Signal Transduction Pathway Smorgasbord

Transcription

1 Molecular Cell Biology Lecture. Oct 28, 2014 Signal Transduction Pathway Smorgasbord Ron Bose, MD PhD Biochemistry and Molecular Cell Biology Programs Washington University School of Medicine

2 Outline 1. Nuclear Hormone Receptors 2. Cytokine Receptors JAK/STAT Pathway 3. PI3-kinase Akt mtor 4. Regulation of Protein Kinases

3 Resources: Nuclear Hormone Receptors tart.html

4 Nuclear Hormone Receptor Superfamily Human genes 2. Major Categories: Thyroid Hormone Receptor (TR)- like Estrogen Receptor (ER)- like Retinoid X Receptor (RXR) like TR, RAR, PPAR, Vitamin D receptor, LiverX Receptor ER, PR, AR, Estrogen Receptor Related, Glucocorticoid receptor, Mineralocorticoid receptor RXR, Hepatocyte nuclear factor-4, etc. Knock-out in mice causes reproductive, developmental, or metabolic abnormalities.

5 AF: Activation Function. Mediate transcriptional activation DNA Binding Domain Ligand Binding Domain

6 AF: Activation Function. Mediate transcriptional activation

7 Bind as homodimers Bind as heterodimers with RXR Hormone response elements are inverted repeats. Hormone response elements are direct repeats.

8 Ligand Present Ligand Absent

9 Movie: Tab 12. Nuclear Hormone Action Model

10 Outline 1. Nuclear Hormone Receptors 2. Cytokine Receptors JAK/STAT Pathway 3. PI3-kinase Akt mtor 4. Regulation of Protein Kinases

11 Cytokine Receptors JAK/STAT Pathway Baker et al., Oncogene (2007) 26,

12 Cytokine Receptors Baker et al., Oncogene (2007) 26,

13 JAK = Janus kinases 4 genes in humans and mice TYK2 (first gene in this family to be identified) JAK1, JAK2, JAK3 Baker et al., Oncogene (2007) 26,

14 STAT= Signal Transducers and Activators of Transcription Baker et al., Oncogene (2007) 26,

15 Cytokine Receptors JAK/STAT Pathway Baker et al., Oncogene (2007) 26,

16 Recptor Tyrosine Kinases Examples EGFR, Her2, etc from Marmor, Skaria, and Yarden 2004

17 Outline 1. Nuclear Hormone Receptors 2. Cytokine Receptors JAK/STAT Pathway 3. PI3-kinase Akt mtor 4. Regulation of Protein Kinases

18 PI3-kinase Akt mtor Songet al., Nature Rev Mol Cell Bio 2012

19 PI3-kinase Akt PtdIns(4,5)P 2 (PIP2) PI3K PTEN PtdIns(3,4,5)P 3 (PIP3) PDK1 Akt Zoncu et al., Nature Rev Mol Cell Bio 2011

20 mtor complexes mtorc1 Rapamycin sensitive Responds to nutrient level, growth factors, energy, and stress. mtorc2 NOT rapamycin sensitive Inputs into mtorc2 less well known. Zoncu et al., Nature Rev Mol Cell Bio 2011

21 mtorc1 substrates S6 kinase 1 (S6K1) eif-4e binding protein (4E-BP) Zoncu et al., Nature Rev Mol Cell Bio 2011

22 mtorc2 substrates Akt mtorc2 PH domain PDK1 2 T308 Kinase Domain 1 S473 3 Downstream substrates: TSC complex, PRAS40, etc. Zoncu et al., Nature Rev Mol Cell Bio 2011

23 Bringing it all together mtor is a signal integrator, like the chips and circuits in your smart phone Zoncu et al., Nature Rev Mol Cell Bio 2011

24 Outline 1. Nuclear Hormone Receptors 2. Cytokine Receptors JAK/STAT Pathway 3. PI3-kinase Akt mtor 4. Regulation of Protein Kinases

25 Manning et al., Science 2002

26 Regulation of Protein Kinases 1. Post-translation modifications. Phosphorylation-dependent Activation Loop 2. Protein-protein interactions Regulatory Subunits Dimers

27 Structure of PKA catalytic domain α Helices β Sheets N-lobe C Helix C-lobe Caplan, Science STKE 2005

28 Structural features of the PKA Activation Loop Illustration from Nolen et al, Mol. Cell, Vol. 15, p , 2004

29 Phosphorylation of the MAP Kinase activation loop Phosphorylation on threonine and tyrosine Phospho-Thr 183 contacts α-c and promotes active conformation Phospho-Thr 183 promotes ERK2 dimerization via conformational changes in C-terminal extension Illustration taken from Huse and Kuriyan, Cell 109, (2002) AKT phosphorylation at T308 is also Activation Loop Phosphorylation

30 MAP Kinase Structure Thr183 Tyr185 Unphosphorylated Phosphorylated Canagarajah et al Cell 90, (1997)

31 MAP Kinase Structure Unphosphorylated Thr183 Phosphorylated Tyr185 Canagarajah et al Cell 90, (1997)

32 Cyclin - Cyclin-dependent kinase (CDK) Complex Cyclin A Cyclin-dependent kinase (Cdk2) Jeffrey et al Nature 376, (1995)

33 Jeffrey et al Nature 376, (1995) C-helix C-helix Activation Loop Activation Loop Cdk2 Cdk2.CyclinA

34 Asymmetric Dimer Formed by the EGFR Kinase Domain EGFR kinase domain asymmetric dimer Zhang, Gureasko, Shen, Cole, and Kuriyan. Cell 2006

35 Summary 1. Nuclear hormone receptors consist of a DNAbinding domain and ligand-binding domain. 2. Cytokine receptors signal through the JAK kinases, which have 2 kinase domains, and the STAT transcription factors. 3. mtor is a signal integrator for metabolic and growth factor signaling. 4. Protein kinases are regulated by PTM s and protein-protein interactions.