EPISODE 55: The Worm’s Stress Network

Welcome to the next episode of the WOrM Podcast 🪱⚡

Today we are looking at how one stress-response protein helps a worm adapt to changing conditions.

At the centre of the story is PMK-1, the C. elegans equivalent of p38 MAP kinase.

Rather than acting through one fixed pathway, PMK-1 changes its molecular partners across development, tissues and environmental stress. The result is a flexible network that helps generate phenotypic plasticity.

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🧬 Meet ContinuumID

The researchers developed ContinuumID, an in vivo proximity-labelling method combining TurboID with an auxin-induced degron.

This allowed them to control when and where proteins near PMK-1 were labelled and identified by mass spectrometry.

They mapped PMK-1 interactions across:

• four developmental windows
• five tissues
• osmotic stress
• ultraviolet stress
• oxidative stress

Together, this created 26 datasets and a spatiotemporal atlas of the PMK-1 interactome.

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🕸️ A huge interaction network

The atlas contained 1,151 candidate interactors.

Some appeared only in particular tissues or conditions. Others formed a stable core shared across development and stress.

These partners included proteins involved in:

• RNA splicing
• transcription
• ribosome biogenesis
• translation
• signalling
• metabolism
• nuclear transport

PMK-1 therefore does more than switch stress genes on and off. It connects environmental sensing to RNA processing, protein production and metabolism.

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⚡ Different stress, different response

PMK-1 responded differently to each challenge.

During osmotic stress, activation rose rapidly and then returned towards baseline.

After ultraviolet exposure, activation remained high while the total pool of PMK-1 became depleted.

Oxidative stress produced a slower, delayed response.

The timing and duration of signalling therefore matter—not just its strength.

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🔄 Partners come and go

Some proteins maintained stable contact with PMK-1.

Others associated or dissociated when stress appeared.

One example was VHP-1, a phosphatase that strongly dissociated after ultraviolet exposure, helping explain the prolonged activation of PMK-1.

A signalling pathway is therefore not a fixed chain.

It is a changing network of molecular contacts.

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🧪 More signalling does not always mean more survival

The researchers reduced individual interactors using RNA interference.

Some knockdowns weakened survival. Some had little effect. Others unexpectedly improved it.

Even proteins from the same pathway could produce positive, negative or neutral outcomes.

Changes in stress-responsive gene expression also did not reliably predict survival.

Survival is an integrated whole-animal outcome shaped by signalling, metabolism, gene expression and tissue health.

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🧠 The take-home message

PMK-1 acts as a molecular hub.

It combines:

development × tissue × environment × molecular context

to generate different biological outcomes.

The pathway does not simply suppress variation.

It helps create the range of responses that allows organisms to adapt when conditions change.

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📄 Paper discussed

Wang Yuan; Luke A. Nunamaker; Yi M. Weaver; Benjamin P. Weaver. (2026)

A Caenorhabditis elegans spatiotemporal proximity atlas reveals the MAPK p38 as a generator of phenotypic plasticity in vivo

Science Signaling, 19: eaeb4530

DOI: 10.1126/scisignal.aeb4530

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