteins are finally reaching the clinic. Yet, their effect on overall survival is limited due to the rapid appearance of drug resistance, a likely consequence of the high intratumoral heterogeneity characteristic of these tumors. In this study, we have attempted to identify those functional alterations that result from KRAS oncoprotein expression during the earliest stages of tumor development. Such functional changes are likely to be maintained during the entire process of tumor progression regardless of additional co-occurring mutations. Single-cell RNA sequencing analysis of murine alveolar type 2 cells expressing a resident Kras oncogene revealed impairment of the type I interferon pathway, a feature maintained throughout tumor progression. This alteration was also present in advanced murine and human tumors harboring additional mutations in the p53 or LKB1 tumor suppressors. Restoration of type I interferon (IFN) signaling by IFN-ß or constitutive active stimulator of interferon genes (STING) expression had a profound influence on the tumor microenvironment, switching them from immunologically "cold" to immunologically "hot" tumors. Therefore, enhancement of the type I IFN pathway predisposes KRAS mutant lung tumors to immunotherapy treatments, regardless of co-occurring mutations in p53 or LKB1.

Apolipoprotein E-ε2 and Resistance to Atherosclerosis in Midlife: The PESA Observational Study.

BACKGROUND: APOE is a known genetic contributor to cardiovascular disease, but the differential role APOE alleles play in subclinical atherosclerosis remains unclear. METHODS: The PESA (Progression of Early Subclinical Atherosclerosis) is an observational cohort study that recruited 4184 middle-aged asymptomatic individuals to be screened for cardiovascular risk and multiterritorial subclinical atherosclerosis. Participants were APOE-genotyped, and omics data were additionally evaluated. RESULTS: In the PESA study, the frequencies for APOE -ε2, -ε3, and -ε4 alleles were 0.060, 0.844, and 0.096, respectively. This study included a subcohort of 3887 participants (45.8±4.3 years of age; 62% males). As expected, APOE-ε4 carriers were at the highest risk for cardiovascular disease and had significantly greater odds of having subclinical atherosclerosis compared with ε3/ε3 carriers, which was mainly explained by their higher levels of low-density lipoprotein (LDL)-cholesterol. In turn, APOE-ε2 carriers were at the lowest risk for cardiovascular disease and had significantly lower odds of having subclinical atherosclerosis in several vascular territories (carotids: 0.62 [95% CI, 0.47-0.81]; P=0.00043; femorals: 0.60 [0.47-0.78]; P=9.96×10-5; coronaries: 0.53 [0.39-0.74]; P=0.00013; and increased PESA score: 0.58 [0.48-0.71]; P=3.16×10-8). This APOE-ε2 atheroprotective effect was mostly independent of the associated lower LDL-cholesterol levels and other cardiovascular risk factors. The protection conferred by the ε2 allele was greater with age (50-54 years: 0.49 [95% CI, 0.32-0.73]; P=0.00045), and normal (<150 mg/dL) levels of triglycerides (0.54 [0.44-0.66]; P=4.70×10-9 versus 0.90 [0.57-1.43]; P=0.67 if ≥150 mg/dL). Omics analysis revealed an enrichment of several canonical pathways associated with anti-inflammatory mechanisms together with the modulation of erythrocyte homeostasis, coagulation, and complement activation in ε2 carriers that might play a relevant role in the ε2's atheroprotective effect. CONCLUSIONS: This work sheds light on the role of APOE in cardiovascular disease development with important therapeutic and prevention implications on cardiovascular health, especially in early midlife. REGISTRATION: URL: https://www.clinicaltrials.gov: NCT01410318.

A Human Hereditary Cardiomyopathy Shares a Genetic Substrate With Bicuspid Aortic Valve.

BACKGROUND: The complex genetics underlying human cardiac disease is evidenced by its heterogenous manifestation, multigenic basis, and sporadic occurrence. These features have hampered disease modeling and mechanistic understanding. Here, we show that 2 structural cardiac diseases, left ventricular noncompaction (LVNC) and bicuspid aortic valve, can be caused by a set of inherited heterozygous gene mutations affecting the NOTCH ligand regulator MIB1 (MINDBOMB1) and cosegregating genes. METHODS: We used CRISPR-Cas9 gene editing to generate mice harboring a nonsense or a missense MIB1 mutation that are both found in LVNC families. We also generated mice separately carrying these MIB1 mutations plus 5 additional cosegregating variants in the ASXL3, APCDD1, TMX3, CEP192, and BCL7A genes identified in these LVNC families by whole exome sequencing. Histological, developmental, and functional analyses of these mouse models were carried out by echocardiography and cardiac magnetic resonance imaging, together with gene expression profiling by RNA sequencing of both selected engineered mouse models and human induced pluripotent stem cell-derived cardiomyocytes. Potential biochemical interactions were assayed in vitro by coimmunoprecipitation and Western blot. RESULTS: Mice homozygous for the MIB1 nonsense mutation did not survive, and the mutation caused LVNC only in heteroallelic combination with a conditional allele inactivated in the myocardium. The heterozygous MIB1 missense allele leads to bicuspid aortic valve in a NOTCH-sensitized genetic background. These data suggest that development of LVNC is influenced by genetic modifiers present in affected families, whereas valve defects are highly sensitive to NOTCH haploinsufficiency. Whole exome sequencing of LVNC families revealed single-nucleotide gene variants of ASXL3, APCDD1, TMX3, CEP192, and BCL7A cosegregating with the MIB1 mutations and LVNC. In experiments with mice harboring the orthologous variants on the corresponding Mib1 backgrounds, triple heterozygous Mib1 Apcdd1 Asxl3 mice showed LVNC, whereas quadruple heterozygous Mib1 Cep192 Tmx3;Bcl7a mice developed bicuspid aortic valve and other valve-associated defects. Biochemical analysis suggested interactions between CEP192, BCL7A, and NOTCH. Gene expression profiling of mutant mouse hearts and human induced pluripotent stem cell-derived cardiomyocytes revealed increased cardiomyocyte proliferation and defective morphological and metabolic maturation. CONCLUSIONS: These findings reveal a shared genetic substrate underlying LVNC and bicuspid aortic valve in which MIB1-NOTCH variants plays a crucial role in heterozygous combination with cosegregating genetic modifiers.

Subclinical atherosclerosis and accelerated epigenetic age mediated by inflammation: a multi-omics study.

AIMS: Epigenetic age is emerging as a personalized and accurate predictor of biological age. The aim of this article is to assess the association of subclinical atherosclerosis with accelerated epigenetic age and to investigate the underlying mechanisms mediating this association. METHODS AND RESULTS: Whole blood methylomics, transcriptomics, and plasma proteomics were obtained for 391 participants of the Progression of Early Subclinical Atherosclerosis study. Epigenetic age was calculated from methylomics data for each participant. Its divergence from chronological age is termed epigenetic age acceleration. Subclinical atherosclerosis burden was estimated by multi-territory 2D/3D vascular ultrasound and by coronary artery calcification. In healthy individuals, the presence, extension, and progression of subclinical atherosclerosis were associated with a significant acceleration of the Grim epigenetic age, a predictor of health and lifespan, regardless of traditional cardiovascular risk factors. Individuals with an accelerated Grim epigenetic age were characterized by an increased systemic inflammation and associated with a score of low-grade, chronic inflammation. Mediation analysis using transcriptomics and proteomics data revealed key pro-inflammatory pathways (IL6, Inflammasome, and IL10) and genes (IL1B, OSM, TLR5, and CD14) mediating the association between subclinical atherosclerosis and epigenetic age acceleration. CONCLUSION: The presence, extension, and progression of subclinical atherosclerosis in middle-aged asymptomatic individuals are associated with an acceleration in the Grim epigenetic age. Mediation analysis using transcriptomics and proteomics data suggests a key role of systemic inflammation in this association, reinforcing the relevance of interventions on inflammation to prevent cardiovascular disease.

A novel phosphatidylinositol 3-kinase (PI3K) inhibitor directs a potent FOXO-dependent, p53-independent cell cycle arrest phenotype characterized by the differential induction of a subset of FOXO-regulated genes.

INTRODUCTION: The activation of the phosphoinositide 3-kinase (PI3K)/AKT signalling pathway is one the most frequent genetic events in breast cancer, consequently the development of PI3K inhibitors has attracted much attention. Here we evaluate the effect of PI3K inhibition on global gene expression in breast cancer cells. METHODS: We used a range of methodologies that include in silico compound analysis, in vitro kinase assays, cell invasion assays, proliferation assays, genome-wide transcription studies (Agilent Technologies full genome arrays), gene set enrichment analysis, quantitative real-time PCR, immunoblotting in addition to chromatin immunoprecipitation. RESULTS: We defined the physico-chemical and the biological properties of ETP-45658, a novel potent PI3K inhibitor. We demonstrated that ETP-45658 potently inhibited cell proliferation within a broad range of human cancer cells, most potently suppressing the growth of breast cancer cells via inhibiting cell cycle. We show that this response is Forkhead box O (FOXO) protein dependent and p53 independent. Our genome-wide microarray analysis revealed that the cell cycle was the most affected biological process after exposure to ETP-45658 (or our control PI3K inhibitor PI-103), that despite the multiple transcription factors that are regulated by the PI3K/AKT signalling cascade, only the binding sites for FOXO transcription factors were significantly enriched and only a subset of all FOXO-dependent genes were induced. This disparity in gene transcription was not due to differential FOXO promoter recruitment. CONCLUSIONS: The constitutive activation of PI3Ks and thus the exclusion of FOXO transcription factors from the nucleus is a key feature of breast cancer. Our results presented here highlight that PI3K inhibition activates specific FOXO-dependent genes that mediate cell cycle arrest in breast cancer cells.

In vivo expansion of a CD9+ decidual-like NK cell subset following autologous hematopoietic stem cell transplantation.

Autologous hematopoietic stem cell transplantation (autoHSCT) is a treatment option for hematological disorders and pediatric solid tumors. After an autoHSCT, natural killer (NK) cells are the first lymphocyte subset returning to normal levels. To uncover global changes during NK cell reconstitution after autoHSCT, we performed RNA-sequencing on NK cells before and after autoHSCT. Results showed profound changes in the gene expression profile of NK cells immediately after autoHSCT. Several biological processes including cell cycle, DNA replication and the mevalonate pathway were enriched. Significantly, we observed that following autoHSCT, NK cells acquired a decidual-like gene expression profile, including the expression of CD9. By using multiparametric flow cytometry, we confirmed the expansion of NK cells expressing CD9 immediately after autoHSCT, which exhibited higher granzyme B and perforin expression levels than CD9- NK cells. These results provide insights into the physiopathology of NK cells during their reconstitution after autoHSCT.

Large-scale gene expression in bone marrow mesenchymal stem cells: a putative role for COL10A1 in osteoarthritis.

OBJECTIVES: To elucidate disease-specific molecular changes occurring in osteoarthritis (OA) by analysing the differential gene expression profiles of bone marrow mesenchymal stem cells (BM-MSCs) from patients with OA compared with those without OA. METHODS: Expression profiles of BM-MSCs from eight paired patients with OA and patients with hip fracture without signs of OA were compared by DNA microarray expression analysis and significant differences were evaluated by computational Gene Set Enrichment Analysis. To validate the involvement of COL10A1 as part of the most downregulated gene set in OA, three tagging single nucleotide polymorphisms were genotyped in 191 patients with OA and 283 controls. COL10A1 expression was also assessed by quantitative RT-PCR in additional subjects. RESULTS: Expression levels in 9% (1967) of the overall transcripts were significantly different (p<0.05) between MSCs from patients with OA and controls (532 genes reached twofold differences: 240 were upregulated and 292 were downregulated). Cell development and differentiation were the functional categories accounting for most genes with altered expression. Interestingly, several genes related to the Wnt/-catenin pathway and collagen genes were downregulated in MSCs from patients with OA. The collagen gene set was clearly downregulated in OA. Furthermore, the expression of COL10A1 was significantly reduced in patients with OA. A genetic association between the COL10A1 rs11965969 polymorphism and OA was also found. CONCLUSION: COL10A1 downregulation seems to have a role in the establishment of a defective and/or unstable subchondral cartilage matrix in OA disease. It is proposed that OA may be linked to the intrinsic defective regenerative potential of BM-MSCs resulting from its reduced expression of fate commitment-related genes.

Long-Term Dabigatran Treatment Delays Alzheimer's Disease Pathogenesis in the TgCRND8 Mouse Model.

BACKGROUND: Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder with important vascular and hemostatic alterations that should be taken into account during diagnosis and treatment. OBJECTIVES: This study evaluates whether anticoagulation with dabigatran, a clinically approved oral direct thrombin inhibitor with a low risk of intracerebral hemorrhage, ameliorates AD pathogenesis in a transgenic mouse model of AD. METHODS: TgCRND8 AD mice and their wild-type littermates were treated for 1 year with dabigatran etexilate or placebo. Cognition was evaluated using the Barnes maze, and cerebral perfusion was examined by arterial spin labeling. At the molecular level, Western blot and histochemical analyses were performed to analyze fibrin content, amyloid burden, neuroinflammatory activity, and blood-brain barrier (BBB) integrity. RESULTS: Anticoagulation with dabigatran prevented memory decline, cerebral hypoperfusion, and toxic fibrin deposition in the AD mouse brain. In addition, long-term dabigatran treatment significantly reduced the extent of amyloid plaques, oligomers, phagocytic microglia, and infiltrated T cells by 23.7%, 51.8%, 31.3%, and 32.2%, respectively. Dabigatran anticoagulation also prevented AD-related astrogliosis and pericyte alterations, and maintained expression of the water channel aquaporin-4 at astrocytic perivascular endfeet of the BBB. CONCLUSIONS: Long-term anticoagulation with dabigatran inhibited thrombin and the formation of occlusive thrombi in AD; preserved cognition, cerebral perfusion, and BBB function; and ameliorated neuroinflammation and amyloid deposition in AD mice. Our results open a field for future investigation on whether the use of direct oral anticoagulants might be of therapeutic value in AD.

Genomic characterization of the first oral avian papillomavirus in a colony of breeding canaries (Serinus canaria).

Papillomaviruses are non-enveloped, DNA viruses that infect skin and mucosa of a wide variety of vertebrates, causing neoplasias or simply persisting asymptomatically. Avian papillomaviruses, with six fully sequenced genomes, are the second most studied group after mammalian papillomaviruses. In this study, we describe the first oral avian papillomavirus, detected in the tongue of a dead Yorkshire canary (Serinus canaria) and in oral swabs of the same bird and other two live canaries from an aviary in Madrid, Spain. Its genome is 8,071 bp and presents the canonical papillomavirus architecture with six early (E6, E7, E1, E9, E2, E4) and two late open reading frames (L1 and L2) and a long control region between L1 and E6. This new avian papillomavirus L1 gene shares a 64% pairwise identity with FcPV1 L1, so it has been classified as a new species (ScPV1) within the Ethapapillomavirus genus. Although the canary died after showing breathing problems, there is no evidence that the papillomavirus caused those symptoms so it could be part of the oral microbiota of the birds. Hence, future investigations are needed to evaluate the clinical relevance of the virus.

A simple and rapid PCR-based method to isolate complete small macronuclear minichromosomes from hypotrich ciliates: 5S rDNA and S26 ribosomal protein gene of Oxytricha (Sterkiella) nova.

Hypotrich ciliates present a macronuclear genome consisting of gene-sized instead of chromosome-sized DNA molecules. Exploiting this unique eukaryotic genome feature, we introduce, for the first time in ciliates, a rapid and easy PCR method using telomeric primers to isolate small complete macronuclear DNA molecules or minichromosomes. Two presumably abundant macronuclear DNA molecules, containing ribosomal genes, were amplified from the Oxytricha (Sterkiella) nova complete genome after using this method, and then were cloned and sequenced. The 5S rDNA sequence of O. (S.) nova is the third one reported among hypotrich ciliates; its primary and secondary structure is compared with other eukaryotic 5S rRNAs. The ribosomal protein S26 gene is the first one reported among ciliates. This "End-End-PCR" method might be useful to obtain similar gene-sized macronuclear molecules from other hypotrich ciliates, and, therefore, to increase our knowledge on ribosomal genes in these eukaryotic microorganisms.

AG-NGS: a powerful and user-friendly computing application for the semi-automated preparation of next-generation sequencing libraries using open liquid handling platforms.

Next-generation sequencing (NGS) is becoming one of the most widely used technologies in the field of genomics. Library preparation is one of the most critical, hands-on, and time-consuming steps in the NGS workflow. Each library must be prepared in an independent well, increasing the number of hours required for a sequencing run and the risk of human-introduced error. Automation of library preparation is the best option to avoid these problems. With this in mind, we have developed automatic genomics NGS (AG-NGS), a computing application that allows an open liquid handling platform to be transformed into a library preparation station without losing the potential of an open platform. Implementation of AG-NGS does not require programming experience, and the application has also been designed to minimize implementation costs. Automated library preparation with AG-NGS generated high-quality libraries from different samples, demonstrating its efficiency, and all quality control parameters fell within the range of optimal values.

Automatic genomics: a user-friendly program for the automatic designing and plate loading of medium-throughput qPCR experiments.

Quantitative PCR (qPCR) remains the method of choice for gene and microRNA (miRNA) expression studies. Many laboratories wish to automate some or all of the steps of medium-throughput qPCR experiments through the use of various types of liquid handling robots. However, it is not uncommon to find cases in which scripts provided by the robot supplier are too rigid for user-specific applications, do not include all the desired options, or are too complicated to be modified by a nonprofessional programmer. Here, we present Automatic Genomics, a program that allows users with a limited programming background to automate medium-throughput qPCR experiments by using commercially available liquid-handling robots. The user is able to optimize the plate design in terms of number of genes, number of samples, and controls.

Characterization of host genetic expression patterns in HIV-infected individuals with divergent disease progression.

The course of HIV-1 infection shows a variety of clinical phenotypes with an important involvement of host factors. We compare host gene expression patterns in CD3+ T cells from two of these phenotypes: long-term non-progressor patients (LTNP) and matched control patients with standard HIV disease progression. Array analysis revealed over-expression of 322 genes in progressors and 136 in LTNP. Up-regulated genes in progressors were mainly implicated in the regulation of DNA replication, cell cycle and DNA damage stimulus and mostly localized into cellular organelles. In contrast, most up-regulated genes in LTNP were located at the plasmatic membrane and involved in cytokine-cytokine receptor interaction, negative control of apoptosis or regulation of actin cytoskeleton. Regarding gene interactions, a higher number of viral genes interacting with cellular factors were seen in progressors. Our study offers new comparative insights related to disease status and can distinguish differentiated patterns of gene expression among clinical phenotypes.

Early peroxisome proliferator-activated receptor gamma regulated genes involved in expansion of pancreatic beta cell mass.

BACKGROUND: The progression towards type 2 diabetes depends on the allostatic response of pancreatic beta cells to synthesise and secrete enough insulin to compensate for insulin resistance. The endocrine pancreas is a plastic tissue able to expand or regress in response to the requirements imposed by physiological and pathophysiological states associated to insulin resistance such as pregnancy, obesity or ageing, but the mechanisms mediating beta cell mass expansion in these scenarios are not well defined. We have recently shown that ob/ob mice with genetic ablation of PPARγ2, a mouse model known as the POKO mouse failed to expand its beta cell mass. This phenotype contrasted with the appropriate expansion of the beta cell mass observed in their obese littermate ob/ob mice. Thus, comparison of these models islets particularly at early ages could provide some new insights on early PPARγ dependent transcriptional responses involved in the process of beta cell mass expansion RESULTS: Here we have investigated PPARγ dependent transcriptional responses occurring during the early stages of beta cell adaptation to insulin resistance in wild type, ob/ob, PPARγ2 KO and POKO mice. We have identified genes known to regulate both the rate of proliferation and the survival signals of beta cells. Moreover we have also identified new pathways induced in ob/ob islets that remained unchanged in POKO islets, suggesting an important role for PPARγ in maintenance/activation of mechanisms essential for the continued function of the beta cell. CONCLUSIONS: Our data suggest that the expansion of beta cell mass observed in ob/ob islets is associated with the activation of an immune response that fails to occur in POKO islets. We have also indentified other PPARγ dependent differentially regulated pathways including cholesterol biosynthesis, apoptosis through TGF-ß signaling and decreased oxidative phosphorylation.

Regulation of the microRNA processor DGCR8 by the tumor suppressor ING1.

The ING family of tumor suppressor proteins controls several cellular functions relevant to antitumor protection, such as cell cycle control, apoptosis, senescence, or migration. ING proteins are functionally linked to the p53 pathway, and they participate in transcriptional control via the recognition of histone marks and recruitment of protein complexes with chromatin-modifying activity to specific promoters. Here, we have investigated the global effect of ING1 in gene regulation through genome-wide analysis of expression profiles in primary embryonic fibroblasts deficient for the Ing1 locus. We find that Ing1 has a predominant role as transcriptional repressor in this setting, affecting the expression of genes involved in a variety of cellular functions. Within the subset of genes showing differential expression, we have identified DGCR8, a protein involved in the early steps of microRNA biogenesis. We show that ING1 binds to the DGCR8 promoter and controls its transcription through chromatin regulation. We also find that ING1 and DGCR8 can cooperate in restraining proliferation. In summary, this study reveals a novel connection between ING1 and a regulator of microRNA biogenesis and identifies new links between tumor suppressor proteins and the microRNA machinery.

Processing of Agilent microRNA array data.

BACKGROUND: The Agilent microRNA microarray platform interrogates each microRNA with several copies of distinct oligonucleotide probes and integrates the results into a total gene signal (TGS), using a proprietary algorithm that makes use of the background subtracted signal. The TGS can be normalized between arrays, and the Agilent recommendation is either not to normalize or to normalize to the 75th percentile signal intensity. The robust multiarray average algorithm (RMA) is an alternative method, originally developed to obtain a summary measure of mRNA Affymetrix gene expression arrays by using a linear model that takes into account the probe affinity effect. The RMA method has been shown to improve the accuracy and precision of expression measurements relative to other competing methods. There is also evidence that it might be preferable to use non-corrected signals for the processing of microRNA data, rather than background-corrected signals. In this study we assess the use of the RMA method to obtain a summarized microRNA signal for the Agilent arrays. FINDINGS: We have adapted the RMA method to obtain a processed signal for the Agilent arrays and have compared the RMA summarized signal to the TGS generated with the image analysis software provided by the vendor. We also compared the use of the RMA algorithm with uncorrected and background-corrected signals, and compared quantile normalization with the normalization method recommended by the vendor. The pre-processing methods were compared in terms of their ability to reduce the variability (increase precision) of the signals between biological replicates. Application of the RMA method to non-background corrected signals produced more precise signals than either the RMA-background-corrected signal or the quantile-normalized Agilent TGS. The Agilent TGS normalized to the 75% percentile showed more variation than the other measures. CONCLUSIONS: Used without background correction, a summarized signal that takes into account the probe effect might provide a more precise estimate of microRNA expression. The variability of quantile normalization was lower compared with the normalization method recommended by the vendor.

Hemizygous subtelomeres of an African trypanosome chromosome may account for over 75% of chromosome length.

African trypanosomes are parasitic protozoa that infect a wide range of mammals, including humans. These parasites remain extracellular in the mammalian bloodstream, where antigenic variation allows them to survive the immune response. The Trypanosoma brucei nuclear genome sequence has been published recently. However, the significant chromosome size polymorphism observed among strains and subspecies of T. brucei, where total DNA content may vary up to 30%, necessitates a comparative study to determine the underlying basis and significance of such variation between parasites. In addition, the sequenced strain (Tb927) presents one of the smallest genomes analyzed among T. brucei isolates; therefore, establishing polymorphic regions will provide essential complementary information to the sequencing project. We have developed a Tb927 high-resolution DNA microarray to study DNA content variation along chromosome I, one of the most size-variable chromosomes, in different strains and subspecies of T. brucei. Results show considerable copy number polymorphism, especially at subtelomeres, but are insufficient to explain the observed size difference. Additional sequencing reveals that >50% of a larger chromosome I consists of arrays of variant surface glycoprotein genes (VSGs), involved in avoidance of acquired immunity. In total, the subtelomeres appear to be three times larger than the diploid core. These results reveal that trypanosomes can utilize subtelomeres for amplification and divergence of gene families to such a remarkable extent that they may constitute most of a chromosome, and that the VSG repertoire may be even larger than reported to date. Further experimentation is required to determine if these results are applicable to all size-variable chromosomes.

Isolation and characterization of a cDNA encoding a putative high mobility group (HMG)--box protein from stored mRNA in resting cysts of the ciliate Oxytricha (Sterkiella) nova: ciliate macronuclear gene encoding a putative HMG-box protein.

We have isolated an cDNA after applying a DDRT-PCR analysis on mRNA from mature resting cysts of the ciliate Oxytricha (Sterkiella) nova. From this cDNA fragment the complete macronuclear minichromosome was obtained by using the Mac-End-PCR method. After cloning and sequencing, this cDNA shown certain similarity to HMG-like proteins. The analysis of the inferred amino acid sequence shown that this putative HMG-like protein has one HMG-box interrupted by a intron. The analysis of others characteristics (including a 3D model) confirms that it is a HMGB family protein. It is the first time that a macronuclear gene encoding a putative HMG-box protein is isolated from resting cysts of a stichotrich ciliate. The possible implications of this stored mRNA in the ciliate cryptobiotic stage are discussed.