Studying the sensitivity of transcription to the nucleotide analog 5,6-dichloro-1-␤-D-ribofuranosylbenzimidazole has led to the discovery of a number of proteins involved in the regulation of transcription elongation by RNA polymerase II. We have developed a highly purified elongation control system composed of three purified proteins added back to isolated RNA polymerase II elongation complexes. Two of the proteins, 5,6-dichloro-1-␤-D-ribofuranosylbenzimidazole sensitivity-inducing factor (DSIF) and negative elongation factor (NELF), act as negative transcription elongation factors by increasing the time the polymerase spent at pause sites. P-TEFb reverses the negative effect of DSIF and NELF through a mechanism dependent on its kinase activity. TFIIF is a general initiation factor that positively affects elongation by decreasing pausing. We show that TFIIF functionally competes with DSIF and NELF, and this competition is dependent on the relative concentrations of TFIIF and NELF.The balance of activity between both positive and negative factors achieves accurate control of many cellular processes. Accumulating evidence indicates that such a process regulates the control of transcription elongation (1). It has been proposed that shortly after initiation, negative transcription elongation factors act upon RNA polymerase II to cause production of short transcripts (2). With the action of P-TEFb the polymerase enters productive elongation and transcription is no longer influenced by the negative factors (3, 4). After this transition, the polymerase is acted upon by general elongation factors such as S-II, TFIIF, ELL, and elongin to generate long transcripts (5-7).The key step in the elongation control process, the transition from abortive elongation to productive elongation, requires the positive elongation factor P-TEFb (1, 3, 4). P-TEFb was originally purified from Drosophila nuclear extracts, as a factor required for reconstitution of 5,6-dichloro-1-␤-D-ribofuranosylbenzimidazole (DRB) 1 sensitivity in in vitro transcription assays (3). Active human P-TEFb consists of a heterodimer of cyclin-dependent kinase 9 (Cdk9) and either cyclin T1, cyclin T2, or cyclin K (8, 9). The elongation properties of P-TEFb are dependent on its kinase activity, and both the kinase and elongation activities are sensitive to the nucleotide analog DRB (3, 4, 8, 10 -12), a kinase inhibitor known for its ability to inhibit transcription elongation (13). P-TEFb is also strongly inhibited by flavopiridol, a drug currently in clinical trials as an anti-cancer treatment that might also be useful as an anti-HIV therapy (14). Depletion of P-TEFb from HeLa nuclear extract (HNE) greatly reduces the ability of RNA polymerase II to produce full-length transcripts and eliminates the DRB sensitivity of that extract (8). The addition of purified P-TEFb to HNE depleted of Cdk9 restores the ability of RNA polymerase II to generate full-length transcripts and restores DRB sensitivity (8, 15).Another factor required for DRB sensitivity, DRB sensitivity...

These results demonstrated that intranasal administration of labelled insulin targeted the CNS through the olfactory nerve pathway in mice.

Deferoxamine (DFO), a metal chelator, has been previously reported to slow the loss of spatial memory in a mouse model of amyloid accumulation when delivered intranasally (IN). In this study, we determined whether IN DFO also has beneficial effects in the P301L mouse, which accumulates hyperphosphorylated tau. Mice were intranasally treated three times per week with either 10% DFO (2.4 mg) or saline for 5 months, and a battery of behavioral tests were conducted before tissue collection and biochemical analyses of brain tissue with Western blot and ELISA. Wild-type (WT) mice statistically outperformed transgenic (TG) saline mice in the radial arm water maze, while performance of TG-DFO mice was not different than WT mice, suggesting improved performance in the radial arm water maze. Other behavioral changes were not evident. Beneficial changes in brain biochemistry were evident in DFO-treated mice for several proteins. The TG mice had significantly less pGSK3β and HIF-1α, with more interleukin-1β and total protein oxidation than wild-type controls, and for each protein, DFO treatment significantly reduced these differences. There was not a significant decrease in phosphorylated tau in brain tissue of DFO-treated mice at the sites we measured. These data suggest that IN DFO is a potential treatment not only for Alzheimer's disease, but also for other neurodegenerative diseases and psychiatric disorders in which GSK3β and HIF-1α play a prominent role.