# The Biochemical Basis for the Mechanics of Cytokinesis

> **NIH NIH R01** · JOHNS HOPKINS UNIVERSITY · 2024 · $68,282

## Abstract

PROJECT SUMMARY
Cytokinesis, the division of a cell into two daughter cells, serves as an elegant cell behavior that highlights the
biomechanical systems required for many cell shape change processes. Over the life of this grant, we have
demonstrated how an interplay of active force production, cortical tension, surface curvature, and viscoelasticity
drive cytokinesis furrow ingression. We identified key molecular pathways that control these properties and found
that the circuitry is wired like a control system complete with feedback loops that allows mechanical and chemical
signals to tune the accumulation of the contractile machinery. In this proposal, we will build upon our
understanding of cytokinesis and this mechano-responsive contractility network. We use a suite of techniques,
including genetics, proteomics, Single Molecule Pulldown (SiMPull), and Fluorescence Correlation and Cross-
Correlation Spectroscopy (FCS/FCCS) to study this network. We discovered that many of the proteins in the
mechano-responsive contractility network are organized into complexes in the cytoplasm, forming Contractility
Kits (CKs). Several CK components have unknown functions in the context of cell contractility and are the subject
of this proposal. Among these, the lectin discoidin 1A, traditionally viewed as a secreted protein, assembles with
the CKs in the cytoplasm and is necessary for a key protein, the actin crosslinker cortexillin I, to localize fully to
the cortex. Moreover, discoidin 1A has a complex genetic relationship with cortexillin I and its binding partner
and regulator IQGAP2. We will determine how discoidin 1 operates in the CKs and promotes cortical assembly.
Next, we are studying two ribonucleoproteins, RNP1A and RNP1B. Both proteins contain predicted RNA-
recognition motifs. RNP1A is also required for normal cortexillin I mRNA levels. We originally identified RNP1A
over-expression as a genetic suppressor of the microtubule-destabilizer nocodazole (same study that gave rise
to the RacE-14-3-3-myosin II pathway that we discovered). We have now found that RNP1A is required for
normal microtubule length. Given the changes in mRNA levels of cortexillin I, we conducted RNAseq analysis
and found that several CK proteins have altered gene expression in rnp1A knockdown cells. To identify RNAs
that the RNP1s might bind, we are using CLIP-Seq and have already found in a preliminary study that RNP1B
may bind to 14-3-3 mRNA. Here, we will flesh out how the RNP1s impact CK assembly and expression. Finally,
we discovered that the adenine nucleotide translocase (ANT, encoded by ancA in Dictyostelium) interacts
genetically with myosin II and racE. Intriguingly, we are finding that CK protein nulls (e.g., cortexillin I) have
reduced metabolic activity, leading to reduced ATP production and a lower energetic state. We will probe how
increasing energy production through ANT can bypass some of the cellular functions of the CK proteins. Overall,
these studies will ...

## Key facts

- **NIH application ID:** 11089747
- **Project number:** 3R01GM066817-20S1
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** DOUGLAS N ROBINSON
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $68,282
- **Award type:** 3
- **Project period:** 2003-08-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11089747

## Citation

> US National Institutes of Health, RePORTER application 11089747, The Biochemical Basis for the Mechanics of Cytokinesis (3R01GM066817-20S1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/11089747. Licensed CC0.

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