Metabolic reprogramming is a hallmark of normal physiological homeostasis, but also of pathological conditions such as cancer. Metabolic pathways are temporary orchestrated to satisfy the shifting demands of growth, proliferation, and differentiation. Growing evidences exist about the regulatory crosstalk between metabolic pathways, cell cycle progression and cell division: our laboratory, among others, has shown that cancer-cell metabolism is reprogrammed through the regulation of metabolic enzymes by various cell cycle regulators. Moreover, we have demonstrated that some of these cell cycle regulators, like the pRB-cdk4-E2F1 pathway, control metabolism of adult non-proliferative cells, and that their activity is altered especially under pathological conditions contributing to obesity and diabetes.
Our projects aim to contribute understanding the crosstalk between metabolism and proliferation.
Participation of the pRB-cdk4-E2F1 pathway in metabolism during normal and pathological conditions.
We have previously shown that the cyclin-dependent kinase 4 (CDK4) plays a role in adipogenesis and in the function of mature adipocytes. We have also proven that the pRB-CDK4-E2F1 pathway represses oxidative metabolism in muscle and in brown adipose tissue, while promoting lipid synthesis and glycolysis in the liver.
Taking advantage of tissue-specific conditional knockout mice for E2f1 and for Cdk4, we are currently exploring the role of E2f1 and Cdk4 in regulating other major metabolic pathways. In particular, we study the role of E2f1 in gluconeogenesis and cholesterol metabolism in the liver, two processes deregulated in diabetes and in cardiovascular diseases, respectively. In parallel, we are trying to elucidate the function of Cdk4 in thermogenesis in brown adipose tissue, an emerging player in regulating energy expenditure, body weight and global metabolic homeostasis.
We are also further characterizing the role of E2F1 in cancer biology. We have identified several novel E2F1 target genes playing a role in glutamine uptake and metabolism, which is key for sustaining proliferation in transformed cells. Our working hypothesis is that E2F1 plays a key role in cancer progression by coupling cell cycle proliferation and DNA synthesis with the regulation of metabolic pathways that provide the necessary metabolic intermediates to sustain cell growth.
Molecular interplay between CDK4 and other signaling pathways that control proliferation and metabolism.
We have recently shown that IRS2 is a novel target of CDK4, highlighting the importance of this cell cycle regulator in modulating insulin-AKT signaling. Interestingly, IRS proteins are involved in the activation of growth factor receptor pathways and transduce mitogenic, anti-apoptotic, and anti-differentiation signals to the cell. Recent data from our laboratory show that CDK4 modulates AMPK and mTOR pathways, two master regulators that sense and integrate nutritional and environmental cues and regulate cell proliferation and metabolism. Significantly, aberrant AKT, AMPK or mTOR signaling is involved in cancer, cardiovascular disease, and diabetes. We are currently exploring the central role of CDK4 integrating several signaling pathways, linking cell proliferation and metabolism in normal and pathological conditions.
Implication of other CDKs in the control of metabolism.
Our laboratory has already shown that members of the CDK family, such as CDK4 and CDK9, respond to nutritional status and are key factors in the regulation of metabolism independently from cell proliferation. Interestingly, other CDKs are expressed in highly metabolic tissues in adult mice and humans, suggesting that they could also play a role in the regulation of metabolism and energy homeostasis. We have generated tissue-specific knockout mice for CDK7 and CDK10 that are being extensively characterized in order to elucidate the role of these novel potential metabolic regulators.
Targeting tumor metabolism.
The metabolism of cancer cells is reprogrammed in order to support their uncontrolled proliferation rates. This process is orchestrated by several oncogenes such as MYC and RAS, emphasizing the importance of shuffling metabolic pathways to sustain cancer progression. Among many others, increased de novo fatty acid (FA) synthesis is a hallmark of tumor cells. De novo synthesized FA are not only used for the generation of new cell membranes, but also for the production of lipid signaling molecules required for carcinogenesis and cancer cell survival. Thus, targeting lipid synthesis is a new promising therapeutic strategy against some types of cancer. We have previously shown that pharmacologic inhibition of the lipogenic enzyme stearoyl-CoA desaturase 1 (SCD1) activity impairs lipid synthesis and results in decreased progression in prostate cancer models. We are now interested in identifying new actors playing a role in cancer lipid metabolism and in finding new drugs that inhibit de novo FA synthesis to target cancer progression.
Prof. Lluis Fajas Coll
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Prof. Lluis Fajas Coll was born in Barcelona, Spain. He studied Biology at the University of Barcelona were he got his Master’s degree. He next moved to the Ernst Boehringer Institute in Vienna, Austria were he did his PhD studies. After two post-doctoral stages in France in the laboratory of Prof. Auwerx at Pasteur Institute in Lille and at the IGMM in Dr. Sardet lab in Montpellier he was recruited as Inserm associated scientist at the IGBMC in Strasbourg. He next was appointed as junior group leader with an Inserm Avenir grant in Montpellier. The main focus of his research has been the link between cell cycle regulation, proliferation and metabolism in the context of metabolic pathologies, such as obesity and diabetes and in the context of cancer. |
Valentin Barquissau
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I am Valentin Barquissau, a southern French scientist. I obtained a PhD in human nutrition at the Université d'Auvergne (Clermont-Ferrand, France) focusing on skeletal muscle metabolism during obesity-induced insulin resistance. In 2012, I moved to Toulouse (France) in Dominique Langin's lab to study white-to-brown adipocyte conversion. Since february 2018, I have joined Lluis Fajas' group to investigate the role of CDK4 in metabolic control, especially in skeletal muscle. Additionally, I plan to improve my knowledge of the Alps in both winter and summer conditions, then do not hesitate to get in touch to share your experience and/or for mountain trips... |
Sarah Geller
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During my different experiences in research laboratories, I have gained increasing interest for molecular and cellular interactions between neural cells (neurons and glia) in the context of reproductive function and metabolism. I performed my master degree in 2009 in the group of Dr. Vincent Prévot, INSERM Lille (France) and then obtained a fellowship of "ministère de la recherche” (French research department) to perform my PhD in the group of Pr. Anne Duittoz and Dr. Yves Tillet at INRA-CNRS of Tours, France. During my master and PhD theses, I studied the role of glial cells (such as astrocytes and olfactory ensheathing cells) in the ontology (proliferation, differentiation and maturation) of hypothalamic neurons which control reproductive function, named GnRH neurons. Following my PhD, I decided to explore the role of glial metabolism in the regulation of reproductive function and whole body metabolism by joining the group of Prof. Luc Pellerin in Lausanne in 2013. During my first post-doctorate, I studied the metabolism of hypothalamic neural cells (astrocytes, tanycytes and GnRH neurons) and their involvement in metabolite sensing (glucose, lactate and free fatty acids). I joined the group of Prof. Lluis Fajas in 2020 to go further into the field of cellular metabolism regulation under physiological and pathological conditions. I currently explore the role of a cell cycle regulator, the kinase cyclin-dependent kinase 4, in the regulation of endocrine hypothalamus as a key modulator of glial ontology and/or glial metabolism, using primary cultures and in vivo approaches of various transgenic mice models. |
Dorian Ziegler
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Dorian studied cellular biology at the Ecole Normale Supérieure de Lyon, France. Early interested in investigating cellular senescence, a cell program involved in the age-related decline of tissues, he performed internship in Pr. Judith Campisi’s lab at the Buck Institute for Research on Aging, California. For his PhD, he joined the lab of Dr. David Bernard, at the Cancer Research Center of Lyon (CRCL) to study the role of metabolic homeostasis in the regulation of cellular senescence. In 2021, he moved to Lausanne in the group of Pr. Luis Fajas, in order to dig deeper into the interplay between metabolism, senescence, cancer and aging. |
Kanishka Parashar
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I am Kanishka Parashar, a new PhD in the group of Prof. Lluis Fajas coll. I come from India, where I did my Master’s degree in Biotechnology at Jamia Millia Islamia, New Delhi, India. For my master’s thesis project, I worked on the project to decipher the role of molecular motor protein Dynein subunits and their role in cell division (mitosis) progression at the Regional centre for Biotechnology, Faridabad India. I obtained my Bachelor’s degree in Life Sciences from University of Delhi, New Delhi, India. I moved to Lausanne in March and I am looking forward to getting to know you all. |
Xavier Berney
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Lab Technician |
Khadidja Kacimi
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Hello, my name is Khadidja Kacimi. I am Algerian, I did my masters degree in molecular and cellular biology in Rennes, France, I did my first internship at the Institute of genetics and development of Rennes (IGDR) where i worked on BRAF inhibitors drug resistance in melanoma cancer. I did my second internship at l'Institut de recherche en santé, environnement et travail (Irset) in Rennes, where I worked on the effect of a probiotic treatment on postpartum depression in a rat model. I have now joined Prof Fajas' Lab to work under the supervision of Dr Sarah GELLER on the role of CDK4 in glial cells in the hypothalamus in metabolism, reproduction and stress. |
