# Molecular mode of action of Juvenile hormone analogs

> **NIH NIH R21** · UNIVERSITY OF KENTUCKY · 2022 · $181,250

## Abstract

Project Summary
Adult mosquitoes transmit pathogens that cause deadly diseases in humans. Therefore, preventing adult
emergence has been used as a strategy to block transmission of pathogens. Juvenile hormones (JH) prevent
metamorphosis and adult emergence; juvenile hormone analogs (JHA) such as methoprene, hydroprene, and
pyriproxyfen have been commercialized for controlling mosquitoes and other disease vectors. However, the
molecular mode of action of JHAs in killing mosquitoes and other insects remains poorly understood. JHAs are
thought to act by preventing larval-pupal metamorphosis. This is precisely how these compounds work in most
lepidopteran insects. However, in dipteran insects such as the yellow fever mosquito, Aedes aegypti, JHA
application does not prevent larval-pupal metamorphosis; the treated larvae undergo pupal ecdysis and die
during the pupal stage. Preliminary studies showed that the pupae developed from methoprene treated larvae
die due to the persistence of larval tissues. A transgenic CRISPR/Cas9 genome editing method was employed
to knockout Ae. aegypti ortholog of the gene coding for ecdysone induced protein 93F (E93) which is known to
regulate programmed cell death (PCD) of larval tissues. The phenotypes of Ae. aegypti E93 knockout animals
are like that observed in JHA treated larvae, suggesting that JHA suppresses E93 expression in preventing the
death of larval tissues, resulting in pupae containing both larval and pupal tissues leading to their death. This
hypothesis will be tested by conducting experiments under two specific aims. In the first specific aim, larval
tissues undergoing PCD will be examined to identify similarities and differences between JHA treatment and
E93 knockout. The status of PCD in tissues dissected from JHA treated and E93 knockout larvae and pupae
will be studied by staining with apoptosis and autophagy marker dyes. In the second specific aim, RNA and
ATAC sequencing, RNAi and reporter assays will be employed to identify genes involved in larval tissue
remodeling and mechanisms of regulation of their expression by JHA working through E93. The function of
E93 acting as a pioneer and an activating transcription factor will be studied. Results from the proposed
research will impact medicine by providing information for the development of vector control methods. The
results from the proposed studies will answer long-standing questions on JHA action in mosquitoes and
increase our understanding of JH action, which could help to develop novel, highly active, and safe methods to
control mosquitoes and other vectors of pathogens that cause diseases in humans.

## Key facts

- **NIH application ID:** 10412123
- **Project number:** 5R21AI163561-02
- **Recipient organization:** UNIVERSITY OF KENTUCKY
- **Principal Investigator:** SUBBA R PALLI
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $181,250
- **Award type:** 5
- **Project period:** 2021-06-01 → 2025-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10412123

## Citation

> US National Institutes of Health, RePORTER application 10412123, Molecular mode of action of Juvenile hormone analogs (5R21AI163561-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10412123. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*