UBQLN1 links proteostasis and mitochondria function to telomere maintenance in human embryonic stem cells

Area of Science:

• Cell Biology
• Genetics
• Stem Cell Research

Background:

• Telomeres protect chromosome ends and are maintained by telomerase or alternative lengthening mechanisms.
• The role of Ubiquilin1 (UBQLN1) in telomere maintenance requires further exploration.
• UBQLN1 expression correlates with telomere length in human embryonic stem cells (hESCs).

Purpose of the Study:

• To investigate the role of UBQLN1 in telomere maintenance in hESCs.
• To elucidate the molecular mechanisms underlying UBQLN1's function in telomere regulation.
• To assess the impact of UBQLN1 deficiency on mitochondrial function and differentiation potential.

Main Methods:

• Generated UBQLN1-deficient hESCs and compared them to wild-type cells.
• Utilized RNA-seq and proteomics to analyze molecular changes.
• Employed immunoprecipitation-mass spectrometry (IP-MS) to identify UBQLN1 interacting proteins.

Main Results:

• UBQLN1 is essential for telomere maintenance in hESCs by promoting mitochondrial function.
• UBQLN1 deficiency results in oxidative stress, proteostasis loss, mitochondrial dysfunction, DNA damage, and telomere attrition.
• Hypoxia or N-acetylcysteine treatment partially mitigated telomere attrition, and UBQLN1 deficiency downregulated neuro-ectoderm differentiation genes.

Conclusions:

• UBQLN1 prevents mitochondrial overload and mitophagy by scavenging ubiquitinated proteins.
• UBQLN1 maintains mitochondrial and telomere integrity through proteostasis regulation.
• UBQLN1 plays a critical role in neuro-ectoderm differentiation.