# PI4KIIα in Late Stage Autophagy

> **NIH NIH R01** · UT SOUTHWESTERN MEDICAL CENTER · 2020 · $365,395

## Abstract

PROJECT SUMMARY
Autophagy is an essential homeostatic process. Under stressful conditions, such as nutrient deprivation,
autophagy is markedly up-regulated to provide a source of raw materials to ensure survival and to dispose of
damaged organelles. Autophagosomes are generated by elongation and closure of phagophores, and
autophagosomes fuse with lysosomes to effect content degradation and recycling. Phosphoinositide lipids
have been implicated in every stage of the autophagic pathway. However, to date, emphasis has been placed
on the function of PI3P in phagophore elongation and closure. We found that PI4P is required for
autophagosome fusion with lysosomes (A:L fusion), a culminating event at the end of the autophagy road.
Furthermore, PI4K2A (PI4KIIα) is uniquely responsible for generating the PI4P on autophagosomes and it acts
downstream of GABARAPs, Atg8 family autophagy proteins that are much less well understood than the LC3
Atg8 family. PI4K2A binds GABARAPs and associates with autophagosomes in a GABARAP- and
palmitoylation-dependent manner. It is activated by starvation and translocates from the perinuclear Golgi
region to autophagosomes. PI4K2A or GABARAP depletion blocks autophagy flux and A:L fusion, resulting in
the formation of abnormally large autophagosomes. This block can be rescued by overexpressing PI4K2A or
increasing intracellular PI4P by “PI4P shuttling.” We hypothesize that GABARAP promotes PI4K2A membrane
trafficking to autophagosomes to generate PI4P in the GABARAP/PI4K2A interactome to activate the A:L
fusion machinery. This hypothesis will be tested as follows: Aim I. Determine how GABARAPs target PI4K2A
to autophagosomes. We will analyze PI4P dynamics and the temporal sequence of PI4K2A recruitment to
autophagosomes. We will determine if GABARAP acts as a trafficking modulator to promote PI4K2A
recruitment, and identify/disrupt the binding motifs to establish functionality of the interaction. Aim 2. Determine
how PI4K2A and PI4P promote A:L fusion. We will focus on the role of PI4K2A in the recruitment and
activation of Rab7, the master regulator of the A:L priming, tethering and fusion. We will test the hypothesis
that Rab7 is targeted to autophagosomes by direct binding to PI4K2A or PI4P and/or by PI4P-mediated
recruitment of the multivalent scaffolding protein, PLEKHM1. Mechanisms whereby PI4K2A/PI4P control the
activity state of Rab7 will be examined. Aim 3. Determine how PI4K2A is regulated during autophagy. The
effects of autophagy-dependent changes in PI4K2A phosphorylation and palmitoylation on targeting and
kinase activity will be examined. A combination of biochemical, cell biological, and state-of-the-art
fluorescence-based nanoimaging approaches will be employed to address these questions. This multi-PI grant
will provide a comprehensive picture of the function and regulation of PI4K2A in its hitherto unexplored role in
autophagy. In doing so, it will establish a novel paradigm for the regulation of autop...

## Key facts

- **NIH application ID:** 9851875
- **Project number:** 5R01GM121536-04
- **Recipient organization:** UT SOUTHWESTERN MEDICAL CENTER
- **Principal Investigator:** JOSEPH P ALBANESI
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $365,395
- **Award type:** 5
- **Project period:** 2017-02-01 → 2022-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9851875

## Citation

> US National Institutes of Health, RePORTER application 9851875, PI4KIIα in Late Stage Autophagy (5R01GM121536-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9851875. Licensed CC0.

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