@article{liang_xiao_yin_hippenmeyer_horowitz_ghashghaei_2013, title={Neural development is dependent on the function of specificity protein 2 in cell cycle progression}, volume={140}, ISSN={["0950-1991"]}, DOI={10.1242/dev.085621}, abstractNote={Faithful progression through the cell cycle is crucial to the maintenance and developmental potential of stem cells. Here, we demonstrate that neural stem cells (NSCs) and intermediate neural progenitor cells (NPCs) employ a zinc-finger transcription factor specificity protein 2 (Sp2) as a cell cycle regulator in two temporally and spatially distinct progenitor domains. Differential conditional deletion of Sp2 in early embryonic cerebral cortical progenitors, and perinatal olfactory bulb progenitors disrupted transitions through G1, G2 and M phases, whereas DNA synthesis appeared intact. Cell-autonomous function of Sp2 was identified by deletion of Sp2 using mosaic analysis with double markers, which clearly established that conditional Sp2-null NSCs and NPCs are M phase arrested in vivo. Importantly, conditional deletion of Sp2 led to a decline in the generation of NPCs and neurons in the developing and postnatal brains. Our findings implicate Sp2-dependent mechanisms as novel regulators of cell cycle progression, the absence of which disrupts neurogenesis in the embryonic and postnatal brain.}, number={3}, journal={DEVELOPMENT}, author={Liang, Huixuan and Xiao, Guanxi and Yin, Haifeng and Hippenmeyer, Simon and Horowitz, Jonathan M. and Ghashghaei, H. Troy}, year={2013}, month={Feb}, pages={552–561} }
 @article{moorefield_yin_nichols_cathcart_simmons_horowitz_2006, title={Sp2 localizes to subnuclear foci associated with the nuclear matrix}, volume={17}, ISSN={["1939-4586"]}, DOI={10.1091/mbc.E05-11-1063}, abstractNote={We have reported that extracts prepared from many human and mouse cell lines show little or no Sp2 DNA-binding activity and that Sp2 has little or no capacity to stimulate transcription of promoters that are activated by Sp1, Sp3, and Sp4. Using an array of chimeric Sp1/Sp2 proteins we showed further that Sp2 DNA-binding activity and trans-activation are each negatively regulated in mammalian cells. As part of an ongoing effort to study Sp2 function and regulation we characterized its subcellular localization in comparison with other Sp-family members in fixed and live cells. We report that 1) Sp2 localizes largely within subnuclear foci associated with the nuclear matrix, and 2) these foci are distinct from promyelocytic oncogenic domains and appear to be stable during an 18-h time course of observation. Deletion analyses identified a 37 amino acid sequence spanning the first zinc-“finger” that is sufficient to direct nuclear matrix association, and this region also encodes a bipartite nuclear localization sequence. A second nuclear matrix targeting sequence is encoded within the Sp2 trans-activation domain. We conclude that Sp2 preferentially associates with the nuclear matrix and speculate that this subcellular localization plays an important role in the regulation of Sp2 function.}, number={4}, journal={MOLECULAR BIOLOGY OF THE CELL}, author={Moorefield, KS and Yin, HF and Nichols, TD and Cathcart, C and Simmons, SO and Horowitz, JM}, year={2006}, month={Apr}, pages={1711–1722} }