As a molecular biologist with a passion for circadian biology, Leonardo de Assis began his research career in Brazil, completed his postdoc in Germany, and is now establishing his own research group at the Department of Chemistry and Molecular Biology at the University AvŠŌ°®, supported by funding from the Wallenberg Centre for Molecular and Translational Medicine (WCMTM). His research bridges wet lab, dry lab, and bioinformatic analysis ā all with a focus on the skin.
For Leonardo, the skin is far more than just a protective barrier. He sees it as a metabolic organ where the bodyās biological clock plays a crucial role.
āTo think of the skin as a metabolic organ might be provocative in some research fields. And in general, you might think of human skin from an aesthetic or cosmetic point of view, especially with its connection to aging. So, the skin is fascinating from many dimensions in everyday life, and in my research, I would like to understand the skin on molecular level and what it reveals about the bodyās inner physiological processes" Leonardo said.
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From basic science to patient benefit
Leonardo is committed to advancing the translational impact of researchābridging the gap between basic science and clinical applications to ultimately benefit patients.
"My laboratory is dedicated to elucidating the molecular underpinnings of the circadian clock in skin biology, investigating its roles in both healthy and diseased states. My primary ambition is to harness these insights to develop therapies that improve patientsā quality of life." Leonardo said.
He is already actively collaborating with other fellows within the WCMTM network, which brings together researchers across basic science, clinical medicine, and data-driven fields.
āIām in contact with systems biology experts and clinical scientists both here in Gothenburg and at other Wallenberg centers in Sweden, and I hope to share the outcomes of these collaborations soon,ā he adds.
The skin as a light sensor
Since the early 2000s, itās been well established that our biological system can sense and respond to day and night ā in other words, to signals from the sun. We have light-sensitive cells in our eyes, containing a photopigment called melanopsin. These cells act as sensors, sending information about light from the outside world to our central biological clock in the brain.
This central clock communicates with different brain regions and helps regulate functions like blood pressure, food intake, and many others. It keeps our bodyās daily rhythms ā our circadian clock ā in sync. The central clock then sends signals to the rest of the body, or peripheral tissues, through changes in core temperature and through hormones such as cortisol and melatonin. This helps keep all our organs and tissues working together on the same time zone ā and of course, this includes the skin.
But ever since my early PhD work, Iāve been puzzled by a gap in this picture. We focus so much on the eyes as light sensors ā but what about the skin? The skin is also exposed to light. While it doesnāt āsee,ā it does detect light and plays a role in regulating many biological processes. Thatās what I want to better understand.ā
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Functions of melanopsin in cancer
During his PhD at the University of SĆ£o Paulo (USP), Leonardo studied the photosensitive system, demonstrating that several processes, such as pigmentation and proliferation in melanocytes, depend on the presence of melanopsin.
Still at USP, Leonardo investigated the light-independent functions of melanopsin in cancer research, demonstrating its critical role in cancer development beyond its conventional function as a light sensor. His studies demonstrated that melanoma cells with defective melanopsin had significantly slower tumor growth, attributed to decreased cell proliferation and increased immune response activation.
Innovative framework
In his second postdoc in Germany, where he spent nearly five years, Leonardo focused on elucidating the circadian effects of thyroid hormones and their therapeutic potential for fatty liver diseases. Immersing himself in omics methods, he developed his skills in circadian systems biology. This innovative framework integrates time as a variable in the intricate analysis of omics data.
Bringing international collaboration to Gothenburg
Leonardo de Assis is part of the collaborative research consortium (CRC) funded by the German Research Foundation (DFG), which aims to bring long-established concepts in circadian biology into clinical practice. The consortium combines basic scientists with clinical researchers and provides opportunities for regular interaction with clinicians. Together with the WCMTM network, it supports his translational goals.
Collectively, the network in Germany, together with the WCMTM network in Sweden, will help me to reach my translational goals, hopefully in the near future!
What is the circadian clock?
The circadian clock is your bodyās internal timekeeper, present in all the cells of the body. It controls daily rhythms in behavior, physiology, and metabolism like sleep-wake cycles, hormone release, body temperature, and digestion. It runs on a roughly 24-hour cycle, synchronized mainly by light and darkness. The clockās master regulator is in the brainās suprachiasmatic nucleus (SCN), in the hypothalamus.
The clock is driven by a feedback loop of clock genes and proteins being produced and released in our cells. Key genes are called CLOCK and BMAL1 proteins that activate genes like PER and CRY. Once PER and CRY proteins build up, they eventually start suppressing their own activity by inhibiting CLOCK-BMAL1. This cycle takes about 24 hours and resets daily when our body receives light cues from the sun.
