Determination of sexDetermination of sex

?

Dr. habil. Kőhidai LászlóDr. habil. Kőhidai LászlóDept. Genetics, Cell- & Immunobiology, Dept. Genetics, Cell- & Immunobiology, Semmelweis UniversitySemmelweis University2014.2014.

Determination of sexDetermination of sex Characterization of sex chrsCharacterization of sex chrs Main types of sex chrs linkedMain types of sex chrs linked inheritanceinheritance Pathological formsPathological forms

Main determining factors of Main determining factors of sexsex

Environmental factorsEnvironmental factors- size of body (marine worms)size of body (marine worms)- temperature (reptiles)temperature (reptiles)

GeneticalGenetical- allelic + environment (wasps)allelic + environment (wasps)- chromosomalchromosomal

Ratio of X chrs and autosomesRatio of X chrs and autosomesautonomic e.g. Drosophilaautonomic e.g. Drosophilanot autonomic e.g. humannot autonomic e.g. human

General characteristics of General characteristics of X chromosomeX chromosome

5% 5% of haploide genomeof haploide genome House-keeping and specialized genesHouse-keeping and specialized genes conserved sequences conserved sequences it does NOT code sex determining factorit does NOT code sex determining factor one of X chrs gets inactive in female (1961)one of X chrs gets inactive in female (1961)

General characteristics of General characteristics of Y chromosomeY chromosome

It was a homologue pair of X chrs in a previous It was a homologue pair of X chrs in a previous phase of phyligenyphase of phyligeny Phenotype of somatic cells is determined by the Phenotype of somatic cells is determined by the testicular hormonestesticular hormones Y chrs acts on testis developement by TDFY chrs acts on testis developement by TDF SRY gene product = TDF (1991)SRY gene product = TDF (1991) SRY codes a Zn-fingered transcription factorSRY codes a Zn-fingered transcription factor SRY is expressed ONLY in:SRY is expressed ONLY in:

- gonadal tissues- gonadal tissues- at the development of testis- at the development of testis

- presence of gonocytes is not a- presence of gonocytes is not aprerequisiteprerequisite

X chrs has X chrs has a homologuea homologue

NO homologue of X chrsNO homologue of X chrs

Housekeeping Housekeeping TestisTestisOther placesOther places

Y chrs.Y chrs.

Known genes of Known genes of Y chromosome Y chromosome

SRY – sex region of X (see below)SRY – sex region of X (see below)

ZFY – code of a Zn-fingered proteinZFY – code of a Zn-fingered protein

AZY – responsible for development of sperm (AZ=azospermia)AZY – responsible for development of sperm (AZ=azospermia)

H-Y – cell surface antigene, present on each cell of malesH-Y – cell surface antigene, present on each cell of males

MSY – long palindromic sequences on the q arm of Y chrsMSY – long palindromic sequences on the q arm of Y chrs

??

!!

Genes of early sex Genes of early sex differentiationdifferentiation

SF-1 SF-1 ‘Steroidogenic’ factor, nuclear receptor which‘Steroidogenic’ factor, nuclear receptor whichregulates expression of steroid hydroxylasesregulates expression of steroid hydroxylases

WT1WT1 Wilm’s tumor locus determined chrs 11p13Wilm’s tumor locus determined chrs 11p13 SOX9SOX9 ‘SRY-releated HMG-box’, chrs 17q24.3-25.1‘SRY-releated HMG-box’, chrs 17q24.3-25.1

about 14 genes about 14 genes MISMISproduct of Sertoli-cells; chrs. 19p13.3product of Sertoli-cells; chrs. 19p13.3

regulatory domaine which binds F-1, its promoterregulatory domaine which binds F-1, its promoterbinds SRYbinds SRY

DSSDSS ‘Dosage Sensitive Sex reversal’, ‘Dosage Sensitive Sex reversal’, Duplication on chrs Xp21.2-p22.2 Duplication on chrs Xp21.2-p22.2

DAX-1 DAX-1 nuklear hormone receptor,nuklear hormone receptor,expressed: testis and adrenal gland expressed: testis and adrenal gland

SRYSRY ‘Sex-determining region product of Y gene, ‘Sex-determining region product of Y gene, transcription factortranscription factor

SRY geneSRY gene

Yp 11.3Yp 11.3 only one, 850 bp exononly one, 850 bp exon highly conservedhighly conserved 79 amino acid containing HMG box79 amino acid containing HMG box

( ‘Highly Mobile Group of proteins)( ‘Highly Mobile Group of proteins)

Bipotencial Bipotencial gonadegonade

OvaryOvary

TestisTestis

FollicularFollicularcellscells

ThecaThecacellscells

Sertoli-Sertoli-cellscells

Leydig Leydig cellscells

FollicleFollicle

AMHAMH

TestosteronTestosteron

SRYSRYSOX9SOX9

DAX1DAX1

WNT4WNT4

SFSF11

SF1SF1

SF1SF1WT1WT1LHX9LHX9

EstrogenEstrogen

GonadesGonades

GenotypeGenotype

PhenotypePhenotype

TestisTestis

MaleMale Female Female

OvaryOvary

Female Female

GonadeGonadedisgenesisdisgenesis

DAX1DAX1

SRYSRY SRYSRY

DAX1DAX1

inactiveinactiveDAX1DAX1

2 copies2 copiesDAX1DAX1

Ref.: Genetics Review Group (1995)Ref.: Genetics Review Group (1995)

Sexually not differentiatedSexually not differentiated

MaleMale Female Female

Ref.:Langman (1981)Ref.:Langman (1981)

Week 4Week 4

Week 6Week 6

Week 8 Week 8 Week 8Week 8

TestisTestisOvaryOvary

Ref.:Langman (1981)Ref.:Langman (1981)

Week 16Week 16 Week 20Week 20

TestisTestis OvaryOvary

Ref.:Langman (1981)Ref.:Langman (1981)

X X ChromosomeChromosome

Y Y ChromosomeChromosome

SRYSRY SF1SF1 SOX9SOX9 TESTISTESTIS

DAX1DAX1

WNT1WNT1

OVARYOVARYRef.: Aberger F.Ref.: Aberger F.

PromoterPromoter AmhAmh

Sox9Sox9

AmhAmh

Sox9Sox9 SF1SF1

Wt-1Wt-1

AmhAmh

Sox9Sox9 SF1SF1

Wt-1Wt-1

GataGata

Ref.: Arango et al. (1999)Ref.: Arango et al. (1999)

Evolution of huma sex chromosomes (1)Evolution of huma sex chromosomes (1)

Sex chrs. DevelopesSex chrs. DevelopesSRY (NRY) blocksSRY (NRY) blocksRecombinationRecombination290-350 Mill.year290-350 Mill.year

Az NRY expansionAz NRY expansion(RBMY, RPS4Y)(RBMY, RPS4Y)

230-300 Mill year230-300 Mill year

NRY expansionNRY expansion(SMCY, UBE1Y)(SMCY, UBE1Y)

130-170 Mill year130-170 Mill year

recomb.recomb. Non-recomb.Non-recomb.X-chrs. spec.X-chrs. spec.

XYXYegg layer egg layer mammalsmammals

XYXYMarsupialsMarsupials

AutosomeAutosomebirdsbirds

recomb.recomb. not rekomb.not rekomb.X-chrs. spec.X-chrs. spec.

TranslocationTranslocation expansionexpansion to PARpto PARp

80-130 Myr80-130 Myr

NRY NRY expansionexpansion(CASKP, (CASKP, DBY)DBY)80-130 Myr80-130 Myr

NRY NRY expansionexpansion(AMELY, (AMELY, KALP)KALP)30-50 Myr30-50 Myr

X-Y X-Y translocatiotranslocationnPCDHYPCDHY3-4 Myr3-4 Myr

XYXYNot human Not human anthropoidsanthropoids

XYXYNon-anthropoid Non-anthropoid

mammalsmammals

XYXYHomo Homo

sapienssapiens

Protocadherin X/YProtocadherin X/Y

Evolution of huma sex chromosomes (1)Evolution of huma sex chromosomes (1)

Y kromoszómaY kromoszóma

X kromoszómaX kromoszóma EmberEmber

EmberEmber

MacskaMacska

MacskaMacska

Conserved loci in mammalian Conserved loci in mammalian X and Y chrsX and Y chrs

Testicular feminisationTesticular feminisation

Genotype: XYGenotype: XYTestosteron in sera is normalTestosteron in sera is normalTestis in the abdominal cavityTestis in the abdominal cavityFeminine statue Feminine statue

Reasons:Reasons:

- error of error of differentiationdifferentiation after testosteron action?after testosteron action?- testosteron can influence testosteron can influence development of Wolff-tubule development of Wolff-tubule at differentiation?at differentiation?

Reason: MUTATION OF Reason: MUTATION OF TESTOSTERON RECEPTORTESTOSTERON RECEPTOR

REASON: Xq11-12 mutation – androgenic receptorREASON: Xq11-12 mutation – androgenic receptor

InactiveInactive genegene

EnhancerEnhancer PromoterPromoter StartStart

Hormone-RecHormone-Reccomplexcomplex

ActiveActive genegene

Activated Activated enhancerenhancer

PromoterPromoter

mRNS synthesismRNS synthesis

HermaphroditismHermaphroditism

True hermaphroditismTrue hermaphroditism

- Both gonadsBoth gonads (ovary and testis) or its tissue (ovary and testis) or its tissue is present in the bodyis present in the body- Male OR femaleMale OR female external sexual organs are external sexual organs are dominantdominant- Forms Forms

46XX – SRY translocation or 46XXY – loss 46XX – SRY translocation or 46XXY – loss of Y chrs of Y chrs

46XY – point mutation of Y chrs46XY – point mutation of Y chrs46XX/46XY mosaicism46XX/46XY mosaicism

(Hermaphroditism is frequent in invertebrates (Hermaphroditism is frequent in invertebrates and plants)and plants)

HermaphroditismHermaphroditism

Pseudo hermaphroditismPseudo hermaphroditism

- Gonad of one sex and the opposite external sex Gonad of one sex and the opposite external sex organsorgans

- Ph masculinusPh masculinusMixed gonad dysgenesis (45X/46XY – gonadal Mixed gonad dysgenesis (45X/46XY – gonadal streak/testis)streak/testis)Testicular feminisation (46XY – pointmutation of Y Testicular feminisation (46XY – pointmutation of Y chrs – testis releases estrogen; ligand is not bind chrs – testis releases estrogen; ligand is not bind by receptors)by receptors)

- Ph femininusPh femininusAdrenogenital syndrome (androgen threatments Adrenogenital syndrome (androgen threatments can induce it)can induce it)

Form of Form of „gene dose compensation”„gene dose compensation”

Only 1 X chrsOnly 1 X chrs is active when there are X chrs’ is active when there are X chrs’ in excess numberin excess number

nnBarrBarr = n = nX X – 1– 1

X recessive mutations: some cells in female are X recessive mutations: some cells in female are „functional hemizygotes”„functional hemizygotes” – this may result – this may result disease disease

An other form of gene dose compensation: An other form of gene dose compensation:

differences in activitydifferences in activity of X chrs in the two sex of X chrs in the two sex

Inactive X chromosomeInactive X chromosome

Barr-bodiesBarr-bodies

‘ ‘Drumstick’ Drumstick’

XYXY

XXXX

Inactivation of X chromosome (1)Inactivation of X chromosome (1)

XistXist expression expression- inhibitor factor- inhibitor factor

Inhibitor factor Inhibitor factor LINE helps in LINE helps in sreading the sreading the effecteffect

XistXist RNA coats RNA coats the the chromosomechromosome

TranscriptionalTranscriptional „ „silencing”silencing”Timing of Timing of asynchron asynchron replicationreplication

Increased Increased macroH2A macroH2A Hypoacethylated:Hypoacethylated: H3; H4H3; H4

X kromoszóma inaktiválódása (2)X kromoszóma inaktiválódása (2)

Xist transcription in embryonic stem cellsXist transcription in embryonic stem cells

Xist is activeXist is activeon both X chrs’on both X chrs’

Inactive X chrsInactive X chrsis covered by is covered by

RNARNA

Only the inactive,Only the inactive,„„RNA-coated” Xchrs RNA-coated” Xchrs

is detectableis detectable

XXXX

XYXY

>>

XYXYXX

==

Mary F. LyonMary F. Lyon

Inactivation of X chromosomeInactivation of X chromosome Takes place Takes place randomlyrandomly in the early phase of in the early phase of development in healthy female development in healthy female

The The same X chrssame X chrs gets inactive in the gets inactive in the offspringoffspring generations of cellsgenerations of cells

A product of A product of Xq13 (Xist)Xq13 (Xist) is significant in the process is significant in the process

Virtually Virtually all genes of X chrall genes of X chr turn into inactive phase turn into inactive phase (except genes responsible for inactivation)(except genes responsible for inactivation)

Female are Female are mosaicmosaic for inactive X chrs as maternal for inactive X chrs as maternal and paternal X chrs get inactive, too and paternal X chrs get inactive, too

Male: Male: constitutionalconstitutional hemizygotes hemizygotesFemale: Female: functionalfunctional hemizygotes hemizygotes

PAR regionsPAR regionsPAR = pseudo autoszomal regionPAR = pseudo autoszomal region

Never gets inactiveNever gets inactive Telomeric position on the two sex chromosomesTelomeric position on the two sex chromosomes PAR1 – 2.6 Mb; PAR2 – 320 kbPAR1 – 2.6 Mb; PAR2 – 320 kb Provide choice for partial meiotic pairing of X-Y chrsProvide choice for partial meiotic pairing of X-Y chrs „ „Obligatory crossing over” in PAR1 (e.g. Xg blood group, Obligatory crossing over” in PAR1 (e.g. Xg blood group,

IL-3 receptor)IL-3 receptor)

Frequent problems resulting Frequent problems resulting disfunctions in sexual differentiationdisfunctions in sexual differentiation

mutations of SRYmutations of SRY disturbed biosynthesis of androgensdisturbed biosynthesis of androgens mutations of androgen receptormutations of androgen receptor errors of AMHerrors of AMH XY/XO mosaicismXY/XO mosaicism Wnt and WT-1 mutations Wnt and WT-1 mutations (differentiation of gononephrotom)(differentiation of gononephrotom)

Sex limited inheritanceSex limited inheritance

The trait is present in the genotype of both The trait is present in the genotype of both sex, however it is expressed only in one sex sex, however it is expressed only in one sex

E.g. hair, menstruation, pelvic parametersE.g. hair, menstruation, pelvic parameters

Incomplet sex restrictionIncomplet sex restriction

Crossing over between pseudoautosomal Crossing over between pseudoautosomal regions of X and Y chrs. regions of X and Y chrs.

XX XX

XX YY

XX YY XX YY XX XX

XX XX

Sex controlled inheritanceSex controlled inheritance

The trait is expressed in both sex, however its The trait is expressed in both sex, however its degree is differentdegree is different

Normal features:Normal features:

Deepness of soundDeepness of sound

BaldnessBaldness

BBBB++

BB++BB++

Male-baldness (androgenes)Male-baldness (androgenes)Female– normalFemale– normal

Male and Female - baldnessMale and Female - baldness

Diseases:Diseases:

gout 80% Mgout 80% MCleft lip/palateCleft lip/palate

Anencephaly - FAnencephaly - FSpina bifidaSpina bifida