THE HUMAN PROTEIN ATLAS BLOG
Previously we have highlighted proteins expressed in the human neural retina. This week's article emphasizes the cellular structure and molecular dynamics of the lens.
The main function of the lens is to focus light on the retina. The passage of light through the cornea, lens and vitreous all the way to the retinal layer of the eye is only possible due to transparency of the tissue. Although the lens is very protein-rich, light absorption and light scattering in the lens is minimal.
The lens comprises non-diving lens cells which are mainly composed of ordered proteins called crystallins...Read more
TPX2 was identified in 1997 as a 100 kDa nuclear protein. In cells TPX2, a is a microtubule nucleation factor that translocates from the nucleus - where it resides during interphase - to the mitotic spindle during mitosis.
The mitotic spindle forms when chromosomes are ready to segregate during cell division and not surprisingly this protein is also found in this specific compartment of the cell! TPX2 is required for the correct formation of the kinetochores that is crucial for the attachment of microtubules, enabling the sister chromatids to be pulled apart. Due to its function TPX2 expression is cell-cycle dependent...Read more
The pituitary gland plays a crucial role in human physiology, and together with the hypothalamus this highly conserved and elegant system form a link between the nervous and endocrine system, by controlling the functions of the thyroid, adrenal glands, and the gonads, and also regulating growth, lactation, and water preservation.
This gland, also called hypophysis, consists of two separate lobes with dual embryonic origin; the anterior (adeno) pituitary gland originates from the oral cavity, and the posterior (neural) pituitary gland develops from the neural plate...Read more
Mitochondria harbors an own genome that renders key proteins involved in production of energy through oxidation of various substrates. Majority of the disorders associated with mitochondrial function are caused by impaired expression of the proteins encoded in the mitochondrial genome. One of these proteins is the translational activator of cytochrome c oxidase 1 (TACO1).
Experimental results reveal that TACO1 is expressed in all tissues within the human body. The protein is detected mainly in the cytoplasm and more precise inside mitochondria. Explore expression and subcellular localization of TACO1 in the Cell Atlas...Read more
Renal cell cancer is a relatively common form of human cancer. Tumors develop in the kidney and have a tendency to grow into renal veins and metastasize to distant organs without the spread to regional lymph nodes as is common for many other tumor types.
This particular case shows a papillary form of renal cell cancer that grows with papillary excrescences into cyst formations and with areas of necrosis. The tumor has been stained with an antibody (HPA005785) that recognizes the CD44 protein.
CD44 is a cell-surface glycoprotein and a receptor for hyaluronic acid that is involved in cell-cell interactions, cell adhesion and migration...Read more
Today, it is time for the first image of the week from the Cancer Atlas!
Lung cancer is one of the deadliest and most common forms of human cancer. Different forms of lung cancer exist and non-small cell lung cancer is the most common form. The cancer image this week is selected from such a lung cancer that has been immunohistochemically stained for the proliferation marker Ki-67 (MKI67). Ki-67 is the most commonly used immunohistochemical marker in rutin cancer diagnostics. The Ki-67 antigen is expressed in all cell nuclei that are active in the cell cycle and thus positive staining in a tumor cell population reflects the level of proliferation in that particular cancer...Read more
In 2017, February 28th will be the day that in Sweden is known as "Fettisdagen", (lit. "Fat Tuesday"), in other countries known as "Mardi Gras", "Faschingsdienstag" or "Shrove Tuesday". This day was originally celebrated in the Christian tradition as the last day of a three day feast to prepare for the forty day long fasting period before Easter. Today it has been popularized and in many places around the world this day is now known for its carnivals.
In Sweden together with some other northern European countries we like to eat "semlor" on Fat Tuesday...Read more
Tissue Atlas group is pleased to announce the launch of the Tissue Image of the Month. Previously, you have had the joy of experiencing interesting images of cellular organelles and proteins described by the Cell Atlas. Now we also hope that you will follow the blog posts and pictures of stained tissues with the same excitement and curiosity, as we dive into the world of histology, immunohistochemistry, cells and tissues.
First up - hairs and hair follicles.
Hair fibers consist of cells called trichocytes. The fibers vary in size, disposition and color due to factors such as age, sex, ethnicity and region of the body...Read more
This week we look at a very spooky protein, BAT3 which localizes to the nucleoplasm (looks like jack o'lanterns if you squint hard enough) and cytoplasm of the cell as seen in Figure 1 in A-431 cells.
In addition to having a spooky name, this protein, also known as BAG6, was first identified as being involved in programmed cell death (apoptosis). Subsequent studies have revealed that BAT3 plays a role in many important cellular processes including gene regulation, protein synthesis, protein quality control, and protein degradation (Binici J & Koch J. 2014)...Read more
It's time for another HPA image of the week! This week we would like to tease an annotation that is not yet publicly available, but is coming soon in the December 4 release of the Cell Atlas.
During the cell cycle, each chromosome containing your DNA replicates. During mitosis, each chromosome lines up with its copy in the middle of the cell. At this point, the copies of each chromosome are pulled apart from each other via a structure called the mitotic spindle. In order for this chromosomal separation to happen correctly, the two copies of each chromosome must be attached to the microtubules via the kinetochore ( DeLuca J.G. et al 2002)...Read more
This week the 2016 Nobel Prize in Physiology or Medicine was announced and has been awarded to Yoshinori Ohsumi for his work in with understanding autophagy. Congratulations to Dr. Ohsumi on his well deserved award! Please read the link above for a great and brief explanation of Dr. Ohsumi's contributions and other important discoveries related to autophagy.
This week we highlight DNA damage regulated autophagy modulator 2 (DRAM2), a well known inhibitor of autophagy. Figure 1 shows an example of DRAM2 in U2 OS human osteosarcoma cells...Read more
Welcome to another HPA image of the week! This week we take a look at another member of the vesicle family, the lysosomes.
In a way, lysosomes can be thought of as the recycling plants of your cells. Lysosomes are small membrane bound vesicular organelles that degrade biomolecules within your cells so that the materials in these molecules can be recycled and used for other cellular processes. Often these biomolecules come from vesicles known as endosomes that bring in materials from outside your cells, however lysosomes are also known to degrade other organelles, and products from within the cell...Read more
Welcome back blog fans! After a brief hiatus the image of the week highlights from the HPA are back! This week we are discussing the Endoplasmic reticulum, which is not just difficult to say, but is where many of your proteins are made.
The endoplasmic reticulum (ER) is one of the largest organelles in the cell. It is a delicate membranous network composed of sheets and tubules that spreads throughout the whole cytoplasm and is actually contiguous to the nuclear membrane. Two major forms of the ER can be distinguished: the rough ER and the smooth ER. Both have different functions...Read more
Though frequently overlooked as being a "catch-all" for proteins that don't reside within another organelle, cytoplasmic proteins are anything but.
One important role of proteins in the cytoplasm is the regulation of gene expression. There are two main ways in which gene expression is regulated; when converting the genetic code in your DNA to RNA (transcription), and when converting RNA to proteins (translation). Though transcription (DNA to RNA) occurs in the nucleus, cytoplasmic proteins are often involved in activating transcription factors which then move to the nucleus to perform transcription.
The protein stained in Fig 1...Read more
Let's have a look at another fascinating compartment of the cell, the centrosome! Located in close proximity to the nucleus, the centrosome is so small that it sometimes suffers from being overlooked. However, despite its humble size it is a very important organelle with great impact on cellular function.
The centrosome was first described in 1888 and has been a very popular organelle to study among biology researchers ever since (Conduit P.T. 2015). The most well characterized function of the centrosome is to serve as the organizing center for the microtubules that build up the internal architecture of the cell, the so-called cytoskeleton...Read more
It's time for another Image of the week! This week's image is brought to us by Diana Mahdessian, who works on the Subcellular protein atlas, and highlights cell division and various stages of mitosis. In previous blogs we have discussed the importance of certain proteins in the cell cycle including dividing centrosomes and FDXR in mitochondria.
The cell cycle is an ordered series of events that ultimately leads to the division of the "mother" cell into two "daughter" cells (cells are given feminine names because they are capable of reproducing).
The cell cycle consists of three distinct phases; interphase, mitosis and cytokinesis...Read more
Welcome back to HPA image of the week! This week we highlight another organelle brought to us by Mikaela Wiking aka HPA_Illuminator, the intermediate filaments!
Intermediate filaments are one of the three cytoskeletons of the cell, together with actin filaments and microtubules.
The expression of intermediate filaments can be extremely dependent on cell type, for example the intermediate filament protein group keratins, discussed in a previous IOTW, are key components in hair, nails and skin...Read more
Welcome back to Image of The Week! We will be periodically highlighting an organelle in the coming image of the week posts, written by members of the Subcellular Human Protein Atlas project. This week we kick things off with a post by HPA_Illuminator, and what better way to start than with the mitochondria, the (true) powerhouse of the cell!!!
Mitochondria are found in almost all human cells, in varying numbers. They are known as the powerhouse of the cell as they are responsible for producing the majority of the energy in your body (in the form of ATP, adenosine triphosphate)...Read more
Welcome to HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by solartech0 who found this image while playing Project Discovery in EVE online.
The protein stained in Fig 1. is an image of ferredoxin reductase (FDXR) found in the mitochondria of the cell. This sample shows a staining of FDXR in A549 adenocarcinomic alveolar basal epithelial cells.
FDXR is a protein involved in cellular metabolism. This process is what provides energy for our cells and is carried out in the mitochondria of the cell...Read more
It's time for another HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by x Truf a member of the Signal Cartel in EVE online who found this image while playing Project Discovery.
The protein stained in Fig 1. is an image of Moesin (MSN) found in the plasma membrane of the cell. This sample shows a staining of MSN in U-251 MG human glioblastoma astrocytoma (brain) cells.
MSN is a member of the ERM family which provide a link between plasma membranes and actin filaments. This link was briefly discussed in a previous blog...Read more
Welcome to another HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by Shiverwarp who found this image while playing Project Discovery in EVE online.
The protein stained in Fig 1. is an image of Coronin, actin binding protein, 2B (CORO2B) found in the focal adhesions and at the plasma membrane of the cell. This sample shows U-251 MG human glioblastoma astrocytoma (brain) cells.
Focal adhesions are transmembrane groups of protein that allow the cell to "grab" the surrounding environment...Read more
Welcome to another HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by Selphentine who pointed out several nice examples of proteins localized to "nuclear speckles". In Project Discovery, citizen scientists are refining our annotations for proteins within the nucleus by labeling these nuclear speckles, previously not annotated in the atlas.
The protein stained in Fig 1. is an image of DEAD (Asp-Glu-Ala-Asp) box polypeptide 39B (DDX39B) seen in the nuclear speckles. This sample shows MCF-7 cells, a human adenocarcinoma cell line from breast cancer...Read more
This week HPA image of the week, I've decided to highlight two of my favorite things, the cell cycle and actin filaments!
The protein labeled in Fig 1. is an image of Cell division cycle 42 effector protein (Rho GTPase binding) 4 (CDC42EP4). In addition to being quite a mouthful, this protein resides in the cytoplasm and is associated with the actin filaments. In this image, CDC42EP4 is seen in U-2 OS human osteosarcoma cells.
As the name suggests, the CDC42EP4 is a protein associated with CDC42, which helps regulate the transition from G1 to S (in which DNA is replicated), and is essential for proper cell cycle progression (Yasuda S et al. 2006)...Read more
This week, the Human Protein Atlas is highlighting a new atlas recently released in HPA 14, The Mouse Brain Atlas. This image from The Mouse Brain Atlas was brought to us by Nadya Petseva, a team member on the project. I know what you're thinking, what's a mouse doing in the "human" protein atlas?!
Though we typically deal with human cells and tissues in the HPA, it is not currently possible to image full human brain at the cellular level, whereas using a mouse brain we can gain key insights into how proteins in the brain function in situ. This makes mice an attractive "model organism" as their brains actually consist of very similar regions to those found in humans...Read more
It's the end of the week, and that means another HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by Aleksandra Shaishi who found this image playing Project Discovery.
The protein labeled in Fig 1. is an image of the antibody HPA006539, which labels solute carrier family 2 (facilitated glucose transporter) (SLC2A) member 3 and member 14. This is what we call a "multi-targeting" antibody as it binds more than one protein...Read more
It's time for another Image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by Yadaryon who pointed out several nice examples of proteins localized to the rim of the nucleoli.
The nucleolus is an organelle within the nucleus of your cells. There may be one or more nucleoli in each nucleus, but they usually occur in small numbers. The primary job of the nucleoli is to assemble ribosomes which in turn make proteins within your cells...Read more
Welcome to the second edition of image of the week. This week's image was brought to us by citizen scientists in Project Discovery. After analyzing the recent data from the project, this image was among the most frequently labeled as "abnormal" by the users.
This is an image of EPB41L1 (erythrocyte membrane protein band 4.1-like 1). This staining is observed in HEP G2 human liver hepatocellular carcinoma cells. As you can clearly see here, there is significant cell-to-cell variation (CCD) in the staining, and even within a single cell at times.
As the name suggests, this is a well known membrane protein...Read more