BAF-1 mobility is regulated by environmental stresses.

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Barrier to autointegration factor (BAF) is crucial for nuclear lamina structure, interacting with lamins, LEM-domain proteins, histones, and DNA.
• BAF protein typically exhibits high mobility within the nuclear lamina, as observed through fluorescence recovery after photobleaching and fluorescence loss in photobleaching assays.

Purpose of the Study:

• To investigate the regulation of Caenorhabditis elegans BAF-1 mobility under various stress conditions, including caloric restriction, food deprivation, and heat shock.
• To determine if the observed changes in BAF-1 mobility are specific or a general response of chromatin-associated proteins.
• To elucidate the molecular mechanisms underlying BAF-1 immobilization during stress, particularly its relationship with protein binding partners.

Main Methods:

• Utilized fluorescence recovery after photobleaching and fluorescence loss in photobleaching techniques to assess BAF-1 mobility in Caenorhabditis elegans.
• Applied caloric restriction, food deprivation, and heat shock as experimental stressors.
• Analyzed the phosphorylation status of BAF-1, specifically Ser-4 phosphorylation, following heat shock.
• Employed missense mutations in BAF-1 to study its binding interactions with partners like emerin in vitro.

Main Results:

• BAF-1 mobility in C. elegans intestinal cells is significantly regulated by caloric restriction, food deprivation, and heat shock.
• Food deprivation did not alter the mobility of other chromatin proteins, such as HPL-1 and HPL-2, indicating a specific response for BAF-1.
• Heat shock induced increased Ser-4 phosphorylation of BAF-1.
• Mutational analysis revealed that BAF-1 immobilization by heat shock correlated with normal or enhanced in vitro binding affinity for emerin.

Conclusions:

• BAF-1 localization and mobility at the nuclear lamina are dynamically regulated by cellular stress.
• BAF-1 immobilization represents a specific cellular response to caloric restriction in C. elegans intestinal cells.
• The interaction between BAF-1 and emerin appears critical for the stress-induced immobilization of BAF-1.