Overview of MARCM-Related Technologies in Drosophila Neurobiological Research.

Mosaic analysis with a repressible cell marker (MARCM)-related technologies are positive genetic mosaic labeling systems that have been widely applied in studies of Drosophila brain development and neural circuit formation to identify diverse neuronal types, reconstruct neural lineages, and investigate the function of genes and molecules. Two types of MARCM-related technologies have been developed: single-colored and twin-colored. Single-colored MARCM technologies label one of two twin daughter cells in otherwise unmarked background tissues through site-specific recombination of homologous chromosomes during mitosis of progenitors. On the other hand, twin-colored genetic mosaic technologies label both twin daughter cells with two distinct colors, enabling the retrieval of useful information from both progenitor-derived cells and their subsequent clones. In this overview, we describe the principles and usage guidelines for MARCM-related technologies in order to help researchers employ these powerful genetic mosaic systems in their investigations of intricate neurobiological topics. © 2020 by John Wiley & Sons, Inc.

Introducing an expanded CAG tract into the huntingtin gene causes a wide spectrum of ultrastructural defects in cultured human cells.

Modeling of neurodegenerative diseases in vitro holds great promise for biomedical research. Human cell lines harboring a mutations in disease-causing genes are thought to recapitulate early stages of the development an inherited disease. Modern genome-editing tools allow researchers to create isogenic cell clones with an identical genetic background providing an adequate "healthy" control for biomedical and pharmacological experiments. Here, we generated isogenic mutant cell clones with 150 CAG repeats in the first exon of the huntingtin (HTT) gene using the CRISPR/Cas9 system and performed ultrastructural and morphometric analyses of the internal organization of the mutant cells. Electron microscopy showed that deletion of three CAG triplets or an HTT gene knockout had no significant influence on the cell structure. The insertion of 150 CAG repeats led to substantial changes in quantitative and morphological parameters of mitochondria and increased the association of mitochondria with the smooth and rough endoplasmic reticulum while causing accumulation of small autolysosomes in the cytoplasm. Our data indicate for the first time that expansion of the CAG repeat tract in HTT introduced via the CRISPR/Cas9 technology into a human cell line initiates numerous ultrastructural defects that are typical for Huntington's disease.

Amiloidosis primaria / Primary amyloidosis

No disponible

Patients with chronic lymphocytic leukaemia and clonal deletion of both 17p13.1 and 11q22.3 have a very poor prognosis.

Detection of a 17p13.1 deletion (loss of TP53) or 11q22.3 deletion (loss of ATM), by fluorescence in situ hybridization (FISH), in chronic lymphocytic leukaemia (CLL) patients is associated with a poorer prognosis. Because TP53 and ATM are integral to the TP53 pathway, we hypothesized that 17p13.1- (17p-) and 11q22.3- (11q-) occurring in the same cell (clonal 17p-/11q-) would confer a worse prognosis than either 17p- or 11q-. We studied 2184 CLL patients with FISH (1995-2012) for the first occurrence of 17p-, 11q-, or clonal 17p-/11q-. Twenty (1%) patients had clonal 17p-/11q-, 158 (7%) had 17p- (including 4 with 17p- and 11q- in separate clones), 247 (11%) had 11q-, and 1759 (81%) had neither 17p- nor 11q-. Eleven of 15 (73%) tested patients with clonal 17p-/11q- had dysfunctional TP53 mutations. Overall survival for clonal 17p-/11q- was significantly shorter (1·9 years) than 17p- (3·1 years, P = 0·04), 11q- (4·8 years, P ≤ 0·0001), or neither 17p- nor 11q- (9·3 years, P ≤ 0·0001). Clonal 17p-/11q- thus conferred significantly worse prognosis, suggesting that loss of at least one copy of both TP53 and ATM causes more aggressive disease. Use of an ATM/TP53 combination FISH probe set could identify these very-high risk patients.

Chronic lymphocytic leukemia with del13q14 as the sole abnormality: dynamic prognostic estimate by interphase-FISH.

This study analyzed 140 patients with isolated del13q14 on interphase FISH (I-FISH), to identify subsets with a different progression risk and to assess the acquisition of additional chromosomal abnormalities (clonal evolution) in treatment-naïve del13q14 patients. A monoallelic deletion (del13qx1) was detected in 123 cases (88%), a biallelic deletion (del13qx2) in eight and a mosaic of monoallelic and biallelic deletions (del13qx1/del13qx2) in nine. In 33% of cases, deletion encompassed the Rb1 locus The median percentage of abnormal nuclei was 50% (15%-96%), and it was higher in patients with a biallelic/mosaic pattern in comparison with patients with monoallelic deletion. Sixty two patients (44%) have been treated; 5-year treatment free survival rate was 56% and the median treatment free survival was 65 months. The baseline percentage of deleted nuclei, as a continuous variable, was related to progression (HR: 1.02; p = 0.001). According to deletion burden, three groups were identified: 64 cases (46%) had <50% deleted nuclei, 47 (33%) had 50-69% deleted nuclei, and 29 (21%) had ≥70% deleted nuclei. The 5-year untreated rate was 70.5% , 52.6% and 28.7% (p < 0.0001), respectively. In multivariate analysis using IGHV mutational status, presence of a nullisomic clone, CD38 expression and percentage of deleted nuclei as covariates, only IGHV mutational status and the percentage of deleted nuclei were independent risk factors for treatment. In 103 patients serially monitored by I-FISH before starting any treatment, we observed a significant increase in the proportion of del13q14 cells, and this increase affected the risk of subsequent treatment requirement (HR 2.54, p = 0.001). The appearance of a new clone was detected in 16 patients (15.5%) and chromosome 13 was involved in 14 of them. I-FISH monitoring proves worthwhile for a dynamic risk stratification and for planning clinical surveillance.

In multiple myeloma, bone-marrow lymphocytes harboring the same chromosomal abnormalities as autologous plasma cells predict poor survival.

Chromosomal abnormalities in plasma cells (PCs) from multiple myeloma (MM) provide a clonal signature to identify malignant cells. BM-lymphocytes from MM aspirates, defined by stringent criteria, were screened for the same chromosomal abnormalities as autologous PCs, including translocations, deletions, and amplifications. For 200 MM patients, we evaluated BM mononuclear cells to identify lymphocytes and autologous PCs on the same slide, followed by interphase fluorescence in situ hybridization to characterize their chromosomal abnormalities. Of all patients having a given chromosomal abnormality(s) in PCs, 45% showed that same abnormality(s) in 2-37% (median = 5%) of BM-lymphocytes. Most translocations, amplifications, and deletions found in MM PCs were also detected in lymphocytes, above the healthy-donor "cut-off." In patients having chromosomally abnormal CD20(-) PCs, chromosomally abnormal lymphocytes were found among CD20+ cells confirming them as B cells. Exceptions were amplification of 1q21 or p53 deletion, which characterize PCs but were undetectable in BM-lymphocytes, suggesting that processes leading to these abnormalities may be exclusive to PCs. For a set of 75 patients whose BM-lymphocytes and PCs were analyzed by all six probe sets, 58% of those with abnormal PC also had abnormal BM-lymphocytes harboring from one to five different abnormalities. Confirming the clinical significance of chromosomally abnormal BM-lymphocytes, MM patients having abnormalities in both lymphocytes and PC had significantly worse survival than those with abnormalities only in PC (HR = 2.68). The presence of at least one chromosomal abnormality in BM-lymphocytes appears to have greater clinical significance than particular abnormalities. Chromosomally abnormal BM-lymphocytes correlate with poor outcome and by extrapolation with more aggressive disease.

Porcine circovirus type 2 morphogenesis in a clone derived from the l35 lymphoblastoid cell line.

Porcine circovirus type 2 (PCV2) is the essential infectious agent of post-weaning multisystemic wasting syndrome (PMWS), one of the most important diseases of swine. Although several studies have described different biological properties of the virus, some aspects of its replication cycle, including ultrastructural alterations, remain unknown. The aim of the present study was to describe for the first time a complete morphogenesis study of PCV2 in a clone of the lymphoblastoid L35 cell line at the ultrastructural level using electron microscopy techniques. Cells were infected with PCV2 at a multiplicity of infection of 10 and examined at 0, 6, 12, 24, 48, 60 and 72h post-infection. PCV2 was internalized by endocytosis, after which the virus aggregated in intracytoplasmic inclusion bodies (ICIs). Subsequently, PCV2 was closely associated with mitochondria, completing a first cytoplasmic phase. The virus entered the nucleus for replication and virus assembly and encapsidation occurred with the participation of the nuclear membrane. Immature virions left the nucleus and formed ICIs in a second cytoplasmic phase. The results suggest that at the end of the replication cycle (between 24 and 48h), PCV2 was released either by budding of mature virion clusters or by lysis of apoptotic or dead cells. In conclusion, the L35-derived clone represents a suitable in-vitro model for PCV2 morphogenesis studies and characterization of the PCV2 replication cycle.

Near-tetraploidy clone can evolve from a hyperdiploidy clone and cause resistance to lenalidomide and bortezomib in a multiple myeloma patient.

Aneuploidy is a very common prognostic factor in multiple myeloma (MM). Nonhyperdiploidy including near-tetraploidy (NT) is a poor prognostic indicator, compared to hyperdiploidy in multiple myeloma (MM). NT results from endoduplication of hypodiploidy. We report of a 55-year-old female patient diagnosed with advanced stage MM with hyperdiploidy and t(8;14)(q24;q32). The patient responded well to lenalidomide and dexamethasone for approximately 1 year. At the time of progression, she had become unresponsive to lenalidomide and subsequently bortezomib, and was found to have NT and loss of choromosome 13. There is another reported patient who had a possible interchange from nonhyperdiploidy to hyperdiploidy status, however, artifact could not be ruled out. To our knowledge, this is the first patient in whom evolution of an abnormal clone from a hyperdiploidy to a NT abnormal clone has been confirmed during the natural course of MM. This evolution is associated with resistance to novel drugs and poor prognosis in MM.

A phage display combined with DNA affinity magnetic system can be applied to a screening of DNA binding proteins, such as transcription factors / Un fago pantalla combinado con un sistema de afinidad magnético al ADN se puede aplicar al exámen de las proteínas de unión al ADN, tales como los factores de transcripción

Here we introduce a new approach for the screening of DNA binding proteins, using a phage library based on a phage display technique. In principal, a complementary DNA (cDNA) library based on the recombinant bacteriophage T7 expressing target proteins on its capsid (phage display) is constructed. These phage particles are hybridized with a biotinylated target DNA fragment which is immobilized on the surface of streptavidin paramagnetic particle (SA-PMP). The phage particles are released from the target DNA fragment by a nuclease treatment and the recovered phages are used to the next round of hybridization. These processes are repeated three times to amplify the target phages in the population. This simple method is faster, and more systemic than other current methods (e.g. yeast one hybrid system). As a proof of this principle, we tried to isolate transcription factors which specifically bind to the promoter region of the Arabidopsis thaliana AtGST11 gene. Two obtained candidates, RING zinc finger protein and AtHB6, showed DNA binding activity to the AtGST11 promoter region. We could validate that our new application of phage display is a superior method for isolation of DNA binding proteins with a broad range of potential applications.

The finding of a reciprocal whole-arm translocation t(X;12)(p10;p10) in association with atypical chronic myeloid leukaemia.

Atypical chronic myeloid leukaemia (aCML) belongs to the myeloproliferative/myelodysplastic category of haematological disease. Main characteristics are marked dysgranulopoiesis, bone marrow dysfunction and the failure to demonstrate the presence of the Philadelphia chromosome or BCR/ABL fusion gene normally associated with CML t(9;22)(q34;q11). It carries a poor prognosis with limited therapeutic options available. Most cases of aCML have one or more karyotypic abnormalities. We highlight a clinical presentation of aCML associated with an acquired reciprocal whole-arm translocation (WAT), t(X;12)(p10;p10), which to our knowledge has not yet been described. We also discuss how such a translocation might lead to tumorigenesis.

A novel approach to the identification and enrichment of cancer stem cells from a cultured human glioma cell line.

Enrichment of cancer stem cells for studies of carcinogenesis remains a difficult issue. We hypothesized that the unique features of cancer stem cells (CSCs) may allow formation of their colonies in vitro with distinct morphology. We therefore investigated the possibility to use morphological diversity of colonies to identify and enrich CSCs from cultured malignant human glioma cells. We found that a small proportion of the cells from a human glioma cell line U251 formed tight and round-shaped colonies in culture. Most cells in such colonies were capable of self-renewal, generating tumor spheres and differentiating into lineages with markers for neurons, astrocytes and oligodendrocytes. In addition, several neural stem cell-related genes were highly expressed by tumor cells in those tight colonies. Our results thus demonstrate a novel approach to the identification and enrichment of CSCs based on unique morphology of their colonies formed in vitro.

Distinct karyotypes in three breast cancer cell lines --21PTCi, 21NTCi, and 21MT-1 --derived from the same patient and representing different stages of tumor progression.

Three breast carcinoma cell lines --21PTCi, 21NTCi, and 21MT-1 --all originating from a 36-year-old woman with metastatic breast cancer, have been characterized previously as stably representing different stages of progression: (nontumorigenic [21PTCi]; tumorigenic, nonmetastatic [21NTCi]; and tumorigenic, weakly metastatic [21MT-1]). These cell lines were investigated for cytogenetic characteristics using G-banding and spectral karyotyping. All three cell lines have multiple chromosome aberrations, but they differ in the types of rearrangements and breakpoints. 21PTCi cells have a modal number (mn) of 56, with 55 types of aberrations, including 16 numeric and 39 structural. 21NTCi cells have a mn of 56, with 70 types of aberrations, including 19 numerical and 51 structural. Finally, 21MT-1 cells have a mn of 54, with 43 types of aberrations, including 14 numerical and 29 structural. The most common rearrangements differ in each cell line [i.e., der(X)t(X;3), der(4)t(1;4), del(6q) and der(19)t(17;19)(q11.2;q13.4) in 21PTCi; der(4)t(1;4), der(12)t(12;15) and -16 in 21NTCi; and der(1)t(1;10), +5, der(6)t(6;7), der(11)t(11;13), -20, and der(20)t(20;21) in 21MT-1]. This cytogenetic result is consistent with previous findings in that the three cell lines represent different stages of tumor progression. We hypothesize that the cytogenetic changes in these cell lines may be related to their distinct biologic characteristics. These three cell lines, with their different karyotypes and biologic characteristics, provide a vital tool for further study of the genetic and epigenetic events involved in transitions between premalignant and malignant phenotypes.