the impact of paternal exposures on gametes and … impact of paternal exposures on gametes and...

The impact of paternal exposures on gametes and progeny

Daniel Hardy, PhD

The Susan Vitali-Lovell Laboratory for Studies in Fetal Programming of Human Health Risks

Maternal, Fetal & Newborn Health DivisionChildren’s Health Research Institute

Departments of Obstetrics and Gynaecologyand Physiology and Pharmacology

Western University

OBJECTIVES: The impact of paternal exposures

on gametes and progeny

1. To discuss DOHaD and the role of histone

modifications in short- and long-term gene regulation.

2. To understand current research on paternal exposures

on spermatogenesis/ART outcomes.

3. To review paternal outcomes on perinatal and long-term

outcomes.

Low Birth Weight

Fetal Growth

and

Development

Infection/

Inflammation

Hypoxia Diet Maternal Body

Composition

Antidepressants,

Nicotine

Adult Disease

Cardiovascular Disease

Type II Diabetes

Dyslipidemia

Developmental Origins of Health and Disease (DOHaD)

Rapid Postnatal

Catch-up Growth

0 5 10 15 20 25 30 35 40 5 10 15 20 45 65+

1st trimester 2nd trimester 3rd trimester Childhood Adolescence Adulthood

WeeksBirth Years

2nd sexual characteristics

Ovary/Oocytes

Gonad

Mammary gland

2nd sexual characteristicsSpermatogenesis

Testicular DescentReproductive tract

Gonadogenesis

Differentiation of Gonad

Adipocyte differentiation

Adrenal gland

Thyroid gland

Pancreas

Pituitary gland

Brain sexual differentiation

Female Male Both

Windows of Susceptibility/Intervention for Developmental Disruption in Humans

Rueda-Clausen et al., 2011

Infection/

Inflammation

Hypoxia Diet Maternal Body

Composition

Antidepressants,

Nicotine

Paternal Contributions to DOHaD

Low Birth Weight

Fetal Growth

and

Development

Adult Disease

Rapid Postnatal

Catch-up Growth

Epigenetic Modifications Involved Underlying

Paternal Influences on Short and Long-term Development

Epigenetic Modifications: functionally relevant modifications to the genome that do not involve alterations in nucleotide sequence.

Includes: (1) DNA Methylation including effects on maternal/paternal imprinting.

(2) Non-coding RNAs (ncRNAs)

(3) Posttranslational Histone Modifications

Role of Posttranslational Histone Modifications to

Histone H3 in Short- and Long-term Gene Regulation

Inactive Chromatin

K9

Me Me Ac

K9 K9

Active Chromatin

Demethylases HAT

HDACHMT

HATs = Histone Acetylases

HMT = Histone Methyl Transferases

HDAC = Histone Deacetylases

A. Active chromatin

Me

H2A H2B

H3 H4

H3K4me

H3K36me

H3K69me

H3Ac

S10P

U

b

H2BK120Ub

Ac

H1

U

b

Me

Ac

Me

H2A H2B

H3 H4

Ub

Ac

H1

Ub

Me

Ac

Me

H2A H2B

H3 H4

U

b

Ac

H1

Ub

Me

Ac

B. Repressive chromatin

H3K9me

H3K27me

H2AK119Ub

Me

H2A H2B

H3 H4

Ub

H1

Ub

MeMe

MeMe

Me

Me

H2A H2B

H3 H4

Ub

H1

Ub

MeMe

MeMe

Me

Me

H2A H2B

H3 H4

Ub

H1

Ub

MeMe

MeMe

Me

H4K20me

PP

PP

PP

Paternal Insults on Spermatogenesis/ART Outcomes

1. Chemotherapeutic Agents (i.e. Bleomycin, Etoposide, Cisplatin

(BEP), Cyclophosamide) – B Robaire.

2. Advancing Age – D Sakkas.

3. Air pollution – SD Perreault.

4. Industrial chemicals (i.e. carbon disulfide, DBCP, lead) - R Dixon.

5. Pesticides (e.g. chlordecone) – J Liddle.

6. Dioxins (e.g. TCDD in Agent Orange) – S. Safe

7. Hydrocarbons (Trichloroethylene, PAHs) – HA Jeng

8. Low dose ionizing radiation - T. Relander

9. Smoking – AS Abdul-Ghani

10. Vitamin Deficiencies – AK Jaiswal

11. Cryopreservation ?


1. Chemotherapeutic Agents (i.e. Bleomycin, Etoposide,

Cisplatin (BEP), Cyclophosamide) – B Robaire.



4. Industrial chemicals (i.e. carbon disulfide, DBCP, lead) - R

Dixon.








• Normally chromatin remodeling is essential for the

‘eviction’ of somatic histones with smaller protamines

facilitating sperm chromatin compaction.

• However in rat, treatment of BEP (3x per week for 3

weeks) increased histone H3 methylation [K9] in

pachytene spermatocytes impairing removal of these

histones and transcriptional repression.

Paternal Outcomes on Spermatogenesis:

Chemotherapeutics (Bleomycin, Etoposide, Cisplatin)

Bagheri-Sereshki et al., 2016


1. Chemotherapeutic Agents (i.e. Bleomycin, Etoposide, Cisplatin

(BEP), Cyclophosamide) – B Robaire.



4. Industrial chemicals (i.e. carbon disulfide, DBCP, lead) - R

Dixon.








Paternal Outcomes on Natural Conception and Assisted

Reproductive Outcomes: Advancing Age

Observed paternal age effect

Natural conceptionFord 2000 (11) Time to conception greater in men ≥40 y

Dunson 2002 (13) Fertility lower in men >35 y

Hassan 2003 (12) Men >45 y with longer time to conception

Intrauterine inseminationMathieu 1995 (21) Pregnancy rate lower in men ≥35 y

Bellver 2008 (23) No effect

IVF and/or ICSI with

autologous oocytesKlonoff-Cohen 2004 (18) Live birth rate lower in men >40 y

De La Rochebrochard 2006 (24) Likelihood of conception lower in men ≥40 y

Ferreira 2010 (17) Pregnancy rate lower per year of advancing paternal age

Humm and Sakkas, 2013

Paternal Outcomes on Spermatogenesis: Advancing Age

• Advancing paternal age is associated

with DNA fragmentation.

Simon et al., 2011.

• DNA damage is attributed to impaired chromatin remodeling

leading to higher histone retention, abnormal P1/P2

ratios, and increased oxidative stress (Carrell et al., 2008).

High Fat Paternal Diet (HFD) Leads to Increased Sperm

DNA Damage: Role of Histone H3 Acetylation

• Histone H3 hyperacetylation leads to increased sperm

DNA damage (Marcon and Boissonneault, 2004).

HFD decreases testes SIRT6, an

HDAC for Histone H3 acetylation

HFD increases testicular Histone H3

[lysine 9] acetylation

What about long-term effects?

Paternal Insults on Perinatal and Long-term Outcomes

1. Chemical carcinogens (e.g. Ethylnitrosoureas) – T. Nagao

• Impaired fertility and postnatal testicular development

2. Estrogen Mimics (i.e. diethylstilbestrol [DES], BPA, pesticides)

• Delay puberty, impair sexual differentiation

3. Modulators of Androgens (i.e. p.p’-DDE, phalates) – P. Foster

• Impaired testicular development

4. Nickel and Iron Exposure – K Doreswamy

• Reduces Implantation Rates, DNA Damage

5. Spray Adhesives/Glues (1-bromopropane) ?

6. Fried Food containing acrylamide ?


7. Paint (Lead) – L Anderson, JR Wilkin

• Offspring of Painters have 6X greater chance to develop

Wilm’s tumour, Alzheimer's.


• Offspring increased risk of leukemia

9. Nickel and Iron Exposure – K Doreswamy


10. Organophosphates (TPP, TDCPP) – HM Stapleton, B Robaire


• Flame Retardants in Furniture?

11. Bisphenol A ?

• Significant maternal effects on offspring, but paternal?


12. Low Dose Ionizing Radiation – KJ Bunch, M Auroux

• Offspring of Fathers exposed to radiation at time of

conception exhibited increased risk of childhood

leukemia, but not if exposure was 3 months prior to

conception.

• Study of 7678 births, radiation-exposed fathers led to

decreased birth weight.

13. Pharmaceuticals/Chemotherapeutics – SE Lewis, M Auroux

a) Cyclophosamide – reduction in learning capacity in

offspring.

b) Streptozotocin – increased oxidative stress.

c) Sildenafil citrate – impairs embryo development.

(PDE Inhibitor)

Paternal Outcomes on Perinatal and Long-term Outcomes :

Advancing Age

• Increased paternal age (>45 years) is associated in the

offspring with increased incidence of :

1. Apert Syndrome

2. Epilepsy

3. Autism

4. Bipolar Disease

5. Huntington's (trinucleotide repeat diseases)

6. Birth defects?

7. Down Syndrome?

8. Childhood mortality [CI: 1.2-2.8]; 45 vs 30 years.

• Mechanisms elusive; however 2 single-nucleotide de novo

polymorphisms/year (25 for 20 year old, 65 for 40 year old).

(Kong et al. 2012)

Paternal Pre-pregnancy Caffeine Consumption Increases Miscarriage Risk

• In a study of 344 pregnancies, the miscarriage risk increased if men

(Hazard Ratio 1.73) drank more than two cups of caffeinated beverages/day.

• This risk was reduced (Hazard Ratio 0.21) if pregnant mother consumed Vitamin B6

and Folic Acid preconception and during pregnancy.

Germaine Buck Louis, PhD, LIFE Study (2005-2009)

Paternal Outcomes on Perinatal and Long-term Outcomes :

Alcohol & Recreational Drugs

• Paternal alcohol consumption leads to rat offspring with:1. Decreased fertility, viability, and litter size in mice exposed

within 5 days of conception (Anderson et al. 1981)

2. Altered thermoregulation, immune capacity, behavior (Friedler,

1988)

3. Decreased circulating testosterone (Cicero et al., 1990)

• Humans, positive correlation between paternal alcohol

consumption and impaired birth weight (Little and Sing, 1985).

• Paternal Methadone exposure in mice leads to decreased

offspring testes and adrenal weight; lower testosterone. (Cicero

et al., 1991).

Paternal Outcomes on Perinatal and Long-term Outcomes:

Smoking

• Strong association between pre-conception paternal

smoking and childhood cancer (Castro-Jimenez et al., 2011).

• Avon Longitudinal Study: earlier father smokes,

higher son’s BMI (Pembrey et al. 2006).

• Paternal, not maternal, cigarette smoking at time of

conception is linked to DNA damage in cord blood

(Laubenthal et al.,2012).

• Epigenetic Mechanism: Smoking induces alterations ncRNA

profiles in spermatozoa; these ncRNAs target DNA

methylation and histone modifications (Marczylo et al., 2012).


Nutrition

• Paternal food deprivation in male mice before conception led

to impaired glucose metabolism in the offspring

(Anderson et al., 2006).

• Low protein diet in male mice from weaning to sexual maturity:

1. Impaired chromatin packaging of sperm

2. Altered DNA methylation in offspring liver

3. Increased expression of offspring hepatic genes

involved in lipid and cholesterol biosynthesis.

(Carone et al., 2010)

• Phytoestrogens (i.e. Genistein – soy product) ?

• Folate Deficiency – offspring hepatic DNA methylation, IGFs

(Mejos et al., 2013).


Obesity

• Paternal, not maternal, total and percentage body fat predictor

of increases in body fat of premenarcheal (5-9 years) girls (Figueroa-Colonastro et al., 2000).

• Framingham Heart Study: earlier onset paternal obesity

associated with offspring liver dysfunction (increased ALT)

and obesity (Loomba et al., 2008).

• Paternal high fat diet leads to increased body weights, fat

depots, and circulating triglycerides in female, but not male,

offspring. Paternal obesity altered male sperm ncRNAs, and

germ cell DNA methylation (Fullston et al., 2013).

Summary: Susceptible Windows of Epigenetic Modifications

for Paternal Germ Line

1. Paternal embryonic

development

2. Paternal prepuberty

3. Spermatogenesis

4. Periconception/Zygote

Soubry et al., 2014

10% of paternal histones

in condensed sperm DNA

Acknowledgements

Dr. Alison Holloway (McMaster)

Dr. Waseem Iqbal

Dr. Lin Zhao

Dr. Gurjeev Sohi

Dr. Jessica Osumek

Andrew Revesz

Peter Vo

Dr. Bryan Richardson

Dr. Tim Regnault

Dr. Dean Betts

Dr. Victor Han

Dr. Nicole Barra

Noelle Ma

Mike Wong

Eric Barry

the impact of paternal exposures on gametes and … impact of paternal exposures on gametes and...

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