what are housekeeping genes?

Question

housekeepiig genes,types and their role.

Answer 1

Some genes are specific to certain cell types. For example there are a certain subset of genes that are used to make a cell into a liver cell, there is a different subset of genes that are used to make a cell into a brain cell, yet another subset of genes that makes a cell into a heart cell. This is because the different types of cells have different functions.

However, all cells share some basic things that every cell must do, such as DNA replicaiton, transcription and translation. So all cells use a certains subset of genes to do the critical functions required by every cell, these are called housekeeping genes.

Answer 2

Some people love to keep a clean house. They don't have to be *neat freaks* to want to keep a clean house.

Then there are the Neat Freak types and I consider them to have Obsessive Compulsive Disorder.

There are some people who have a clean house, but it is cluttered, because theu do not have the closet/cupboard space to put things away and the clutter looks messy.

Then there are the people who can live with a bit of dust here and there, and let the dishes and laundry go for a few days at a time before they finally get around to doing them

Then there are the types of people who just live in total filth, with dog droppings and cat droppings and trash all over the floor, etc, etc..

Are we born with housekeeping genes? NO, I doubt it.. Cleaning is something that all of us have to Learn how to do. Some people never had a mom or dad to teach them to clean and so they just simply do Not know how to clean and they need to take some classes. (if there is such a thing as cleaning classes) lol.

Also some people are just to lazy to get up off their butt and spend the couple hours a day that it takes to get their house together..

Which type are you? lol

Answer 3

Housekeeping genes are those genes that are expressed in all cells because all cells have to do some basic functions needed for their survival, whether they are gland cells, nerve cells, etc.
This is opposed to luxury genes that are specifically activated in specialised cells.
To find out what are the housekeeping genes in man, I am giving you the reference below in the source column.

Answer 4

Housekeeping genes are often genes involved in the maintenance of a cell, hence their name. In research they are often used as a control or used to be able to compare two different assays.
Normally you say (hope ) that they are expressed eaqually in all cells and tissues (they are not entirely, so you use more than one to overcome this, and from different pathways).
I have used it in Nothern and qRT-PCR, and you normalise against the housekeeping genes to get a (semi) quantitative measure

Answer 5

Housekeeping Genes
genes that are generally always expressed and thought to be involved in routine cellular metabolism. genes that are common regardless of the organism that code for essential metabolic processes and substances.

Answer 6

these are constitutive genes which are transcribed and translated continually as their products are required by the cell to carry out specific functions.

Answer 7

house keeping genes means in the hotels, lodges, etc. they are keep clean the rooms or ..........

Answer 8

A housekeeping gene is typically a constitutive gene that is transcribed at a relatively constant level. The housekeeping gene's products are typically needed for maintenance of the cell. It is generally assumed that their expression is unaffected by experimental conditions. Examples include actin, GAPDH and ubiquitin.

HOUSEKEEPING GENES are constitutively expressed to maintain cellular function. As such, they are presumed to produce the minimally essential transcripts necessary for normal cellular physiology. With the advent of microarray technology, it has recently become possible to identify at least the "starter set" of housekeeping genes, as exemplified by the work of Velculescu et al., as well as by Warrington et al. in a paper published in this journal previously. In that paper, Warrington et al. examined the expression of 7,000 full-length genes in 11 different human tissues, both adult and fetal, to determine the suite of transcripts that were commonly expressed throughout human development and in different tissues. They identified 535 transcripts via microarray hybridization as likely candidates for housekeeping genes, or, as the authors proposed, "maintenance" genes.

Among the findings of this previous study was the fact that there are constitutively expressed genes particular to certain tissues, as well as sets of genes expressed only in the fetus or only in the adult. Cluster analysis was employed to identify groups of transcripts expressed in the seven adult tissues studied (695) and the four fetal tissues tested (767). The analytical technology was able to detect fluctuations in expression between fetal and adult samples, indicating that such genes, while permanently activated, are perhaps not required at the same level throughout development. Forty-seven transcripts commonly expressed between fetal and adult samples did not vary in expression level and might serve as useful internal controls for other expression profiling experiments.

In this online release of Physiological Genomics, Hsiao et al. (Ref. 1; see page 97 in this release) extend the findings of Warrington et al. (3) to focus on the tissue-selective gene clusters that appear characteristic of particular organs. Their data has been logged into a database (HuGE Index: Human Gene Expression Index, http://www.hugeindex.org) which is intended to serve as a benchmark compendium of expression profiles of various human tissue to enable researchers to make comparisons of normal states and disease. Hsiao et al. (1) reverse-transcribed cDNAs from RNA extracted from 19 different tissue types, then hybridized cRNAs made from the resulting transcript pool to Affymetrix GeneChip HuGeneFL oligonucleotide human genome microarrays. They identified any gene expressed in all 19 tissues as a housekeeping/maintenance gene; then, they identified tissue-selective genes using principal component analysis.

The 451 maintenance genes encode proteins that mediate cellular functions such as transcription, translation, and signaling. Of these genes, 358 were common to the previous study. As would be expected, differences in expression levels of the housekeeping genes from one tissue to another could be used to separate and cluster different tissues successfully according to tissue type (certainly, if these tissues can be visually distinguished from each other, than there must exist genes that accurately separate the tissues as well). Further statistical analysis revealed groups of tissue-selective genes predominantly expressed in a single tissue type; for example, among the muscle-selective genes were those associated with contraction, such as tropomyosin, or with glucose metabolism, such as lactate dehydrogenase. Additionally, genes were identified whose expression levels varied the most significantly between patient samples. For example, in lung, integrin-ß2 was among genes with a coefficient of variation greater than two standard deviations from the mean. The authors (1) noted that variation in integrin-ß2 is involved in a predisposition to recurrent bacterial lung infections.

This paper by Hsiao et al. (1) and the previous work by Warrington et al. (3) are important in highlighting the potential that gene expression profiling holds for characterizing normal biological states and disease states. Their findings that particular genes are highly variable among normal individuals brings up the questions of the precise definition of a housekeeping gene.



Is a housekeeping gene expressed at the same level throughout the day or life of an organ?
Certainly, genes are differentially expressed during development, but what about lower frequency cycles? For example, there are many tissues in the body that respond to glucocorticoids. Since serum cortisol levels can normally vary two- to threefold during the course of a day, expression of particular genes in those tissues may vary several-fold or greater depending on when samples are acquired. Genes responding to other hormones, such as insulin, luteinizing hormone, or follicle-stimulating hormone, may vary at a different frequency or amplitude (for instance, gene expression peaking meal to meal, or month to month). Thus all the genes present at one point of the cycle may differ from those present at a different point. How can we expand the definition of housekeeping genes to include these genes that change as a course of normal molecular physiology?

Is a housekeeping gene expressed at the same level throughout an organ?
At a rough level for particular organs, it may be the case that a few samples of liver accurately reflect the other parts of the liver. Can the same be said for muscle? Certainly, different parts of the brain and placenta may express different genes, and each sample differs in homogeneity of cell types. How can we expand the definition of housekeeping genes in this hierarchical sense; that is, if a gene is a housekeeping gene in a subcomponent of an organ, is it considered a housekeeping gene in the entire organ?

Does the list of housekeeping genes constitute the minimum set of genes that need to be expressed for a cell to survive?
Is there any cell type that expresses only this set of genes? If a cell requires expression of either gene A, B, or C for its normal functioning, would we consider any one of these genes in the set of housekeeping genes? How can we expand the definition of housekeeping genes to consider genes that potentially share functioning?

The list of normal genes in normal tissues described in this issue will become a valuable resource for many investigators. It is encouraging that the authors are making online queries against this data possible. Starting with this list of housekeeping genes, some of the next bioinformatics questions to ask of this data set could include the following two important items. First, over 270 genes on the HuGeneFL microarray have been annotated with the molecular function of DNA binding, and over 150 genes are known to code for proteins with zinc fingers. How do all of these potential transcription factors fare in the list of housekeeping genes? Are there specific transcription factors that are always present in every tissue? Second, over 4,900 genes on the HuGeneFL microarray have been linked to Online Mendelian Inheritance in Man (OMIM) disease entries through LocusLink. Are the diseases linked to housekeeping genes more likely to affect multiple organs than those diseases linked to non-housekeeping genes?

Continued delineation of the transcriptome in normal tissues like the work by Hsiao et al.will certainly allow these and many other explorations of genomic physiology..