Distinct cytoplasmic and nuclear functions of the stress induced protein DDIT3/CHOP/GADD153

• DDIT3, also known as GADD153 or CHOP, encodes a basic leucine zipper transcription factor of the dimer forming C/EBP family. DDIT3 is known as a key regulator of cellular stress response, but its target genes and functions are not well characterized. Here, we applied a genome wide microarray based expression analysis to identify DDIT3 target genes and functions. By analyzing cells carrying tamoxifen inducible DDIT3 expression constructs we show distinct gene expression profiles for cells with cytoplasmic and nuclear localized DDIT3. Of 175 target genes identified only 3 were regulated by DDIT3 in both cellular localizations. More than two thirds of the genes were downregulated, supporting a role for DDIT3 as a dominant negative factor that could act by either cytoplasmic or nuclear sequestration of dimer forming transcription factor partners. Functional annotation of target genes showed cell migration, proliferation and apoptosis/survival as the most affected categories. Cytoplasmic DDIT3 affected more migration associated genes, while nuclear DDIT3 regulated more cell cycle controlling genes. Cell culture experiments confirmed that cytoplasmic DDIT3 inhibited migration, while nuclear DDIT3 caused a G1 cell cycle arrest. Promoters of target genes showed no common sequence motifs, reflecting that DDIT3 forms heterodimers with several alternative transcription factors that bind to different motifs. We conclude that expression of cytoplasmic DDIT3 regulated 94 genes. Nuclear translocation of DDIT3 regulated 81 additional genes linked to functions already affected by cytoplasmic DDIT3. Characterization of DDIT3 regulated functions helps understanding its role in stress response and involvement in cancer and degenerative disorders.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinsk bioteknologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Medical Biotechnology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

Nyckelord

Antineoplastic Agents

Hormonal

pharmacology

Blotting

Western

Cell Adhesion

Cell Cycle

Cell Movement

Cell Nucleus

drug effects

genetics

metabolism

Cell Proliferation

Cells

Cultured

Cytoplasm

drug effects

metabolism

Fibroblasts

cytology

drug effects

metabolism

Fibrosarcoma

drug therapy

genetics

metabolism

Flow Cytometry

Gene Expression Profiling

Green Fluorescent Proteins

genetics

Humans

Liposarcoma

drug therapy

genetics

metabolism

Oligonucleotide Array Sequence Analysis

Promoter Regions

Genetic

genetics

RNA

Messenger

genetics

Real-Time Polymerase Chain Reaction

Recombinant Proteins

genetics

metabolism

Reverse Transcriptase Polymerase Chain Reaction

Tamoxifen

pharmacology

Transcription Factor CHOP

genetics

metabolism

Tumor Markers

Biological

genetics

metabolism

genetics

Publikations- och innehållstyp

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