# Cytoskeletal Mechanisms of Platelet Formation

> **NIH NIH R01** · BRIGHAM AND WOMEN'S HOSPITAL · 2020 · $433,889

## Abstract

The purpose of this proposal is to investigate the cell biological and molecular pathways that
regulate platelet production. Although it is well established that megakaryocytes generate
platelets by remodeling their cytoplasm into proplatelet extensions, which serve as assembly
lines for platelet production, many unanswered questions remain regarding the mechanisms of
platelet biogenesis. In particular, our understanding of the process by which megakaryocytes
initiate proplatelet production is poorly understood. We have recently used a novel
microinjection approach to discover a cytoplasmic factor, called proplatelet-promoting factor
(PPF) that triggers platelet production when injected into megakaryocytes. Even though our
preliminary data have clarified some questions about the basic nature of PPF activity, we only
have a cursory understanding of its regulation and mechanism of action. Obtaining this
fundamental knowledge is crucial for evaluating the scope of PPF action and determining how it
functions in proplatelet initiation. Therefore, in Specific Aim 1 we propose to define the
biological nature of PPF activity and isolate PPF so that we can understand how this
cytoplasmic factor controls proplatelet induction. Although the mechanism by which the
cytoskeleton regulates proplatelet initiation is unknown, the spatial and temporal disassembly of
the centrosome after the injection of PPF, but before proplatelet initiation, suggests a role for the
centrosome in proplatelet induction. This exciting new data suggests that centrosome
disassembly powers induction of proplatelet production, a hypothesis that will be tested in
Specific Aim 2. Finally, in Specific Aim 3 we will use a high-content microscopy screen to
identify molecules that drive platelet production. Using proplatelet image analysis, we will test
thousands of drug molecule candidates for their ability to stimulate or inhibit platelet production.
Target pathway analysis, secondary screens, and dose-response curves will be used to identify
compound “hits.” We will then establish whether hits are efficacious in animal models. Taken
together, we expect that findings made as a result of this investigation will provide an improved
understanding of the molecular mechanisms that regulate platelet formation and lay the
foundation for novel therapeutic approaches to accelerate platelet production in patients with
thrombocytopenia.

## Key facts

- **NIH application ID:** 9912219
- **Project number:** 5R01HL068130-19
- **Recipient organization:** BRIGHAM AND WOMEN'S HOSPITAL
- **Principal Investigator:** JOSEPH E ITALIANO
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $433,889
- **Award type:** 5
- **Project period:** 2001-07-01 → 2020-11-02

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9912219

## Citation

> US National Institutes of Health, RePORTER application 9912219, Cytoskeletal Mechanisms of Platelet Formation (5R01HL068130-19). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/9912219. Licensed CC0.

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