Albumin (Alb: is the most important protein in human plasma, accounting for 40%-60% of total plasma protein, which can effectively maintain body nutrition and osmotic pressure, and is closely related to human health.

Recently, a new study led by the University of California revealed that albumin not only facilitates sperm fertilization by activating the human voltage-gated proton channel (hHv1) that exists in the human body, but also enables white blood cells to secrete inflammatory mediators to fight infection.

Related research results were published in Nature Communications entitled "Direct activation of the proton channel by albumin leads to human sperm capacitation and sustained release of inflammatory mediators by neutrophils".

The human voltage-gated proton channel (hHv1) is a homotetrameric protein. Each subunit consists of a voltage sensing domain and a pore domain. The voltage sensing domain plays a role in sensing the membrane potential and controlling the switch of the channel. Studies showed that the proton channel can not only be expressed in various cell types and tissues, but also has the function of adjusting the pH value of the cell. It is highly selective for protons while other cations cannot pass through the proton channel, which was found to play an important role in macrophages and neutrophils in the blood.

In this latest study, in order to gain insight into how albumin triggers sperm fertilization and stimulates neutrophils to release mediators in the innate immune response, researchers analyzed the physiological connection and activation mechanism between Alb and hHv1, which are closely related to human health.

It was found that because Alb is low in semen but high in female reproductive tract, when Alb interacts with hHv1, it will activate sperm when entering the female reproductive tract and produce an acrosome reaction, thereby promoting the implantation of the fertilized egg. This is also the main reason why albumin supplementation can increase the success rate of in vitro fertilization (IVF).

According to the first author of the study, “in addition to helping sperm capacitation, the interaction between Alb and hHv1 can also push neutrophils to produce and secrete inflammatory mediators that kill bacteria and fight infections, thereby avoiding inflammation-induced diseases. "

In 2016, a study pointed out that in addition to being beneficial to sperm capacitation and fighting infection, Alb can also inhibit the proliferation of cancer cells by activating hHv1. Studies have found that tumor cells use hHv1 expression as the main mechanism to maintain the intracellular pH value by promoting the number of protons.

Alb is more than a powerful resistance to cancer. An article published in Nature Neuroscience in 2012 pointed out that hHv1 also involves a wide range of biological processes and has a significant role in tissue damage during ischemic stroke and renal hypertension damage. This further proves the power of this protein.

In short, this breakthrough provides new ideas for improving fertility and suppressing inflammatory diseases caused by innate immune responses. At present, the research has been supported by the National Institutes of Health, the US-Israel Binational Science Foundation, and other institutions, and it is given great expectations that the outcomes could benefit the public as soon as possible.

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