Highlights d Circadian depletion of GCs is required for reactivation of GR target genes d Ultradian and constant hormone treatments result in distinct RNA bursting patterns d The GR dwell time and bound fraction determine RNA burst duration and frequency d Stimulation with GCs induces co-bursting of proximal and distal transcription sites

Huntington disease (HD) is a neurodegenerative disorder caused by an expansion of a polyglutamine (polyQ) domain in the N-terminal region of huntingtin (htt). PolyQ expansion above 35-40 results in disease associated with htt aggregation into inclusion bodies. It has been hypothesized that expanded polyQ domains adopt multiple potentially toxic conformations that belong to different aggregation pathways. Here, we used atomic force microscopy to analyze the effect of a panel of antihtt antibodies (MW1-MW5, MW7, MW8, and 3B5H10) on aggregate formation and the stability of a mutant htt-exon1 fragment. Two antibodies, MW7 (polyproline-specific) and 3B5H10 (polyQ-specific), completely inhibited fibril formation and disaggregated preformed fibrils, whereas other polyQ-specific antibodies had widely varying effects on aggregation. These results suggest that expanded polyQ domains adopt multiple conformations in solution that can be readily distinguished by monoclonal antibodies, which has important implications for understanding the structural basis for polyQ toxicity and the development of intrabody-based therapeutics for HD.

Pannexin 3 (Panx3) and connexin 43 (Cx43; also known as GJA1) are two major gap junction proteins expressed in osteoblasts. Here, we studied their functional relationships in skeletal formation by generating showed no obvious abnormalities, except for less mineralization of the skull. In Panx3 −/− mice, proliferation of chondrocytes and osteoblasts increased and differentiation of these cells was inhibited. Panx3 promoted expression of osteogenic proteins such as ALP and Ocn (also known as ALPL and BGLAP, respectively), as well as Cx43, by regulating Osx (also known as SP7) expression. Panx3 was induced in the early differentiation stage and reduced during the maturation stage of osteoblasts, when Cx43 expression increased in order to promote mineralization. Furthermore, only Panx3 functioned as an endoplasmic reticulum (ER) Ca 2+ channel to promote differentiation, and it could rescue mineralization defects in Cx43 −/− calvarial cells. Our findings reveal that Panx3 and Cx43 have distinct functions in skeletal formation.