Prokineticin 2 in Olfactory Bulb Neurogenesis and Neuronal Control of

Reproduction

Chengkang (CK) ZHANG PhD

Dept of PharmacologyUniversity of California - Irvine

Prokineticins

• PK1/EG-VEGF and PK2 are ~10KDa cysteine-rich secreted proteins• Binds to two G-Protein Coupled Receptors: PKR1 and PKR2• PK1 and PK2 involved in diverse biological processes.

– GI motility (PK1), circadian rhythms (PK2), endocrine tissue angiogenesis (PK1), tumor angiogenesis (PK2) and pain sensitization (PK1, PK2), and neurogenesis (PK2)

Prokineticin 1Prokineticin 2

Frog Bv8Snake MIT1

CERDVQCGGATCCAISLWLRGLRMCTPLGREGEECHPGCDKDSQCGGGMCCAVSIWVKSIRICTPMGKLGDSCHPLCDKDVQCGSGTCCAASAWSRNIRFCIPLGNSGEDCHPACERDLQCGKGTCCAVSLWIKSVRVCTPVGTSGEDCHPA* * ** * *

SHKVPFFRKRKHHTCPCLPNLLCSRFPDGRYRCSMDLKNINFTRKVPFFGRRMHHTCPCLPGLACLRTSFNRFICLAQKSHKVPYDGKRLSSLCPCKSGLTCSK.SGEKFKCSSHKIPFSGQRMHHTCPCAPNLACVQTSPKKFKCLSKS

MRGATRVSIMLLLVTVSDCMRSLCCAPLLLLLLLPPLLLTPPAGDA

MKCFAQIVVLLLVIAFSHG

signaling peptide

AVITGAAVITGAAVITGAAVITGA

* * * *

Proliferation of neural stem cells

Neuronal Progenitors

Differentiationinto

Immature neurons

Migration to

Final location

Integration into a

Neural circuit

Maturation to a fully functional

neuron

Neurogenesis in adult mammalian brain

PKR2

/ G

FAP

PKR2

/ P

SA-N

CAM

PKR2

/ P

SA-N

CAM

PK2

Reciprocal expression patterns of PK2 and its receptor PKR2 in

SVZ-OB

Control PK2 PK2 + A1MPK1

Migration of Neuronal Progenitors towards PK2 Migration blocked by PK2 Antagonist: A1MPK1 PK2 increased motility of NPC

Chemoattractive effect of PK2 on neuronal progenitors

PK2 promotes the neuronal differentiation of neural progenitors

Defects in OB development of PK2-/- mice

WT OB KO OB WT PG WT PG0

20

40

60

80

100

*

*Brd

U P

os

tive

Ce

lls(p

er

mm

2)↑Cell Death

WT KO WT pg KO pg0

10

20

30

40 *

**TU

NE

L P

ost

ive

Cel

ls(p

er

mm

2)

↓Cell migration

WT

KO

WT KO

↓OB size

bHLH proneural factors and PK2 in the OB

Ngn1 and MASH1 activate PK2 expression by binding to E-boxes on PK2 promoter

Summary• PKR2 is expressed in neuronal progenitors from the SVZ

• PK2 acts as a chemoattractant for neuronal progenitors

• PK2 promotes neuronal differentiation of NPC

• PK2 -/- mice have severe defect in OB development

• PK2 is a functional target gene of bHLH factors for OB development

Mutations in PK2 and PKR2 genes as new etiology for Kallmann syndrome (KS) and normosmic idiopathic hypogonadotropic

hypogonadism (IHH)

Hypoplasia of the reproductive organs in Pk2-/- mice

Gonadotropin-releasing hormone (GnRH) regulates the hypothalamo-pituitary-gonadal (HPG) axis in all vertebrates studied. GnRH neurons that regulate the HPG axis are primarily derived from progenitor cells in the nasal compartment (NC) and migrate along olfactory system derived fibers across the cribriform plate to destinations in the forebrain

MCE, (2001), 173-184

Abnormality of the GnRH neurons in Pk2-/- mice

GnRH neuron does not express PKR2

A. B. C.

D. E. F.

G. H. I.

PKR2 GnRH Merge

E13.5VNO

E13.5 Basal Forebrain

AdultPreoptic Area

A. B. C. D.

E. F. G. H.

Defect of GnRH neuron migration in embryonic Pk2-/- mice

E16.5 Pk2+/+

E16.5 Pk2-/-

Nasal Septum OB MPO ME

OB

OB

*

PK2 gene mutations in KS and nIHH patients

PKR2 gene mutations in KS and nIHH patients

Acknowledgements

Zhou Lab• Michelle Y. Cheng• Roy Jia-Da Li• Kwan Ng• Kate Burton• Wang-Ping Hu• Alex Lee• Chong-Wei Wen

Collaborators• Bill Crowley (MGH)• Nelly Pettiloud (MGH)• Pam Mellon (UCSD)

• Yi Sun (UCLA)• Michael E. Greenberg (HMS)• David Anderson (Caltech)