# Role of CEBPb in flow-dependent endothelial dysfunction and atherosclerosis

> **NIH NIH R01** · EMORY UNIVERSITY · 2023 · $754,037

## Abstract

Atherosclerosis is a chronic inflammatory disease and preferentially occurs in arterial regions exposed to
disturbed blood flow (d-flow) while those in the stable flow (s-flow) regions are protected. The mechanisms by
which d-flow and s-flow regulate atherogenesis are still not well-understood. To address this critical knowledge
gap, we recently conducted a scRNAseq and a scATACseq assay using the mouse partial carotid ligation (PCL)
model of atherosclerosis caused by d-flow. The study revealed that d-flow dramatically alters endothelial
transcriptome and epigenomic profiles, reprogramming them into the inflammatory, mesenchymal (EndMT), and
immune cell-like (EndICLT) phenotypes, which we defined as “endothelial reprogramming (EndRep)”. While the
pro-atherogenic role of inflammation and EndMT is well-established, the mechanisms and role of EndICLT and
EndRep in atherosclerosis are unknown. We identified CEBPb through a reanalysis of our scRNAseq and
scATACseq datasets as a candidate transcription factor that could regulate EndRep. Our preliminary data further
show that the expression of CEBPb increased by d-flow in vivo and cultured HAECs. CEBPb produces three
different protein isoforms, LAP1, LAP2, and LIP, through alternative translation. Surprisingly, CEBPb is
translated primarily as the LIP protein in HAECs. Further, d-flow stimulates the nuclear localization of LIP in
HAECs, and overexpression of LIP dramatically induces EndRep (endothelial inflammation, EndMT, and
EndICLT). Our proteomics study shows that LIP binds the PSMB9 immunoproteasome protein, and d-flow-
increases the PSMB9 activity. Furthermore, prior studies showed that LIP induces cancer-type metabolic
reprogramming. Therefore, we hypothesize that d-flow stimulates nuclear expression of LIP, which binds to
PSMB9, leading to EndRep and atherosclerosis. We will test the hypothesis with three aims. Aim 1 will determine
the effect of d-flow on LIP nuclear expression and its role in EndRep. EC-specific-Confetti mice will be used for
lineage tracing to validate the flow regulation of EndICLT and EndRep. HAECs treated with si-CEBPb or LIP
plasmid and mice with EC-specific LIP overexpression (LIPEC-OE) or LIP deficiency (LIPDEF) will be used. An
ultrasound-guided method will be used to deliver LIP to the left carotid of LIPDEF mice to induce EndRep. Aim 2
will determine how LIP induces EndRep in ECs flow-dependent manner. scRNAseq & scATACseq assays will
be conducted using the LIPEC-OE and LIPDEF mice with the PCL to identify LIP and flow-regulated genes/pathways.
Flow-regulation of PSMB9 activity and its role in LIP-induced EndRep will be determined in HAECs and mice
using siRNAs and PSMB9 inhibitors. Aim 3 will determine the role of LIP in atherosclerosis in a flow- and PSMB9-
dependent manner. Atherosclerosis in LIPEC-OE and LIPDEF will be studied in the acute PCL and chronic model
using AAV-PCSK9 and western diet with or without PSMB9 inhibitor treatment. scRNAseq and scATACseq
analy...

## Key facts

- **NIH application ID:** 10638650
- **Project number:** 1R01HL168383-01
- **Recipient organization:** EMORY UNIVERSITY
- **Principal Investigator:** Hanjoong Jo
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $754,037
- **Award type:** 1
- **Project period:** 2023-03-15 → 2027-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10638650

## Citation

> US National Institutes of Health, RePORTER application 10638650, Role of CEBPb in flow-dependent endothelial dysfunction and atherosclerosis (1R01HL168383-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10638650. Licensed CC0.

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