Mabel Hokin

Last updated
Mabel R. Hokin
Mabel R. Hokin - portrait.jpg
Born(1924-02-09)February 9, 1924
Sheffield, England, UK
DiedAugust 17, 2003(2003-08-17) (aged 79)
Madison, Wisconsin, USA
NationalityBritish
Other namesMabel Ruth Neaverson, Mabel Davison, Mabel Hokin-Neaverson (post-1971 publications)
CitizenshipBritish
Alma materUniversity of Sheffield
Known forDiscovery of the phosphoinositide effect
Spouse(s)Dennis Davison (m. 1946; d. 1952), Lowell Hokin (m. 1953; d. 1971; three children),
Bernard Biales
(m. 2003)
[ citation needed ]
Scientific career
FieldsBiochemistry, Neurochemistry
InstitutionsMcGill University, University of Wisconsin
Doctoral advisor Quentin Gibson

Mabel Ruth Hokin (1924-2003) was a biochemist who spent most of her professional career conducting fundamental research in the University of Wisconsin Medical School. She is most well known for the work she did early in her career, along with then-husband Lowell Hokin, in the study of stimulated phosphoinositide turnover in secretory tissues, a key component of transmembrane signaling and many other cell regulatory processes which became known as the 'PI Effect'. [1]

Contents

Early life

Mabel Ruth Neaverson was born to working-class parents in the Heeley district of Sheffield, England in early 1924. She had two younger sisters, Mary and Dorothy. Mabel took to academic pursuits at an early age, excelling in elementary and grammar school as well as at bible scholarship. She spent 1942 to 1943 working in the Women's Land Army, where, among other things, she helped administer a refugee camp for Czech Jews. (Mabel converted to Judaism ten years later.)[ citation needed ]

She also became interested in costume design and theater, where she met her first husband, actor and playwright Dennis Davison.

Mabel worked as a technician in the Medical Research Council Unit for Research in Cell Metabolism under Hans Krebs at the University of Sheffield from 1943 to 1946, and enrolled as a student in 1946, continuing to work for Krebs. Krebs recognized Mabel's scientific mind and talent in the laboratory, and urged her to pursue doctoral work, which she began in 1949 after receiving her Bachelor of Science Honors degree in physiology. She did her graduate research under Quentin Gibson in the Physiology department. In a short time, Mabel met Krebs' graduate student Lowell Hokin, and the two began a romantic as well as professional relationship. Mabel received her Ph.D. in 1952.

Scientific career

Mabel and Lowell Hokin conducted research in fundamental biochemistry together from their doctoral research days in Sheffield, to their work at McGill University in the 1950s, up to the mid-1960s at the University of Wisconsin. From the mid-1960s, Mabel worked in her own areas of research with a particular focus on neurochemistry after she received a primary appointment in the Department of Psychiatry along with a joint appointment in the Department of Physiological Chemistry in the University of Wisconsin Medical School.

Mabel and Lowell's most significant [2] work came very early in their careers, and was first published in their seminal 1953 paper [3] in the Journal of Biological Chemistry. In it, Mabel and Lowell described experiments in which they stimulated enzyme secretion in slices of pigeon pancreas in the presence of media containing the radioisotope P32. They found that the phospholipid fraction from the stimulated slices, formerly thought to contain fairly inert structural components of cell membranes, contained up to 9 times as much P32 as it did in the non-stimulated control samples. In a 1955 paper [4] Lowell and Mabel showed that the bulk of the P32 went into phosphatidate and 'a phosphoinositide' that was later identified as phosphatidylinositol (PtdIns). They then showed that this metabolic response, which became known as the 'PI effect', occurred in a variety of stimulated tissues, such as pigeon pancreas (1958), [5] suggesting that it plays a widespread role in cell regulation. Mabel and Lowell summarized their cell membrane biochemistry research in a 1965 article [6] in Scientific American. In 1974, Mabel provided some of the first experimental evidence that launched the modern phase of work in this area [7] (she published as M. Hokin-Neaverson after her 1971 divorce from Lowell).

In the 1970s, Mabel became interested in the biochemistry of the brain, or neurochemistry, and, as a full professor, led the Laboratory for Neurochemistry Research in the Department of Psychiatry in the University of Wisconsin Medical School, which was conveniently located in the same building as the physiological chemistry, pharmacology, and anatomy departments, where her colleagues worked and from which she drew graduate students. She delved into undergraduate teaching at one point, teaching a course on drugs and the mind in the early 1970s, but her primary teaching activity was guiding graduate students and teaching graduate biochemistry courses. Unlike her earlier research, which exclusively employed animal tissues, Mabel also studied blood samples from humans, including mentally ill patients, and contributed to the understanding of the biochemical basis of mental illness, showing the first biochemical marker for one of the major psychoses. [8] Mabel's assistant, Ken Sadeghian, worked with her from the 1960s until her retirement.

Interest in the PI effect waned in the 1960s and 1970s, but experienced a resurgence in the 1980s [1] due to advances in technology and understanding of cell membrane biochemistry. Mabel and Lowell became regarded [2] as founders of an important and still growing field of biochemistry and cell biology — the many roles of inositol phospholipids in cell function — for which they were honored at a 1996 symposium at the University of Wisconsin that gathered their colleagues from around the world. Their early work was highlighted in a 20th anniversary review of the discovery of inositol-1,4,5-trisphosphate as a second messenger, [9] and their 1953 and 1958 JBC articles were celebrated as "JBC Classics" in 2005. [10]

Personal life

Most of Mabel's life was spent under a shadow cast by autoimmune illness. At the age of 16 she was diagnosed with lupus and given a dire prognosis for longevity. It turned out, however, to be a nonfatal autoimmune connective tissue disease with which Mabel struggled for the rest of her life. In the mid-1960s, treatment with steroids became established, and Mabel's steroid treatment led to degradation of her hip joints. She was an early recipient of artificial hips at Mayo Clinic in 1972.[ citation needed ]

Mabel and Lowell had hoped to move to the United States after finishing their doctoral work in Sheffield, but Mabel's earlier activities as chair of the Sheffield University Socialist Society and member, along with then-husband Dennis Davison, of the Communist Party of Great Britain, led to her being blacklisted from entry into the United States during the McCarthy Era.[ citation needed ] Instead, Mabel and Lowell obtained positions at the Montreal General Hospital Research Institute at McGill University in 1953. While conducting research at McGill they petitioned the United States government to allow Mabel entry into the U.S., but it was not until 1957 that they were able to move to their new jobs in Wisconsin. From their arrival in Montreal in 1953 to their departure in 1957, Mabel was unable to attend any research conferences in the United States.[ citation needed ]

Wisconsin was chosen for several reasons: Lowell received a junior faculty appointment in the Department of Physiological Chemistry, Mabel obtained a position in the department that allowed her to continue her research with Lowell, and Lowell's parents lived close by in Peoria, Illinois.

Mabel had three children. In 1966 the family moved to a home on Lake Mendota, where Mabel lived for the rest of her life.[ citation needed ]

Mabel and Lowell were divorced in 1971.

In 1986, Mabel and Bernard Biales, who had worked in her lab at one time, began a relationship that lasted until her death. They married in hospice on July 22, 2003.

Mabel Hokin died in Madison on August 17, 2003. [2] [11]

Related Research Articles

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In biochemistry, a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the high-energy ATP molecule donates a phosphate group to the substrate molecule. This transesterification produces a phosphorylated substrate and ADP. Conversely, it is referred to as dephosphorylation when the phosphorylated substrate donates a phosphate group and ADP gains a phosphate group. These two processes, phosphorylation and dephosphorylation, occur four times during glycolysis.

Inositol trisphosphate or inositol 1,4,5-trisphosphate abbreviated InsP3 or Ins3P or IP3 is an inositol phosphate signaling molecule. It is made by hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), a phospholipid that is located in the plasma membrane, by phospholipase C (PLC). Together with diacylglycerol (DAG), IP3 is a second messenger molecule used in signal transduction in biological cells. While DAG stays inside the membrane, IP3 is soluble and diffuses through the cell, where it binds to its receptor, which is a calcium channel located in the endoplasmic reticulum. When IP3 binds its receptor, calcium is released into the cytosol, thereby activating various calcium regulated intracellular signals.

<span class="mw-page-title-main">Hans Krebs (biochemist)</span> British biochemist (1900–1981)

Sir Hans Adolf Krebs, FRS was a German-British biologist, physician and biochemist. He was a pioneer scientist in the study of cellular respiration, a biochemical process in living cells that extracts energy from food and oxygen and makes it available to drive the processes of life. He is best known for his discoveries of two important sequences of chemical reactions that take place in the cells of nearly all organisms, including humans, other than anaerobic microorganisms, namely the citric acid cycle and the urea cycle. The former, often eponymously known as the "Krebs cycle", is the sequence of metabolic reactions that allows cells of oxygen-respiring organisms to obtain far more ATP from the food they consume than anaerobic processes such as glycolysis can supply; and its discovery earned Krebs a Nobel Prize in Physiology or Medicine in 1953. With Hans Kornberg, he also discovered the glyoxylate cycle, a slight variation of the citric acid cycle found in plants, bacteria, protists, and fungi.

<span class="mw-page-title-main">Wortmannin</span> Chemical compound

Wortmannin, a steroid metabolite of the fungi Penicillium funiculosum, Talaromyces wortmannii, is a non-specific, covalent inhibitor of phosphoinositide 3-kinases (PI3Ks). It has an in vitro inhibitory concentration (IC50) of around 5 nM, making it a more potent inhibitor than LY294002, another commonly used PI3K inhibitor. It displays a similar potency in vitro for the class I, II, and III PI3K members although it can also inhibit other PI3K-related enzymes such as mTOR, DNA-PKcs, some phosphatidylinositol 4-kinases, myosin light chain kinase (MLCK) and mitogen-activated protein kinase (MAPK) at high concentrations Wortmannin has also been reported to inhibit members of the polo-like kinase family with IC50 in the same range as for PI3K. The half-life of wortmannin in tissue culture is about 10 minutes due to the presence of the highly reactive C20 carbon that is also responsible for its ability to covalently inactivate PI3K. Wortmannin is a commonly used cell biology reagent that has been used previously in research to inhibit DNA repair, receptor-mediated endocytosis and cell proliferation.

In biochemistry, dephosphorylation is the removal of a phosphate (PO43−) group from an organic compound by hydrolysis. It is a reversible post-translational modification. Dephosphorylation and its counterpart, phosphorylation, activate and deactivate enzymes by detaching or attaching phosphoric esters and anhydrides. A notable occurrence of dephosphorylation is the conversion of ATP to ADP and inorganic phosphate.

<span class="mw-page-title-main">Phosphatidylinositol (3,4,5)-trisphosphate</span> Chemical compound

Phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3), abbreviated PIP3, is the product of the class I phosphoinositide 3-kinases' (PI 3-kinases) phosphorylation of phosphatidylinositol (4,5)-bisphosphate (PIP2). It is a phospholipid that resides on the plasma membrane.

<span class="mw-page-title-main">Phosphoinositide 3-kinase</span> Class of enzymes

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<span class="mw-page-title-main">Phospholipase C</span> Class of enzymes

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<span class="mw-page-title-main">PDK2</span> Protein-coding gene in the species Homo sapiens

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<span class="mw-page-title-main">PI4KB</span> Protein-coding gene in the species Homo sapiens

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<span class="mw-page-title-main">PIKFYVE</span> Protein-coding gene in the species Homo sapiens

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<span class="mw-page-title-main">PLCD3</span> Protein-coding gene in the species Homo sapiens

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References

  1. 1 2 JW Putney Jr (1981). "Recent hypotheses regarding the phosphatidylinositol effect". Life Sciences. 29 (12): 1183–1194. doi:10.1016/0024-3205(81)90221-6. PMID   7029181.
  2. 1 2 3 Bob Michell (2003). "Obituary: Mabel R. Hokin" (PDF). The Biochemist. 25: 62–63. doi: 10.1042/BIO02506062 .
  3. Mabel R. Hokin & Lowell E. Hokin (1953). "Enzyme secretion and the incorporation of P32 into phospholipides of pancreas slices". Journal of Biological Chemistry. 203 (2): 967–977. doi: 10.1016/S0021-9258(19)52367-5 . PMID   13084667.
  4. L.E. Hokin & M.R. Hokin (1955). "Effects of acetylcholine on the turnover of phosphoryl units in individual phospholipids of pancreas slices and brain cortex slices". Biochimica et Biophysica Acta. 18 (1): 102–110. doi:10.1016/0006-3002(55)90013-5. PMID   13260248.
  5. Lowell E. Hokin & Mabel R. Hokin (1958). "Phosphoinositides and Protein Secretion in Pancreas Slices". Journal of Biological Chemistry. 233 (4): 805–810. doi: 10.1016/S0021-9258(18)64659-9 . PMID   13587496.
  6. Lowell E. Hokin & Mabel R. Hokin (1965). "The Chemistry of Cell Membranes". Scientific American. 213 (4): 78–86. Bibcode:1965SciAm.213d..78H. doi:10.1038/scientificamerican1065-78. PMID   5825732.
  7. M Hokin-Neaverson (1974). "Acetylcholine causes a net decrease in phosphatidylinositol and a net increase in phosphatidic acid in mouse pancreas". Biochemical and Biophysical Research Communications. 58 (3): 763–768. doi:10.1016/S0006-291X(74)80483-3. PMID   4365414.
  8. Hokin-Neaverson M, Spiegel DA, Lewis WC (Nov 1974). "Deficiency of erythrocyte sodium pump activity in bipolar manic-depressive psychosis". Life Sciences. 15 (10): 1739–1748. doi:10.1016/0024-3205(74)90175-1. PMID   4620986.
  9. Robin F. Irvine (July 2003). "20 years of Ins(1,4,5)P3, and 40 years before". Nature Reviews Molecular Cell Biology. 4 (7): 586–590. doi:10.1038/nrm1152. ISSN   1471-0072. PMID   12838341. S2CID   19570134.
  10. Nicole Kresge, Robert D. Simoni and Robert L. Hill (2005). "A Role for Phosphoinositides in Signaling: the Work of Mabel R. Hokin and Lowell E. Hokin". Journal of Biological Chemistry. 280: e27.
  11. Mabel R. Hokin dies, 2003