1. sigma-aldrich.com/cellsignaling Hypothetical Model on the Functions of the WRN, BLM and MRE11

2. sigma-aldrich.com/cellsignaling Hypothetical Model on the Functions of the WRN, BLM and MRE11 WRN and BLM are genes encoding DNA helicases mutated in the human progeria syndromes: Werner and Bloom Syndromes. MRE11 complex is mutated in genetic instability syndromes: Nijmegen breakage syndrome and ataxia telangiectasia-like disorder. All three may be involved in the resolution of a stalled replication fork and in checkpoint signaling during S phase. DNA replication fork stalling results in the formation of abnormal structures and occurs at frequencies sufficient to be a significant source of endogenous DNA damage. BLM may be recruited to these sites resulting in its phosphorylation by ataxia telangiectasia mutated protein- related protein (ATR). The activated or phosphorylated BLM determines the proper recruitment of the MRE11 complex. WRN may be required at this point to provide endonuclease or helicase activity. Also at this stage, WRN may be phosphorylated by ATR or by MRE11 and NBS1, resulting in checkpoint reinforcement. Replication recovery can also involve homologous recombination (HR) and BRCA1 and RAD51. Adapted from Franchitto A. et al, Human Molecular Genetics 11:2447, 2002.

3. sigma-aldrich.com/cellsignaling mRNP Transport through the Nuclear Pore Complex (NPC)

4. sigma-aldrich.com/cellsignaling Cargo Import by the Importin  -Importin  Pathway

5. sigma-aldrich.com/cellsignaling Modular Structure of Transcription Factors

6. sigma-aldrich.com/cellsignaling Transcription Activation by Nuclear Receptors [1 of 2]

7. sigma-aldrich.com/cellsignaling Transcription Activation by Nuclear Receptors [2 of 2]

8. sigma-aldrich.com/cellsignaling Coupled RNA Splicing and Nuclear Export

9. sigma-aldrich.com/cellsignaling RNA Polyadenylation

10. sigma-aldrich.com/cellsignaling Mammalian mRNA Polyadenylation Machinery

11. sigma-aldrich.com/cellsignaling RNA Maturation

12. sigma-aldrich.com/cellsignaling RNA-guided Epigenetic Control of Gene Expression

13. sigma-aldrich.com/cellsignaling Phosphorylation-driven Regulatory Switch from Transcription Initiation to Elongation