# A viable kinase-inactive RIPK3 D143N mouse model reveals its scaffold function in driving TNF-induced inflammatory disorder

## TL;DR

A new mouse model shows that RIPK3's non-kinase function promotes inflammation, offering insights into treating inflammatory diseases.

## Contribution

A viable kinase-inactive RIPK3 mouse model reveals its scaffold role in inflammation without affecting development.

## Key findings

- Ripk3D143N/D143N mice are viable and fertile, showing kinase activity is not essential for development.
- The RIPK3 D143N mutation blocks necroptosis and rescues embryonic lethality in caspase-8-deficient mice.
- RIPK3's scaffold function drives inflammation via JAK-STAT1, reduced by JAK1/2 inhibition.

## Abstract

RIPK3 is a key regulator of necroptosis, but the specific roles of its kinase-dependent and -independent functions in disease pathogenesis remain poorly understood. Here, we generated and characterized RIPK3 D143N kinase-dead knock-in mice, a novel kinase-inactive model that selectively disrupts RIPK3 kinase activity without inducing spontaneous apoptosis. Unlike previously reported kinase-inactive Ripk3D161N/D161N mice, which exhibit embryonic lethality by triggering apoptosis, Ripk3D143N/D143N mice are viable and fertile, demonstrating that RIPK3 kinase activity is dispensable for development. The RIPK3 D143N mutation effectively blocks necroptosis induced by multiple stimuli and fully rescues embryonic lethality of caspase-8-deficient mice. Notably, Ripk3D143N/D143N mice were significantly less protected from TNF-driven inflammatory disease than RIPK3-deficient mice, revealing a critical kinase-independent role for RIPK3. This scaffold function drives inflammation and tissue damage through JAK-STAT1 activation, as pharmacological inhibition of JAK1/2 effectively reduces disease pathogenesis. Thus, our findings establish Ripk3D143N/D143N mice as a valuable model for dissecting the kinase and scaffold functions of RIPK3, and highlights the therapeutic potential of targeting its scaffold function in inflammatory diseases.

Schematic diagram showing the kinase-dependent and kinase-independent function in cell death and inflammation. A novel kinase-inactive RIPK3 mouse model (Ripk3D143N/D143N) defines the kinase-dependent and kinase-independent role of RIPK3 in cell death and inflammation.

Schematic diagram showing the kinase-dependent and kinase-independent function in cell death and inflammation. A novel kinase-inactive RIPK3 mouse model (Ripk3D143N/D143N) defines the kinase-dependent and kinase-independent role of RIPK3 in cell death and inflammation.