Date of Award
8-19-2021
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Biology
First Advisor
Nawab Ali
Abstract
In pursuit of understanding the heterogeneity and physiological significance of multiple inositol polyphosphate phosphatase 1 (Minpp1), we have studied its isoforms for distinct motifs, subcellular distribution, and enzymatic potential. Initially, we took a Bioinformatics & Computational Biology approach exploring the proteome diversity of the Minpp1 utilizing the current NCBI database. We noticed three different minpp1 variants translated into three isoforms of Minpp1 proteins with varying molecular weight. A link between the minpp1 variant-2 gene and ER-stress, using real-time PCR, suggests a functional similarity between minpp1 variant-1 and variant-2. A detailed study on motifs revealed Minpp1 isoform-2 as the only other isoform, besides isoform-1, carrying acid phosphatase (AP) motif but no ER-retention signal. In confocal microscopy, we recognized that Minpp1 isoform-2 was scattered more towards the cell periphery where it co-localizes with plasma membrane (PM)-destined multivesicular bodies (MVBs) biomarker CD63. We used MCF-7 cells to establish that Minpp1 isoform-2 is secreted into exosomes. Brefeldin A (BFA) treatment resulted in overexpression of exosomes-associated Minpp1 isoform-2, suggesting its secretion via an unconventional route involving endocytic-generated vesicles and its link to ER stress. We further demonstrated that the exosome-associated Minpp1 isoform-2 was enzymatically active. Together, our data support the possibility that the enzymatically active Minpp1 isoform-2 in extracellular space could truncate any anti-proliferative actions of extracellular InsPs.
Recommended Citation
Zubair, Mohd, "Heterogeneity in Multiple Inositol Polyphosphate Phosphatase1 (MINPP1): Identification and Characterization of an Isoform-2 in Exosomes" (2021). Theses and Dissertations. 1025.
https://research.ualr.edu/etd/1025
