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GPR88 is an orphan G protein-coupled receptor (GPCR) belonging to the Class A rhodopsin-like family. Although initially identified as a striatum-specific receptor in humans and rodents (designated as Strg/GPR88), it is also expressed at low levels in the cerebral cortex, the central extended amygdala, the lateral and cortical regions, the hypothalamus, and other brain areas.

GPR88 primarily couples with intracellular Gi protein subtypes; by inhibiting adenylyl cyclase (AC) activity and reducing the production of the downstream second messenger cAMP, it modulates intracellular signaling cascades. Its core physiological mechanism involves the precise regulation of striatal dopaminergic signaling systems. GPR88 co-localizes with dopamine D1 and D2 receptors on medium spiny neurons (MSNs) and can directly attenuate D1 receptor-mediated excitatory cellular responses; additionally, it functionally inhibits μ-opioid and κ-opioid receptor signaling, thereby participating in the regulation of reward and pain processing.

The HEK293 Human GPR88 Cell Line model effectively simulates the in vivo GPR88 signal transduction process, the principle is illustrated in the figure below.

Figure 1. Schematic diagram of the HEK293 Human GPR88 Cell Line model

Figure 1. HTRF cAMP Assay with GPR88 HEK293(C16).

Cell Resuscitation
1)Rapidly thaw the frozen cells in a 37 °C water bath for approximately 60 seconds. Once thawed (which may take slightly less or more than 60 seconds), immediately transfer the cell suspension from the cryovial into a 15 mL centrifuge tube containing 10 mL of pre-warmed HEK293 Human GPR88 Cell Line complete culture medium.
2)Centrifuge cells at 1000 rpm for 5 min to remove medium, then resuspend cells in 5 mL of pre-warmed complete medium.
3)Transfer the cell suspension into a T25 culture flask and incubate at 37 °C with 5% CO₂.
4)After approximately 24–36 hours, replace the medium or passage the cells to remove non-adherent dead cells.

Subculturing procedure
1)When the cell density reaches the appropriate confluency for passaging, wash the cells with PBS, then add 1 mL trypsin to detach the cells. When more than 80% of the cells detach upon gently tapping the culture flask, add complete culture medium to terminate digestion. Gently pipette to obtain a single-cell suspension, transfer to a 15 mL centrifuge tube, and centrifuge at 1000 rpm for 5 minutes.

2)Discard supernatant after centrifugation. Resuspend cells in fresh medium to a single-cell suspension and transfer to a new culture flask for continued growth.

Cell Freezing
After trypsinization and centrifugation of cells from each T75 flask or 10 cm culture dish, discard the supernatant. Add 2 mL of cryopreservation medium (90% FBS + 10% DMSO), gently resuspend thoroughly, and aliquot into two cryovials. Immediately place the cryovials into a controlled-rate freezing container (e.g., Nalgene 5100-0001), fill with isopropanol to the indicated level, and store at −80 °C. After 24 hours, transfer the cryovials to liquid nitrogen for long-term storage.