A negative regulatory region of the murine Hox11 gene

Treatment for salivary gland hypofunction at both initial and advanced stages of Sjögren-like disease: a comparative study of bone marrow therapy versus spleen cell therapy with a 1-year monitoring period

BACKGROUND AIMS

Non-obese diabetic mice (NOD) exhibit autoimmune Sjögren-like disease (SS-like). We reported previously that a combined-therapy consisting of immuno- and cell-based therapy rescued NOD from SS-like. However, therapies tested to date on NOD mice were aimed at the initial phase of SS-like. It is unknown whether therapies are effective in restoring salivary function when given at an advanced phase of SS-like.

METHODS

The efficacy of two therapies (bone marrow versus spleen cells) was compared head-to-head for halting/reversing salivary hypofunction at two critical time points of SS-like (7-week-old NOD with normal saliva output and 20-week-old NOD with minimal saliva). NOD mice were divided into four groups: (i) control, (ii) complete Freund's adjuvant (CFA), (iii) bone marrow transplants with CFA or (iv) spleen cell transplants with CFA. Mice were monitored 8-12 months after therapy.

RESULTS

Both cell therapies were effective during the initial phase of SS-like; salivary flow rates were maintained between 80-100% of pre-symptomatic levels. Spleen cell therapy was better than bone marrow when administered in the initial phase of SS-like. When cell therapies were given at an advanced phase of SS-like (20 weeks and older), salivary flow rates improved but were at best 50% of pre-symptomatic levels. Both cell therapies decreased tumor necrosis factor-α, transforming growth factor-β1 levels and T and B cells while increasing epidermal growth factor and regulatory T cells. Elevated serum epidermal growth factor levels were measured in spleen-treated mice.

CONCLUSIONS

A therapeutic effect in advanced phase disease, albeit in mice, holds promise for humans in which Sjögren syndrome is generally not diagnosed until a late stage.

Extensive molecular mapping of TCRα/δ- and TCRβ-involved chromosomal translocations reveals distinct mechanisms of oncogene activation in T-ALL

Chromosomal translocations involving the TCR loci represent one of the most recurrent oncogenic hallmarks of T-cell acute lymphoblastic leukemia (T-ALL) and are generally believed to result from illegitimate V(D)J recombination events. However, molecular characterization and evaluation of the extent of recombinase involvement at the TCR-oncogene junction has not been fully evaluated. In the present study, screening for TCRβ and TCRα/δ translocations by FISH and ligation-mediated PCR in 280 T-ALLs allowed the identification of 4 previously unreported TCR-translocated oncogene partners: GNAG, LEF1, NKX2-4, and IL2RB. Molecular mapping of genomic junctions from TCR translocations showed that the majority of oncogenic partner breakpoints are not recombinase mediated and that the regulatory elements predominantly used to drive oncogene expression differ markedly in TCRβ (which are exclusively enhancer driven) and TCRα/δ (which use an enhancer-independent cryptic internal promoter) translocations. Our data also imply that oncogene activation takes place at a very immature stage of thymic development, when Dδ2-Dδ3/Dδ3-Jδ1 and Dβ-Jβ rearrangements occur, whereas the bulk leukemic maturation arrest occurs at a much later (cortical) stage. These observations have implications for T-ALL therapy, because the preleukemic early thymic clonogenic population needs to be eradicated and its disappearance monitored.

A Pbx1-dependent genetic and transcriptional network regulates spleen ontogeny

The genetic control of cell fate specification, morphogenesis and expansion of the spleen, a crucial lymphoid organ, is poorly understood. Recent studies of mutant mice implicate various transcription factors in spleen development, but the hierarchical relationships between these factors have not been explored. In this report, we establish a genetic network that regulates spleen ontogeny, by analyzing asplenic mice mutant for the transcription factors Pbx1, Hox11 (Tlx1), Nkx3.2 (Bapx1) and Pod1 (capsulin, Tcf21). We show that Hox11 and Nkx2.5, among the earliest known markers for splenic progenitor cells, are absent in the splenic anlage of Pbx1 homozygous mutant (-/-) embryos, implicating the TALE homeoprotein Pbx1 in splenic cell specification. Pbx1 and Hox11 genetically interact in spleen formation and loss of either is associated with a similar reduction of progenitor cell proliferation and failed expansion of the splenic anlage. Chromatin immunoprecipitation assays show that Pbx1 binds to the Hox11 promoter in spleen mesenchymal cells, which co-express Pbx1 and Hox11. Furthermore, Hox11 binds its own promoter in vivo and acts synergistically with TALE proteins to activate transcription, supporting its role in an auto-regulatory circuit. These studies establish a Pbx1-Hox11-dependent genetic and transcriptional pathway in spleen ontogeny. Additionally, we demonstrate that while Nkx3.2 and Pod1 control spleen development via separate pathways, Pbx1 genetically regulates key players in both pathways, and thus emerges as a central hierarchical co-regulator in spleen genesis.

An enhancer element for expression of the Ncx (Enx, Hox11L1) gene in neural crest-derived cells

The murine Ncx (Enx, Hox11L1) gene is specifically expressed in a neuronal subset of neural crest-derived tissues. In attempts to elucidate the regulatory DNA element of the tissue-specific expression, we sequenced the 5'-flanking region of the Ncx gene. The transcriptional initiation site was determined at 297 nucleotides (-297) upstream from the ATG start codon (+1). A retinoic acid response element was located on the region between -1163 and -1150. Transient transfection assays with the 5'-flanking sequences fused to the luciferase gene showed that the region between -1387 and -1368 was crucial for the tissue-specific enhancer activity. Furthermore, nuclear proteins extracted from neural crest-derived cells such as murine and human neuroblastoma cells bind to the DNA region between -1387 and -1368. This DNA element was also conserved in the 5'-flanking region of the human NCX gene. Our observations strongly suggest that the DNA element (between -1387 and -1368) contributes to tissue-specific expression of the Ncx gene in murine and human species.

A GATA-dependent nkx-2.5 regulatory element activates early cardiac gene expression in transgenic mice

nkx-2.5 is one of the first genes expressed in the developing heart of early stage vertebrate embryos. Cardiac expression of nkx-2.5 is maintained throughout development and nkx-2.5 also is expressed in the developing pharyngeal arches, spleen, thyroid and tongue. Genomic sequences flanking the mouse nkx-2.5 gene were analyzed for early developmental regulatory activity in transgenic mice. Approximately 3 kb of 5′ flanking sequence is sufficient to activate gene expression in the cardiac crescent as early as E7.25 and in limited regions of the developing heart at later stages. Expression also was detected in the developing spleen anlage at least 24 hours before the earliest reported spleen marker and in the pharyngeal pouches and their derivatives including the thyroid. The observed expression pattern from the −3 kb construct represents a subset of the endogenous nkx-2.5 expression pattern which is evidence for compartment-specific nkx-2.5 regulatory modules. A 505 bp regulatory element was identified that contains multiple GATA, NKE, bHLH, HMG and HOX consensus binding sites. This element is sufficient for gene activation in the cardiac crescent and in the heart outflow tract, pharynx and spleen when linked directly to lacZ or when positioned adjacent to the hsp68 promoter. Mutation of paired GATA sites within this element eliminates gene activation in the heart, pharynx and spleen primordia of transgenic embryos. The dependence of this nkx-2. 5 regulatory element on GATA sites for gene activity is evidence for a GATA-dependent regulatory mechanism controlling nkx-2.5 gene expression. The presence of consensus binding sites for other developmentally important regulatory factors within the 505 bp distal element suggests that combinatorial interactions between multiple regulatory factors are responsible for the initial activation of nkx-2.5 in the cardiac, thyroid and spleen primordia.