Signal Transduction Pathway Smorgasbord Ron Bose, MD PhD - - PowerPoint PPT Presentation

Signal Transduction Pathway Smorgasbord

Ron Bose, MD PhD

Biochemistry and Molecular Cell Biology Programs Lab: 4515 McKinley Research Building, 3rd floor Washington University School of Medicine Molecular Cell Biology Lecture. Oct. 24, 2017

What is the connection? Signal Transduction

Outline

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

Resources: Nuclear Hormone Receptors

https://www.nursa.org/nursa/index.jsf Online Course: https://www.nursa.org/nursa/flashTutorial/gene/nu clearReceptor/start.jsf Reference: McKenna NJ and O'Malley BW. An interactive course in nuclear receptor signaling: concepts and models. Sci STKE. 2005, tr22.

Nuclear Hormone Receptor Superfamily

• 1. 48 Human genes
• 2. Major Categories:

Knock-out in mice causes reproductive, developmental, or metabolic abnormalities.

Thyroid Hormone Receptor (TR)- like TR, RAR, PPAR, Vitamin D receptor, LiverX Receptor Estrogen Receptor (ER)- like ER, PR, AR, Estrogen Receptor Related, Glucocorticoid receptor, Mineralocorticoid receptor Retinoid X Receptor (RXR) like RXR, Hepatocyte nuclear factor-4, etc.

AF: Activation Function. Mediate transcriptional activation

DNA Binding Domain Ligand Binding Domain

www.nursa.org/

AF: Activation Function. Mediate transcriptional activation www.nursa.org/

www.nursa.org/ Bind as homodimers Bind as heterodimers with RXR Hormone response elements are inverted repeats. Hormone response elements are direct repeats.

Ligand Present Ligand Absent

www.nursa.org/

Movie: https://nursa.org/nursa/about/tutorial.jsf Tab 12. Nuclear Hormone Action Model

www.nursa.org/

Outline

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

Cytokine Receptors – JAK/STAT Pathway

Baker et al., Oncogene (2007) 26, 6724–6737

Cytokine Receptors

Baker et al., Oncogene (2007) 26, 6724–6737

JAK = Janus kinases

Baker et al., Oncogene (2007) 26, 6724–6737

4 genes in humans and mice

• TYK2 (first gene in this family to be identified)
• JAK1, JAK2, JAK3

STAT= Signal Transducers and Activators of Transcription

Baker et al., Oncogene (2007) 26, 6724–6737

Cytokine Receptors – JAK/STAT Pathway

Baker et al., Oncogene (2007) 26, 6724–6737

from Marmor, Skaria, and Yarden 2004

Recptor Tyrosine Kinases Examples– EGFR, Her2, etc

Outline

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

PI3-kinase – Akt – mTOR

Songet al., Nature Rev Mol Cell Bio 2012

PI3-kinase – Akt

PtdIns(4,5)P2

(PIP2)

PtdIns(3,4,5)P3

(PIP3)

PI3K PTEN

Akt

PDK1

Zoncu et al., Nature Rev Mol Cell Bio 2011

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

mTORC1 substrates

• S6 kinase 1 (S6K1)
• eIF-4E binding protein (4E-BP)

Zoncu et al., Nature Rev Mol Cell Bio 2011

mTORC2 substrates

Akt

Zoncu et al., Nature Rev Mol Cell Bio 2011

PH

domain

Kinase Domain

PDK1 mTORC2

S473 T308

Downstream substrates: TSC complex, PRAS40, etc.

1 3 2

Bringing it all together

Zoncu et al., Nature Rev Mol Cell Bio 2011

mTOR is a signal integrator, like the chips and circuits in your smart phone

Outline

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

Manning et al., Science 2002

More information available at: http://kinase.com/web/current/

Regulation of Protein Kinases

• 1. Post-translation modifications.
• Phosphorylation-dependent
• Activation Loop
• 2. Protein-protein interactions
• Regulatory Subunits
• Dimers

Structure of PKA catalytic domain

C Helix

N-lobe C-lobe

α Helices β Sheets

Caplan, Science STKE 2005

Illustration from Nolen et al, Mol. Cell, Vol. 15, p.661-675, 2004

Structural features of the PKA Activation Loop

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, 275-282 (2002)

AKT phosphorylation at T308 is also Activation Loop Phosphorylation

Unphosphorylated

MAP Kinase Structure

Thr183 Tyr185 Canagarajah et al Cell 90, 859-869 (1997)

Phosphorylated

Thr183 Tyr185 Canagarajah et al Cell 90, 859-869 (1997)

Unphosphorylated

MAP Kinase Structure

Phosphorylated

Cyclin - Cyclin-dependent kinase (CDK) Complex

Cyclin-dependent kinase (Cdk2) Cyclin A

Jeffrey et al Nature 376, 313-320 (1995)

Cdk2 Cdk2.CyclinA

Jeffrey et al Nature 376, 313-320 (1995)

C-helix C-helix Activation Loop Activation Loop

Asymmetric Dimer Formed by the EGFR Kinase Domain

EGFR kinase domain asymmetric dimer

Zhang, Gureasko, Shen, Cole, and Kuriyan. Cell 2006

Summary

• 1. Nuclear hormone receptors consist of a DNA-

binding 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.