Colletti, Grace
(2012)
STUDY OF TRPML CHANNELS REVEALS INSIGHT INTO ENDOCYTIC MALFUNCTION, ORGANELLE CROSSTALK, AND THE ACTIVATION OF PRO-APOPTOTIC PATHWAYS.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
This is the latest version of this item.
Abstract
Mucolipidosis type IV (MLIV) is a lysosomal storage disease resulting from mutations in the gene MCOLN1, which codes for a transient receptor potential family ion channel TRPML1 (Mucolipin-1). MLIV has an early onset and is characterized by developmental delays, motor and cognitive deficiencies, gastric abnormalities, retinal degeneration and corneal cloudiness. The degenerative aspects of MLIV have been attributed to cell death, whose mechanisms remain to be delineated in MLIV and most other lysosomal storage diseases. The function of TRPML1 is still not completely understood in the cell. In order to address the function of this channel as well as the consequences of its loss, we have studied TRPML1 and a closely related channel TRPML3 using proteomic, transcriptional, and ion channel activity assays. Structure/function analyses of TRPML (Mucolipin) channels revealed that the closely related TRPML3 channel conducts K+, Na2+, Ca2+, and Fe2+, but does not conduct transition metals such as Cu2+ and Co2+. The permeability of the channel can be disrupted by mutations to the pore domain and a constitutively active channel mutation abolishes transition metal block of both TRPML1 and TRPML3. The similarities in TRPML sequence and the activity of the constitutively active mutants suggests that these channels may share similar activity profiles, which supports previous reports that TRPML1 may function to regulate lysosomal Ca2+ and Fe2+ in order to promote proper lysosomal fission/fusion events and function. Our proteomic and transcriptional analyses reveal that acute downregulation of TRPML1 results in apoptosis in a cathepsin B and Bax dependent manner. This is the first evidence that acute TRPML1 loss is linked to apoptosis and my work provides a preliminary mechanism for this process. Furthermore, TRPML1 loss results in increased NFκB levels as well as altered transcription of genes outside the previously identified lysosomal gene expression network. This suggests that loss of TRPML1 results in cellular changes that affect downstream transcriptional targets and induces cellular responses, such as apoptosis. Taken together, these data shed light on the importance of TRPML1 function and may help us understand the cellular role of this channel and how its loss results in cell death.
Share
| Citation/Export: |
|
| Social Networking: |
|
Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
31 January 2012 |
| Date Type: |
Publication |
| Defense Date: |
29 November 2011 |
| Approval Date: |
31 January 2012 |
| Submission Date: |
8 December 2011 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
147 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Biological Sciences |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Mucolipin-1, TRPML1, Mucolipidosis Type IV, Cathepsin B mediated apoptosis, Endocytic malfunction, Transition metal toxicity, TRPML3 |
| Date Deposited: |
31 Jan 2012 16:47 |
| Last Modified: |
15 Nov 2016 13:55 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/10738 |
Available Versions of this Item
-
STUDY OF TRPML CHANNELS REVEALS INSIGHT INTO ENDOCYTIC MALFUNCTION, ORGANELLE CROSSTALK, AND THE ACTIVATION OF PRO-APOPTOTIC PATHWAYS. (deposited 31 Jan 2012 16:47)
[Currently Displayed]
Metrics
Monthly Views for the past 3 years
Plum Analytics
Actions (login required)
 |
View Item |
![[feed]](/images/feed-icon-32x32.png){kind=icon}