PMID:27133166

Mitochondrial Stress Induces Chromatin Reorganization to Promote Longevity and UPR(mt).

LIN-65 is a nuclear co-factor that works with the histone methyltransferase MET-2 to establish H3K9 di-methylation during mitochondrial stress

"Mitochondrial stress response activation requires the di-methylation of histone H3K9 through the activity of the histone methyltransferase met-2 and the nuclear co-factor lin-65."
Mitochondrial stress causes widespread chromatin changes through H3K9me2 marks, with LIN-65 being required for this response

"We find that mitochondrial stress causes widespread changes in chromatin structure through histone H3K9 di-methylation marks traditionally associated with gene silencing."
The chromatin reorganization mediated by LIN-65 and MET-2 promotes UPR-mt activation and lifespan extension

"a metabolic stress response is established and propagated into adulthood of animals through specific epigenetic modifications that allow for selective gene expression and lifespan extension."

file:worm/lin-65/lin-65-deep-research-falcon.md

Falcon deep research report on C. elegans lin-65 (Q95XN0)

The best-supported primary function of LIN-65 is as an intrinsically disordered nuclear cofactor/scaffold for the H3K9 methyltransferase MET-2/SETDB1, promoting MET-2 nuclear accumulation, stability, and assembly into perinuclear heterochromatin foci that enable H3K9me2-linked heterochromatin formation and repression.

"Across genetics, imaging, and proteomics, the best-supported primary function of **LIN-65** in *C. elegans* is as an **intrinsically disordered nuclear cofactor/scaffold** that promotes **MET-2/SETDB1 nuclear accumulation, stability, and assembly into perinuclear heterochromatin foci**, enabling robust **H3K9me2-linked heterochromatin formation, repression of repeats/developmental genes, and perinuclear chromatin organization**. "
A central modern definition of LIN-65 is as an essential cofactor/scaffold for the worm SETDB1 homolog MET-2; LIN-65 physically associates with MET-2 and is required for MET-2 foci formation, nuclear enrichment, and robust H3K9 dimethylation.

"A central modern definition of LIN-65 is as an essential cofactor/scaffold for the histone H3 lysine 9 (H3K9) methyltransferase **MET-2** (the worm SETDB1 homolog). "
LIN-65 lacks a canonical enzymatic activity or classical reader domain and is largely low-complexity/unstructured with a predicted coiled-coil and a folded C-terminal domain, consistent with a multivalent assembly factor rather than a catalytic effector.

"LIN-65 is not defined by a canonical enzymatic activity or a classical reader domain. Instead, it is described as largely **intrinsically disordered/low-complexity**, with predicted structural elements that include a **coiled-coil** and a **folded C-terminal domain** "
LIN-65 is proposed to be a functional counterpart (or convergent analog) of mammalian ATF7IP/MCAF1, an established SETDB1 cofactor that promotes SETDB1 nuclear localization and function.

"LIN-65 is proposed to be a functional counterpart (or convergent analog) that promotes SETDB1/MET-2 nuclear localization and function. "
Proteomics and reciprocal pulldowns identified LIN-65 and ARLE-14 as the major stable interactors of MET-2, supporting a MET-2/LIN-65/ARLE-14 heterochromatin module.

"Proteomics and reciprocal pulldown experiments in embryos identified **LIN-65** and **ARLE-14** as the major stable interactors of MET-2 "
The MET-2/LIN-65 heterochromatin foci are dynamic and sensitive to 1,6-hexanediol, consistent with a condensate/phase-separation-like assembly mechanism driven by intrinsically disordered scaffolding.

"LIN-65-associated foci are sensitive to **1,6-hexanediol**, supporting a condensate/weak-interaction assembly mechanism consistent with intrinsically disordered scaffolding. "
Historically lin-65 was defined genetically as a synMuvB/class B gene that acts antagonistically to Ras signaling in vulval development through parallel genetic pathways (Ceol et al. 2006).

"classified it as **synMuvB**, a class that acts antagonistically to Ras signaling in vulval development through parallel genetic pathways. "
lin-65 is required for mitochondrial stress-induced chromatin reorganization and for full UPR-mt activation, functioning with MET-2 in stress-dependent H3K9me2 remodeling.

"**lin-65** is required for mitochondrial stress–induced chromatin reorganization and for full **UPRmt** activation. "