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Activins belong to the transforming growth factor-beta (TGF-β) superfamily and are dimeric glycoproteins formed by two β subunits linked via disulfide bonds. In mammals, there are four genes encoding β subunits: *INHBA* (encoding βA), *INHBB* (encoding βB), *INHBC* (encoding βC), and *INHBE* (encoding βE). Through homo- or heterodimerization, these subunits form various activin members, primarily including Activin A (βA-βA), Activin B (βB-βB), and Activin AB (βA-βB), as well as Activin C (βC-βC) and Activin E (βE-βE), the functions of which have been investigated more recently.

Activin E is a homodimer composed of two βE subunits; it is primarily synthesized and secreted into the circulation by the liver, functioning as a key hepatokine. Activin E is a specific natural ligand for ALK7 (also known as ACVR1C), and their interaction is highly selective. While its signaling relies on the classical type II receptors ActRIIA and ActRIIB as co-components, Activin E—unlike the ubiquitously expressed Activin A—is naturally resistant to follistatin. This means its signaling is less susceptible to inhibition by this endogenous antagonist, allowing for more autonomous regulation. The ALK7 receptor is highly expressed in adipose tissue (particularly white adipose tissue) but shows very low expression in most other peripheral tissues; this expression pattern confers significant tissue specificity upon the Activin E-ALK7 signaling axis.

The HEK293 Human Activin E/ALK7 Effector Reporter Cell model effectively simulates the in vivoActivin Activin E/ALK7 signal transduction process, the principle is illustrated in the figure below.

Figure 1. Schematic diagram of the HEK293 Human Activin E/ALK7 Effector Reporter Cell model

Figure 2. Recombinant Activin E/ALK7 Effector Reporter Cell stably expressing Activin E/ALK7.

Figure 3. Dose Response of Recombinant Human Activin E in Activin E/ALK7 Effector Reporter Cell( C34).


Figure 4. Inhibition of Human Activin E Induced Reporter Activity by ALK7 Blocking Ab in ActivinE/ALK7 Effector Reporter Cell( C34).

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 Activin E/ALK7 Effector Reporter Cellcomplete 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.