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CRAZY ABOUT BIOMECIDINE

Having a look into frog oocytesTRANSLATIONAL CONTROL OF mRNAs BY CYTOPLASMIC POLYADENYLATION DURING MEIOSIS1

TRANSLATIONAL CONTROL OF mRNAs BY CYTOPLASMIC POLYADENYLATION DURING MEIOSISGene expression

Gene regulation

Translational control of mRNAs

CPEBs & cytoplasmic polyadenylation

Meiosis and translational control of mRNAs mediated by CPEBs

CPEBs beyond meiosis

2GENE EXPRESSION

Genetic informationEffectorsCell signalingCell adhesionEnzymesDefine the structureTransport

3GENE EXPRESSION

Genetic informationEffectorsCell signalingCell adhesionEnzymesDefine the structureTransportKey steps in gene expressionRNA transcription: from DNA to RNA

RNA processing: from RNA to mRNA

mRNA transport: from the nucleus to the cytoplasm

Protein translation: from mRNA to protein4GENE EXPRESSION

Genetic informationEffectorsCell signalingCell adhesionEnzymesDefine the structureTransport

RNA processing

DNAPre-mRNAmRNA5GENE EXPRESSION

Genetic informationEffectorsCell signalingCell adhesionEnzymesDefine the structureTransportmRNA featuresCDS5UTR3UTR5 capAAAAAAAAAA

AUGUGA6GENE EXPRESSION

Genetic informationEffectorsCell signalingCell adhesionEnzymesDefine the structureTransportProtein translation

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TRANSLATIONAL CONTROL OF mRNAs BY CYTOPLASMIC POLYADENYLATION DURING MEIOSISGene expression

Gene regulation

Translational control of mRNAs

CPEBs & cytoplasmic polyadenylation

Meiosis and translational control of mRNAs mediated by CPEBs

CPEBs beyond meiosis

8GENE REGULATION

EVERY CELL IN A GIVEN ORGANISM CONTAINS THE SAME GENETIC INFORMATIONDIFFERENCES IN GENE EXPRESSION9GENE REGULATIONEvery step in gene expression is regulatedTRANSCRIPTIONAccessibility of DNA

Transcriptional regulation

10GENE REGULATION

Every step in gene expression is regulatedRNA PROCESSINGAlternative splicing

Alternative 3UTR formation: different 3UTR

AAACDS5UTR3UTR5 capAAAAUGCDSAUGTRANSCRIPTIONAccessibility of DNA

Transcriptional regulation 11GENE REGULATION

Every step in gene expression is regulatedRNA PROCESSINGAlternative splicing

Alternative 3UTR formation: different 3UTR PROTEIN TRANSLATIONGlobal vs. mRNA specific regulation

Translational repression precluding ribosome recruitment or progression through the mRNA

TRANSCRIPTIONAccessibility of DNA

Transcriptional regulation 12

TRANSLATIONAL CONTROL OF mRNAs BY CYTOPLASMIC POLYADENYLATION DURING MEIOSISGene expression

Gene regulation

Translational control of mRNAs

CPEBs & cytoplasmic polyadenylation

Meiosis and translational control of mRNAs mediated by CPEBs

CPEBs beyond meiosis

13TRANSLATIONAL CONTROL OF mRNAsWHY mRNAs should be stored in the cytoplasm instead of being immediately translated?

AAAAAAAAAAAAnucleuscytoplasmAAAAAA

A

AAAAAAOnce transcribed, mRNAs can have different fates.14TRANSLATIONAL CONTROL OF mRNAsWHY mRNAs should be stored in the cytoplasm instead of being immediately translated?

Rapid response

Absolutely required in situations with absence of transcriptionTo solve long distances(axons can extend up to 1 meter!)

15TRANSLATIONAL CONTROL OF mRNAsmRNA translation can be divided into 3 phases: initiation, elongation and termination

All mRNAs exit the nucleus with a long poly(A) tail and should be efficiently translated

INITIATION is the phase more tightly controlled16TRANSLATIONAL CONTROL OF mRNAsHOW TO CONTROL TRANSLATION AT INITITATION?sequestering initiation factors

blocking the 5 cap

shortening the poly(A) tailAAAAAAAAAAAAA4G4E4E4E-BPSequester initiation factors17TRANSLATIONAL CONTROL OF mRNAsHOW TO CONTROL TRANSLATION AT INITITATION?sequestering initiation factors

blocking the 5 cap

shortening the poly(A) tailAAAAAAAAAAAAA4G4EAAAAAAAAAAAAA4EBlock the 5 cap no recruitment of the ribosome18TRANSLATIONAL CONTROL OF mRNAsHOW TO CONTROL TRANSLATION AT INITITATION?sequestering initiation factors

blocking the 5 cap

shortening the poly(A) tailAAAAAAAAAAAAA4G4EA4EShorten the poly(A) tail no close loop19TRANSLATIONAL CONTROL OF mRNAsHOW TO CONTROL TRANSLATION AT INITITATION?sequestering initiation factors

blocking the 5 cap

shortening the poly(A) tailAAAAAAAAAAAAA4G4ETRANSLATIONAL REPRESSION doesnt last forever!!!

Activation of mRNA translationCell stimuli

releasing initiation factors

allowing the 5 cap to interact with initiation factors

elongating the poly(A) tailHow to activate translation?20

TRANSLATIONAL CONTROL OF mRNAs BY CYTOPLASMIC POLYADENYLATION DURING MEIOSISGene expression

Gene regulation

Translational control of mRNAs

CPEBs & cytoplasmic polyadenylation

Meiosis and translational control of mRNAs mediated by CPEBs

CPEBs beyond meiosis

21CPEBs and CYTOPLASMIC POLYADENYLATIONA4ENO TRANSLATIONPolyadenylation can happen in the cytoplasm!!!! AAAAAAAAAAAAA4G4ETRANSLATION

22CPEBs and CYTOPLASMIC POLYADENYLATIONCPEBs play an essential role

RNA binding proteins

Bind to specific sequences in the 3UTR of target mRNAs

Have a dual function!!!!

CPEB in repressionCPEB in activationCPEB recruits other proteins that shorten the poly(A) tail and block the capCPEB recruits other proteins that elongate the poly(A) tailWHAT MAKES THE DIFFERENCE????

stimulusKinase activation23

TRANSLATIONAL CONTROL OF mRNAs BY CYTOPLASMIC POLYADENYLATION DURING MEIOSISGene expression

Gene regulation

Translational control of mRNAs

CPEBs & cytoplasmic polyadenylation

Meiosis and translational control of mRNAs mediated by CPEBs

CPEBs beyond meiosis

24MEIOSIS and CPEBs

25MEIOSIS and CPEBs

Model system: Xenopus laevis oocytes

Oocytes arrested at the prophase of meiosis I (progesterone makes them progress to metaphase of meiosis II)

Eggs arrested at the metaphase of meiosis II (fertilization makes them finish meiosis and start embryonic divisions)

Oocytes Eggs progesteronefertilization26MEIOSIS and CPEBs

Model system: Xenopus laevis oocytes

Prophase I arrested oocytes grow until they are fully competent for development: 6 growth stages

>1.2mm!(human: 0.12mm)Accumulation of molecular reserves

Like maternal mRNAs!

MEIOSIS AND FIRST EMBRYIONIC DIVISIONS HAPPEN IN THE ABSENCE OF TRANSCRIPTION!PROTEIN EXPRESSION DUE TO TRANSLATIONAL ACTIVATION OF mRNAs!27MEIOSIS and CPEBs

sVI. Oocytes progesteroneRequires activation of translation of stored mRNAsModel system: Xenopus laevis oocytes

Meiotic progression requires protein translation!!!!

28MEIOSIS and CPEBs

Model system: Xenopus laevis oocytes

Meiotic progression requires protein translation!!!!

Stage VI oocytes store A LOT of maternal mRNAs repressed by CPEB1

+ progesterone

MEIOSIS RESUMPTIONCPEB1 is phosphorylatedActivation of translation of mRNAs

29MEIOSIS and CPEBs

CPEB1 is not the only one! CPEB4 takes the job in late meiotic phases.

Oocytes arrested prog.CPEB1CPEB4CPEB1 degradedCPEB4 synthetized repression activation30MEIOSIS and CPEBs

CPEB1 is not the only one! CPEB4 takes the job in late meiotic phases.

They both recognize the same elements in the 3UTR of target mRNAs.

CPEB1 degradedCPEB4 synthetized

progesteroneAurora A kinase activityCPEB1 repression activationOocytes arrested 31CURIOSITY

THE POWER OF THE CYTOPLASM!Early development happens in the absence of transcription Everything you need for early development is contained in the egg cytoplasm

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TRANSLATIONAL CONTROL OF mRNAs BY CYTOPLASMIC POLYADENYLATION DURING MEIOSISGene expression

Gene regulation

Translational control of mRNAs

CPEBs & cytoplasmic polyadenylation

Meiosis and translational control of mRNAs mediated by CPEBs

CPEBs beyond meiosis

33CPEBs BEYOND MEIOSIS

CPEBs are involved in local translation in dendrites

CPEBs are required for long term memoryCPEBs are involved in cell proliferation, angiogenesis

CPEB4 is involved in pancreatic adenocarcinoma

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Ral Mndez Lab35