Mohammad Al-bataineh, DVM, MS, PhDPost-doctoral Scholar

Rebecca Hughey LaboratoryRenal-Electrolyte Division

The Protective Role of MUC1/β-catenin Pathway in Acute Kidney Injury

N

C

Autocatalytic cleavage within SEA module

membrane

Near perfect tandem repeats

N-l

inke

d g

lyca

ns

O-l

inke

d g

lyc

ans

MUC1 is a transmembrane glycoprotein with an extracellular mucin-like domain that yields protection from pathogens

MUC1 overexpression in tumors is a bad prognosis for the patient

MUC1 expression in tumor cell lines: Pro-survival and anti-apoptotic activities Modulates transcriptional activities after nuclear targeting

Highly conserved across species

exhibits multiple sites for protein docking and phosphorylation involved in signal transduction (e.g., HIF1a, GSK3β, β-catenin)

MUC1 in the kidney: Apical expression on all polarized epithelia during

development Found in the DCT and CD in adult kidneys Found in the PT during development and after injury

Muc1 protein - immunblotting

Muc1 is induced during ischemia-reperfusion injury (IRI)

C57BL/6 MICE19 min ischemiaN=3-5 miceT= 0-72 h

Kidney cortex

Muc1 is targeted to the nucleus during IRI (4 h recovery)

Kidney function and morphology are protected by Muc1 during IRI

C57BL/6 Muc1 KOt=0 congested congested n=3

t=24 h 5, 5, 5, 5 5, 5, 5 n=3-4

t=72 h recovering calcification n=5-6Wu et al., J. Clin. Invest. 117:2847–2859 (2007)

Muc1 enhances the hypoxia-inducible factor-1 (HIF-1) protective pathway during IRI

19 min ischemiat=4 h

lactate dehydrogenase A, enolase, pyruvate kinase M2, and pyruvate dehydrogenase kinase 1

The HIF-1 protective pathway is enhanced by the nuclear targeting of Muc1 in a mouse kidney model of IRI

How the b-catenin protective pathway is regulated in kidneys under metabolic stress conditions like IRI?

Kidney International (2012) 82, 537–547

Kidney function Kidney morphology

Cancer Res 2005; 65: (22). November 15, 2005

In cancer cell lines:

Hypothesis

Muc1 is protective in a mouse kidney model of IRI also through stabilization and transactivation of the b-catenin protective pathway.

Induction of b-catenin during IRI is absent in Muc1 KO mice

b-catenin co-IP with MUC1 in Human kidney proximal tubule HK-2 cells

Nuclear targeting of b-catenin during IRI is absent in Muc1 KO mice

Does MUC1 modulate b-catenin activities during IRI ?

Activation of TCF4 during IRI is significantly reduced in Muc1 KO mice

Activation of Akt is significantly reduced during IRI in the absence of Muc1

Induction of survivin during IRI is absent in Muc1 KO mice

SUMMARYMuc1 stabilizes b-catenin, enhances its nuclear translocation, and augments expression of its downstream targets in a mouse model of AKI.

Muc1 protects the kidney during IRI through transactivation of the b-catenin protective pathway, as evidenced by:

activation of pro-survival factors like activated Akt, survivin, TCF4, and its target cyclin D1

repression of pro-apoptotic factors; such as p53, and cleaved caspase 3 (consistent with decreased apoptosis)

What is the specific role and mechanism of b-catenin signaling during kidney injury, recovery and repair?

Future studies

University of Pittsburgh

Renal-Electrolyte Division

Rebecca Hughey Carol L Kinlough (Truschel)Paul PolandNúria M Pastor-Soler

Department of Pathology

Sheldon I Bastacky Satdarshan (Paul) MongaSucha Singh

Pediatrics

Jackie Ho

Funding

NIH R01NRSA (F32) NIDDK O’Brien Kidney Center (P30)

Mayo Clinic, Scottsdale, AZ

Sandra J Gendler and Cathy S Madsen

Indiana University, Indianapolis, IN

Timothy A Sutton and Henry E Mang

Vanderbilt University, Nashville, TN

Volker H Haase and Hanako Kobayashi

ACKNOWLEDGMENTS