Honors Theses

Affiliation

College of Agriculture and Life Sciences, Biochemistry, Nutrition and Health Promotion

College

College of Agriculture and Life Sciences, College of Arts and Sciences

College

College of Agriculture and Life Sciences

Department

Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology

Department

Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology

Degree

Bachelor of Science

Degree

Bachelor of Science (B.S.)

Major

Biochemistry, Microbiology

Document Type

Immediate Open Access

Abstract

Matrix metalloproteinases (MMPs) are a family of highly regulated zinc and calcium dependent endopeptidases that have a crucial role in a multitude of biological processes. While the extracellular function of MMPs as effectors of the extracellular matrix (ECM) and their role in cell surface signaling regulation has been well studied, their intracellular function and role in central nervous system (CNS) still tends to be elusive. While the intimidating task of analyzing the 23 different human MMPs with sometimes overlapping function remains an obstacle, models such as Drosophila melanogaster with only two MMPs, dMMP1 and dMMP2, provide an ideal start. To better understand the intracellular role of MMPs in the CNS, we expressed Green Fluorescent Protein (GFP)- tagged dMMPs in SH-SY5Y neuroblastoma cells and C6 glioblastoma cell lines. Lipofection of GFP-dMMPs in SH-SY5Y cells enhanced nuclear rupture and reduced cell viability (coupled with increased apoptosis) as compared to GFP alone. In non-liposomal transfection experiments, dMMP1 localized to both the cytoplasm and the nucleus whereas dMMP2 had predominantly cytoplasmic localization in both neural and glial cell lines. Cytoplasmic localization demonstrated co-localization of dMMPs with cytoskeleton proteins which suggests a possible role of dMMPs in cell morphology. This was further supported by transient dMMP expression experiments that showed that dMMPs significantly increased neurite formation and length in neuronal cell lines. Inhibition of endogenous MMPs decreased neurite formation, length and βIII Tubulin protein levels in differentiated SH-SY5Y cells. Further, transient expression experiments showed similar changes in glial cell morphology, wherein dMMP expression increased glial process formation and process length. Interestingly, C6 cells expressing dMMPs had a glia-like appearance, suggesting MMPs may be involved in intracellular glial differentiation. Inhibition or suppression of endogenous MMPs in C6 cells 7 increased process formation, increased process length, modulated glial fibrillary acidic protein (GFAP) expression, and induced distinct glial-like phenotypes. Taken together, the results strongly support the intracellular role that dMMPs can play in apoptosis, cytoskeleton remodeling, and cell differentiation. This study further reinforces the use of Drosophila MMPs to dissect out the precise mechanisms whereby they exert their intracellular roles.

Date Defended

4-30-2021

Thesis Director

Krishnan, Natraj

Second Committee Member

Rai, Aswathy

Third Committee Member

Oppenheimer, Seth

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