Altered Stra13 and Dec2 circadian gene expression in hypoxic cells

Area of Science:

• Molecular Biology
• Chronobiology
• Cancer Research

Background:

• The circadian system synchronizes mammalian physiology with the light/dark cycle.
• Altered circadian clock gene expression is linked to tumor progression, but molecular mechanisms are unclear.

Purpose of the Study:

• To investigate the molecular links between hypoxia signaling and circadian clock gene expression.
• To determine the role of Stra13 and Dec2 in hypoxia-induced alterations of the circadian system.

Main Methods:

• Utilized serum-shocked fibroblasts treated with CoCl2 (hypoxia mimic).
• Analyzed circadian expression of clock genes (Rev-erbalpha, Bmal1) and clock-controlled genes (Dbp).
• Performed cotransfection assays to assess the interaction of STRA13 and DEC2 with CLOCK:BMAL1.
• Studied a transplantable osteosarcoma tumor model in vivo.

Main Results:

• Stra13 and Dec2 were overexpressed and lost rhythmicity under hypoxia.
• Circadian expression of Rev-erbalpha, Bmal1, and Dbp was altered under hypoxia.
• STRA13 and DEC2 antagonized CLOCK:BMAL1-dependent transactivation.
• Hypoxia in osteosarcoma tumors showed altered expression of Stra13, Dec2, Rev-erbalpha, Bmal1, and Dbp.

Conclusions:

• Overexpression of Stra13 and Dec2 links hypoxia signaling to disrupted circadian clock gene expression.
• These findings provide molecular insights into how hypoxia influences circadian rhythms and potentially cancer progression.