Product details
Synonyms = MRE11 homolog, double strand break repair nuclease , ATLD , HNGS1 , MRE11A , MRE11B
Antibody type = Recombinant Rabbit monoclonal / IgG
Clone = HMV328
Positive control = Colon: A strong nuclear MRE11 staining should be seen in all cells.
Negative control = Cancer with previously documented MRE11 negativity: All cancer cells should remain MRE11 negative while a strong nuclear MRE11 staining should be seen in all non-neoplastic cells.
Cellular localization =Intracellular
Reactivity = Human
Application = Immunohistochemistry
Dilution = 1:100 – 1:200
Intended Use = Research Use Only
Relevance of Antibody
MRE11 is Critical for DNA double strand break repair.
Biology Behind
Double-strand break repair protein MRE11 (also named MRE11A) is an 80,6 kDa (predominant isoform) protein coded by the MRE11 gene on chromosome 11q21. Together with RAD50 and NBS1, MRE11 forms the MRN complex which is a key element in DNA damage response (DDR) and possesses both single-stranded DNA endonuclease and 3′ to 5′ exonuclease activities. The MRN complex is an early sensor for locating double strand DNA breaks (DSBs) and plays a direct role in both DSB repair and the recruiting of DDR proteins and activation of their downstream signaling. It regulates repair of DNA double-strand breaks in several contexts, including replication, telomere homeostasis, meiosis, apoptosis and immune system development. The MRN complex is involved in multiple different pathways of DSBs repair, including homologous recombination (HR), non-homologous end joining (NHEJ) and the (most error prone) pathway of microhomology-mediated end joining (MMEJ) repair. MRE11 is one of 6 enzymes required for MMEJ. MRE11 and the MRN complex are thought to play a key role in cancer radiosensitivity. MRE11 overexpressing cancers are generally considered to be more radioresistant and low-expressors are regarded as chemo-sensitive although this rule may not apply to all cancer types. Several MRE11 inhibitors are currently investigated in clinical trials as radiosensitizers.
Staining Pattern in Normal Tissues
Images describing the MRE11 staining pattern in normal tissues obtained by the antibody HMV328 are shown in our “Normal Tissue Gallery”.
Brain | Cerebrum | Distinct nuclear MRE11 staining of all cells. |
Cerebellum | Variable nuclear MRE11 staining of all cells. The staining is strongest in Purkinje cells while it is rather weak in the granule cell layer. | |
Endocrine Tissues | Thyroid | Strong nuclear MRE11 staining of all cells. |
Parathyroid | Strong nuclear MRE11 staining of all cells. | |
Adrenal gland | Distinct nuclear MRE11 staining of all cells. | |
Pituitary gland | Distinct nuclear MRE11 staining of all cells. | |
Respiratory system | Respiratory epithelium | Strong nuclear MRE11 staining of all cells. |
Lung | Strong nuclear MRE11 staining of all cells. | |
Gastrointestinal Tract | Salivary glands | Strong nuclear MRE11 staining of all cells. |
Esophagus | Strong nuclear MRE11 staining of all cells. Slight decrease of MRE11 staining of squamous epithelium from the basal/suprabasal to the superficial cell layers. | |
Stomach | Strong nuclear MRE11 staining of all cells. A distinct cytoplasmic MRE11 staining of parietal cells represents a (tolerable) cross-reactivity. | |
Duodenum | Strong nuclear MRE11 staining of all cells. | |
Small intestine | Strong nuclear MRE11 staining of all cells. | |
Appendix | Strong nuclear MRE11 staining of all cells. | |
Colon | Distinct nuclear MRE11 staining of all cells. Slight but significant decrease of MRE11 staining from the crypt base to the superficial epithelial cell layers. | |
Rectum | Distinct nuclear MRE11 staining of all cells. Slight but significant decrease of MRE11 staining from the crypt base to the superficial epithelial cell layers. | |
Liver | Nuclear MRE11 staining of most cells. Staining is clearly weakest in hepatocytes where it varies from negative to moderate. | |
Gallbladder | Strong nuclear MRE11 staining of all cells. | |
Pancreas | Strong nuclear MRE11 staining of all cells. | |
Genitourinary | Kidney | Strong nuclear MRE11 staining of all cells. |
Urothelium | Strong nuclear MRE11 staining of all cells. | |
Male genital | Prostate | Strong nuclear MRE11 staining of all cells. |
Seminal vesicles | Strong nuclear MRE11 staining of all cells. | |
Testis | Strong nuclear MRE11 staining of all cells. Additional cytoplasmic staining of one tubular cell type (Sertoli cells?). The staining intensity of germ cells decreases from spermatogonia to spermatids. | |
Epididymis | Strong nuclear MRE11 staining of all cells. | |
Female genital | Breast | Strong nuclear MRE11 staining of all cells. |
Uterus, myometrium | Strong nuclear MRE11 staining of all cells. | |
Uterus, ectocervix | Strong nuclear MRE11 staining of all cells. | |
Uterus endocervix | Strong nuclear MRE11 staining of all cells. | |
Uterus, endometrium | Strong nuclear MRE11 staining of all cells. | |
Fallopian Tube | Strong nuclear MRE11 staining of all cells. | |
Ovary | Strong nuclear MRE11 staining of all cells. | |
Placenta early | Strong nuclear MRE11 staining of all cells. Some cytoplasmic staining of trophoblast cells does also occur. | |
Placenta mature | Nuclear MRE11 staining of all cells. However, the nuclear staining is somewhat weaker in syncytiotrophoblast cells than in all other cell types. | |
Amnion | Strong nuclear MRE11 staining of all cells. | |
Chorion | Strong nuclear MRE11 staining of all cells. | |
Skin | Epidermis | Strong nuclear MRE11 staining of all cells. |
Sebaceous glands | Strong nuclear MRE11 staining of all cells. | |
Muscle/connective tissue | Heart muscle | Strong nuclear MRE11 staining of all cells. |
Skeletal muscle | Strong nuclear MRE11 staining of all cells. | |
Smooth muscle | Strong nuclear MRE11 staining of all cells. A weak to moderate cytoplasmic MRE11 staining occurs in some samples. | |
Vessel walls | Strong nuclear MRE11 staining of all cells. | |
Fat | Strong nuclear MRE11 staining of all cells. | |
Stroma | Strong nuclear MRE11 staining of all cells. | |
Endothelium | Strong nuclear MRE11 staining of all cells. | |
Bone marrow/ lymphoid tissue | Bone marrow | Strong nuclear MRE11 staining of all cells. |
Lymph node | Strong nuclear MRE11 staining of all cells. | |
Spleen | Strong nuclear MRE11 staining of all cells. | |
Thymus | Strong nuclear MRE11 staining of all cells. A few dispersed cells stand out because of a particularly strong nuclear MRE11 staining. | |
Tonsil | Strong nuclear MRE11 staining of all cells. | |
Remarks | The vast majority of cell types show a strong MRE11 staining in the nuclei. |
These findings are largely consistent with the RNA data described in the Human Protein Atlas (Tissue expression MRE11).
Positive control = Colon: A strong nuclear MRE11 staining should be seen in all cells.
Negative control = Cancer with previously documented MRE11 negativity: All cancer cells should remain MRE11 negative while a strong nuclear MRE11 staining should be seen in all non-neoplastic cells.
Staining Pattern in Relevant Tumor Types
A variable level of MRE11 staining is seen in the cells of most cancers. Only a few cancers completely lack MRE11 staining.
The TCGA findings on MRE11 RNA expression in different tumor categories have been summarized in the Human Protein Atlas.
Compatibility of Antibodies
No data available at the moment
Protocol Recommendations
IHC users have different preferences on how the stains should look like. Some prefer high staining intensity of the target stain and even accept some background. Others favor absolute specificity and lighter target stains. Factors that invariably lead to more intense staining include higher concentration of the antibody and visualization tools, longer incubation time, higher temperature during incubation, higher temperature and longer duration of the heat induced epitope retrieval (slide pretreatment). The impact of the pH during slide pretreatment has variable effects and depends on the antibody and the target protein.
All images and data shown here and in our image galleries are obtained by the manual protocol described below. Other protocols resulting in equivalent staining are described as well.
Manual protocol
Freshly cut sections should be used (less than 10 days between cutting and staining). Heat-induced antigen retrieval for 5 minutes in an autoclave at 121°C in pH 7,8 Target Retrieval Solution buffer. Apply HMV328 at a dilution of 1:200 at 37°C for 60 minutes. Visualization of bound antibody by the EnVision Kit (Dako, Agilent) according to the manufacturer’s directions.
Potential Research Applications
- The interplay between MRE11 and its complex network needs to be further evaluated.
- The predictive role of both decreased and elevated MRE11 expression on cancer radiosensitivity must be further investigated.
- The clinical potential of the diverse MRE11 inhibitors awaits clarification.
Evidence for Antibody Specificity in IHC
There are two ways how the specificity of antibodies can be documented for immunohistochemistry on formalin fixed tissues. These are: 1. Comparison with a second independent method for target expression measurement across a large number of different tissue types (orthogonal strategy), and 2. Comparison with one or several independent antibodies for the same target and showing that all positive staining results are also seen with other antibodies for the same target (independent antibody strategy).
Orthogonal validation: For the antibody HMV328, specificity of its nuclear staining is consistent by the good concordance of the immunostaining data with data from three independent RNA screening studies, including the Human Protein Atlas (HPA) RNA-seq tissue dataset, the FANTOM5 project, and the Genotype-Tissue Expression (GTEx) project, which are all summarized in the Human Protein Atlas (Tissue expression MRE11). In agreement with HMV328 immunostaining data, MRE11 expression predominated in the bone marrow and lymphoid tissues. However, orthogonal validation is not optimal for assessing ubiquitously expressed proteins.
Comparison of antibodies: True expression of MRE11 in all cell types with nuclear MRE11 positivity by HMV328 is corroborated by an identical nuclear staining obtained by a commercially available independent second antibody (termed “validation antibody”). Most of all, both antibodies showed several characteristic nuclear staining patterns which included a decreased staining intensity in maturing cells of the spermiogenesis, superficial cell layers of non-keratinizing squamous epithelium (esophagus), syncytiotrophoblast cells of the mature placenta, and in hepatocytes of the liver as well as a particularly strong staining in few dispersed cells in the thymus and in Purkinje cells of the cerebellum.
A cytoplasmic staining of only HMV328 in parietal cells of the stomach, and of the validation antibody in the liver, testicular Leydig cells, and a subset of adrenocortical cells were considered cross-reactivities of the individual antibodies. An occasional cytoplasmic staining of smooth muscle, trophoblast cells of the first trimenon placenta, and a tubular cell type of the testis by both antibodies was also considered as “probably non-specific” because of the propensity of both antibodies to display cytoplasmic cross-reactivity. Considering that the relevant staining of MRE11 must be nuclear, all these certain and potential cross-reactive cytoplasmic stainings are considered “tolerable”.