José Díaz Maldonado

@josediazm.bsky.social

PhD student in the Puigserverlab @Harvard | BS. Biochemistry @ PUC 🇨🇱 | Interested in mitochondria and gene expression.

A long-standing mystery in cholesterol biology: why is ER cholesterol sensing so switch-like rather than gradual? Our answer: cholesteryl ester phase separation in the ER membrane, which converts small lipid changes into a cooperative transcriptional response. www.biorxiv.org/content/10.6...

ER cholesteryl ester phase separation underlies switch-like cholesterol sensing

Cellular lipid homeostasis requires mechanisms that detect subtle changes in lipid abundance and trigger rapid, coordinated responses. The INSIG/SCAP/SREBP2 pathway provides a central feedback system ...

biorxiv.org

1/ Mitochondrial Na⁺ links metabolism, Ca2+ signaling and disease. We know how it gets in, how it gets out, and proteins that use it. But: we've never actually seen Na⁺ in single mitochondria in live cells. We started with an unusual observation, went down a rabbit hole & found some cool biology .

A mitochondrion showing Ca2+ entering through the MCU, exchanged for Na+ by NCLX, Complex I acting as a Na+/H+ exchanger, and various transporters that use Na+ to move their substrates in and out of the mitochondria

New paper! How do RNAs "know" where to go inside a cell? We dug into the sequence elements that route RNAs to the right place. It turns out that, in mammals, they're surprisingly massive (>200 nt), multipartite, and wonderfully complicated. 🧵

🚨Excited to announce a new preprint from our lab, where we describe an ancient metabolic axis that controls mitochondrial genome copy number; a mechanism we uncovered in human cells that stretches through evolution to control mtDNA in flies, yeast and even plants!

biorxiv.org