Positive regulation of Fas gene expression by MSSP and abrogation of Fas-mediated apoptosis induction in MSSP-deficient mice

Photobiomodulation therapy with light-emitting diode in stimulating adipose tissue mitochondria

Low-level laser therapy (LLLT) is known for its ability to induce a photochemical process, primarily targeting mitochondria, a process referred to as photobiomodulation (PBM). Recently, its use has been attributed as an adjunct in obesity treatment, to stimulate lipolysis and apoptosis. However, the pathway of stimulation remains uncertain. Thus, the objective of this study was to understand whether mitochondrial stimulation occurs in adipose tissue cells after PBM therapy, which could lead to the processes of lipolysis and apoptosis. A non-randomized clinical trial was conducted using a split abdomen design in obese women who received red and infrared LED photobiomodulation therapy (PBMT). The patients underwent bariatric surgery, and adipose tissue samples were collected for immunohistochemical analysis with primary mitochondrial antibodies. Adipose tissue samples subjected to LED intervention exhibited positivity in mitochondrial antibodies for cAMP, DRP1, FAS, FIS1, MFN2, and OPA1 (p<0.001) compared to the control group. In conclusion, we observed that PBMT was capable of generating mitochondrial stimulation in adipose tissue cells, as evidenced by the positive antibody signals. This finding suggests that mitochondrial stimulation could be the mechanism and action underlying adipose tissue lipolysis and apoptosis.

Regulatory Mechanisms of Metamorphic Neuronal Remodeling Revealed Through a Genome-Wide Modifier Screen in Drosophila melanogaster

During development, neuronal remodeling shapes neuronal connections to establish fully mature and functional nervous systems. Our previous studies have shown that the RNA-binding factor alan shepard (shep) is an important regulator of neuronal remodeling during metamorphosis in Drosophila melanogaster, and loss of shep leads to smaller soma size and fewer neurites in a stage-dependent manner. To shed light on the mechanisms by which shep regulates neuronal remodeling, we conducted a genetic modifier screen for suppressors of shep-dependent wing expansion defects and cellular morphological defects in a set of peptidergic neurons, the bursicon neurons, that promote posteclosion wing expansion. Out of 702 screened deficiencies that covered 86% of euchromatic genes, we isolated 24 deficiencies as candidate suppressors, and 12 of them at least partially suppressed morphological defects in shep mutant bursicon neurons. With RNA interference and mutant alleles of individual genes, we identified Daughters against dpp (Dad) and Olig family (Oli) as shep suppressor genes, and both of them restored the adult cellular morphology of shep-depleted bursicon neurons. Dad encodes an inhibitory Smad protein that inhibits bone morphogenetic protein (BMP) signaling, raising the possibility that shep interacted with BMP signaling through antagonism of Dad. By manipulating expression of the BMP receptor tkv, we found that activated BMP signaling was sufficient to rescue loss-of-shep phenotypes. These findings reveal mechanisms of shep regulation during neuronal development, and they highlight a novel genetic shep interaction with the BMP signaling pathway that controls morphogenesis in mature, terminally differentiated neurons during metamorphosis.

Neuronal remodeling during metamorphosis is regulated by the alan shepard (shep) gene in Drosophila melanogaster

Peptidergic neurons are a group of neuronal cells that synthesize and secrete peptides to regulate a variety of biological processes. To identify genes controlling the development and function of peptidergic neurons, we conducted a screen of 545 splice-trap lines and identified 28 loci that drove expression in peptidergic neurons when crossed to a GFP reporter transgene. Among these lines, an insertion in the alan shepard (shep) gene drove expression specifically in most peptidergic neurons. shep transcripts and SHEP proteins were detected primarily and broadly in the central nervous system (CNS) in embryos, and this expression continued into the adult stage. Loss of shep resulted in late pupal lethality, reduced adult life span, wing expansion defects, uncoordinated adult locomotor activities, rejection of males by virgin females, and reduced neuropil area and reduced levels of multiple presynaptic markers throughout the adult CNS. Examination of the bursicon neurons in shep mutant pharate adults revealed smaller somata and fewer axonal branches and boutons, and all of these cellular phenotypes were fully rescued by expression of the most abundant wild-type shep isoform. In contrast to shep mutant animals at the pharate adult stage, shep mutant larvae displayed normal bursicon neuron morphologies. Similarly, shep mutant adults were uncoordinated and weak, while shep mutant larvae displayed largely, although not entirely, normal locomotor behavior. Thus, shep played an important role in the metamorphic development of many neurons.

Transactivation of microRNA-383 by steroidogenic factor-1 promotes estradiol release from mouse ovarian granulosa cells by targeting RBMS1

Our previous studies have shown that microRNA-383 (miR-383) is one of the most down-regulated miRNA in TGF-β1-treated mouse ovarian granulosa cells (GC). However, the roles and mechanisms of miR-383 in GC function during follicular development remain unknown. In this study, we found that miR-383 was mainly expressed in GC and oocytes of mouse ovarian follicles. Overexpression of miR-383 enhanced estradiol release from GC through targeting RNA binding motif, single stranded interacting protein 1 (RBMS1). miR-383 inhibited RBMS1 by affecting its mRNA stability, which subsequently suppressed the level of c-Myc (a downstream target of RBMS1). Forced expression of RBMS1 or c-Myc attenuated miR-383-mediated steroidogenesis-promoting effects. Knockdown of the transcription factor steroidogenic factor-1 (SF-1) significantly suppressed the expression of Sarcoglycan zeta (SGCZ) (miR-383 host gene), primary and mature miR-383 in GC, indicating that miR-383 was transcriptionally regulated by SF-1. Luciferase and chromatin immunoprecipitation assays revealed that SF-1 specifically bound to the promoter region of SGCZ and directly transactivated miR-383 in parallel with SGCZ. In addition, SF-1 was involved in regulation of miR-383- and RBMS1/c-Myc-mediated estradiol release from GC. These results suggest that miR-383 functions to promote steroidogenesis by targeting RBMS1, at least in part, through inactivation of c-Myc. SF-1 acts as a positive regulator of miR-383 processing and function in GC. Understanding of regulation of miRNA biogenesis and function in estrogen production will potentiate the usefulness of miRNA in the control of reproduction and treatment of some steroid-related disorders.

Cancer associated epigenetic transitions identified by genome-wide histone methylation binding profiles in human colorectal cancer samples and paired normal mucosa

BACKGROUND

Despite their well-established functional roles, histone modifications have received less attention than DNA methylation in the cancer field. In order to evaluate their importance in colorectal cancer (CRC), we generated the first genome-wide histone modification profiles in paired normal colon mucosa and tumor samples.

METHODS

Chromatin immunoprecipitation and microarray hybridization (ChIP-chip) was used to identify promoters enriched for histone H3 trimethylated on lysine 4 (H3K4me3) and lysine 27 (H3K27me3) in paired normal colon mucosa and tumor samples from two CRC patients and for the CRC cell line HT29.

RESULTS

By comparing histone modification patterns in normal mucosa and tumors, we found that alterations predicted to have major functional consequences were quite rare. Furthermore, when normal or tumor tissue samples were compared to HT29, high similarities were observed for H3K4me3. However, the differences found for H3K27me3, which is important in determining cellular identity, indicates that cell lines do not represent optimal tissue models. Finally, using public expression data, we uncovered previously unknown changes in CRC expression patterns. Genes positive for H3K4me3 in normal and/or tumor samples, which are typically already active in normal mucosa, became hyperactivated in tumors, while genes with H3K27me3 in normal and/or tumor samples and which are expressed at low levels in normal mucosa, became hypersilenced in tumors.

CONCLUSIONS

Genome wide histone modification profiles can be used to find epigenetic aberrations in genes associated with cancer. This strategy gives further insights into the epigenetic contribution to the oncogenic process and may identify new biomarkers.

Regulation of Fas-mediated immune homeostasis by an activation-induced protein, Cyclon

Activation-induced cell death (AICD) plays an essential role in the contraction of activated T cells after eradication of pathogen. Fas (APO-1/CD95) is one of the key cell surface proteins that mediate AICD in CD4(+) and CD8(+) T cells. Despite its prime importance in cell death, regulation of Fas expression in T cells is poorly understood. Here we show that Cyclon, a newly identified cytokine-inducible protein, is induced in T cells on T-cell receptor ligation and important for immune homeostasis. Transgenic expression of Cyclon ameliorated autoimmune phenotype in mice lacking subunits of IL-2R. Transgenic expression of Cyclon markedly enhanced AICD through increased expression of Fas whose expression is essential for Cyclon action. Finally, we demonstrated that activated but not resting CD4(+) T cells with targeted deletion of a Cyclon allele show reduced AICD and expression of Fas, indicating a critical role of Cyclon in Fas expression in activated T cells. We think that our data provide insight into expression regulation of Fas in T cells.

Multiple gene expression classifiers from different array platforms predict poor prognosis of colorectal cancer

PURPOSE

This study aimed to develop gene classifiers to predict colorectal cancer recurrence. We investigated whether gene classifiers derived from two tumor series using different array platforms could be independently validated by application to the alternate series of patients.

EXPERIMENTAL DESIGN

Colorectal tumors from New Zealand (n = 149) and Germany (n = 55) patients had a minimum follow-up of 5 years. RNA was profiled using oligonucleotide printed microarrays (New Zealand samples) and Affymetrix arrays (German samples). Classifiers based on clinical data, gene expression data, and a combination of the two were produced and used to predict recurrence. The use of gene expression information was found to improve the predictive ability in both data sets. The New Zealand and German gene classifiers were cross-validated on the German and New Zealand data sets, respectively, to validate their predictive power. Survival analyses were done to evaluate the ability of the classifiers to predict patient survival.

RESULTS

The prediction rates for the New Zealand and German gene-based classifiers were 77% and 84%, respectively. Despite significant differences in study design and technologies used, both classifiers retained prognostic power when applied to the alternate series of patients. Survival analyses showed that both classifiers gave a better stratification of patients than the traditional clinical staging. One classifier contained genes associated with cancer progression, whereas the other had a large immune response gene cluster concordant with the role of a host immune response in modulating colorectal cancer outcome.

CONCLUSIONS

The successful reciprocal validation of gene-based classifiers on different patient cohorts and technology platforms supports the power of microarray technology for individualized outcome prediction of colorectal cancer patients. Furthermore, many of the genes identified have known biological functions congruent with the predicted outcomes.