Biology Essay Example: Standard Differentiation Hierarchy

One of the compartments of a standard differentiation hierarchy is the luminal progenitor compartment found in mammalian cells [1]. According to Dr. Rossi 15.20, Telomeres are imperative for genome integrity although their regulation is little known. Macias and Hinck note that the mammalian gland changes during puberty aided by the cell differentiation schemes [2]. Studies done show that at the pre-pubertal stage, the mammary glands are made up of a rudimentary ductal structure in the mammary pad [3]. However, this structure changes at the start of the puberty by initiating a proliferative stage consisting of side-branching of the duct and lobuloalveolar development [4]. Another compartment is the intestinal stem cell compartment which is one of the tissues with a rapid turnover as recorded by Umar [5]. Such tissues lose numerous cells on a daily basis, as aspect attributed to the crucial turnover as a result of environmental exposure and tissue function. The effects of turn over require coordination between progenitor cells and upstream stem self-renewal schemes and the production of effector cells.

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Characteristics of Intestinal Stem Cell and Luminal Progenitor Compartments

Intestinal stem cell compartment contains somatic stem cells which are known to maintain homeostasis as they organize themselves in a way which enables the maintenance of proliferative output [6]. Studies carried on the colon, and small intestine helps in identifying the injury sensitive and proliferating stem cells and also injury-resistant quiescent cells [7]. The cells' organization helps the cells to avoid DNA damage, a scenario which can result in oncogenic transformation. Also, this arrangement aids in achieving a capacity which can maintain the output to match the demands exhibited by high-turnover tissues.

Conversely, the luminal progenitor compartment contains a site associated with telomere dysfunction [8]. It should be noted that telomeres exhibit repeat sequences and proteins which eliminate the possibility of the creation of end-to-end chromosome fusions [9]. Normal tissues with continuous and high cell turnover, telomeres are contained in the primitive cells at long lengths. However, luminal cells have been associated with shorter telomeres and are independent of age.

How Their Outputs Are Controlled

The output in the intestinal stem cell compartment is controlled through assuming a unique arrangement which maintains homeostasis in tissues. It is evident that the epithelial cells are exposed continuously to xenobiotics and pathogens necessitating the need for rapid regeneration. Besides, the tissue must ensure cellular proliferation and death are controlled to achieve a steady state. Since exposure to pathogens contributes to the pathogens contributing to cell death, a rapid generation provides a substantial number of cells are present to counteract the effects of pathogens to the body.

In the luminal progenitor compartment, the output is controlled by a transcription factor referred to as STAT5A which is activated by EGF and prolactin [10]. When STAT5A is lacking, stem cells fail to produce progenitor cells in the alveoli. In cases where progenitor cells are produced, the progenitors fail to proliferate and cannot survive. Besides, in cases where the stem cells produce progenitor cells with the ability to proliferate, daughter cells are not generated.

Differences in Homeostatic and Stress Conditions

One of the differences in the homeostatic condition is that the intestinal stem cell compartment must always exhibit a homeostatic state where a balance must occur between the cells being produced and destroyed. The regenerative schemes in the intestinal stem cell compartment are due to the presence of short-lived progenitors. On the other hand, the luminal progenitor compartment exhibits homeostatic conditions at the adult stage [11]. In this case, the luminal progenitors are tasked with ensuring the cell survival is guaranteed.

When the stress conditions are considered, the intestinal cell compartment exhibits oncogenic stress which aids in the production of basal cells. Oncogenic stress involves the presence of a gene which can encode a protein with the ability to initiate cell transformation [12]. Conversely, the luminal progenitor compartment displays the presence of genotoxic stress emanating from the deleterious genotoxic events in the process of cell division [13]. The genotoxic stress is dependent on the present telomeres which are present in this compartment.

References

Kannan N, Huda N, Tu L, Droumeva R, Aubert G, Chavez E et al. The luminal progenitor compartment of the normal human mammary gland constitutes a unique site of telomere dysfunction. Stem Cell Reports. (2013): 1(1): 28-37. doi: 10.1016/j.stemcr.2013.04.003.

Macias H, Hinck L. Mammary gland development. Wiley interdisciplinary reviews. Developmental Biology. 2012; 1(4), 533-57.

Sternlicht M. Key stages in mammary gland development: the cues that regulate ductal branching morphogenesis. Breast Cancer Research: BCR. 2015; 8(1): 201.

Garner O, Bush K, Nigam K, Yamaguchi Y, Xu D, Esko J, et al. Stage-dependent regulation of mammary ductal branching by heparan sulfate and HGF-cMet signaling. Developmental Biology. 2011 July; 355(2): 394-403.

Umar S. Intestinal stem cells. Current Gastroenterology Reports. 2010; 12(5).340-8.

Biteau, B, Hochmuch C, Jasper H. Maintaining tissue homeostasis: Dynamic control of somatic stem cell activity. Cell stem Cell. 2011; 9(5): 402-11.

Kim K, Yang V, Bialkowska A. The Role of Intestinal Stem Cells in Epithelial Regeneration Following Radiation-Induced Gut Injury. Current Stem Cell Reports. 2017; 3(4): 320-332.

Giraddi R, Shehata M, Gallard M, Blasco M, Simons B, Stingl J. Stem and progenitor cell division kinetics during postnatal mouse mammary gland development. Nature Communications. 2015; 8487(2015): 1-12.

He H, Multani A, Cosme-Blanco W, Tahara H, Ma J, Pathak S, Deng Y, et al. (2006). POT1b protects telomeres from end-to-end chromosomal fusions and aberrant homologous recombination. The EMBO Journal. 2006; 25(21): 5180-90.

Yamaji D, Na R, Feuermann Y, Pechhold S, Chen W, Robinson G, Hennighausen L. Development of mammary luminal progenitor cells is controlled by the transcription factor STAT5A. Genes & development. 2009; 23(20): 2382-7.

Visvader J, Stingl J. Mammary stem cells and the differentiation hierarchy: current status and perspectives. Genes & Development. 2014; 28(11): 1143-58.

Hein S, Haricharan S, Johnston A, Toneff M, Reddy J, Dong J, et al. Luminal epithelial cells within the mammary gland can produce basal cell upon oncegonic stress. Oncogene. 2016 March; 35 (11): 1461-1467.

Privette V, Kappes F, Nassar N, Wells S. Stacking the DEK: From chromatin topology to cancer stem cells. Cell Cycle (Georgetown, Tex.). 2013; 12(1): 51-66.