# Directing membrane function with inositol lipids in health and disease

> **NIH NIH R35** · UNIVERSITY OF PITTSBURGH AT PITTSBURGH · 2020 · $391,250

## Abstract

PROJECT SUMMARY/ABSTRACT
 Tightly regulated flux of materials and signals across the exquisitely organized plasma membrane (PM) is
essential for healthy cellular function. Disruption of this careful choreography is a common mechanism
underlying the pathogenesis of many genetic and infectious diseases. Therefore, a central problem in cell
biology is to understand the key molecular components that direct this intricate organization of signaling,
transport and structural machinery at the PM. A phospholipid located in the cytosolic leaflet,
phosphatidylinositol 4,5-bisphosphate (PIP2), is a key regulator of PM function, controlling recruitment and/or
activation of this protein machinery. Yet how PIP2 levels are regulated to ensure each PM function has access
to enough lipid to ensure correct operation, and how PIP2 is able to regulate each function discretely, is poorly
understood. The goal of our research is therefore to develop a detailed mechanistic understanding of how cells
regulate PIP2 levels in the PM, and how this facilitates regulation of individual PIP2-dependent functions. The
goal of this application is to identify fundamental mechanisms in cell culture models, and to apply the new
insights and approaches to physiological and disease-relevant systems through our established network of
collaborators. Firstly, we will determine the nanoscopic organization of PIP2 molecules in the PM and
determine their enrichment at sites of specific PM function. To accomplish this goal, we will probe and
manipulate lipid enrichment at sites of cytoskeletal, signaling or trafficking functions with nanometer resolution,
using super-resolution optical imaging approaches and chemical genetics. Secondly, we will delineate the
mechanisms that regulate global PM PIP2 levels, by identifying the molecular components driving negative
feedback of PIP2 synthesis. Thirdly, we will identify the biological functions of PIP2 5-phosphatase enzymes, as
well as the mechanism of pathogenesis for disease-associated mutations in these enzymes. To accomplish
this goal, we will identify where endogenous 5-phosphatase enzymes act in the cell, where PIP2 accumulates
after loss of these enzymes, and what cellular phenotypes are triggered by the resulting accumulation of PIP2.
We will employ innovative approaches throughout, combining super-resolution imaging of PIP2 and its myriad
effector proteins with chemical genetics to acutely manipulate PIP2 with exquisite spatial and temporal
precision. The proposed research is significant because it will uncover fundamental mechanisms that
choreograph the interplay of PM functions, and consequently provide a crucial first step in developing new
approaches to experimentally or therapeutically manipulate these functions in isolation.

## Key facts

- **NIH application ID:** 9978831
- **Project number:** 5R35GM119412-05
- **Recipient organization:** UNIVERSITY OF PITTSBURGH AT PITTSBURGH
- **Principal Investigator:** Gerald R Hammond
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $391,250
- **Award type:** 5
- **Project period:** 2016-08-01 → 2021-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9978831

## Citation

> US National Institutes of Health, RePORTER application 9978831, Directing membrane function with inositol lipids in health and disease (5R35GM119412-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9978831. Licensed CC0.

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