Sp1 in Astrocyte Is Important for Neurite Outgrowth and Synaptogenesis
MOLECULAR NEUROBIOLOGY
Authors: Hung, Chia-Yang; Hsu, Tsung-, I; Chuang, Jian-Ying; Su, Tsung-Ping; Chang, Wen-Chang; Hung, Jan-Jong
Abstract
In this study, we found that Sp1 was highly expressed in astrocytes, implying that Sp1 might be important for the function of astrocytes. Sp1/GFAP-Cre-ERT2 conditional knockout mice were constructed to study the role of Sp1 in astrocytes. Knockout of Sp1 in astrocytes altered astrocytic morphology and decreased GFAP expression in the cortex and hippocampus but did not affect cell viability. Loss of Sp1 in astrocytes decreased the number of neurons in the cortex and hippocampus. Conditioned medium from primary astrocytes with Sp1 knockout disrupted neuronal dendritic outgrowth and synapse formation, resulting in abnormal learning, memory, and motor behavior. Sp1 knockout in astrocytes altered gene expression, including decreasing the expression of Toll-like receptor 2 and Cfb and increasing the expression of C1q and C4Bp, thereby affecting neurite outgrowth and synapse formation, resulting in disordered neuron function. Studying these gene regulations might be beneficial to understanding neuronal development and brain injury prevention.
HPV8 activates cellular gene expression mainly through Sp1/3 binding sites
VIROLOGY
Authors: Kirschberg, Matthias; Heuser, Sandra; Syed, Adnan S.; Steger, Gertrud; Majewski, Slawomir; Hufbauer, Martin; Akguel, Baki
Abstract
The human papillomavirus type 8 (HPV8) is associated with skin cancer development. The goal of this study was to investigate the effects of HPV8 oncoproteins on cellular gene expression and the identification of key regulators. We performed affymetrix microarray analyses to identify differentially expressed genes and common sequence motifs and identified Sp1/3 binding sites as being crucial. In transient transfection assays, we confirmed that HPV8-E7 stimulates the activity of Sp1/3 promoters. Interestingly, the HPV8-E7(L23A) mutant, which cannot trigger keratinocyte invasion was unable to activate fibronectin gene expression. In skin models or HPV8 positive skin cancers we found a peculiar deposition of fibronectin in the dermal compartment, and a correlation of Sp3 and fibronectin in the nucleus of HPV8-positive keratinocytes. Taken together, we identified that HPV8-E7 exerts control over cellular gene expression through Sp1/3 binding motifs, which may contribute to HPV8-mediated keratinocyte transformation and subsequent fibronectin-dependent invasion.