The Effects of Expression of Thermolabile R789C and R992C Collagen II Mutants on Cell Behavior and Extracellular Matrix Structure and Function

2011 2011

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Abstract (summary)

The hallmark feature of mutations in COL2A1 is alterations of skeletal development with highly variable clinical severity. The resulting spectrum of chondrodysplasia phenotypes ranges from perinatal lethality to milder disturbances such as premature osteoarthritis. There has been a great deal of time and effort put into the development of gene and cell therapies targeted at overcoming the devastating effects of disorders due to mutations in collagenous genes, with particular emphasis on osteogenesis imperfecta; however, the majority of these previous endeavors have been relatively ineffective. Very little has been done to determine the minimal therapeutic conditions which would be necessary in order to achieve clinical efficacy, i.e. restore normal function to affected tissues. In order to design effective therapies, there remains a need to gain an understanding of what these minimal conditions are, which likely vary significantly between tissues and mutation types.

Here, I examined the molecular and cellular effects of expression of the thermolabile R789C and R992C collagen II mutants on extracellular matrix organization and cell behavior. Through recombinant expression of these mutants in a cell-based, inducible experimental system, we are able to effectively modulate the expression levels of exogenous collagens, thereby altering their contribution from 0% to 30% of the total collagen pool. By expressing mutant collagens at 100% capacity at the onset of the experiment, we are able to promote the incorporation of mutant collagens into cell/matrix systems and then monitor remodeling and recovery after reducing their expression to 75, 50, 25, or 0% of the original 100%. Quantitative studies of PDI and BiP, indicators of intracellular stress and the unfolded protein response, as well as analysis of apoptosis, suggest that these processes are attenuated during the recovery period only in the complete absence of expression of mutant molecules. Under conditions where expression of R789C and R992C is only partially reduced, these processes continue with no relief from intracellular stress or apoptosis. My studies suggest that therapies targeted at remodeling tissues affected by thermolabile collagen mutants may only be achieved by completely suppressing expression of mutant molecules rather than through their partial elimination.

Indexing (details)

Molecular biology;
Cellular biology;
0307: Molecular biology
0379: Cellular biology
0487: Biochemistry
Identifier / keyword
Pure sciences; Biological sciences; Cartilage; Collagen; Extracellular matrix; Skeletal dysplasia; Spondyloepiphyseal dysplasia; Unfolded protein response
The Effects of Expression of Thermolabile R789C and R992C Collagen II Mutants on Cell Behavior and Extracellular Matrix Structure and Function
Jensen, Deborah Anne
Number of pages
Publication year
Degree date
School code
DAI-B 72/12, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Fertala, Andrzej
Committee member
Pacifici, Maurizio; Uitto, Jouni; Williams, Charlene
Thomas Jefferson University
Cell and Developmental Biology
University location
United States -- Pennsylvania
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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