CMSA long noncoding RNA regulates photoperiod-sensitive male sterility, an essential component of hybrid rice(2012) doi: 10.1073/pnas.1121374109 A non-coding RNA locus mediates environment-conditioned male sterility in rice. (2012) Cell Research 22:791–792. doi:10.1038/cr.2012.43Comparative expression profiling of miRNA during anther development in genetic male sterile and wild type cotton. (2013) BMC Plant Biology 13:66Differential Proteomic Analysis of Anthers between Cytoplasmic Male Sterile and Maintainer Lines in Capsicum annuum L.(2013) Int. J. Mol. Sci. 14(11), 22982-22996; doi:10.3390/ijms141122982Transcriptome map of plant mitochondria reveals islands of unexpected transcribed regions (2011) BMC Genomics 12: 279. Heterozygous alleles restore male fertility to cytoplasmic male-sterile radish (Raphanus sativus L.): a case of overdominance(2013) J. Exp. Bot. 64: 2041-2048.

AgingGenome

1. DNA damage2. Epigenetic shifts3. Telomere shortening

Cellular level1. Mitochondria: ROS, DNA damage, other2. Misfolded proteins3. Dysfunctional stem cells

Organismal level1. Autoimmune, other defects in immune system2. Defective signaling

Apoptosis Two basic steps: commitment and executionCommitment depends on interplay between various signalsBax & Bcl2 have opposite effects2 main pathways: extrinsic & intrinsic

Procaspase 8 binds FADD Procaspase 8 is processed to caspase 8= initiator caspaseCaspase 8 converts procaspase 3 to active form = executionerCaspase-3 & CAD execute the cell

Intrinsic pathwayUsually Bcl-2 protects mitoIntracellular damage activates Bad or Bax

ApoptosisUsually Bcl-2 protects mitoIntracellular damage activates Bad or BaxBad/Bax releases cyt c & AIF

ApoptosisIntracellular damage activates Bad/BaxBad/Bax release cyt c & AIFCyt c, Apaf-1 & procaspase-9 form complex = apoptosome

ApoptosisIntracellular damage activates Bad/BaxBad/Bax release cyt c & AIFCyt c, Apaf-1 & procaspase-9 form complex = apoptosomeApoptosome processes procaspase -9 to caspase-9 = initiator caspase

ApoptosisIntracellular damage activates Bad/BaxBad/Bax release cyt c & AIFCyt c, Apaf-1 & procaspase-9 form complex = apoptosomeApoptosome processes procaspase -9 to caspase-9 = initiator caspaseCaspase-9 converts caspase 3 to active form = executioner

ApoptosisIntracellular damage activates Bad/BaxBad/Bax release cyt c & AIFCyt c, Apaf-1 & procaspase-9 form complex = apoptosomeApoptosome processes procaspase -9 to caspase-9 = initiator caspaseCaspase-9 converts caspase 3 to active form = executionerCaspase 3 & CADexecute the cell

ApoptosisIntracellular damage activates Bad/BaxBad/Bax release cyt c & AIFAIF induces CAD

ApoptosisIntracellular damage activates Bad/BaxBad/Bax release cyt c & AIFAIF induces CADDestroys DNA

ApoptosisIntracellular damage activates Bad/BaxBad/Bax release cyt c & AIFAIF induces CADDestroys DNAFlips PS outside

ApoptosisIntracellular damage activates Bad/BaxBad/Bax release cyt c & AIFAIF induces CADDestroys DNAFlips PS outsidePhagocytic cells eatvesicles with external PS

ApoptosisTwo basic steps: commitment and executionCommitment depends on interplay between various signalsTNF often stimulates recovery instead!

Apoptosis in immunityPD1 receptor on T cells blocks apoptosisBinds PDL1 or PDL2 presented by other cells, including tumors

Apoptosis in immunityPD1 receptor on T cells blocks apoptosisBinds PDL1 or PDL2 presented by other cells, including tumorsPDL1 inhibitors are a new class of cancer drug

Autophagy

•Intracellular recycling process – lysosomes (animals);vacuoles (plants)

Autophagy

•Intracellular recycling process – lysosomes (animals);vacuoles (plants)

•Removes misfolded proteins, bad organelles, intracell pathogens

Autophagy

•Intracellular recycling process – lysosomes (animals);vacuoles (plants)

•Removes misfolded proteins, bad organelles, intracell pathogens

•Promotes survival!

Autophagy

•Intracellular recycling process – lysosomes (animals);vacuoles (plants)

•Removes misfolded proteins, bad organelles, intracell pathogens

•Promotes survival! Reallocates nutrients to vital processes!

Autophagy

•Removes misfolded proteins, bad organelles, intracell pathogens

•Promotes survival! Reallocates nutrients to vital processes!

•Best way to get rid of bad mito w/o killing cell!

Autophagy

•Removes misfolded proteins, bad organelles, intracell pathogens

•Promotes survival! Reallocates nutrients to vital processes!

•Best way to get rid of bad mito w/o killing cell!

•Associated with increased longevity in caloric restriction

Autophagy

•Associated with increased longevity in caloric restriction

•Upregulated upon nutrient or growth factor deprivation

Autophagy

•Associated with increased longevity in caloric restriction

•Upregulated upon nutrient or growth factor deprivation

•Triggers PCD distinct from apoptosis if can’t cope

• No caspase or CAD, chromatin laddering

• Occurs inside lysosomes

Autophagy

•Triggers PCD distinct from apoptosis if

can’t cope

• No caspase or CAD, chromatin laddering

• Occurs inside lysosomes

•Highly regulated!

Autophagy

•Triggers PCD distinct from apoptosis if

can’t cope

• No caspase or CAD, chromatin laddering

• Occurs inside lysosomes

•Highly regulated!

•Mis-regulation associated with heart

disease, diabetes and many more

Pyroptosis

PCD associated with

antimicrobial

responses in

inflammation

Pyroptosis

PCD associated with antimicrobial responses in inflammation

Toll-like receptors bind PAMPs, eg bacterial flagellins

Pyroptosis

PCD associated with antimicrobial responses in inflammation

Toll-like receptors bind PAMPs, eg bacterial flagellins

Activated NOD-like receptors (NLRs) initiate assembly of pyroptosome

Pyroptosis

PCD associated with antimicrobial responses in inflammation

Toll-like receptors bind PAMPs, eg bacterial flagellins

Activated NOD-like receptors (NLRs) initiate assembly of pyroptosome

Pyroptosome activates

Caspase-1

Pyroptosis

PCD associated with antimicrobial responses in inflammation

Toll-like receptors bind PAMPs, eg bacterial flagellins

Activated NOD-like receptors (NLRs) initiate assembly of pyroptosome

Pyroptosome activates

Caspase-1

Caspase-1 executes cell,

Releasing PAMPs and

cytokines

Pyroptosis

PCD associated with antimicrobial responses in inflammation

Toll-like receptors bind PAMPs, eg bacterial flagellins

Activated NOD-like receptors (NLRs) initiate assembly of pyroptosome

Pyroptosome activates

Caspase-1

Caspase-1 executes cell,

Releasing PAMPs and

Cytokines

Reason for depletion of

CD4 cells in AIDS

Necroptosis

PCD associated with viral infections

Necroptosis

PCD associated with viral infections

Infected cells release TNF

Necroptosis

PCD associated with viral infections

Infected cells release TNF

TNFR activates RIPK1

RIPK1 binds RIPK3 to form necrosome

Necroptosis

PCD associated with viral infections

Infected cells release TNF

TNFR activates RIPK1

RIPK1 binds RIPK3 to form necrosome

Necrosome activates MLKL

which permeabilizes membranes

Necroptosis vs apoptosisTend to inhibit each other, but do have overlap

Necroptosis vs apoptosisTend to inhibit each other, but do have overlapFail-safe for viruses that block apoptosis

FerroptosisPCD dependent on intra-cellular ironTriggered by inhibition of cystine uptake

FerroptosisPCD dependent on intra-cellular ironTriggered by inhibition of cystine uptakeReduced cystine uptake leads to the production of lethal lipid ROS

FerroptosisPCD dependent on intra-cellular ironTriggered by inhibition of cystine uptakeReduced cystine uptake leads to the production of lethal lipid ROSErastin etc trigger it

FerroptosisPCD dependent on intra-cellular ironTriggered by inhibition of cystine uptakeReduced cystine uptake leads to the production of lethal lipid ROSErastin etc trigger itFerrostatin blocks it

Autophagy

– Plant PCD• Changes in shape and position of

mitochondria (Mitochondrial morphology transition, MMT)

• Nuclear condensation

• Condensation of PM from cell wall

• Deregulated: dev’l defects, lethality

(Scott & Logan, 2008, Plant Signaling & Behavior)

MMT

Plant PCD In vegetative developmentIn vegetative development

– Suspensor degradation during embryo devt

– Root cap devt and aerenchyma formation

– Shaping of leaves

Kawashima & Goldberg, 2009

PCD : Patterning in the lace plant leaf

http://www.youtube.com/watch?v=9gis4HK1XPg

http://completeaquarium.blogspot.com/2008/04/aponogeton-madagascariensis-lace-plant.html

PCD: aerenchyma formation

• Aerenchyma– Tissue for gas exchange– Aquatic species– Induced by submergence– Constitutive in rice:

adaptation to floodingvisible in all rice root types, except in small lateral roots

Rebouillat et al., Rice 2009

Plant PCD• In vegetative development

– Tracheary element formation

PCD-specific hydrolytic enzymes accumulate in vacuole S1-nucleasecysteine proteases

Vacuole enlargesburstsreleases enzymesautolysis of cellcontents & partof cw

Copyright ©2008 American Society of Plant Biologists

Poulter, N. S., et al. Plant Physiol. 2008;146:1358-1367

Model for integration of cytoskeletal events triggered by SI

Plant PCD• In reproductive development– Tapetum and stomium degradation in anther

– Female gametophyte devt

– Flower senescence

– Incompatibility reactions

http://bifi.unizar.es/research/pro_pro_inter_elec_transfer/research.php

Developed independently?

Or evolved from a common ancestral cell death process?

Some mol. components -- conserved

e.g., PARP1,Bax-inhibitor-1, Defender against Apoptotic Death-1

PCD : Evolutionary perspective

• Caspases– Cysteine proteases

– Mol switches that activate c death

• Plants have proteases w/ caspase-like activities :

• Vacuolar processing enzymes (VPEs)

PCD : Evolutionary perspective

Gao et al., Plant Signaling & Behav. 2008

http://bifi.unizar.es/research/pro_pro_inter_elec_transfer/research.php

Mitochondria --sensor of death signals &initiator of biochem processes leading to cell death

PCD : role of mitochondrion

PCD : a role for chloroplasts

PCD occurs indepen-dently of chloroplasts

• Chloroplasts – determine severity

of & number of cells undergoing AL-PCD

– ROS• Elevated levels –

physiological damage

• Signaling mol.

Gao et al., Plant Signaling & Behav. 2008

Cell death due to biotic/abiotic stress

Abiotic stresses:Temperature extremes

Ozone

Hypoxia

Mediated by plant hormonesEthylene

Jasmonic acid

Salicylic acid

Regulators: Reactive oxygen species (ROS):Superoxide anion radicalHydrogen peroxide (H2O2)

Nitric oxide (NO)

Steffens and Sauter, Plant Cell, 2009