hsf1

Heat shock factor protein 1, also known as heat shock transcription factor 1, HSF1, and HSTF1, is a cytoplasm and nucleus protein that belongs to the HSF family. HSF1 is the major transcription factor of HSPs (heat shock proteins) in response to various stresses. Wild type HSF1 (heat shock transcriptional factor 1) is normally inactive. HSF1 / HSTF1 is a DNA-binding protein that specifically binds heat shock promoter elements (HSE) and activates transcription. In higher eukaryotes, HSF is unable to bind to the HSE unless the cells are heat shocked. HSF1 / HSTF1 protects cells and organisms against various types of stress, either by triggering a complex response that promotes cell survival or by triggering cell death when stress-induced alterations cannot be rescued. HSF1 / HSTF1 is the key protein in regulating the stress response. It can be activated under heat, oxidative, or other stress conditions. Dominant-positive and dominant-negative HSF1 are two types of HSF1 mutants. Both of them gain DNA binding activity in the absence of stress. Also, dominant-positive HSF1 acquires transcriptional activity, which dominant-negative HSF1 does not acquire. HSF1 / HSTF1 was also reported to contribute to cell resistance against genotoxic stress, such as that caused by doxorubicin, an anticancer drug in common clinical use.

Fibroblast growth factor 4(FGF-4) is a heparin binding member of the FGF family. The human FGF4 cDNA encodes 206 amino acids (aa) with a 33 aa signal sequence and a 173 aa mature protein with an FGF homology domain that contains a heparin binding region near the C-terminus. Mature human FGF4 shares 91%, 82%, 94% and 91% aa identity with mouse, rat, canine and bovine FGF4, respectively. Human FGF-4 has been shown to exhibit cross species activity. Expression of FGF-4 and its receptors, FGF R1c, 2c, 3c and 4, is spatially and temporally regulated during embryonic development. FGF-4 is proposed to play a physiologically relevant role in human embryonic stem cell selfrenewal. It promotes stem cell proliferation, but may also aid differentiation depending on context and concentration, and is often included in embryonic stem cell media in vitro. FGF-4 is mitogenic for fibroblasts and endothelial cells in vitro and has autocrine transforming potential. It is a potent angiogenesis promoter in vivo and has been investigated as therapy for coronary artery disease.

FGF (fibroblast growth factor) signalling is known to be required for many aspects of mesoderm formation and patterning during Xenopus development and has been implicated in regulating genes required for the specification of both blood and skeletal muscle lineages. Fibroblast growth factor 4 (FGF4) signaling induces differentiation from embryonic stem cells (ESCs) via the phosphorylation of downstream molecules such as mitogen-activated protein kinase/extracellular signal-related kinase (MEK) and extracellular signal-related kinase 1/2 (ERK1/2). Fibroblast Growth Factor 4 (FGF-4) could not only increase the proliferation of bone marrow mesenchymal stem cells (BMSCs), but also induce BMSCs into hepatocyte-like cells in vitro. FGF4 transduced BMSCs contributed to liver regeneration might by the transplanted microenvironment. The FGF4-bFGF BMSCs thus can enhance the survival of the transplanted cells, diminish myocardial fibrosis, promote myocardial angiogenesis, and improve cardiac functions.