ERK1c regulates Golgi fragmentation during mitosis.

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Extracellular signal-regulated kinase 1c (ERK1c) is an alternatively spliced variant of ERK1.
• ERK1c exhibits distinct regulatory mechanisms compared to other ERK isoforms.
• The specific functions of ERK1c, particularly within the Golgi apparatus, remain underexplored.

Purpose of the Study:

• To investigate the role of ERK1c in Golgi functions during mitosis.
• To elucidate the involvement of ERK1c in MEK-induced mitotic Golgi fragmentation.
• To understand ERK1c's contribution to cell cycle regulation.

Main Methods:

• Utilized synchronized cells to study ERK1c expression and activity during the cell cycle.
• Employed immunofluorescence to assess ERK1c colocalization with Golgi markers.
• Applied small interfering RNA (siRNA) to deplete ERK1c and performed overexpression studies.
• Monitored mitotic progression and Golgi fragmentation dynamics.

Main Results:

• ERK1c expression and activity significantly increased during late G2 and mitosis.
• ERK1c was found to colocalize predominantly with Golgi markers.
• ERK1c depletion attenuated, while overexpression enhanced, mitotic Golgi fragmentation.
• ERK1c's modulation of Golgi fragmentation impacted mitotic progression.

Conclusions:

• ERK1c plays a specific role in regulating mitotic Golgi fragmentation.
• ERK1c is essential for normal cell cycle progression through its effects on the Golgi.
• While ERK1 and ERK2 also participate in mitosis, ERK1c's Golgi-specific function is unique.
• ERK1c extends the signaling specificity of the Ras-MEK pathway by engaging ERK1/2-independent mechanisms.