ADAMTS4 and ADAMTS5 knockout mice are protected from versican but not aggrecan or brevican proteolysis during spinal cord injury.

Kadir Demircan,Rukiye Hasgul,M Ramazan Yigitoglu,Veli Ugurcu,Gulfer Ozturk,Sumeyya Akyol,Tomoko Yonezawa,Daniel R Mcculloch,Omer Akyol,Vehap Topcu,Tomoyuki Takigawa,Satoshi Hirohata

doi:10.1155/2014/693746

Abstract

The chondroitin sulfate proteoglycans (CSPGs) aggrecan, versican, and brevican are large aggregating extracellular matrix molecules that inhibit axonal growth of the mature central nervous system (CNS). ADAMTS proteoglycanases, including ADAMTS4 and ADAMTS5, degrade CSPGs, representing potential targets for ameliorating axonal growth-inhibition by CSPG accumulation after CNS injury. We investigated the proteolysis of CSPGs in mice homozygous for Adamts4 or Adamts5 null alleles after spinal cord injury (SCI). ADAMTS-derived 50–60 kDa aggrecan and 50 kDa brevican fragments were observed in Adamts4−/−, Adamts5−/−, and wt mice but not in the sham-operated group. By contrast Adamts4−/− and Adamts5−/− mice were both protected from versican proteolysis with an ADAMTS-generated 70 kDa versican fragment predominately observed in WT mice. ADAMTS1, ADAMTS9, and ADAMTS15 were detected by Western blot in Adamts4−/− mice' spinal cords after SCI. Immunohistochemistry showed astrocyte accumulation at the injury site. These data indicate that aggrecan and brevican proteolysis is compensated in Adamts4−/− or Adamts5−/− mice by ADAMTS proteoglycanase family members but a threshold of versican proteolysis is sensitive to the loss of a single ADAMTS proteoglycanase during SCI. We show robust ADAMTS activity after SCI and exemplify the requirement for collective proteolysis for effective CSPG clearance during SCI.

Highlights

The extracellular matrix (ECM) is important for structural and functional development and maintenance of the central nervous system (CNS)
A predominant ∼60 kDa band, representing the G1-NITEGE Nterminal aggrecan fragment generated by ADAMTS proteoglycanases, with an accompanying ∼50 kDa band that was readily detectable in all cases except in the sham group (Figure 1), clearly indicating that spinal cord injury (SCI) was responsible for the induction of aggrecan proteolysis
These data suggested that ADAMTS4, ADAMTS5, or the other 5 members of the ADAMTS aggrecanase family (ADAMTS1, ADAMTS8, ADAMTS9, ADAMTS15, and ADAMTS20) might cooperate in aggrecan cleavage during spinal cord injury

Summary

Introduction

The extracellular matrix (ECM) is important for structural and functional development and maintenance of the central nervous system (CNS). Following SCI, we observed significant ADAMTS generated aggrecan cleavage by Western blot analysis in wild-type, Adamts4−/−, and Adamts5−/− mice (Figure 1).

Results

Conclusion