# PI3 Kinase Inactivation in Myelodysplastic Syndrome

> **NIH NIH R56** · ALBERT EINSTEIN COLLEGE OF MEDICINE · 2021 · $99,999

## Abstract

Regulation of Autophagy by PI3 Kinase in Myelodysplastic Syndrome
Myelodysplastic Syndrome (MDS) is a blood disease driven by molecular abnormalities in
hematopoietic stem cells (HSCs). Anemia is a common cause of morbidity in MDS patients.
However, the mechanistic basis for the impaired HSC differentiation and erythroid maturation
that leads to anemia in MDS patients is unclear. The PI3 kinase (PI3K) pathway is activated by
many hematopoietic cytokines and growth factors, and is important for erythropoiesis. We
generated a new triple knockout (TKO) mouse model in which deletion of the PI3K genes
Pik3ca, Pik3cb, and Pik3cd in HSCs causes pancytopenia and myelodysplasia with impaired
HSC differentiation. We observed that autophagic degradation is impaired in TKO HSCs, and
that treatment with autophagy-inducing drugs improves HSC differentiation. We hypothesize
that inactivation of PI3K dysregulates autophagic degradation in HSCs, leading to impaired HSC
differentiation and erythropoiesis, which promotes MDS. Consistent with this, we observed that
the phosphatase PTEN, which counteracts PI3K signaling, is upregulated in a subset of MDS
patients. To more directly address the roles of PI3K in erythropoiesis, we plan to analyze
erythropoiesis in the TKO;Mx1-Cre bone marrow transplant mouse model by performing
CD71/Ter119 flow cytometry on the bone marrow and spleen. We will also generate the
TKO;SCL-Cre-ERT mouse model, in which the PI3K genes can be deleted in HSCs after
tamoxifen administration without transplantation. After Cre-mediated excision of Pik3ca, Pik3cb,
and Pik3cd in HSCs, we will analyze blood counts, bone marrow histology, survival, and will
perform CD71/Ter119 flow cytometry on the bone marrow and spleen to analyze erythropoiesis.
To determine whether dysregulated autophagy plays a role in human MDS, we propose to
examine autophagy in the stem cell compartment in MDS samples from the four different IPSSR
categories (low, intermediate-1, intermediate-2, and high-risk). We will measure autophagy in
HSCs and progenitors using intracellular flow cytometry for LC3II and P62 in cytokine-free
media, with and without chloroquine treatment to measure autophagic flux. In addition, we will
perform quantitative RT-PCR on CD34+ cells for PTEN expression from each MDS sample. We
will also perform Western analysis for PTEN and phospho-AKT (pAKT), and will correlate PTEN
and pAKT levels with autophagy induction in the same MDS samples. These experiments will
better characterize the erythropoiesis defects that result from PI3K deletion and dysregulated
autophagy in mouse HSCs, and will determine whether PI3K inactivation correlates with
impaired autophagy in human MDS stem cells

## Key facts

- **NIH application ID:** 10476196
- **Project number:** 1R56DK130895-01
- **Recipient organization:** ALBERT EINSTEIN COLLEGE OF MEDICINE
- **Principal Investigator:** Kira Gritsman
- **Activity code:** R56 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $99,999
- **Award type:** 1
- **Project period:** 2021-09-17 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10476196

## Citation

> US National Institutes of Health, RePORTER application 10476196, PI3 Kinase Inactivation in Myelodysplastic Syndrome (1R56DK130895-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10476196. Licensed CC0.

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